0000950170-23-004668 | 10-K | XBRL Viewer

Balance Sheet Components

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):


	December 31,
	2022		2021
Cash	$	135,819	$	111,422
Commercial paper		—		1,000
Money market funds		19,881		58,801
Total cash and cash equivalents	$	155,700	$	171,223

At December 31, 2022 and 2021, a total of $92.5 million and $91.2 million, respectively, of the Company’s cash and cash equivalents were held outside of the U.S. in its foreign subsidiaries to be used primarily for its China operations.

Investments

The Company’s investments consist primarily of available-for-sale debt investments. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s investments by major investments type are summarized in the tables below (in thousands):


	December 31, 2022
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Corporate bonds	$	83,080	$	—	$	(1,072	)	$	82,008
Commercial paper		57,381		—		—			57,381
U.S. government bonds		112,547		5		(1,207	)		111,345
Agency bonds		11,690		—		(222	)		11,468
Asset-backed securities		2,484		—		(10	)		2,474
Foreign government bonds		5,007		—		(27	)		4,980
Convertible promissory note		1,000		—		—			1,000
Total investments	$	273,189	$	5	$	(2,538	)	$	270,656

	December 31, 2021
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Corporate bonds	$	183,136	$	2	$	(492	)	$	182,646
Commercial paper		68,079		—		—			68,079
U.S. government bonds		91,840		—		(318	)		91,522
Agency bonds		23,339		—		(64	)		23,275
Asset-backed securities		27,105		—		(18	)		27,087
Foreign government bonds		9,165		—		(11	)		9,154
Total investments	$	402,664	$	2	$	(903	)	$	401,763

The following table summarizes, for all available for sale securities in an unrealized loss position, the fair value and gross unrealized loss by length of time the security has been in a continual unrealized loss position (in thousands):


	December 31, 2022
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses
Corporate bonds	$	6,738	$	(147	)	$	75,270	$	(925	)	$	82,008	$	(1,072	)
U.S. government bonds		22,326		(13	)		67,909		(1,194	)		90,235		(1,207	)
Agency bonds		—		—			11,468		(222	)		11,468		(222	)
Asset-backed securities		2,474		(10	)		—		—			2,474		(10	)
Foreign government bonds		—		—			4,980		(27	)		4,980		(27	)
Total	$	31,538	$	(170	)	$	159,627	$	(2,368	)	$	191,165	$	(2,538	)

	December 31, 2021
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses
Corporate bonds	$	177,124	$	(492	)	$	—	$	—		$	177,124	$	(492	)
U.S. government bonds		91,522		(318	)		—		—			91,522		(318	)
Agency bonds		23,274		(64	)		—		—			23,274		(64	)
Asset-backed securities		27,087		(18	)		—		—			27,087		(18	)
Foreign government bonds		9,155		(11	)		—		—			9,155		(11	)
Total	$	328,162	$	(903	)	$	—	$	—		$	328,162	$	(903	)

The contractual maturities of the available-for-sale investments were as follows (in thousands):


	December 31, 2022
	Amortized Cost		Estimated Fair Value
Within one year - Bond and mutual funds	$	268,709	$	266,308
After one year through three years		4,480		4,348
Total investments	$	273,189	$	270,656

The Company periodically reviews its available-for-sale investments for other-than-temporary impairment. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period and its intent to sell. For debt securities, the Company also considers whether (i) it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. During the three years ended December 31, 2022, the Company did not recognize any other-than-temporary impairment loss.

Inventories

Inventories consisted of the following (in thousands):


	December 31,
	2022		2021
Raw materials	$	1,241	$	1,363
Work-in-progress		36,003		21,499
Finished goods		3,192		8,153
Total inventories	$	40,436	$	31,015

The provision to write-down excess and obsolete inventory were immaterial as of December 31, 2022 and December 31, 2021.

Prepaid expenses and other current assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	December 31,
	2022			2021
Contract assets	$	17,488		$	66,909
Deferred revenues from associated contracts		(17,488	)		(58,909	)
Net unbilled contract assets		—			8,000
Prepaid assets		9,730			7,383
Other current assets		4,353			5,070
Total prepaid expenses and other current assets	$	14,083		$	20,453

The unbilled contract assets of $17.5 million as of December 31, 2022 was related to unbilled co-development revenue under the AstraZeneca China Amendment. The unbilled contract assets as of December 31, 2021 included $49.8 million related to transfer price true up for bulk drug product under the Astellas Europe Agreement, $9.1 million related to unbilled co-development revenue under the AstraZeneca China Amendment, and the $8.0 million unbilled upfront license payment under the Eluminex Agreement. See the Eluminex Agreements section in Note 3, Collaboration Agreements, License Agreement and Revenues, for details.

Property and Equipment

Property and equipment consisted of the following (in thousands):


	December 31,
	2022			2021
Leasehold improvements	$	102,580		$	103,352
Laboratory equipment		21,175			19,300
Machinery		9,642			8,339
Computer equipment		9,486			9,670
Furniture and fixtures		6,200			6,201
Construction in progress		204			2,423
Total property and equipment	$	149,287		$	149,285
Less: accumulated depreciation		(128,682	)		(121,008	)
Property and equipment, net	$	20,605		$	28,277

Depreciation expense for the years ended December 31, 2022, 2021 and 2020 was $10.0 million, $10.2 million and $11.7 million, respectively.

Accrued and Other Current Liabilities

Accrued and other current liabilities consisted of the following (in thousands):


	December 31,
	2022		2021
Preclinical and clinical trial accruals	$	57,780	$	56,283
API and bulk drug product price true-up		75,055		—
Acquired in-process research and development asset		—		35,000
Payroll and related accruals		22,562		20,909
Accrued co-promotion expenses - current		36,677		25,746
Contract liabilities to pharmaceutical distributors		390		3,176
Roxadustat profit share to AstraZeneca		7,280		7,895
Property taxes and other taxes		7,691		12,610
Professional services		5,480		6,074
Other		6,858		4,906
Total accrued and other current liabilities	$	219,773	$	172,599

The accrued liabilities of $75.1 million for API and bulk drug product price true-up as of December 31, 2022 resulted from changes in estimated variable consideration of $6.5 million associated with the API shipments fulfilled under the terms of the Astellas Japan Amendment, $57.4 million associated with the bulk drug product transferred under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement, and $11.2 million associated with the bulk drug product shipments to AstraZeneca under the terms of the AstraZeneca Master Supply Agreement. See the Drug Product Revenue section in Note 3, Collaboration Agreements, License Agreement and Revenues, for details.

The acquired IPR&D asset of $35.0 million as of December 31, 2021 was related to the upfront payment to HiFiBiO under the HiFiBiO Agreement. See Note 2, Summary of Significant Accounting Policies - License Acquisition Agreement, for details.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2022

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

Schedule II: Valuation and Qualifying Accounts

(in thousands)


					Charged
			Charged		to Other
	Balance at		(Credited)		Accounts -
	Beginning of		to Statement		Liabilities			Deductions,			Balance at
	Year		of Operation		and Equity			Net			End of Year
Valuation allowances for deferred tax assets
Year ended December 31, 2022	$	409,810	$	68,159	$	—		$	—		$	477,969
Year ended December 31, 2021	$	337,824	$	71,986	$	—		$	—		$	409,810
Year ended December 31, 2020	$	213,847	$	123,977	$	—		$	—		$	337,824

Allowances for rebates, discounts and adjustments
Year ended December 31, 2022	$	14,443	$	39,082	$	1,050		$	(53,226	)	$	1,349
Year ended December 31, 2021	$	548	$	44,258	$	(734	)	$	(29,629	)	$	14,443
Year ended December 31, 2020	$	1,102	$	16,497	$	(14,867	)	$	(2,184	)	$	548

Leases

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Leases

The Company’s long-term property lease with Alexandria for its corporate headquarters in San Francisco, California, had an initial term of 15 years, scheduled to expire in 2023. The original lease was accounted for as a finance lease.

On June 1, 2021, the Company entered into an amendment with Alexandria to extend the lease to 2028 (“Lease Amendment”). Under the terms of the Lease Amendment, the Company has two optional rights to each extend the lease for an additional five years. The lease contract provides for a fixed annual rent, with scheduled increases of two percent that occur on each anniversary of the rent commencement date through 2023, and with scheduled increases of three percent that occur on each anniversary of the rent commencement date through 2028. This lease requires the Company to pay all costs of ownership, operation, and maintenance of the premises, including without limitation all operating costs, insurance costs, and taxes.

The Company determined that the Lease Amendment was a lease modification, effective June 1, 2021, and thus reassessed the lease classification, remeasured the related lease liability using an updated discount rate, and adjusted the related right-of-use asset under the lease modification guidance under the ASC 842. Accordingly, on June 1, 2021, the Company determined that the modified lease be accounted for as an operating lease, and therefore derecognized the previous finance lease right-of-use asset of $24.6 million and the related finance lease liability of $32.6 million, and recognized an operating lease right-of-use asset of $93.2 million and the related operating lease liability of $101.2 million. Starting June 1, 2021, the cash payment related to this lease was classified as an operating activity.

During the first quarter of 2021, after FibroGen Beijing’s previous long-term lease agreement expired, the Company entered into a new lease agreement with the landlord for the same pilot plant located in Beijing Yizhuang Biomedical Park of BDA. The new lease term is five year, scheduled to expire in 2026, and is treated as an operating lease. Accordingly, the Company recorded $3.4 million in the operating right-of-use assets and total operating lease liabilities, respectively. The lease contract provides for fixed quarterly rent payments, and requires the Company to pay operating and maintenance costs.

The Company currently has several additional real estate leases for office spaces in Shanghai and Beijing, China, which are treated as operating leases. These leases have lease terms ranging from one to five years, expiring in 2025. These lease contracts provide for fixed quarterly rent payments, and require the Company to pay operating and maintenance costs, and a fixed amount for property management fees.

In addition, the Company has several immaterial lease arrangements in China and U.S. for office equipment, scientific devices and automobile leases, with contracted lease terms ranging from one to five years, treated as finance leases or operating leases.

The Company’s lease assets and related lease liabilities were as follows (in thousands):


		December 31,
	Balance Sheet Line Item	2022			2021
Assets
Finance:
Right-of-use assets cost		$	2,367		$	2,165
Accumulated amortization			(1,932	)		(1,404	)
Finance lease right-of-use assets, net	Other assets		435			761
Operating:
Right-of-use assets cost			101,990			100,912
Accumulated amortization			(22,097	)		(9,800	)
Operating lease right-of-use assets, net	Operating lease right-of-use assets		79,893			91,112
Total lease assets		$	80,328		$	91,873

Liabilities
Current:
Finance lease liabilities	Accrued and other current liabilities	$	36		$	11
Operating lease liabilities	Operating lease liabilities, current		10,292			10,944
Non-current:
Finance lease liabilities	Other long-term liabilities		137			3
Operating lease liabilities	Operating lease liabilities, non-current		79,593			88,776
Total lease liabilities		$	90,058		$	99,734

The components of lease expense were as follows (in thousands):


		Years Ended December 31,
	Statement of Operations Line Item	2022			2021			2020
Finance lease cost:
Amortization of right-of-use assets	Cost of goods sold; Research and development; Selling, general and administrative expenses	$	587		$	4,639		$	10,369
Interest on lease liabilities	Interest expense		—			628			1,932
Operating lease cost	Cost of goods sold; Research and development; Selling, general and administrative expenses		17,125			10,722			1,151
Sublease income	Selling, general and administrative expenses		(3,373	)		(1,271	)		(1,201	)
Total lease cost		$	14,339		$	14,718		$	12,251

Supplemental cash flow information related to leases were as follows (in thousands):


	Years Ended December 31,
	2022		2021			2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	15,497	$	10,022		$	951
Operating cash flows from finance leases		2		629			1,896
Financing cash flows from finance leases		135		5,489			12,620
Non-cash: Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases		261		450			662
Operating leases		1,704		3,585			1,072
Non-cash: Increase (decrease) resulting from lease modification:
Finance lease right-of-use assets		—		(24,654	)		—
Operating lease right-of-use assets		—		93,222			—
Finance lease liabilities, current		—		(12,587	)		—
Operating lease liabilities, current		—		9,221			—
Finance lease liabilities, non-current		—		(20,009	)		—
Operating lease liabilities, non-current	$	—	$	91,943		$	—

Lease term and discount rate were as follows:


	December 31,
	2022			2021
Weighted-average remaining lease term (years):
Finance leases		4.9			1.1
Operating leases		5.8			6.8
Weighted-average discount rate:
Finance leases		6.20	%		4.64	%
Operating leases		4.75	%		4.75	%

Maturities of lease liabilities as of December 31, 2022 are as follows (in thousands):


Year Ending December 31,	Finance Leases			Operating Leases
2023	$	44		$	13,915
2024		41			17,302
2025		40			18,448
2026		39			18,000
2027		36			18,476
Beyond 2027		—			17,400
Total future lease payments		200			103,541
Less: Interest		(27	)		(13,656	)
Present value of lease liabilities	$	173		$	89,885

Equity and Stock-based Compensation - Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Employee Stock Purchase Plans (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average estimated fair value	$ 14.72	$ 35.58	$ 31.55
Employee stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 8 months 12 days	5 years 8 months 12 days	5 years 8 months 12 days
Expected volatility	66.80%	61.90%	67.10%
Risk-free interest rate	2.20%	0.80%	0.80%
Expected dividend yield	0.00%	0.00%	0.00%
Weighted average estimated fair value	$ 7.88	$ 20.21	$ 18.36
Employee stock purchase plans [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	58.50%	47.10%	47.50%
Expected volatility, maximum	97.60%	104.40%	77.10%
Risk-free interest rate, minimum	0.10%	0.00%	0.10%
Risk-free interest rate, maximum	4.50%	2.20%	2.90%
Expected dividend yield	0.00%	0.00%	0.00%
Weighted average estimated fair value	$ 8.60	$ 12.40	$ 17.53
Employee stock purchase plans [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months
Employee stock purchase plans [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	2 years	2 years	2 years

Net Loss Per Share - Schedule of Weighted Impacts of Outstanding Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	11,962	10,416	7,564
Employee stock options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	9,520	8,461	6,694
RSUs, PRSUs and TSR awards [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	2,137	1,538	564
ESPP [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	305	417	306

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation

The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (“U.S. GAAP”). The consolidated financial statements include the accounts of the Company, its wholly owned subsidiaries and its majority-owned subsidiaries, FibroGen Europe and FibroGen China Anemia Holdings, Ltd. (“FibroGen Cayman”). All inter-company transactions and balances have been eliminated in consolidation. For any variable interest entity (“VIE”) for which FibroGen is not the primary beneficiary, the Company uses the equity method of accounting.

The Company operates in one reportable segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs.

Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no impact on previously reported financial position, results of operations, or cash flows.

Foreign Currency Translation

The reporting currency of the Company and its subsidiaries is the U.S. dollar.

The functional currency of FibroGen Europe is the Euro. The functional currency of FibroGen (China) Medical Technology Development Co., Ltd. (“FibroGen Beijing”) is CNY. As such, monetary assets and liabilities of FibroGen Europe and FibroGen Beijing in currencies other than their functional currencies are remeasured using exchange rates in effect at the end of the period. The assets and liabilities of FibroGen Europe and FibroGen Beijing are translated to U.S. dollars at exchange rates in effect at the balance sheet date. All income statement accounts are translated at monthly average exchange rates. Resulting foreign currency translation adjustments are recorded directly in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity (deficit).

The functional currency of FibroGen, Inc. and all other subsidiaries is the U.S. dollar. Accordingly, monetary assets and liabilities in the non-functional currency of these subsidiaries are remeasured using exchange rates in effect at the end of the period. Revenues and costs in local currency are remeasured using average exchange rates for the period, except for costs related to those balance sheet items that are remeasured using historical exchange rates. The resulting remeasurement gains and losses are included within interest income and other, net in the consolidated statements of operations as incurred and have not been material for all periods presented.

Use of Estimates

The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions include valuation and recognition of revenue, specifically, estimates in variable consideration for drug product sales, and estimates in transaction price per unit for the China performance obligation (as defined and discussed under Revenue Recognition below). On an ongoing basis, management reviews these estimates and assumptions. Changes in facts and circumstances may alter such estimates and actual results could differ from those estimates.

Concentration of Credit Risk

The Company is subject to risks associated with concentration of credit for cash and cash equivalents. Outside of short-term operating needs, the majority of cash on hand is invested in U.S. treasuries, corporate bonds, commercial paper and money market funds. Any remaining cash is deposited with major financial institutions primarily in the U.S., China and the Cayman Islands. At times, such deposits may be in excess of insured limits. The Company has not experienced any loss on its deposits of cash and cash equivalents. Included in current assets are significant balances of accounts receivable as follows:


	December 31,
	2022			2021
Falikang — Related party		65	%		—	%
Astellas — Related party		9	%		63	%
AstraZeneca		16	%		34	%

As of December 31, 2022, the aggregate accounts receivable related to roxadustat sales in China from distributors represented 10% of the consolidated accounts receivable, with no material balance from any individual distributor. As of December 31, 2021, the accounts receivable related to roxadustat sales in China from Beijing Falikang Pharmaceutical Co., Ltd. (“Falikang”) and direct sales to distributors were not material.

Other Risks and Uncertainties

The Company’s future results of operations involve a number of risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, the results of clinical trials and the achievement of milestones, research developments, actions by regulatory authorities, market acceptance of the Company’s product candidates, competition from other products and larger companies, the liquidity and capital resources of the Company, intellectual property protection for the Company's proprietary technology, strategic relationships, and dependence on key individuals, suppliers, clinical organization, and other third parties.

Cash, Cash Equivalents and Restricted Time Deposits

The Company considers all highly liquid investments with maturities of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents also include money market accounts and various deposit accounts. Restricted time deposits include an irrevocable standby letter of credit as security deposit for a long-term property lease with the Company’s landlord. Restricted time deposits were $2.1 million at each of December 31, 2022 and 2021. As of December 31, 2022 and 2021, a total of $92.5 million and $91.2 million, respectively, of the Company’s cash and cash equivalents was held outside of the U.S. in the Company’s foreign subsidiaries to be used primarily for the Company’s China operations.

Investments

As of December 31, 2022, the Company’s investments consist primarily of diversified bonds, commercial paper, and money market funds. Those investments with original maturities of greater than three months and remaining maturities of less than 12 months (365 days) are considered short-term investments. Those investments with maturities greater than 12 months (365 days) from the balance sheet date are considered long-term investments. When such investments are held, the Company’s investments classified as available-for-sale are recorded at fair value based upon quoted market prices at period end. Unrealized gains and losses for available-for-sale debt investments that are deemed temporary in nature are recorded in accumulated other comprehensive income (loss) as a separate component of stockholder’ equity. Marketable equity securities are equity securities with readily determinable fair value, and are measured and recorded at fair value. Realized and unrealized gains or losses resulting from changes in value and sale of the Company’s marketable equity investments are recorded in other income (expenses) in the consolidated statement of operations.

A decline in the fair value of any security below cost that is deemed other than temporary results in a charge to earnings and the corresponding establishment of a new cost basis for the security. Premiums and discounts are amortized (accreted) over the life of the related security as an adjustment to its yield. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of investments sold.

Trade accounts receivable

The allowance for credit losses is based on the Company’s assessment of the collectability of customer accounts. The Company makes estimates of expected credit losses for the allowance for doubtful accounts by considering factors such as historical experience, credit quality, the age of the accounts receivable balances, current economic and regulatory conditions that may affect a customer’s ability to pay, and estimates of expected future losses. The Company’s bad debt expense for the years ended December 31, 2022, 2021 and 2020 and the allowance for doubtful accounts as of December 31, 2022 and 2021 were immaterial.

Credit losses – Available-for-sale debt securities

The Company periodically assesses its available-for-sale investments for other-than-temporary impairment. For debt securities in an unrealized loss position, the Company first considers its intent to sell, or whether it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis. If either of these criteria are met, the amortized cost basis of such debt securities is written down to fair value through interest and other, net.

For debt securities in an unrealized loss position that do not meet the aforementioned criteria, the Company assesses whether the decline in the fair value of such debt securities has resulted from credit losses or other factors. The Company considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and any adverse conditions specifically related to the securities, among other factors. If this assessment indicates that a credit loss may exist, the Company then compares the present value of cash flows expected to be collected from such securities to their amortized cost basis. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded through interest and other, net, limited by the amount that the fair value is less than the amortized cost basis. Any additional impairment not recorded through an allowance for credit losses is recognized in other comprehensive income.

Changes in the allowance for credit losses are recorded as provision for, or reversal of, credit loss expense. Losses are charged against the allowance when the Company believes that an available-for-sale security is confirmed uncollectable or when either of the criteria regarding intent or requirement to sell is met.

Inventories

Inventories are stated at the lower of cost or net realizable value, on a first-in, first-out, or FIFO, basis. The cost of the Company’s inventories in China is determined using full absorption and standard costing method. The Company reviews the standard cost of raw materials, work-in-process and finished goods annually and more often as appropriate to ensure that its inventories approximate current actual cost. The cost of the Company’s inventories in the U.S. uses actual costs to determine its cost basis. The cost of inventories includes direct material cost, direct labor and manufacturing overhead.

When the technical feasibility of the Company’s future commercialization is considered probable and the future economic benefit is expected to be realized, based on management’s judgment, the Company capitalizes pre-launch inventory costs prior to regulatory approval. A number of factors are considered, including the status in the validation process in significant jurisdictions, regulatory application and approval process, and terms and condition for future sale of such inventory or future alternative use. The pre-launch inventory cost includes purchase cost of raw materials, cost paid to contract manufacturers for inventory manufacturing, freight and custom charges, and certain direct internal labor and overhead expenses.

The Company periodically reviews its inventories to identify obsolete, slow-moving, excess or otherwise unsaleable items. If obsolete, excess or unsaleable items are observed and there are no alternate uses for the inventory, an inventory valuation adjustment is recorded through a charge to cost of goods sold on the Company’s consolidated statements of operations. Inventory valuation adjustments require judgment including consideration of many factors, such as estimates of future product demand and product expiration period, among others.

Property and Equipment

Property and equipment are recorded at cost and depreciated over their estimated useful lives using the straight-line method. Computer equipment, laboratory equipment, machinery and furniture and fixtures are depreciated over three to five years. Leasehold improvements are recorded at cost and amortized over the term of the lease or their useful life, whichever is shorter.

Equity method investment - Variable Interest Entity

Under the Accounting Standards Codification (“ASC”) 810, Consolidation (“ASC 810”), when the Company obtains an economic interest in an entity, it evaluates the entity to determine if it should be deemed a VIE, and, if so, whether the Company is the primary beneficiary and is therefore required to consolidate the VIE, based on significant judgment whether the Company (i) has the power to direct the activities that most significantly impact the economic performance of the VIE and (ii) has the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE.

On an ongoing basis, the Company re-evaluates the VIE assessment based on potential changes in facts and circumstances, including but not limited to, the shareholder loans to the entity and the execution of any future significant agreements between the entity and its shareholders and/or other third parties.

Leases

The Company determines if an arrangement is or contains a lease at inception date when it is given control of the underlying assets. The Company elected the practical expedient not to apply the lease recognition and measurement requirements to short-term leases, which is any lease with a term of 12 months or less as of the commencement date that does not include an option to purchase the underlying asset that the lessee is reasonably certain to exercise.

Lease right-of-use (“ROU”) assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As its leases do not typically provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The Company reassesses the incremental borrowing rate periodically for application to any new leases or lease modifications, which approximates the rate at which the Company would borrow, on a secured basis, in the country where the lease was executed. For any lease modification, the Company reassesses the lease classification, remeasures the related lease liability using an updated discount rate, and adjusts the related ROU asset under the lease modification guidance under the ASC 842.

Lease ROU assets include any lease payments made and initial direct costs incurred. The Company has lease agreements with lease and non-lease components. The Company generally accounts for each lease component separately from the non-lease components, and excludes all non-lease components from the calculation of minimum lease payments in measuring the ROU asset and lease liability.

The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease terms.

Regarding leases denominated in a foreign currency, the related ROU assets and the corresponding ROU asset amortization costs are remeasured using the exchange rate in effect at the date of initial recognition; the related lease liabilities are remeasured using the exchange rate in effect at the end of the reporting period; the lease costs and interest expenses related to lease liability accretion are remeasured using average exchange rates for the reporting period.

Finance leases are included in finance lease ROU assets, finance lease liabilities, current and non-current on the Company’s consolidated balance sheets. Operating leases are included in operating lease ROU assets, operating lease liabilities, current and non-current on the Company’s consolidated balance sheets.

Impairment of Long-Lived Assets

The Company continually evaluates whether events or circumstances have occurred that indicate that the estimated remaining useful life of its long-lived assets may warrant revision or that the carrying value of these assets may be impaired. If the Company determines that an impairment trigger has been met, the Company evaluates the realizability of its long-lived assets (asset group) based on a comparison of projected undiscounted cash flows from use and eventual disposition with the carrying value of the related asset. Any write-downs (which are measured based on the difference between the fair value and the carrying value of the asset) are treated as permanent reductions in the carrying amount of the assets (asset group). Based on this evaluation, the Company believes that, as of each of the balance sheet dates presented, none of the Company’s long-lived assets were impaired. The Company had no impairment of long-lived assets for the years ended December 31, 2022 and 2021. The Company’s impairment of long-lived assets for the year ended December 31, 2020 was immaterial.

Liability Related to Sale of Future Revenues

The Company accounts for the sale of future revenue as a debt, because the risks and rewards to the investor are limited by the terms of the transaction as discussed further in Note 8, Liability Related to Sale of Future Revenues. The difference between the carrying amount of the initial liability and the gross proceeds received is accounted for as a discount. The Company recognizes interest expense based on an estimated effective annual interest rate, which is affected by the amount and timing of revenues recognized and changes in the timing of forecasted revenues. Quarterly, the Company reassesses the expected revenues and the timing of such revenues, recalculates the amortization and effective interest rate and adjusts the accounting prospectively as needed.

Revenue Recognition

Revenues under collaboration agreements

The Company’s collaboration agreements include multiple performance obligations comprised of promised services, or bundles of services, that are distinct. Services that are not distinct are combined with other services in the agreement until they form a distinct bundle of services. The Company’s process for identifying performance obligations and an enumeration of each obligation for each agreement is outlined in Note 3, Collaboration Agreements, License Agreement and Revenues. Determining the performance obligations within a collaboration agreement often involves significant judgment and is specific to the facts and circumstances contained in each agreement.

The Company has identified the following material promises under its collaboration agreements: (1) license of FibroGen technology, (2) the performance of co-development services, including manufacturing of clinical supplies and other services during the development period, and (3) manufacture of commercial supply. The evaluation as to whether these promises are distinct, and therefore represent separate performance obligations, is described in more detail in Note 3, Collaboration Agreements, License Agreement and Revenues.

For revenue recognition purposes, the Company determines that the terms of its collaboration agreements begin on the effective date and end upon the completion of all performance obligations contained in the agreements. In each agreement, the contract term is defined as the period in which parties to the contract have present and enforceable rights and obligations. The Company believes that the existence of what it considers to be substantive termination penalties on the part of the counterparty create sufficient incentive for the counterparty to avoid exercising its right to terminate the agreement.

The transaction price for each collaboration agreement is determined based on the amount of consideration the Company expects to be entitled for satisfying all performance obligations within the agreement. The Company’s collaboration agreements include payments to the Company of one or more of the following: non-refundable upfront license fees; co-development billings; development, regulatory, and commercial milestone payments; payments from sales of active pharmaceutical ingredient (“API”); payments from sales of bulk drug product and royalties on net sales of licensed products.

Upfront license fees are non-contingent and non-refundable in nature and are included in the transaction price at the point when the license fees become due to the Company. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

Co-development billings resulting from the Company’s research and development efforts, which are reimbursable under its collaboration agreements, are considered variable consideration. Determining the reimbursable amount of research and development efforts requires detailed analysis of the terms of the collaboration agreements and the nature of the research and development efforts incurred. Prior to CKD approval in the third quarter of 2021, determining the amount of variable consideration from co-development billings required the Company to make estimates of future research and development efforts, which involved significant judgment. Co-development billings are allocated entirely to the co-development services performance obligation when amounts are related specifically to research and development efforts necessary to satisfy the performance obligation, and such an allocation is consistent with the allocation objective.

Milestone payments are also considered variable consideration, which requires the Company to make estimates of when achievement of a particular milestone becomes probable. Similar to other forms of variable consideration, milestone payments are included in the transaction price when it becomes probable that such inclusion would not result in a significant revenue reversal. Milestones are therefore included in the transaction price when achievement of the milestone becomes probable.

For arrangements that include sales-based royalties and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, royalty revenue resulting from its collaboration arrangements was immaterial.

The transaction price is allocated to performance obligations based on their relative standalone selling price (“SSP”), with the exception of co-development billings allocated entirely to co-development services performance obligations. The SSP is determined based on observable prices at which the Company separately sells the products and services. If an SSP is not directly observable, then the Company will estimate the SSP considering marketing conditions, entity-specific factors, and information about the customer or class of customer that is reasonably available. The process for determining SSP involves significant judgment and includes consideration of multiple factors, including assumptions related to the market opportunity and the time needed to commercialize a product candidate pursuant to the relevant license, estimated direct expenses and other costs, which include the rates normally charged by contract research and contract manufacturing organizations for development and manufacturing obligations, and rates that would be charged by qualified outsiders for committee services.

Significant judgment may be required in determining whether a performance obligation is distinct, determining the amount of variable consideration to be included in the transaction price, and estimating the SSP of each performance obligation. An enumeration of the Company’s significant judgments is outlined in Note 3, Collaboration Agreements, License Agreement and Revenues.

For each performance obligation identified within an arrangement, the Company determines the period over which the promised services are transferred and the performance obligation is satisfied. Service revenue that was recognized over time was based on progress toward complete satisfaction of the performance obligation. For each performance obligation satisfied over time, the Company assesses the proper method to be used for revenue recognition, either an input method to measure progress toward the satisfaction of services or an output method of determining the progress of completion of performance obligation.

Revenue under license agreements

Under a license agreement, if the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from upfront license fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company determines whether the combined performance obligation is satisfied over time or at a point in time. If the combined performance obligation is satisfied over time, the Company uses judgment in determining the appropriate method of measuring progress for purposes of recognizing revenue from the up-front license fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

Product revenue, net

Product revenue, net consists of revenues from sales of roxadustat commercial product to Falikang, and directly to pharmaceutical distributors located in one province in China that are not covered by Falikang. Falikang is jointly owned by AstraZeneca AB (“AstraZeneca”) and FibroGen Beijing. The Company is not the primary beneficiary of Falikang for accounting purposes, as AstraZeneca is the final decision maker for all the roxadustat commercialization activities, and the Company lacks the power criterion to direct the activities of Falikang (see Note 4, Equity method investment - Variable Interest Entity).

Sales to Falikang

Falikang became fully operational in January 2021, at which time FibroGen Beijing began selling roxadustat commercial product to Falikang. Falikang is FibroGen Beijing’s primary customer in China and substantially all roxadustat product sales to distributors in China are made by Falikang. Falikang bears inventory risk once it receives and accepts the product from FibroGen Beijing, and is responsible for delivering product to its distributors.

The promises identified under the AstraZeneca China Agreement (as defined in Note 3, Collaboration Agreements, License Agreement and Revenues), including the license, co-development services and manufacturing of commercial supplies have been bundled into a single performance obligation (“China performance obligation”). Amounts of the transaction price allocable to this performance obligation under the Company’s agreements with AstraZeneca as outlined in Note 3, Collaboration Agreements, License Agreement and Revenues, are deferred until control of the manufactured commercial product is transferred to AstraZeneca.

The initiation of roxadustat sales to Falikang marked the beginning of the China performance obligation. Revenue is recognized at a point in time when control of roxadustat commercial product is transferred to Falikang. Revenue is recognized based on the estimated transaction price per unit and actual quantity of product delivered during the reporting period. Specifically, the transaction price per unit is determined based on the overall transaction price over the total estimated sales quantity for the estimated performance period in which the Company determined it is likely those sales would occur. The price per unit is subject to reassessment on a quarterly basis, which may result in cumulative catch up adjustments due to changes in estimates.

The overall transaction price for FibroGen Beijing’s product sales to Falikang includes the following elements of consideration:

●

Non-refundable upfront license fees; development, regulatory, and commercial milestone payments based on the AstraZeneca China Agreement allocated to the China performance obligation;

●

Co-development billings resulting from the Company’s research and development efforts, which are reimbursable under the AstraZeneca China Agreement;

●

Interim profit/loss share between FibroGen Beijing and AstraZeneca from April 1, 2020 through December 31, 2020; and

●

Net transaction price from product sales to Falikang from January 1, 2021 onwards. The net transaction price includes the following elements:

Gross transaction price: The gross transaction price is based on a percentage of Falikang’s net sales to its distributors, which takes into account Falikang’s operating expenses and its payments to AstraZeneca for roxadustat sales and marketing efforts, capped at a percentage of Falikang’s net roxadustat sales.

Profit share: The gross transaction price is then adjusted for an estimated amount to achieve the 50/50 profit share from current period roxadustat net sales in China. The adjustments to date have been a reduction to the transaction price and the related accounts receivable from Falikang.

The non-refundable upfront license fees constitute a fixed consideration. The remainder of the above are variable consideration components, which may be constrained, and included in the transaction price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period when the uncertainty associated with the variable consideration is subsequently resolved. The calculation of the above variable consideration includes significant assumptions such as total sales quantity, performance period, gross transaction price and profit share, which require significant judgment.

Any net transaction price in excess of the revenue recognized is deferred, and will be recognized over future periods as the performance obligations are satisfied.

Direct Sales to Distributors

The Company sells roxadustat in China directly to a number of pharmaceutical distributors located in one province in China that are not covered by Falikang. These pharmaceutical distributors are the Company’s customers. Hospitals order roxadustat through a distributor and the Company ships the product directly to the distributors. The delivery of roxadustat to a distributor represents a single performance obligation. Distributors are responsible for delivering product to end users, primarily hospitals. Distributors bear inventory risk once they receive and accept the product. Product revenue is recognized when control of the promised good is transferred to the customer in an amount that reflects the consideration that the Company expects to be entitled to in exchange for the product.

The period between the transfer of control of the promised goods and when the Company receives payment is based on 60-day payment terms. As such, product revenue is not adjusted for the effects of a significant financing component.

Product revenue is recorded at the net sales prices that includes the following estimates of variable consideration:

●

Price adjustment: When China’s National Healthcare Security Administration releases price guidance for roxadustat under the National Reimbursement Drug List, any channel inventories that have not been sold through by distributors, or to patients by hospitals and retailers, would be eligible for a price adjustment under the price protection. The price adjustment is calculated based on estimated channel inventory levels;

●

Contractual sales rebate: The contractual sales rebate is calculated based on the stated percentage of gross sales by each distributor in the distribution agreement entered between FibroGen and each distributor. The contractual sales rebate is recorded as a reduction to revenue at the point of sale to the distributor;

●

Non-key account hospital listing award: A one-time fixed-amount award is offered to a distributor who successfully lists the product with an eligible hospital, and who meets certain requirements. For the year ended December 31, 2020, the non-key account hospital listing award was capitalized when the distributor meets eligibility requirements, and amortized as reduction to product revenue over future sales orders made by the distributor until exhausted. For the years ended December 31, 2022 and 2021, the non-key account hospital listing award was immaterial and recorded as a reduction to revenue when distributor meets eligibility requirements;

●

Other discounts and rebates, including key account hospital sales rebate and transfer fee discount, are generally based on a percentage of eligible gross sales made by the distributor and recorded as a reduction to revenue at the point of sale to the distributor; and

●

Sales returns: Distributors can request to return product to the Company only due to quality issues or for product purchased within one year prior to the product’s expiration date.

The calculation of the above variable consideration is based on gross sales to the distributor, or estimated utilizing best available information from the distributor, maximum known exposures and other available information including estimated channel inventory levels and estimated sales made by the distributor to hospitals, which involve a significant judgment.

The above rebates and discounts all together are eligible to be applied against the distributor’s future sales order, limited to certain maximums until such rebates and discounts are exhausted. These rebates and discounts are recorded as contract liabilities at the time they become eligible and in the same period that the related revenue is recorded. Due to the distributor’s legal right to offset, at each balance sheet date, the liability for rebates and discounts are presented as reductions of gross accounts receivable from the distributor, or as a current liability to the distributor to the extent that the total amount exceeds the gross accounts receivable or when the Company expects to settle the discount in cash. The distributor’s legal right of offset is calculated at the individual distributor level.

Drug product revenue

Drug product revenue includes commercial-grade API or bulk drug product sales to AstraZeneca and Astellas Pharma Inc. (“Astellas”) in support of pre-commercial preparation prior to the New Drug Application (“NDA”) or Marketing Authorization Application approval, and to Astellas for ongoing commercial launch in Japan and Europe. Drug product revenue is recognized when the Company fulfills the inventory transfer obligations.

The amount of variable consideration that is included in the transaction price may be constrained, and is included in the drug product revenue only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period when the uncertainty associated with the variable consideration is subsequently resolved. Estimating variable consideration and the related constraint requires the use of significant management judgment. The Company reviews new information that may affect its variable consideration estimate at every reporting period and records revenue adjustment, if certain and material. Actual amounts of consideration ultimately received in the future may differ from the Company’s estimates, for which the Company will adjust these estimates and affect the drug product revenue in the period such variances become known.

As each of the Company’s collaboration agreements provide for annual true up to the considerations paid for its commercial supplies, the Company will re-evaluate the transaction price in each reporting period and record adjustment to revenue as uncertain events are resolved or other changes in circumstances occur.

License Acquisition Agreement

In June 2021, the Company entered into an exclusive license and option agreement (the “HiFiBiO Agreement”) with HiFiBiO Therapeutics (“HiFiBiO”), pursuant to which the Company exclusively licensed all product candidates in HiFiBiO’s Galectin-9 program and subsequently exclusively licensed all product candidates in HiFiBiO’s CCR8 program in December 2021. Under the terms of the HiFiBiO Agreement, the Company has paid a $25.0 million upfront payment to HiFiBiO during the year ended December 31, 2021, and recorded a $35.0 million upfront payment for the CCR8 option exercise in accrued liabilities as of December 31, 2021, which was paid during the first quarter of 2022. HiFiBiO may receive up to a total of an additional $345 million in future clinical, regulatory, and commercial milestone payments for each program. HiFiBiO will also be eligible to receive tiered royalties based upon worldwide net sales. We expect to file INDs on product candidates for both the CCR8 and Galectin-9 programs in 2023.

The acquisition of these licenses was accounted for as an asset acquisition. The above-mentioned upfront payments of $60.0 million related to the license and options acquisition meets the definition of an in-process research and development asset (“IPR&D asset”) under the ASC 730, Research and Development. They relate to particular research and development projects and are determined to have no alternative future uses and thus have no separate economic value. Therefore, these upfront payments were recorded as research and development expenses during the year ended December 31, 2021, and the cash payments were reflected as investing activities in the consolidated statement of cash flows during the years ended December 31, 2022 and 2021, respectively.

Contingent consideration payments will be evaluated and recognized when they become probable and reasonably estimable. The related IPR&D asset will only be capitalized if it has an alternative future use other than in a particular research and development project. Otherwise, amounts allocated to IPR&D asset that have no alternative use will be expensed. As of December 31, 2022, all programs were at the early stage of development and the contingencies related to the milestone payments had not been resolved, therefore no contingent consideration was recognized. The Company will reassess the probability of future option payments and contingent payments on a quarterly basis.

Research and Development Expenses

Research and development expenses consist of above-mentioned expense for acquired IPR&D asset, independent research and development costs and the gross amount of costs associated with work performed under collaboration agreements. Research and development costs include employee-related expenses, expenses incurred under agreements with clinical research organizations, other clinical and preclinical costs and allocated direct and indirect overhead costs, such as facilities costs, information technology costs and other overhead. All research and development costs are expensed as incurred.

Clinical Trial Accruals

Clinical trial costs are a component of research and development expenses. The Company accrues and expenses clinical trial activities performed by third parties based upon actual work completed in accordance with agreements established with clinical research organizations and clinical sites. The Company determines the costs to be recorded based upon validation with the external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services.

Selling, General and Administrative Expenses

Selling, general and administrative (“SG&A”) expenses consist primarily of employee-related expenses for executive, operational, finance, legal, compliance and human resource functions. SG&A expenses also include facility-related costs, professional fees, accounting and legal services, other outside services including co-promotional expenses associated with our commercialization efforts in China, recruiting fees and expenses associated with obtaining and maintaining patents.

Income Taxes

The Company utilizes the asset and liability method of accounting for income taxes, which requires the recognition of deferred tax assets and liabilities for expected future consequences of temporary differences between the financial reporting and income tax bases of assets and liabilities using enacted tax rates. Management makes estimates, assumptions and judgments to determine the Company’s provision for income taxes and for deferred tax assets and liabilities, and any valuation allowances recorded against the Company’s deferred tax assets. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent the Company believes that recovery is not likely, the Company must establish a valuation allowance.

The calculation of the Company’s current provision for income taxes involves the use of estimates, assumptions and judgments while taking into account current tax laws, interpretation of current tax laws and possible outcomes of future tax audits. The Company has established reserves to address potential exposures related to tax positions that could be challenged by tax authorities. Although the Company believes its estimates, assumptions and judgments to be reasonable, any changes in tax law or its interpretation of tax laws and the resolutions of potential tax audits could significantly impact the amounts provided for income taxes in the Company’s consolidated financial statements.

The calculation of the Company’s deferred tax asset balance involves the use of estimates, assumptions and judgments while taking into account estimates of the amounts and type of future taxable income. Actual future operating results and the underlying amount and type of income could differ materially from the Company’s estimates, assumptions and judgments thereby impacting the Company’s financial position and results of operations.

During 2020, the Company transferred certain intellectual property rights relating to its Chinese business between its wholly owned subsidiaries that are based in different tax jurisdictions. See Note 13, Income Taxes, for more information. The establishment of a deferred tax asset from the intra-entity transfer of intangible assets required the Company to make significant estimates and assumptions to determine the fair value of intellectual property rights transferred, which include but are not limited to, its expectations of discount rate, revenue volume and price. The accuracy of these estimates could be affected by unforeseen events or actual results, and the sustainability of the Company’s future tax benefits is dependent upon the acceptance of these valuation estimates and assumptions by the taxing authorities.

The Company has adopted ASC 740-10, Accounting for Uncertainty in Income Taxes, that prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in the Company’s income tax return, and also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition.

The Company includes interest and penalties related to unrecognized tax benefits within income tax expense in the Consolidated Statements of Operations.

Stock-Based Compensation

The Company maintains equity incentive plans under which equity awards are granted to employees, which are comprised of stock options, service-based restricted stock units (“RSUs”), performance-based RSUs (“PRSUs”), and total shareholder return (“TSR”) awards.

The Company measures and recognizes compensation expense for all stock options, RSUs and PRSUs granted to its employees and directors based on the estimated fair value of the award on the grant date. The Company uses the Black-Scholes valuation model to estimate the fair value of stock option awards. The determination of the grant date fair value of options using the Black-Scholes valuation model is affected by the Company’s estimated common stock fair value and requires management to make a number of assumptions including the expected life of the option, the volatility of the underlying stock, the risk-free interest rate and expected dividends. The Company determines the fair value of RSUs and PRSUs using the fair value of our common stock on the date of grant. To estimate the fair value of the TSR awards, the Company uses the Monte Carlo valuation model to simulate the probabilities of achievement, which requires management to make a number of assumptions including 30-day average price, volatility of the underlying stock and the Company’s peers, and the risk-free interest rate.

The compensation cost of service-based stock options and restricted stock units is recognized net of any estimated forfeitures on a straight-line basis over the employee requisite service period. Compensation cost for PRSUs is expensed over the respective vesting periods when the achievement of performance criteria is probable. Compensation cost for the TSR awards is recognized over the requisite service period, regardless of when, if ever, the market condition is satisfied.

The Company believes that the fair value of stock options granted to non-employees is more reliably measured than the fair value of the services received.

Comprehensive Income (Loss)

The Company is required to report all components of comprehensive income (loss), including net loss, in the consolidated financial statements in the period in which they are recognized. Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on investments and foreign currency translation adjustments. Comprehensive gains (losses) have been reflected in the consolidated statements of comprehensive income (loss) for all periods presented.

Recently Issued and Adopted Accounting Guidance

In March 2020, the Financial Accounting Standards Board (“FASB”) issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”), which provides companies with optional financial reporting alternatives to reduce the cost and complexity associated with the accounting for contracts and hedging relationships affected by reference rate reform. Subsequently in January 2021, the FASB issued ASU 2021-01, Reference Rate Reform (Topic 848): Scope, which clarifies ASU 2020-04 and provides certain optional expedients that allow derivative instruments impacted by changes in the interest rate used for margining, discounting or contract price alignment to qualify for certain optional relief. ASU 2021-01 is effective in the same timeframe as ASU2020-04. The Company did not elect to apply any of the expedients or exceptions as of and for the years ended December 31, 2022 and 2021. In December 2022, the FASB issued ASU 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848, which deferred the sunset date in Topic 848 from December 31, 2022 to December 31, 2024. The Company has certain lease arrangements that were accounted for with reference to the London Inter-Bank Offered Rate (“LIBOR”). The Company has evaluated the options for transitioning away from LIBOR for these arrangements and concluded that there is no material impact on its consolidated financial statements and related disclosures affected by reference rate reform.

Leases - Components of Lease Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Finance lease cost:
Amortization of right-of-use assets	$ 587	$ 4,639	$ 10,369
Interest on lease liabilities	0	628	1,932
Operating lease cost	17,125	10,722	1,151
Sublease income	(3,373)	(1,271)	(1,201)
Total lease cost	$ 14,339	$ 14,718	$ 12,251

Equity and Stock based compensation - Schedule of Assumptions used to Estimate Fair Value of TSR Awards (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average estimated fair value	$ 14.72	$ 35.58	$ 31.55
TSR [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	3 years 10 months 24 days
Expected volatility	69.00%
Risk-free interest rate	1.80%
Expected dividend yield	0.00%
Weighted average estimated fair value	$ 24.01

Equity and Stock-based Compensation - Employee Stock Purchase Plan - Additional information (Detail) - 2014 ESPP [Member] - shares	1 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase of common stock shares at discount	15.00%
Percentage of fair value exercise price grant date	85.00%
Number of common stock reserved for issuance	1,600,000
Common stock reserved for future issuance, Description		The Company has reserved 1,600,000 shares of its common stock for issuance under the 2014 ESPP and shares reserved for issuance increases January 1 of each year, which commenced on January 1, 2016, by the lesser of (i) a number of shares equal to 1% of the total number of outstanding shares of common stock on December 31 immediately prior to the date of increase; (ii) 1,200,000 shares or (iii) such number of shares as may be determined by the board of directors.
Percentage of common stock reserved for future issuance	1.00%
Increase in number of shares of common stock reserved for future issuance, shares	1,200,000
Shares purchased by employees		327,298	213,505	143,876

Equity Method Investment - Variable Interest Entity

12 Months Ended

Dec. 31, 2022

Acquisition And Variable Interest Entity [Abstract]

Equity Method Investment - Variable Interest Entity

Equity method investment - Variable Interest Entity

Falikang is a distribution entity jointly owned by AstraZeneca and FibroGen Beijing. FibroGen Beijing owns 51.1% of the outstanding shares of Falikang.

Pursuant to the guidance under ASC 810, the Company concluded that Falikang qualifies as a VIE. As Falikang is a distribution entity and AstraZeneca is the final decision maker for all the roxadustat commercialization activities, the Company lacks the power criterion, while AstraZeneca meets both the power and economic criteria under the ASC 810 to direct the activities of Falikang that most significantly impact its performance. Therefore, the Company is not the primary beneficiary of this VIE for accounting purposes. As a result, the Company accounts for its investment in Falikang under the equity method, and Falikang is not consolidated into the Company’s consolidated financial statements. The Company records its total investments in Falikang as an equity method investment in an unconsolidated VIE in the consolidated balance sheet. In addition, the Company recognizes its proportionate share of the reported profits or losses of Falikang as investment gain or loss in unconsolidated VIE in the consolidated statement of operations and as an adjustment to its investment in Falikang in the consolidated balance sheet. Falikang has not incurred material profit or loss to date. The Company may provide shareholder loans to Falikang to meet necessary financial obligations as part of its operations. To date, there has been no such loans.

The Company’s equity method investment in Falikang was as follows for the year ended December 31, 2022 (in thousands):


Entity	Ownership Percentage			Balance at December 31, 2021		Share of Net Income		Currency Translation			Balance at December 31, 2022
Falikang		51.1	%	$	3,825	$	1,573	$	(337	)	$	5,061

Falikang is considered as a related party to the Company. See Note 14, Related Party Transactions, for related disclosures.

On an ongoing basis, the Company re-evaluates the VIE assessment based on changes in facts and circumstances, including but not limited to, the shareholder loans received by Falikang and the execution of any future significant agreements between Falikang and its shareholders and/or other third parties.

The Company assessed the impairment of its equity method investment whenever events or changes in circumstances indicate that a decrease in value of the investment has occurred that is other than temporary.

Collaboration Agreements,License Agreement and Revenues - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	$ 140,734	$ 235,309	$ 176,319
Unbilled contract asset	17,488	66,909
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	11,086	962	$ 8,906
Drug Product Revenue [Member] \| API Shipment [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	$ (4,000)	$ 2,100

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI https://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Basis of Presentation

The Company operates in one reportable segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs.

Foreign Currency Translation

The reporting currency of the Company and its subsidiaries is the U.S. dollar.

Use of Estimates

Concentration of Credit Risk


	December 31,
	2022			2021
Falikang — Related party		65	%		—	%
Astellas — Related party		9	%		63	%
AstraZeneca		16	%		34	%

Other Risks and Uncertainties

Cash, Cash Equivalents and Restricted Time Deposits

Investments

Trade Accounts Receivable

Trade accounts receivable

Credit Losses – Available-For-Sale Debt Securities

Credit losses – Available-for-sale debt securities

Inventories

Property and Equipment

Equity Method Investment - Variable Interest Entity

Equity method investment - Variable Interest Entity

Leases

Impairment of Long-Lived Assets

Revenue Recognition

Revenues under collaboration agreements

Revenue under license agreements

Product revenue, net

Sales to Falikang

The overall transaction price for FibroGen Beijing’s product sales to Falikang includes the following elements of consideration:

●

Non-refundable upfront license fees; development, regulatory, and commercial milestone payments based on the AstraZeneca China Agreement allocated to the China performance obligation;

●

Co-development billings resulting from the Company’s research and development efforts, which are reimbursable under the AstraZeneca China Agreement;

●

Interim profit/loss share between FibroGen Beijing and AstraZeneca from April 1, 2020 through December 31, 2020; and

●

Net transaction price from product sales to Falikang from January 1, 2021 onwards. The net transaction price includes the following elements:

Any net transaction price in excess of the revenue recognized is deferred, and will be recognized over future periods as the performance obligations are satisfied.

Direct Sales to Distributors

Product revenue is recorded at the net sales prices that includes the following estimates of variable consideration:

●

Sales returns: Distributors can request to return product to the Company only due to quality issues or for product purchased within one year prior to the product’s expiration date.

Drug product revenue

License Acquisition Agreement

Research and Development Expenses

Clinical Trial Accruals

Selling, General and Administrative Expenses

Income Taxes

The Company includes interest and penalties related to unrecognized tax benefits within income tax expense in the Consolidated Statements of Operations.

Stock-Based Compensation

The Company believes that the fair value of stock options granted to non-employees is more reliably measured than the fair value of the services received.

The Company estimates the fair value of stock options using the Black-Scholes option valuation model. The fair value of employee stock options and RSUs is being amortized on a straight-line basis over the requisite service period of the awards. Compensation cost for PRSUs is expensed over the respective vesting periods when the achievement of performance criteria is probable. The Company estimates the fair value of the TSR awards using the Monte Carlo valuation model to simulate the probabilities of achievement. Compensation cost for the TSR awards is recognized over the requisite service period, regardless of when, if ever, the market condition is satisfied. The fair market value of common stock is based on the closing price of the Company’s common stock as reported on the Nasdaq Global Select Market on the date of the grant.

The fair value of employee stock-based compensation is estimated using the following assumptions:

•

Expected Term. Expressed as a weighted-average, the expected life of the options is based on the average period the stock options are expected to be outstanding and was based on the Company’s historical information of the option exercise patterns and post-vesting termination behavior as well as contractual terms of the instruments. The expected term of 2014 ESPP shares is the average of the remaining purchase periods under each offering period. The expected term of TSR awards is determined based on the grant date to the end of the performance period.

•

Expected Volatility. The Company considers its historical volatility data for volatility considerations for its ESPP. Historically, the expected volatility for all other stock-based compensation types was based upon a blend of the Company’s and comparable public entities’ historical volatility. Since the third quarter of 2020, the expected volatility for all other stock-based compensation types is currently based upon the Company’s historical volatility data.

•

Risk-Free Interest Rate. Expressed as a weighted-average, the risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the Company’s respective stock-based compensation types.

•

Expected Dividend Yield. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future.

Comprehensive Income (Loss)

Recently Issued and Adopted Accounting Guidance

Collaboration Arrangements and Revenues

Astellas Agreements

Astellas Japan Agreement

In June 2005, the Company entered into a collaboration agreement with Astellas for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in Japan (“Astellas Japan Agreement”). Under this agreement, Astellas paid license fees and other consideration totaling $40.1 million (such amounts were fully received as of February 2009). Under the Astellas Japan Agreement, the Company is also eligible to receive from Astellas an aggregate of approximately $132.5 million in potential milestone payments, comprised of (i) up to $22.5 million in milestone payments upon achievement of specified clinical and development milestone events (such amounts were fully received as of July 2016), (ii) up to $95.0 million in milestone payments upon achievement of specified regulatory milestone events, and (iii) up to approximately $15.0 million in milestone payments upon the achievement of specified commercial sales milestone. The Astellas Japan Agreement also provides for tiered payments based on net sales of product (as defined) in the low 20% range of the list price published by the Japanese Ministry of Health, Labour and Welfare, adjusted for certain elements, after commercial launch.

During the fourth quarter of 2020, the Japanese Ministry of Health, Labour and Welfare approved EVRENZO® (roxadustat) for the treatment of anemia of CKD in adult patients not on dialysis. This approval triggered a $15.0 million milestone payable to the Company by Astellas under the Astellas Japan Agreement. Accordingly, the consideration of $15.0 million associated with this milestone was included in the transaction price and allocated to performance obligations under the Astellas Japan Agreement in the fourth quarter of 2020, substantially all of which was recognized as revenue during the year ended December 31, 2020 from performance obligations satisfied or partially satisfied.

The aggregate amount of the considerations received under the Astellas Japan Agreement, through December 31, 2022 totals $105.1 million excluding drug product revenue that is discussed under the Drug Product Revenue section below.

In 2018, FibroGen and Astellas entered into an amendment to the Astellas Japan Agreement that allows Astellas to manufacture roxadustat drug product for commercialization in Japan (the “Astellas Japan Amendment”). Under this amendment, FibroGen would continue to manufacture and supply roxadustat API to Astellas for the roxadustat commercial launch in Japan. The commercial terms of the Astellas Japan Agreement relating to the transfer price for roxadustat for commercial use remain substantially the same, reflecting an adjustment for the manufacture of drug product by Astellas rather than FibroGen. The related drug product revenue is described under the Drug Product Revenue section below.

Astellas Europe Agreement

In April 2006, the Company entered into a separate collaboration agreement with Astellas for the development and commercialization of roxadustat for the treatment of anemia in Europe, the Middle East, the Commonwealth of Independent States and South Africa (“Astellas Europe Agreement”). Under the terms of the Astellas Europe Agreement, Astellas paid license fees and other upfront consideration totaling $320.0 million (such amounts were fully received as of February 2009). The Astellas Europe Agreement also provides for additional development and regulatory approval milestone payments up to $425.0 million, comprised of (i) up to $90.0 million in milestone payments upon achievement of specified clinical and development milestone events (such amounts were fully received as of 2012), and (ii) up to $335.0 million in milestone payments upon achievement of specified regulatory milestone events. Under the Astellas Europe Agreement, Astellas committed to fund 50% of joint development costs for Europe and North America, and all territory-specific costs. The Astellas Europe Agreement also provides for tiered payments based on net sales of product (as defined) in the low 20% range.

On March 21, 2022, EVRENZO® (roxadustat) was registered with the Russian Ministry of Health. The Company evaluated the regulatory milestone payment associated with the approval in Russia under the Astellas Europe Agreement and concluded that this milestone was achieved in the first quarter of 2022. Accordingly, the consideration of $25.0 million associated with this milestone was included in the transaction price and allocated to performance obligations under the Astellas Europe Agreement, all of which was recognized as revenue during the year ended December 31, 2022 from performance obligations satisfied.

During the third quarter of 2021, the European Commission approved EVRENZO® (roxadustat) for the treatment of adult patients with symptomatic anemia associated with CKD. Astellas has launched EVRENZO in Germany, the United Kingdom, the Netherlands, and Austria. This approval triggered a total of $120.0 million milestone payable to the Company by Astellas under the Astellas Europe Agreement. Accordingly, the consideration of $120.0 million associated with these milestones was included in the transaction price and allocated to performance obligations under the Astellas Europe Agreement, all of which was recognized as revenue during the year ended December 31, 2021 from performance obligations satisfied.

The aggregate amount of the considerations received under the Astellas Europe Agreement through December 31, 2022 totals $685.0 million, excluding drug product revenue that is discussed under the Drug Product Revenue section below.

Under the Astellas Europe Agreement, Astellas has an option to purchase roxadustat bulk drug product in support of commercial supplies. During the first quarter of 2021, the Company entered into an EU Supply Agreement with Astellas (“Astellas EU Supply Agreement”) to define general forecast, order, supply and payment terms for Astellas to purchase roxadustat bulk drug product from FibroGen in support of commercial supplies. The related drug product revenue is described under the Drug Product Revenue section below.

Accounting for the Astellas Agreements

For each of the Astellas agreements, the Company has evaluated the promised services within the respective arrangements and has identified performance obligations representing those services and bundles of services that are distinct.

Promised services that were not distinct have been combined with other promised services to form a distinct bundle of promised services, with revenue being recognized on the bundle of services rather than the individual services. There are no right-of-return provisions for the delivered items in the Astellas agreements.

As of December 31, 2022, the transaction price for the Astellas Japan Agreement, excluding manufacturing services that is discussed separately below, included $40.1 million of non-contingent upfront payments, $65.0 million of variable consideration related to payments for milestones achieved, and $12.1 million of variable consideration related to co-development billings. The transaction price for the Astellas Europe Agreement, excluding manufacturing services that is discussed separately below, included $320.0 million of non-contingent upfront payments, $365.0 million of variable consideration related to payments for milestones achieved, and $219.2 million of variable consideration related to co-development billings.

For the technology license under the Astellas Japan Agreement and the Astellas Europe Agreement, SSP was determined primarily by using the discounted cash flow (“DCF”) method, which aggregates the present value of future cash flows to determine the valuation as of the effective date of each of the agreements. The DCF method involves the following key steps: 1) the determination of cash flow forecasts and 2) the selection of a range of comparative risk-adjusted discount rates to apply against the cash flow forecasts. The discount rates selected were based on expectations of the total rate of return, the rate at which capital would be attracted to the Company and the level of risk inherent within the Company. The discounts applied in the DCF analysis ranged from 17.5% to 20.0%. The Company’s cash flow forecasts were derived from probability-adjusted revenue and expense projections by territory. Such projections included consideration of taxes and cash flow adjustments. The probability adjustments were made after considering the likelihood of technical success at various stages of clinical trials and regulatory approval phases. SSP also considered certain future royalty payments associated with commercial performance of the Company’s compounds, transfer prices and expected gross margins.

The promised services that were analyzed, along with their general timing of satisfaction and recognition as revenue, are as follows:

(1)

License to the Company’s technology existing at the effective date of the agreements. For both of the Astellas agreements, the license was delivered at the beginning of the agreement term. In both cases, the Company concluded at the time of the agreement that its collaboration partner, Astellas, would have the knowledge and capabilities to fully exploit the licenses without the Company’s further involvement. However, the Astellas Japan Agreement has contractual limitations that might affect Astellas’ ability to fully exploit the license and therefore, potentially, the conclusion as to whether the license is capable of being distinct. In the Astellas Japan Agreement, Astellas does not have the right to manufacture commercial supplies of the drug. In order to determine whether this characteristic of the agreement should lead to a conclusion that the license was not distinct in the context of the agreement, the Company considered the ability of Astellas to benefit from the license together with other resources readily available to Astellas. Finally, the Company considered the fact that at the time of delivery of the license, the development services were beyond the preclinical development phase and any remaining development work in either agreement would not be expected to result in any significant modification or customization to the licensed technology. As such, the development services are separately identifiable from the licensed technology, indicating that the license is a distinct performance obligation.

Manufacturing rights. In the case of the Astellas Japan Agreement, the Company retained manufacturing rights largely because of the way the parties chose for FibroGen to be compensated under the agreement. At the time the agreement was signed, the Company believed that it was more advantageous upon commercialization to have a transfer price revenue model in place as opposed to a traditional sales-based model. The manufacturing process does not require specialized knowledge or expertise uniquely held by FibroGen, and notwithstanding contractual restrictions, Astellas could employ manufacturing services from readily available third parties in order to benefit from the license. Therefore, along with the foregoing paragraph, the Company determined that the license in Japan is a distinct performance obligation despite the retention of manufacturing rights by the Company.

In summary, the Company concludes that item (1) represents a performance obligation. The portion of the transaction price allocated to this performance obligation based on a relative SSP basis was recognized as revenue in its entirety at the point in time the license transfers to Astellas.

(2)

Co-development services (Astellas Europe Agreement). This promise relates to co-development services that were reasonably expected to be performed by the Company at the time the collaboration agreement was signed and is considered distinct. Co-development billings are allocated entirely to the co-development services performance obligation as amounts are related specifically to research and development efforts necessary to satisfy the performance obligation related to CKD approval, and such an allocation is consistent with the allocation objective. Through the third quarter of 2021 upon the approval of CKD, revenue was recognized over time based on progress toward complete satisfaction of the performance obligation. The Company used an input method to measure progress toward the satisfaction of the performance obligation, which was based on costs of labor hours and out-of-pocket expenses incurred relative to total expected costs to be incurred. Subsequently, the Company accounts for the development services for the indications related to chemotherapy-induced anemia and myelodysplastic syndromes separately as services are provided. There was no provision for co-development services in the Astellas Japan Agreement.

(3)

License to the Company’s technology developed during the term of the agreement and development (referred to as “when and if available”) and information sharing services. These promises are generally satisfied throughout the term of the agreements.

(4)

Manufacturing of clinical supplies of products. This promise is satisfied as supplies for clinical product are delivered for use in the Company’s clinical trial programs during the development period, or pre-commercialization period.

(5)

Committee service. This promise is satisfied throughout the course of the agreements as meetings are attended.

Items (2)-(5) are bundled into a single performance obligation that is distinct given the fact that all are highly interrelated during the development period (pre-commercial phase of development) such that satisfying them independently is not practicable. For the revenue recognized over time based on progress toward complete satisfaction of the performance obligation, the Company uses an input method to measure progress toward the satisfaction of the performance obligation, which is based on costs of labor hours or full time equivalents and out-of-pocket expenses incurred relative to total expected costs to be incurred, and updates the measure of progress in each reporting period.

(6)

Manufacturing commercial supplies of products. This promised service is distinct as services are not interrelated with any of the other performance obligations. Payments received for commercial supplies of products represent sales-based payments related predominately to the license of intellectual property under both Astellas agreements. Revenue is recognized as supplies are shipped for commercial use during the commercialization period. See the Drug Product Revenue section below.

Under the Astellas Japan Amendment, the drug product revenue represents variable consideration and is estimated based on the quantity of product shipped, actual listed price for roxadustat issued by the Japanese Ministry of Health, Labour and Welfare and possible future changes to the listed price, adjusted for the timing of and estimated bulk product strength mix intended to be manufactured by Astellas, estimated cost to convert the API to bulk drug product tablets, and estimated yield from the manufacture of bulk product tablets, among others.

Under the Astellas Europe Agreement, the drug product revenue amount represents variable consideration and is estimated based on the quantity of product transferred and an estimated price. The estimated price is based on the contractual transfer price percentage applied on the estimated weighted average net sales price per strength, which is estimated to be realized by Astellas from the end sale of roxadustat in its approved territories.

License Revenue and Development Revenue Recognized Under the Astellas Agreements

License amounts identified below are included in the “License revenue” line item in the consolidated statements of operations. All other elements identified below are included in the “Development and other revenue” line item in the consolidated statements of operations.

Amounts recognized as license revenue and development revenue under the Astellas Japan Agreement were as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021		2020
Astellas Japan Agreement	License revenue	$	—	$	—	$	14,323
	Development revenue	$	284	$	248	$	1,220

The transaction price related to consideration received through December 31, 2022 and accounts receivable has been allocated to each of the following performance obligations under the Astellas Japan Agreement, along with any associated deferred revenue as follows (in thousands):


Astellas Japan Agreement	Cumulative Revenue Through December 31, 2022		Deferred Revenue at December 31, 2022		Total Consideration Through December 31, 2022
License	$	100,347	$	—	$	100,347
Development revenue		16,882		—		16,882
Total license and development revenue	$	117,229	$	—	$	117,229

Amounts recognized as license revenue and development revenue under the Astellas Europe Agreement were as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021		2020
Astellas Europe Agreement	License revenue	$	22,590	$	108,434	$	—
	Development revenue	$	9,624	$	21,679	$	17,954

The transaction price related to consideration received through December 31, 2022 and accounts receivable has been allocated to each of the following performance obligations under the Astellas Europe Agreement, along with any associated deferred revenue as follows (in thousands):


Astellas Europe Agreement	Cumulative Revenue Through December 31, 2022		Deferred Revenue at December 31, 2022		Total Consideration Through December 31, 2022
License	$	618,975	$	—	$	618,975
Development revenue		280,265		—		280,265
Total license and development revenue	$	899,240	$	—	$	899,240

The license revenue and development revenue recognized under the Astellas Europe Agreement for the year ended December 31, 2022 included an increase in revenue of $25.0 million relating to performance obligations satisfied during the year. The remainder of the transaction price related to the Astellas Europe Agreement includes $5.0 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period.

AstraZeneca Agreements

AstraZeneca U.S./Rest of World (“RoW”) Agreement

Effective July 30, 2013, the Company entered into a collaboration agreement with AstraZeneca for the development and commercialization of roxadustat for the treatment of anemia in the U.S. and all other countries in the world, other than China, not previously licensed under the Astellas Europe and Astellas Japan Agreements (“AstraZeneca U.S./RoW Agreement”). China is covered by a separate agreement with AstraZeneca described below. Under the terms of the AstraZeneca U.S./RoW Agreement, AstraZeneca paid upfront, non-contingent, non-refundable and time-based payments totaling $374.0 million (such amounts were fully received as of June 2016). Under the AstraZeneca U.S./RoW Agreement, AstraZeneca also agreed to pay an aggregate of approximately $875.0 million in potential milestone payments, comprised of (i) up to $65.0 million in milestone payments upon achievement of specified clinical and development milestone events, (ii) up to $325.0 million in milestone payments upon achievement of specified regulatory milestone events, (iii) up to $160.0 million in milestone payments related to activity by potential competitors and (iv) up to approximately $325.0 million in milestone payments upon the achievement of specified commercial sales events.

Under the AstraZeneca U.S./RoW Agreement, the Company and AstraZeneca will equally share in the development costs of roxadustat not already paid for by Astellas, up to a total of $233.0 million (i.e. the Company’s share of development costs is $116.5 million, which was reached in 2015). Development costs incurred by FibroGen during the development period in excess of the $233.0 million (aggregated spend) are fully reimbursed by AstraZeneca. AstraZeneca will pay the Company tiered royalty payments on AstraZeneca’s future net sales (as defined in the agreement) of roxadustat in the low 20% range. In addition, the Company will receive a transfer price for shipment of commercial product based on a percentage of AstraZeneca’s net sales (as defined in the agreement) in the low- to mid-single digit range.

The aggregate amount of the considerations received under the AstraZeneca U.S./RoW Agreement through December 31, 2022 totals $439.0 million, excluding drug product revenue that is discussed under the Drug Product Revenue section below.

In 2020, the Company entered into a Master Supply Agreement with AstraZeneca under the AstraZeneca U.S./RoW Agreement (“AstraZeneca Master Supply Agreement”) to define general forecast, order, supply and payment terms for AstraZeneca to purchase roxadustat bulk drug product from FibroGen in support of commercial supplies. The related drug product revenue is described under the Drug Product Revenue section below.

AstraZeneca China Agreement

Effective July 30, 2013, the Company (through its subsidiaries affiliated with China) entered into a collaboration agreement with AstraZeneca for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in China (“AstraZeneca China Agreement”). Under the terms of the AstraZeneca China Agreement, AstraZeneca agreed to pay upfront consideration totaling $28.2 million (such amounts were fully received in 2014). Under the AstraZeneca China Agreement, the Company is also eligible to receive from AstraZeneca an aggregate of approximately $348.5 million in potential milestone payments, comprised of (i) up to $15.0 million in milestone payments upon achievement of specified clinical and development milestone events, (ii) up to $146.0 million in milestone payments upon achievement of specified regulatory milestone events, and (iii) up to approximately $187.5 million in milestone payments upon the achievement of specified commercial sales and other events. The AstraZeneca China Agreement is structured as a 50/50 profit or loss share (as defined), which was amended under the AstraZeneca China Amendment discussed below in the third quarter of 2020, and provides for joint development costs (including capital and equipment costs for construction of the manufacturing plant in China), to be shared equally during the development period.

The aggregate amount of the considerations received for milestone and upfront payments under the AstraZeneca China Agreement through December 31, 2022 totals $77.2 million.

AstraZeneca China Amendment

In July 2020, FibroGen China Anemia Holdings, Ltd., FibroGen Beijing, and FibroGen International (Hong Kong) Limited and AstraZeneca entered into an amendment, relating to the development and commercialization of roxadustat in China (the “AstraZeneca China Amendment”). Under the AstraZeneca China Amendment, in September 2020, FibroGen Beijing and AstraZeneca completed the establishment of a jointly owned entity, Falikang, which performs roxadustat distribution, as well as conducts sales and marketing through AstraZeneca.

Under the AstraZeneca China Amendment, the interim period is defined as the period from April 1, 2020 to the time when Falikang is fully operational. Falikang became fully operational in January 2021. The calculation for profit or loss share related to sales of roxadustat in China has changed for the period from April 1, 2020 onwards. With effect from April 1, 2020, the Parties have changed the method under which commercial expenses incurred by AstraZeneca are calculated and billed. AstraZeneca’s co-promotion expenses for their sales and marketing efforts are now subject to a cap of a percentage of net sales. In addition, the AstraZeneca China Amendment has allowed for a higher cost of manufacturing incurred by FibroGen Beijing to be included in the profit or loss share calculation, subject to an annual cap, among other changes.

As a result, the interim period during the year ended December 31, 2020 primarily included the following activities:

•

Co-promotion expenses: The AstraZeneca China Amendment revised the payment arrangements and calculation of the historical unpaid co-promotion expenses to AstraZeneca for its sales and marketing efforts associated with the commercial sales for roxadustat in China since the product launch. Under the AstraZeneca China Amendment, a portion of the historical unpaid co-promotion expenses was adjusted to reduce the amount owed by FibroGen Beijing and the current period co-promotion expenses are capped at a percentage of net roxadustat sales in China. As a result, in the third quarter of 2020, the Company reversed approximately $84.4 million of previously accrued co-promotion expenses payable, which was recorded as a reduction to selling, general and administrative expenses, where these expenses were initially recorded during the periods from the initiation of commercial activities in the first quarter of 2019 to the second quarter of 2020. The co-promotion expenses for the years ended December 31, 2022, 2021 and 2020, capped at a percentage of net roxadustat sales in China, were $4.4 million, $4.7 million and $27.2 million, respectively, included in the selling, general and administrative expenses.

•

Profit share: Profit/loss share between FibroGen Beijing and AstraZeneca is based on a calculation of the current period net roxadustat sales in China and deductible expenses pursuant to the AstraZeneca China Agreement. Based on the calculation revised under the AstraZeneca China Amendment, profit was achieved during the third and fourth quarter of 2020. As a result, the Company recorded a profit share liability of $7.3 million and $7.9 million to AstraZeneca as of December 31, 2022 and 2021, respectively, in the accrued and other current liabilities, which correspondingly reduced the deferred revenue related to the performance obligation in accordance with the AstraZeneca China Agreement.

Since Falikang became fully operational in January 2021, substantially all direct roxadustat product sales to distributors in China are made by Falikang, while FibroGen Beijing continues to sell roxadustat product directly in one province in China. FibroGen Beijing manufactures and supplies commercial product to Falikang based on a gross transaction price, which is adjusted for the estimated profit share. In addition, AstraZeneca now bills the co-promotion expenses to Falikang and to FibroGen Beijing, respectively, for its services provided to the respective entity. AstraZeneca is entitled to reimbursement of its sales and marketing expenses up to a cumulative capped amount of a percentage of net sales. Once such amount is reached, AstraZeneca will bill the co-promotion expenses based on actual costs as incurred plus a markup on a prospective basis, which is currently expected to continue through 2028. Development costs continue to be shared 50/50 between the Parties.

The related net product revenue recognized from the sales to Falikang and the sales directly to distributors are discussed under the Product Revenue, Net section below.

Accounting for the AstraZeneca Agreements

The Company evaluated whether the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement should be accounted for as a single or separate arrangements and concluded that the agreements should be accounted for as a single arrangement with the presumption that two or more agreements executed with a single customer at or around the same time should be presumed to be a single arrangement. The key points the Company considered in reaching this conclusion are as follows:

While the two agreements were largely negotiated separately, those negotiations proceeded concurrently, and were intended to be completed contemporaneously, presuming AstraZeneca decided to proceed with licenses in all regions available.

Throughout negotiations for both agreements, the Company and the counterparties understood and considered the possibility that one arrangement may be executed without the execution of the other arrangement. However, the preference for the Company and the counterparties during the negotiations was to execute both arrangements concurrently.

The two agreements were executed as separate agreements because different development, regulatory and commercial approaches required certain terms of the agreements to be structured differently, rather than because the Company or the counterparties considered the agreements to be fundamentally separate negotiations.

Accordingly, as the agreements are being accounted for as a single arrangement, upfront and other non-contingent consideration received and to be received has been and will be pooled together and allocated to each of the performance obligations in both the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement based on their relative SSPs.

For each of the AstraZeneca agreements, the Company has evaluated the promised services within the respective arrangements and has identified performance obligations representing those services and bundled services that are distinct.

Promised services that were not distinct have been combined with other promised services to form a distinct bundle of promised services, with revenue being recognized on the bundle of services rather than the individual promised services. There are no right-of-return provisions for the delivered items in the AstraZeneca agreements.

As of December 31, 2022, the transaction price for the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement, excluding manufacturing services that is discussed separately below, included $402.2 million of non-contingent upfront payments, $114.0 million of variable consideration related to payments for milestones considered probable of being achieved, $610.5 million of variable consideration related to co-development billings, offset by $7.3 million of variable consideration related to profit share under the AstraZeneca China Amendment.

For the AstraZeneca agreements, the Company allocated the transaction price to the various performance obligations based on the relative SSP of each performance obligation, with the exception of co-development billings and commercial sale of product. Co-development billings under the AstraZeneca U.S./RoW Agreement were allocated entirely to the U.S./RoW co-development services performance obligation, and co-development billings under the AstraZeneca China Agreement were allocated entirely to the combined performance obligation under the AstraZeneca China Agreement. Commercial sale of product under the AstraZeneca U.S./ROW Agreement is entirely allocated to the manufacturing commercial supply of products performance obligation, and commercial sale of product under the AstraZeneca China Agreement is allocated entirely to the combined China performance obligation.

For revenue recognition purposes, the Company determined that the terms of its collaboration agreements with AstraZeneca begin on the effective date and end upon the completion of all performance obligations contained in the agreements. The contract term is defined as the period in which parties to the contract have present and enforceable rights and obligations. The Company believes that the requirement to continue funding development for a substantive period of time and the loss of product rights, along with non-refundable upfront payments already remitted by AstraZeneca, represent substantive termination penalties that create significant disincentive for AstraZeneca to exercise its right to terminate the agreement.

For the technology license under the AstraZeneca U.S./RoW Agreement, SSP was determined based on a two-step process. The first step involved determining an implied royalty rate that would result in the net present value of future cash flows to equal to zero (i.e. where the implied royalty rate on the transaction would equal the target return for the investment). This results in an upper bound estimation of the magnitude of royalties that a hypothetical acquirer would reasonably pay for the forecasted cash flow stream. The Company’s cash flow forecasts were derived from probability-adjusted revenue and expense projections. Such projections included consideration of taxes and cash flow adjustments. The probability adjustments were made after considering the likelihood of technical success at various stages of clinical trials and regulatory approval phases. The second step involved applying the implied royalty rate, which was determined to be 40%, against the probability-adjusted projected net revenues by territory and determining the value of the license as the net present value of future cash flows after adjusting for taxes. The discount rate utilized was 17.5%.

AstraZeneca U.S./RoW Agreement:

The promised services that were analyzed, along with their general timing of satisfaction and recognition as revenue, are as follows:

(1)

License to the Company’s technology existing at the effective date of the agreements. For the AstraZeneca U.S./RoW Agreement, the license was delivered at the beginning of the agreement term. The Company concluded that AstraZeneca has the knowledge and capabilities to fully exploit the license under the AstraZeneca U.S./RoW Agreement without the Company’s further involvement. Finally, the Company considered the fact that at the time of delivery of the license, the development services were beyond the preclinical development phase and any remaining development work would not be expected to result in any significant modification or customization to the licensed technology. As such, the development services are separately identifiable from the licensed technology, indicating that the license is a distinct performance obligation. Therefore, the Company has concluded that the license is distinct and represents a performance obligation. The portion of the transaction price allocated to this performance obligation based on a relative SSP basis is recognized as revenue in its entirety at the point in time the license transfers to AstraZeneca.

(2)

Co-development services. This promise relates to co-development services that were reasonably expected to be performed by the Company at the time the collaboration agreement was signed and is distinct. Co-development billings are allocated entirely to the co-development services performance obligation as amounts are related specifically to research and development efforts necessary to satisfy the performance obligation, and such an allocation is consistent with the allocation objective. Through the end of 2021, revenue was recognized over time based on progress toward complete satisfaction of the performance obligation. The Company used an input method to measure progress toward the satisfaction of the performance obligation related to CKD approval, which is based on costs of labor hours or full time equivalents and out-of-pocket expenses incurred relative to total expected costs to be incurred. Subsequently, the Company accounts for the development services for other significant indications related to chemotherapy-induced anemia and myelodysplastic syndromes separately as services are provided.

(3)

(4)

Information sharing and committee service. These promises are satisfied throughout the course of the agreement as services are provided.

Items (2)-(4) are bundled into a single performance obligation that is distinct given the fact that all are highly interrelated during the development period (pre-commercial phase of development) such that delivering them independently is not practicable. For the revenue recognized over time based on progress toward complete satisfaction of the performance obligation, the Company uses an input method to measure progress toward the satisfaction of the performance obligation, which is based on costs of labor hours or full time equivalents and out-of-pocket expenses incurred relative to total expected costs to be incurred, and updates the measure of progress in each reporting period.

(5)

Manufacturing commercial supplies of products. This promise is distinct as services are not interrelated with any of the other performance obligations. Revenue is recognized as supplies are shipped for commercial use during the commercialization period. The drug product revenue amount represents variable consideration and is estimated based on the quantity of product shipped and an estimated price for each individual purchase order. The estimated price is based on the contractual transfer price percentage applied on the estimated weighted average net sales price, which is estimated to be realized by AstraZeneca from the end sale of roxadustat in its approved territories. See the Drug Product Revenue section below.

AstraZeneca China Agreement:

The promised services that were analyzed are consistent with the AstraZeneca U.S./RoW Agreement, except for license to the Company’s technology existing at the effective date of the agreement, described as follows:

•

License to the Company’s technology existing at the effective date of the agreement. The license was delivered at the beginning of the agreement term. However, the AstraZeneca China Agreement has contractual limitations that might affect AstraZeneca’s ability to fully exploit the license and therefore, potentially, the conclusion as to whether the license is distinct in the context of the agreement. In the AstraZeneca China Agreement, AstraZeneca does not have the right to manufacture commercial supplies of the drug. In order to determine whether this characteristic of the arrangement should lead to a conclusion that the license was not distinct in the context of the agreement, the Company considered the ability of AstraZeneca to benefit from the license on its own or together with other resources readily available to AstraZeneca.

For the AstraZeneca China Agreement, the Company retained manufacturing rights as an essential part of a strategy to pursue domestic regulatory pathway for product approval, which requires the regulatory licensure of the manufacturing facility in order to commence commercial shipment. The prospects for the collaboration as a whole would have been substantially different had manufacturing rights been provided to AstraZeneca. The Company holds the rights to manufacture commercial drug product in China. Therefore, AstraZeneca cannot benefit from the license on its own or together with other readily available resources. Accordingly, all the promises identified, including the license, co-development services and manufacturing of commercial supplies, under the AstraZeneca China Agreement have been bundled into a single performance obligation and amounts of the transaction price allocable to this performance obligation are deferred until control of the manufactured commercial drug product has begun to transfer to AstraZeneca.

In accordance with the AstraZeneca China Amendment, once Falikang is fully operational, which commenced in January 2021, substantially all product sales will be made by Falikang directly to the distributors in China, while the Company continues to sell directly in one province in China. Revenue is recognized at a point in time when control of roxadustat commercial product is transferred to Falikang. For the Company’s direct sales of commercial drug product, revenue is recognized when control of the promised good is transferred to the customer in an amount that reflects the consideration that the Company expects to be entitled to in exchange for the product. See the Product Revenue, Net section below.

Product Revenue, Net

Product revenue, net from the sales of roxadustat commercial product in China was as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


	Years Ended December 31,
	2022			2021			2020
Direct Sales:
Gross revenue	$	12,366		$	13,727			89,027
Price adjustment		242			(982	)		—
Non-key account hospital listing award		49			95			(9,325	)
Contractual sales rebate		(624	)		(832	)		(6,189	)
Other discounts and rebates		(332	)		(21	)		(923	)
Sales returns		1			83			(92	)
Direct sales revenue, net		11,702			12,070			72,498

Sales to Falikang:
Gross transaction price		112,544			97,531			—
Profit share		(43,716	)		(34,759	)		—
Net transaction price		68,828			62,772			—
Decrease (increase) in deferred revenue		2,339			(27,204	)		—
Sales to Falikang revenue, net		71,167			35,568			—
Total product revenue, net	$	82,869		$	47,638		$	72,498

Direct Sales

Product revenue from direct roxadustat product sales to distributors in China is recognized in an amount that reflects the consideration that the Company expects to be entitled to in exchange for those products, net of sales rebates and discounts.

The total discounts and rebates were $0.7 million, $1.7 million and $16.4 million for the years ended December 31, 2022, 2021 and 2020, respectively. The discounts and rebates consisted of the contractual sales rebate calculated based on the stated percentage of gross sales by each distributor in the distribution agreement entered between FibroGen and each distributor. The contractual sales rebate was $0.6 million, $0.8 million and $6.2 million, for the years ended December 31, 2022, 2021 and 2020, respectively. The discounts and rebates for the year ended December 31, 2021 also consisted of $1.0 million of price adjustments recorded based on government-listed price guidance and estimated channel inventory levels. In the second quarter of 2020, the Company amended the agreement with its pharmaceutical distributors, which triggered accounting modifications particularly related to the non-key account hospital listing award. As a result, for the year ended December 31, 2020, the non-key account hospital listing award was $9.3 million, which was recorded as a reduction to the revenue and calculated based on eligible non-key account hospital listings to date achieved by each distributor with certain requirements met during the period. All other rebates and discounts, including sales return allowance were immaterial for the periods presented.

The rebates and discounts that the Company’s pharmaceutical distributors have earned are eligible to be applied against future sales orders, limited to certain maximums until such rebates and discounts are exhausted. These rebates and discounts are recorded as contract liabilities at the time they become eligible in the same period that the related revenue is recorded. Due to the Company’s legal right to offset, at each balance sheet date, the rebates and discounts are presented as reductions to gross accounts receivable from the distributor, or as a current liability to the distributor to the extent that the total amount exceeds the gross accounts receivable or when the Company expects to settle the discount in cash. The Company’s legal right to offset is calculated at the individual distributor level. The following table includes a roll-forward of the related contract liabilities (in thousands):


	Balance at December 31, 2021			Additions			Deduction		Currency Translation and Other		Balance at December 31, 2022
Product revenue - Direct sales - contract liabilities	$	(3,176	)	$	(653	)	$	3,222	$	217	$	(390	)

The above contract liabilities were included in accrued and other current liabilities in the consolidated balance sheet. As of December 31, 2022 and 2021, the total rebates and discounts reflected as reductions to gross accounts receivable for direct sales was $0.9 and $1.1 million, respectively.

Sales to Falikang – China Performance Obligation

Since Falikang became fully operational in January 2021, substantially all direct roxadustat product sales to distributors in China are made by Falikang. FibroGen Beijing manufactures and supplies commercial product to Falikang. The net transaction price for FibroGen Beijing’s product sales to Falikang is based on a gross transaction price, which is adjusted to account for the 50/50 profit share for the period.

The roxadustat sales to Falikang marked the beginning of the Company’s China performance obligation under the Company’s agreements with AstraZeneca. Product revenue is based on the transaction price of the China performance obligation. Revenue is recognized when control of the product is transferred to Falikang, in an amount that reflects the allocation of the transaction price to the performance obligation satisfied during the reporting period. Any net transaction price in excess of the revenue recognized is added to the deferred balance to date, and will be recognized over future periods as the performance obligations are satisfied.

Periodically, the Company updates its assumptions such as total sales quantity, performance period and other inputs including foreign currency translation impact, among others. Following updates to its estimates, the Company recognized $2.3 million from the previously deferred revenue of the China performance obligation during the year ended December 31, 2022. The product revenue recognized for the year ended December 31, 2022 included an increase in revenue of $1.4 million resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied in previous periods.

Comparatively, following updates to its estimates, the Company deferred $27.2 million from the net transaction price to Falikang, which was included in the related deferred revenue of the China performance obligation during the year ended December 31, 2021.

The following table includes a roll-forward of the related deferred revenue that is considered as a contract liability (in thousands):


	Balance at December 31, 2021			Additions			Recognized as Revenue		Currency Translation and Other		Balance at December 31, 2022
Product revenue - AstraZeneca China performance obligation - deferred revenue	$	(171,516	)	$	(77,195	)	$	71,167	$	1,898	$	(175,646	)

Deferred revenue includes amounts allocated to the China performance obligation under the AstraZeneca arrangement as revenue recognition associated with this unit of accounting is tied to the commercial launch of the products within China and to when the control of the manufactured commercial products is transferred to AstraZeneca. As of December 31, 2022, approximately $21.0 million of the above deferred revenue related to the China unit of accounting was included in short-term deferred revenue, which represents the amount of deferred revenue associated with the China unit of accounting that is expected to be recognized within the next 12 months, associated with the commercial sales in China.

Due to the Company’s legal right to offset, at each balance sheet date, the rebates and discounts, mainly related to profit sharing, are presented as reductions to gross accounts receivable from Falikang, which was $0.5 million and $13.4 million as of December 31, 2022 and 2021, respectively.

Drug Product Revenue

Drug product revenue from commercial-grade API or bulk drug product sales to Astellas and AstraZeneca was as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


	Years Ended December 31,
	2022		2021			2020
Astellas Japan Agreement	$	9,480	$	2,056		$	4,281
Astellas Europe Agreement		1,606		1,130			—
AstraZeneca U.S./RoW Agreement		—		(2,224	)		4,625
Drug product revenue	$	11,086	$	962		$	8,906

Astellas Japan Agreement

During the year ended December 31, 2020, the Company fulfilled shipment obligations under the terms of Astellas Japan Amendment with Astellas, and recognized related drug product revenue of $8.2 million in the same period. During the year ended December 31, 2020, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of the Astellas Japan Amendment, and accordingly recorded a reduction of $4.0 million to the drug product revenue. Specifically, the change in estimated variable consideration was based on the API held by Astellas at the period end, adjusted to reflect the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, estimated cost to convert the API to bulk product tablets, and estimated yield from the manufacture of bulk product tablets, among others.

During the year ended December 31, 2021, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment, and accordingly recorded adjustments to the drug product revenue of $2.1 million. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, estimated cost to convert the API to bulk product tablets, and estimated yield from the manufacture of bulk product tablets, among others.

During the first quarter of 2022, the Company fulfilled a shipment obligation under the terms of Astellas Japan Amendment, and recognized related drug product revenue of $9.8 million in the same period. During the fourth quarter of 2022, the Company fulfilled a shipment obligation under the terms of Astellas Japan Amendment, and recognized related drug product revenue of $8.4 million in the same period.

In addition, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of Japan Amendment with Astellas, and recorded a reduction to the drug product revenue of $8.7 million during the year ended December 31, 2022. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect foreign currency translation impact, the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, estimated cost to convert the API to bulk product tablets, and estimated yield from the manufacture of bulk product tablets, among others. This amount was included in accrued liabilities and as of December 31, 2022, the related balance in accrued liabilities was $6.5 million, representing the Company’s best estimate that this amount will be paid within the next 12 months.

Astellas Europe Agreement

During the fourth quarter of 2020, the Company transferred bulk drug product from process validation supplies for commercial purposes under the terms of the Astellas Europe Agreement. As a result, the Company recorded $6.0 million as deferred revenue as of December 31, 2020, due to a high degree of uncertainty associated with the final consideration.

During the first quarter of 2021, the Company transferred bulk drug product from process validation supplies for commercial purposes under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement. The Company recorded the consideration of $11.8 million from this inventory transfer as deferred revenue as of December 31, 2021, due to a high degree of uncertainty associated with the final consideration. During the fourth quarter of 2021, the Company transferred bulk drug product for commercial purposes under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement, and recognized the related fully-burdened manufacturing costs of $1.0 million as drug product revenue, and recorded $8.3 million as deferred revenue as of December 31, 2021, due to a high degree of uncertainty associated with the final consideration.

During the fourth quarter of 2021, the Company updated its estimate of variable consideration related to the bulk drug product inventory transfers fulfilled under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement, and recorded an unbilled contract asset of $49.8 million, which was offset by related deferred revenue under the Astellas Europe Agreement and Astellas EU Supply Agreement. Specifically, the change in estimated variable consideration was based on the bulk drug product held by Astellas at the period end, adjusted to reflect the changes in the estimated transfer price, among others.

During the second quarter of 2022, the Company transferred bulk drug product for commercial purposes under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement, and recognized the related fully-burdened manufacturing costs of $1.0 million as drug product revenue, and recorded $23.2 million as deferred revenue due to a high degree of uncertainty associated with the variable consideration for revenue recognition purposes.

During the first quarter of 2022, the Company billed and received $49.2 million from Astellas related to the annual transfer price true up for bulk drug product transferred for commercial purposes. This amount was recorded in deferred revenue and netted against an unbilled contract asset as of December 31, 2021. The Company updated its estimate of variable consideration related to the bulk drug product transferred in prior years. Specifically, the change in estimated variable consideration was based on the bulk drug product held by Astellas at the period end, adjusted to reflect the changes in the estimated transfer price, forecast information, shelf-life estimates and other items. As a result, during the year ended December 31, 2022, the Company reclassified a total of $57.4 million from the related deferred revenue to accrued liabilities. As of December 31, 2022, the related balance in accrued liabilities was $57.4 million, representing the Company’s best estimate that this amount will be paid within the next 12 months.

In addition, the Company recognized royalty revenue of $0.6 million and $0.2 million as drug product revenue from the deferred revenue under the Astellas Europe Agreement during the years ended December 31, 2022 and 2021, respectively. The remainder of the deferred revenue will be recognized as and when uncertainty is resolved, based on the performance of roxadustat product sales in the Astellas territory.

AstraZeneca U.S./RoW Agreement

During the first half of 2021 and during the year ended December 31, 2020, the Company shipped bulk drug product to AstraZeneca as commercial supply under the terms of the Master Supply Agreement. Based on the complete response letter issued by the U.S. Food and Drug Administration in August 2021, the Company evaluated the impact of these developments in revising its estimates of variable consideration associated with drug product revenue. As a result, the Company updated the estimated transaction price for these shipments, and recorded $11.2 million as deferred revenue as of December 31, 2021. The related drug product revenue was $(2.2) million and $4.6 million for the years ended December 31, 2021 and 2020, respectively.

During the first quarter of 2022, the Company evaluated the current developments in the U.S. market, and updated its estimates of variable consideration associated with bulk drug product shipments to AstraZeneca in prior years as commercial supply. As a result, during the year ended December 31, 2022, the Company reclassified $11.2 million from the related deferred revenue to accrued liabilities. As of December 31, 2022, the related balance in accrued liabilities was $11.2 million, representing its best estimate that this amount will be paid within the next 12 months.

The following table includes a roll-forward of the above-mentioned deferred revenues that are considered as contract liabilities related to drug product (in thousands):


	Balance at December 31, 2021			Additions			Recognized as Revenue		Reclassified to Accrued Liability / Accounts Payable		Balance at December 31, 2022
Astellas Japan Agreement	$	(1,974	)	$	(2,226	)	$	—	$	4,200	$	—
Astellas Europe Agreement		(25,891	)		(72,408	)		619		57,377		(40,303	)
AstraZeneca U.S./RoW Agreement		(11,171	)		—			—		11,171		—
Drug product revenue - deferred revenue	$	(39,036	)	$	(74,634	)	$	619	$	72,748	$	(40,303	)

Fair Value Measurements

In accordance with the authoritative guidance on fair value measurements and disclosures under U.S. GAAP, the Company presents all financial assets and liabilities and any other assets and liabilities that are recognized or disclosed at fair value on a nonrecurring basis. The guidance defines fair value, establishes a framework for measuring fair value in generally accepted accounting principles and expands disclosures about fair-value measurements. The guidance also requires fair value measurements be classified and disclosed in one of the following three categories:

Level 1: Quoted prices in active markets for identical assets or liabilities.

Level 2: Observable inputs other than quoted prices in active markets for identical assets or liabilities.

Level 3: Unobservable inputs.

The Company values certain assets and liabilities, focusing on the inputs used to measure fair value, particularly in instances where the measurement uses significant unobservable (Level 3) inputs. The Company’s financial instruments are valued using quoted prices in active markets (Level 1) or based upon other observable inputs (Level 2). The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and considers factors specific to the asset or liability. In addition, the categories presented do not suggest how prices may be affected by the size of the purchases or sales, particularly with the largest highly liquid financial issuers who are in markets continuously with non-equity instruments, or how any such financial assets may be impacted by other factors such as U.S. government guarantees. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The availability of observable data is monitored to assess appropriate classification of financial instruments within the fair value hierarchy. Depending upon the availability of such inputs, specific securities may transfer between levels. In such instances, the transfer is reported at the end of the reporting period.

Collaboration Agreements, License Agreement and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Detail) - Astellas Agreement [Member] $ in Thousands	Dec. 31, 2022 USD ($)
Japan [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	$ 117,229
Deferred Revenue	0
Total Consideration	117,229
Japan [Member] \| License Revenue [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	100,347
Deferred Revenue	0
Total Consideration	100,347
Japan [Member] \| Development Revenue [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	16,882
Deferred Revenue	0
Total Consideration	16,882
Europe [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	899,240
Deferred Revenue	0
Total Consideration	899,240
Europe [Member] \| License Revenue [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	618,975
Deferred Revenue	0
Total Consideration	618,975
Europe [Member] \| Development Revenue [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	280,265
Deferred Revenue	0
Total Consideration	$ 280,265

Net Loss Per Share

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Net Loss Per Share

12.

Net Loss Per Share

Potential common shares that would have the effect of increasing diluted earnings per share are considered to be anti-dilutive and as such, these shares are not included in the calculation of diluted earnings per share. The Company reported a net loss for each of the years ended December 31, 2022, 2021 and 2020. Therefore, dilutive common shares are not assumed to have been issued since their effect is anti-dilutive for these periods.

Diluted weighted average shares excluded the following potential common shares related to stock options, RSUs, PRSUs and TSR awards, and shares to be purchased under the 2014 Employee Stock Purchase Plan (“ESPP”) for the periods presented as they were anti-dilutive (in thousands):


	Years Ended December 31,
	2022		2021		2020
Employee stock options		9,520		8,461		6,694
RSUs, PRSUs and TSR awards		2,137		1,538		564
ESPP		305		417		306
		11,962		10,416		7,564

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (293,654)	$ (290,023)	$ (189,291)
Other comprehensive income (loss):
Foreign currency translation adjustments	75	1,235	(3,207)
Available-for-sale investments:
Unrealized gain (loss) on investments, net of tax effect	(1,632)	(899)	(545)
Other comprehensive gain (loss), net of taxes	(1,557)	336	(3,752)
Comprehensive loss	$ (295,211)	$ (289,687)	$ (193,043)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

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+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

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+ Details

Balance Sheet Components - Schedule of Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accrued Liabilities, Current [Abstract]
Preclinical and clinical trial accruals	$ 57,780	$ 56,283
API and bulk drug product price true-up	75,055	0
Acquired in-process research and development asset	0	35,000
Payroll and related accruals	22,562	20,909
Accrued co-promotion expenses - current	36,677	25,746
Contract liabilities to pharmaceutical distributors	390	3,176
Roxadustat profit share to AstraZeneca	7,280	7,895
Property taxes and other taxes	7,691	12,610
Professional services	5,480	6,074
Other	6,858	4,906
Total accrued and other current liabilities	$ 219,773	$ 172,599

Balance Sheet Components - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 149,287	$ 149,285
Less: accumulated depreciation	(128,682)	(121,008)
Property and equipment, net	20,605	28,277
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	102,580	103,352
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	21,175	19,300
Machinery [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	9,642	8,339
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	9,486	9,670
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,200	6,201
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 204	$ 2,423

Related Party Transactions

12 Months Ended

Dec. 31, 2021

Related Party Transactions

14.

Related Party Transactions

Astellas is an equity investor in the Company and considered a related party. During the years ended December 31, 2022, 2021 and 2020, the Company recorded license and development revenue related to collaboration agreements with Astellas of $32.5 million, $130.4 million, and $33.5 million, respectively. During the years ended December 31, 2022, 2021 and 2020, the Company also recorded drug product revenue from Astellas of $11.1 million, $3.2 million, and $4.3 million, respectively. See Note 3, Collaboration Agreements, License Agreement and Revenues, for details.

The Company’s expense related to collaboration agreements with Astellas was immaterial for each of the three years ended December 31, 2022.

As of December 31, 2022 and 2021, accounts receivable from Astellas were $1.5 million and $10.9 million, respectively.

As of December 31, 2022 and 2021, total deferred revenue from Astellas were $40.3 million and $27.9 million, respectively.

As of December 31, 2022, the amount due to Astellas was $63.9 million. As of December 31, 2021, the amount due to Astellas was immaterial.

Falikang, an entity jointly owned by FibroGen Beijing and AstraZeneca is an unconsolidated VIE accounted for as an equity method investment, and considered as a related party to the Company. FibroGen Beijing owns 51.1% of Falikang’s equity. See Note 4, Equity method investment - Variable Interest Entity, for details.

For the years ended December 31, 2022 and 2021, the net product revenue from sales to Falikang were $71.2 million, and $35.6 million, respectively. See the Product Revenue, Net section in Note 3, Collaboration Agreements, License Agreement and Revenues, for details. The other income from Falikang were immaterial for each of the three years ended December 31, 2022.

For the years ended December 31, 2022, 2021 and 2020, the investment income (loss) in Falikang was $1.6 million, $1.0 million, and $(0.2) million, respectively. As of December 31, 2022 and 2021, the Company’s equity method investment in Falikang were $5.1 million and $3.8 million, respectively. See Note 4, Equity method investment - Variable Interest Entity, for details.

As of December 31, 2022, accounts receivable, net, from Falikang were $10.5 million. As of December 31, 2021, accounts receivable, net, from Falikang was zero.

As of December 31, 2022, the total deferred revenue from Falikang was zero. As of December 31, 2021, the total deferred revenue from Falikang was $1.2 million.

Collaboration Agreements, License Agreement and Revenues - Summary of License Revenue and Development Revenue Recognized under Agreement (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	$ 140,734	$ 235,309	$ 176,319
License Revenue [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	22,590	116,434	14,323
Development Revenue [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	24,189	70,275	80,592
Development Revenue [Member] \| Europe [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	9,624	21,679	17,954
Astellas Agreement [Member] \| License Revenue [Member] \| Japan [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	0	0	14,323
Astellas Agreement [Member] \| License Revenue [Member] \| Europe [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	22,590	108,434	0
Astellas Agreement [Member] \| Development Revenue [Member] \| Japan [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	284	248	1,220
AstraZeneca Agreements [Member] \| China [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	0	0	(90)
AstraZeneca Agreements [Member] \| License Revenue [Member] \| U.S./RoW and China [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	0	0	0
AstraZeneca Agreements [Member] \| Development Revenue [Member] \| U.S./RoW and China [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	$ 12,519	$ 48,345	$ 61,508

Balance Sheet Components - Schedule of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Cash and Cash Equivalents [Abstract]
Cash	$ 135,819	$ 111,422
Commercial paper	0	1,000
Money market funds	19,881	58,801
Total cash and cash equivalents	$ 155,700	$ 171,223

Liability Related to Sale of Future Royalties (Tables)

12 Months Ended

Dec. 31, 2022

Schedule of Activity of Liability Related to Sale of Future Revenues

The table below shows the activity of the liability related to sale of future revenues for the year ended December 31, 2022:


	Year Ended December 31, 2022
Liability related to sale of future revenues - beginning balance	$	—
Proceeds from sale of future revenues, gross		50,000
Less: Initial issuance costs		(250	)
Less: Transaction costs		(1,453	)
Interest expense recognized		1,036
Liability related to sale of future revenues - ending balance		49,333
Less: Current portion classified within accrued and other current liabilities		—
Liability related to sale of future revenues, non-current	$	49,333

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Schedule of Components of Loss Before Income Taxes

The components of loss before income taxes are as follows (in thousands):


	Years Ended December 31,
	2022			2021			2020
Domestic	$	(307,056	)	$	(268,499	)	$	(195,617	)
Foreign		12,187			(22,184	)		6,888
Loss before provision for income taxes	$	(294,869	)	$	(290,683	)	$	(188,729	)

Schedule of Components of Provision For Income Taxes

The provision for income taxes consists of the following (in thousands):


	Years Ended December 31,
	2022		2021		2020
Current:
Federal	$	—	$	—	$	—
State		—		—		—
Foreign		358		347		360
Total current		358		347		360
Deferred:
Federal		—		—		—
State		—		—		—
Foreign		—		—		—
Total deferred		—		—		—
Total provision for income taxes	$	358	$	347	$	360

Schedule of Reconciliation Between Statutory Federal Income Tax Rate and Effective Tax Rate

The following is the reconciliation between the statutory federal income tax rate and the Company’s effective tax rate:


	Years Ended December 31,
	2022			2021			2020
Tax at statutory federal rate		21.0	%		21.0	%		21.0	%
State tax		—	%		—	%		—	%
Stock-based compensation expense		(2.5	)%		(1.8	)%		2.4	%
Benefit due to intercompany transfer of assets		—	%		—	%		41.7	%
Valuation allowance on intercompany transfer of assets		—	%		—	%		(41.7	)%
Net operating losses not benefitted		(16.3	)%		(16.8	)%		(23.2	)%
Foreign net operating losses not benefitted		0.9	%		(1.6	)%		0.7	%
Deduction limitation on executive compensation		(0.2	)%		(0.3	)%		(0.8	)%
Global intangible low-taxed income		(2.8	)%		(0.4	)%		—	%
Other		(0.2	)%		(0.2	)%		(0.3	)%
Total		(0.1	)%		(0.1	)%		(0.2	)%

Schedule of Significant Components of Deferred Tax Assets

Significant components of the Company’s deferred tax assets are as follows (in thousands):


	December 31,
	2022			2021
Federal and state net operating loss carryforwards	$	166,708		$	167,135
Tax credit carryforwards		106,131			78,832
Foreign net operating loss carryforwards		49,990			38,117
Capitalized research and development expenses		45,125			—
Stock-based compensation		8,616			10,050
Lease obligations		18,442			20,415
Reserves and accruals		4,929			6,067
Deferred revenue		21,624			20,101
Intangible assets		69,159			84,625
Other		1,277			825
Subtotal		492,001			426,167
Less: Valuation allowance		(477,969	)		(409,810	)
Net deferred tax assets		14,032			16,357

Fixed assets		(13,101	)		(16,357	)
Non-deductibale accrued expenses		(931	)		—
Net deferred tax liabilities		(14,032	)		(16,357	)
Total net deferred tax assets	$	—		$	—

Schedule of Reconciliation of the Beginning and Ending Amounts of Unrecognized Income Tax Benefits

A reconciliation of the beginning and ending amounts of unrecognized income tax benefits during the three years ended December 31, 2022 is as follows (in thousands):


	Federal and State
Balance as of December 31, 2019	$	32,263
Decrease due to prior positions		(137	)
Increase due to current year position		16,448
Balance as of December 31, 2020		48,574
Decrease due to prior positions		(245	)
Increase due to current year position		8,415
Foreign exchange rate differential		927
Balance as of December 31, 2021		57,671
Increase due to prior positions		6,954
Increase due to current year position		9,074
Foreign exchange rate differential		(908	)
Balance as of December 31, 2022	$	72,791

Equity and Stock-based Compensation - Stock Plans - Summary of Stock Option Transactions (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares
Share-Based Payment Arrangement [Abstract]
Outstanding, Beginning Balance, Shares \| shares	8,967
Granted, Shares \| shares	2,902
Exercised, Shares \| shares	(179)
Expired, Shares \| shares	(1,847)
Forfeited, Shares \| shares	(755)
Outstanding, Ending Balance, Shares \| shares	9,088
Vested and expected to vest, Shares \| shares	8,614
Exercisable, Shares \| shares	4,730
Outstanding, Beginning Balance, Weighted Average Exercise Price per Share \| $ / shares	$ 34.84
Granted, Weighted Average Exercise Price per Share \| $ / shares	14.72
Exercised, Weighted Average Exercise Price per Share \| $ / shares	8.24
Expired, Weighted Average Exercise Price per Share \| $ / shares	34.36
Forfeited, Weighted Average Exercise Price per Share \| $ / shares	32.89
Outstanding, Ending Balance, Weighted Average Exercise Price per Share \| $ / shares	29.19
Vested and expected to vest, Weighted Average Exercise per Share \| $ / shares	29.61
Exercisable, Weighted Average Exercise Price per Share \| $ / shares	$ 35.07
Outstanding, Weighted Average Remaining Contractual Life	7 years 10 days
Vested and expected to vest, Weighted Average Remaining Contractual Life	6 years 11 months 4 days
Exercisable, Weighted Average Remaining Contractual Life	5 years 5 months 12 days
Outstanding, Aggregate Intrinsic Value \| $	$ 6,232
Vested and expected to vest, Aggregate Intrinsic Value \| $	5,770
Exercisable, Aggregate Intrinsic Value \| $	$ 1,438

Summary of Significant Accounting Policies - Additional Information (Detail)		12 Months Ended
	Jun. 16, 2021 USD ($)	Dec. 31, 2022 USD ($) Segment	Dec. 31, 2021 USD ($)
Accounting Policy [Line Items]
Number of operating segment \| Segment		1
Highly liquid investment maturity period		three months or less
Restricted time deposits		$ 2,100,000	$ 2,100,000
Cash and cash equivalents		$ 155,700,000	171,223,000
Short term investments maturity		12 months
Long term Investments Maturity		12 months
Impairment of long-lived assets		$ 0	0
Impairment of inatangible assets finite lived		$ 0	0
Description of payment term		The period between the transfer of control of the promised goods and when the Company receives payment is based on 60-day payment terms.
Description of sales return		Distributors can request to return product to the Company only due to quality issues or for product purchased within one year prior to the product’s expiration date.
Accumulated deficit		$ (1,557,688,000)	(1,264,034,000)
Accumulated other comprehensive loss		$ (5,720,000)	(4,163,000)
AstraZeneca Agreements [Member]
Accounting Policy [Line Items]
Profit share percent		50.00%
HiFiBiO Agreement [Member]
Accounting Policy [Line Items]
Initial upfront payment	$ 25,000,000.0
Maximum additional future clinical, regulatory, and commercial milestone payments	$ 345,000,000
HiFiBiO Agreement [Member] \| IPR&D Asset [Member]
Accounting Policy [Line Items]
Initial upfront payment			60,000,000.0
HiFiBiO Agreement [Member] \| Accrued Liabilities
Accounting Policy [Line Items]
Initial upfront payment			35,000,000.0
Minimum [Member] \| Computer Equipment [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life		3 years
Minimum [Member] \| Laboratory Equipment [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life		3 years
Minimum [Member] \| Machinery [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life		3 years
Minimum [Member] \| Furniture and Fixtures [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life		3 years
Maximum [Member] \| Computer Equipment [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life		5 years
Maximum [Member] \| Laboratory Equipment [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life		5 years
Maximum [Member] \| Machinery [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life		5 years
Maximum [Member] \| Furniture and Fixtures [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life		5 years
Foreign subsidiaries [Member]
Accounting Policy [Line Items]
Cash and cash equivalents		$ 92,500,000	$ 91,200,000
Accounts Receivable from Distributors [Member] \| Credit Concentration Risk [Member] \| Roxadustat [Member]
Accounting Policy [Line Items]
Concentration risk, percentage		10.00%

Product Development Obligations

12 Months Ended

Dec. 31, 2022

Debt Disclosure [Abstract]

Product Development Obligations

The Technology Development Center of the Republic of Finland (“TEKES”) product development obligations consist of 11 separate advances (each in the form of a note agreement) received by FibroGen Europe between 1996 and 2008 from TEKES. These advances are granted on a project-by-project basis to fund various product development efforts undertaken by FibroGen Europe only. Each separate note is denominated in EUR and bears interest (not compounded) calculated as one percentage point less than the Bank of Finland rate in effect at the time of the note, but no less than 3.0%.

If the research work funded by TEKES does not result in an economically profitable business or does not meet its technological objectives, TEKES may, on application from FibroGen Europe, forgive each of these loans, including accrued interest, either in full or in part. As of December 31, 2022 and 2021, the Company had U.S. Dollar equivalent of $10.1 million and $10.7 million of principal outstanding, respectively, and $6.8 million and $6.9 million of interest accrued, respectively, which were presented in the product development obligations line on the consolidated balance sheets.

The Company is not a guarantor of these loans, and these loans are not repayable by FibroGen Europe until it has distributable funds.

The Company

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The Company

FibroGen, Inc. (“FibroGen” or the “Company”) is headquartered in San Francisco, California, with subsidiary offices in Beijing and Shanghai, People’s Republic of China (“China”). FibroGen is a leading biopharmaceutical company developing and commercializing a pipeline of first-in-class therapeutics. The Company applies its pioneering expertise in hypoxia-inducible factor (“HIF”) biology, 2-oxoglutarate enzymology, and connective tissue growth factor to advance innovative medicines for the treatment of anemia, fibrotic disease, and cancer.

Pamrevlumab, a human monoclonal antibody targeting connective tissue growth factor, is in Phase 3 clinical development for the treatment of idiopathic pulmonary fibrosis, locally advanced unresectable pancreatic cancer and Duchenne muscular dystrophy. To date, the Company has retained exclusive worldwide rights for pamrevlumab.

Roxadustat is an oral small molecule inhibitor of HIF prolyl hydroxylase activity. Roxadustat (爱瑞卓®, EVRENZOTM) is approved in China, Europe, Japan, and numerous other countries for the treatment of anemia in chronic kidney disease (“CKD”) for patients who are on dialysis and not on dialysis.

Roxadustat is in Phase 3 clinical development for: anemia associated with myelodysplastic syndromes, in the U.S. and Europe, and chemotherapy-induced anemia in China.

The Company has a pipeline of late-stage clinical programs as well as preclinical drug candidates at various stages of development that include both small molecules and biologics. FibroGen’s goal is to build a diversified pipeline with novel drugs that will address unmet patient needs in oncology, immunology, and fibrosis.

Income Taxes - Schedule of Significant Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Components of Deferred Tax Assets and Liabilities [Abstract]
Federal and state net operating loss carryforwards	$ 166,708	$ 167,135
Tax credit carryforwards	106,131	78,832
Foreign net operating loss carryforwards	49,990	38,117
Capitalized research and development expenses	45,125	0
Stock-based compensation	8,616	10,050
Lease obligations	18,442	20,415
Reserves and accruals	4,929	6,067
Deferred revenue	21,624	20,101
Intangible assets	69,159	84,625
Other	1,277	825
Subtotal	492,001	426,167
Less: Valuation allowance	(477,969)	(409,810)
Net deferred tax assets	14,032	16,357
Fixed assets	(13,101)	(16,357)
Non-deductibale accrued expenses	(931)	0
Net deferred tax liabilities	(14,032)	(16,357)
Total net deferred tax assets	$ 0	$ 0

Liability Related to Sale of Future Royalties

12 Months Ended

Dec. 31, 2022

On November 4, 2022, the Company entered into a Revenue Interest Financing Agreement (the “RIFA”) with NQ Entity, L.P. (“NovaQuest”), pursuant to which the Company granted a percentage interest in the Company’s future revenues under the Astellas Agreements, for a consideration of $50.0 million (“Investment Amount”) before advisory fees. The Company has evaluated the terms of the RIFA and concluded that the Investment Amount should be accounted for as debt because the risks and rewards to NovaQuest are limited by the terms of the transaction.

Under the terms of the Astellas Agreements, the Company is entitled to drug product revenue and milestone payments upon occurrence of certain events. See the Astellas Agreements section in Note 3, Collaboration Agreements, License Agreement and Revenue, for details.

Effective as of November 2022, the Company sold to NovaQuest 22.5% of its drug product revenue and 10.0% (20.0% for fiscal year 2028 and thereafter) of its revenue from milestone payments under the Astellas Agreements. The Company received $49.8 million from NovaQuest at an initial funding on November 17, 2022, representing the gross proceeds of $50.0 million (the “Initial Investment Amount”) net of initial issuance costs, and accounted for this transaction as long-term debt as of December 31, 2022.

The Company may prepay its obligations to NovaQuest in full at any time during the term of RIFA. The prepayment amount varies from $80.0 million to $125.0 million less any revenue interest payments made up to such prepayment date. Under the RIFA the Company shall pay to NovaQuest up to a specified maximum amount (“Payment Cap”) of (a) $100.0 million, if the payment is made on or before December 31, 2028; (b) $112.5 million, if the payment is made is on or after January 1, 2029, but on or before December 31, 2029; or (c) $125.0 million, if the payment is made after January 1, 2030.

After January 1, 2028, if the product (as defined) is not commercialized for a consecutive twelve-month period, then, the payments owed under the RIFA by the Company to NovaQuest for each fiscal year shall be the greater of: (i) the amount which would otherwise be due pursuant to revenue interest payments terms; or (ii) $10.0 million.

Before December 31, 2028, if the sum of all payments under the RIFA paid to NovaQuest, does not equal or exceed $62.5 million, then the Company shall pay NovaQuest the difference of these two amounts by no later than March 1, 2029 (“True-Up Payment One”). If, by no later than December 31, 2030, the sum of all payments under the RIFA paid to NovaQuest does not equal or exceed $125.0 million, then the Company shall pay NovaQuest the difference of these two amounts by no later than March 1, 2031.

NovaQuest will retain this entitlement until it has reached the Payment Cap, at which point 100% of such revenue interest on future global net sales of Astellas will revert to the Company.

The payments to NovaQuest will be accounted for as a reduction of debt. The total debt discount and transaction costs of $1.7 million, will be amortized as interest expense based on the projected balance of the liability as of the beginning of each period. The Company estimated an effective annual interest rate of approximately 19.67% for the year ended December 31, 2022. Over the course of the RIFA, the effective interest rate will be affected by the amount and timing of drug product revenue and revenue from milestone payments recognized, the changes in the timing of forecasted drug product revenue and revenue from milestone payments, and the timing of the Company’s payments to NovaQuest. On a quarterly basis, the Company will reassess the expected total revenue and the timing of such revenue, recalculate the amortization of debt discount and transactions costs and effective interest rate, and adjust the accounting prospectively as needed.

As payments are made to NovaQuest, the balance of the liability related to sale of future revenues is being effectively repaid over the life of the RIFA.

During the year ended December 31, 2022, the Company recognized, under Astellas Agreements, license revenue of $22.6 million and development revenue of $2.4 million related to a $25.0 million regulatory milestone, and drug product revenue of $11.1 million. See Note 3, Collaboration Agreements, License Agreement and Revenue, for details. During the year ended December 31, 2022, the Company recognized the related non-cash interest expense of $1.0 million.

The table below shows the activity of the liability related to sale of future revenues for the year ended December 31, 2022:


	Year Ended December 31, 2022
Liability related to sale of future revenues - beginning balance	$	—
Proceeds from sale of future revenues, gross		50,000
Less: Initial issuance costs		(250	)
Less: Transaction costs		(1,453	)
Interest expense recognized		1,036
Liability related to sale of future revenues - ending balance		49,333
Less: Current portion classified within accrued and other current liabilities		—
Liability related to sale of future revenues, non-current	$	49,333

Based on the current estimates of drug product revenue and revenue from milestone payments under the Astellas Agreements, and taking into the consideration of the terms discussed above, the Company anticipates to reach a Payment Cap up to $125.0 million by 2031.

Equity and Stock-based Compensation - Non-Controlling Interests and Subsidiary Stock - Additional information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Nov. 19, 2014	Jan. 31, 2013
Class Of Stock [Line Items]
Preferred stock, shares outstanding	0	0
IPO [Member]
Class Of Stock [Line Items]
Conversion rights, shares issued upon conversion of each preferred share			958,996
FibroGen Europe [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	42,619,022	42,619,022
Preferred stock redemption percentage	Redemption Right — If a Preferred Share can be redeemed by a majority shareholder owning more than ninety percent (90%) of the shares of FibroGen Europe in accordance with the provisions of the Finnish Limited Liability Companies Act, the minority holders of Preferred Shares have the right to request redemption of their shares.
Minimum percentage of shareholder's approval to call for redemption of preferred shares	90.00%
Preferred stock, voting rights	one vote
Conversion rights, shares issued upon conversion of each preferred share	1
FibroGen Europe [Member] \| Series A [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	1,700,845	1,700,845
FibroGen Europe [Member] \| Series B [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	1,875,000	1,875,000
FibroGen Europe [Member] \| Series C [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	1,599,503	1,599,503
FibroGen Europe [Member] \| Series D [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	1,520,141	1,520,141
FibroGen Europe [Member] \| Series E [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	459,565	459,565
FibroGen Europe [Member] \| Series F [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	5,714,332	5,714,332
FibroGen Europe [Member] \| Series G [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	9,927,500	9,927,500
FibroGen Europe [Member] \| Series H [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	19,822,136	19,822,136
FibroGen Cayman [Member]
Class Of Stock [Line Items]
Conversion rights, shares issued upon conversion of each preferred share	1
Convertible promissory note		$ 0.7		$ 0.6
Convertible promissory note interest rate	2.00%
Conditions of payment of interest, convertible promissory note	0
FibroGen Cayman [Member] \| Series A [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	6,758,000	6,758,000
Preferred shares issued, price per share	$ 1.00
Cash dividend percentage	6.00%

Segment and Geographic Information - Additional information (Detail) - Segment	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2020
Number of operating segment	1
Customer Concentration Risk [Member] \| Percentage of Revenue [Member] \| Roxadustat [Member]
Concentration risk, percentage		42.00%
Customer Concentration Risk [Member] \| Percentage of Accounts Receivable [Member] \| Roxadustat [Member]
Concentration risk, percentage		64.00%

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Summary of Outstanding Non-cancelable Purchase Obligations

As of December 31, 2022, the Company had the following outstanding non-cancelable purchase obligations (in thousands):


	Purchase Obligations Due In The Year Ending December 31,
	2023		2024		Total
Manufacture and supply of pamrevlumab	$	85	$	22,310	$	22,395
Manufacture and supply of roxadustat		6,126		2,369		8,495
Other purchases and programs		21,698		1,167		22,865
Total	$	27,909	$	25,846	$	53,755

Segment and Geographic Information - Summary of Finance and Operating Lease Right of Use Assets by Geographical Location (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Total finance lease right-of-use assets	$ 435	$ 761
Total operating lease right-of-use assets	79,893	91,112
United States [Member]
Total finance lease right-of-use assets	424	730
Total operating lease right-of-use assets	76,273	87,113
China [Member]
Total finance lease right-of-use assets	11	31
Total operating lease right-of-use assets	$ 3,620	$ 3,999

Commitments and Contingencies - Additional Information (Detail) $ in Millions	2 Months Ended	12 Months Ended
	May 31, 2021 PutativeClassAction	Dec. 31, 2022 USD ($)
Commitments And Contingencies [Line Items]
Putative securities class action complaints filed \| PutativeClassAction	5
Research and Preclinical Stage Development Programs [Member]
Commitments And Contingencies [Line Items]
Maximum future milestone payments \| $		$ 697.9

Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Valuation Allowances for Deferred Tax Assets [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 409,810	$ 337,824	$ 213,847
Charged (Credited) to Statement of Operation	68,159	71,986	123,977
Charged to Other Accounts - Liabilities and Equity	0	0	0
Deductions, Net	0	0	0
Balance at End of Year	477,969	409,810	337,824
Valuation Allowances for Rebates, Discounts and Adjustments [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	14,443	548	1,102
Charged (Credited) to Statement of Operation	39,082	44,258	16,497
Charged to Other Accounts - Liabilities and Equity	1,050	(734)	(14,867)
Deductions, Net	(53,226)	(29,629)	(2,184)
Balance at End of Year	$ 1,349	$ 14,443	$ 548

Equity and Stock-based Compensation - Stock Plans - Additional information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Feb. 28, 2022	Sep. 30, 2014	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total intrinsic value of options exercised			$ 1,438
RSUs released and issued net of shares withheld for taxes			779,539
Weighted-average fair value of awards granted			$ 14.68	$ 30.19	$ 29.99
Weighted average fair value of stock options granted			14.72	$ 35.58	$ 31.55
PRSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted, Shares	280,450
TSR [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average fair value of stock options granted			$ 24.01
Granted, Shares	280,450
RSUs, PRSUs and TSR awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of vesting rights			100.00%
Maximum [Member] \| PRSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of vesting rights	200.00%
Maximum [Member] \| TSR [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of vesting rights	200.00%
Minimum [Member] \| PRSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of vesting rights	0.00%
Minimum [Member] \| TSR [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of vesting rights	0.00%
2005 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of stock options			4 years
2005 Stock Plan \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period of stock options			10 years
2014 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of stock options			5 years
Expiration period of stock options			10 years
Termination date of equity incentive plan			Nov. 12, 2024
Option vesting term			Option vesting schedules are determined by the Company at the time of issuance and generally have a four year vesting schedule (25% vesting on the first anniversary of the vesting base date and quarterly thereafter over the next 3 years).
Number of common stock reserved for issuance			11,523,829
Common stock reserved for future issuance, Description			Shares reserved for issuance increases on January 1 of each year commencing on January 1, 2016 and ending on January 1, 2024 by the lesser of (i) the amount equal to 4% of the number of shares issued and outstanding on December 31 immediately prior to the date of increase or (ii) such lower number of shares as may be determined by the board of directors. As of December 31, 2022, the Company has reserved 11,523,829 shares of its common stock that remains unissued for issuance under the 2014 Plan.
Percentage of common stock reserved for future issuance		4.00%
Number of common stock repurchased			0	0
Total intrinsic value of options exercised			$ 800	$ 13,100	$ 89,600
2014 Equity Incentive Plan \| First Anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of vesting rights			25.00%
2014 Equity Incentive Plan \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair value exercise price grant date			100.00%

Equity and Stock-based Compensation - Summary of Common Stock Reserved for Future Issuance (Detail) - shares shares in Thousands	Dec. 31, 2022	Dec. 31, 2021
Class Of Stock [Line Items]
Common stock outstanding	94,166	92,881
Stock options outstanding	9,088	8,967
RSUs outstanding	3,669	2,304
Shares reserved for future stock options and RSUs grant	11,524	10,253
Total shares of common stock reserved	123,820	119,176
ESPP [Member]
Class Of Stock [Line Items]
Shares reserved for future ESPP offering	5,373	4,771

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Schedule of Weighted Impacts of Outstanding Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share


	Years Ended December 31,
	2022		2021		2020
Employee stock options		9,520		8,461		6,694
RSUs, PRSUs and TSR awards		2,137		1,538		564
ESPP		305		417		306
		11,962		10,416		7,564

Balance Sheet Components - Summary of Contractual Maturities of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 273,189	$ 402,664
Estimated Fair Value	270,656	$ 401,763
Within one year - Bond and mutual funds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	268,709
Estimated Fair Value	266,308
After one year through three years
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	4,480
Estimated Fair Value	$ 4,348

Balance Sheet Components - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Investments [Abstract]
Raw materials	$ 1,241	$ 1,363
Work-in-progress	36,003	21,499
Finished goods	3,192	8,153
Total inventories	$ 40,436	$ 31,015

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Fair Values of Financial Assets Measured on Recurring Basis

The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands):


	December 31, 2022
	Level 1		Level 2		Level 3		Total
Money market funds	$	19,881	$	—	$	—	$	19,881
Corporate bonds		—		82,008		—		82,008
Commercial paper		—		57,381		—		57,381
U.S. government bonds		98,972		12,373		—		111,345
Agency bonds		—		11,468		—		11,468
Asset-backed securities		—		2,474		—		2,474
Foreign government bonds		—		4,980		—		4,980
Convertible promissory note		—		—		1,000		1,000
Total	$	118,853	$	170,684	$	1,000	$	290,537

	December 31, 2021
	Level 1		Level 2		Level 3		Total
Money market funds	$	58,801	$	—	$	—	$	58,801
Corporate bonds		—		182,646		—		182,646
Commercial paper		—		69,079		—		69,079
U.S. government bonds		91,522		—		—		91,522
Agency bonds		—		23,275		—		23,275
Asset-backed securities		—		27,087		—		27,087
Foreign government bonds		—		9,154		—		9,154
Total	$	150,323	$	311,241	$	—	$	461,564

Liability Related to Sale of Future Royalties - Schedule of Activity of Liability Related to Sale of Future Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Liability Related to Sale of Future Royalties [Abstract]
Liability related to sale of future revenues - beginning balance	$ 0
Proceeds from sale of future revenues, gross	50,000
Less: Initial issuance costs	(250)
Less: Transaction costs	(1,453)
Interest expense recognized	1,036
Liability related to sale of future revenues - ending balance	49,333	$ 0
Less: Current portion classified within accrued and other current liabilities	0
Liability related to sale of future revenues, non-current	$ 49,333

Collaboration Agreements,License Agreement and Revenues - Roll-forward of Related Contract Liabilities (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
AstraZeneca Agreements [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2021	$ (171,516)
Additions	(77,195)
Currency Translation and Other	1,898
Recognized as Revenue	71,167
Balance at December 31, 2022	(175,646)
Product [Member] \| Direct Sales [Member] \| Contract Liabilities [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2021	(3,176)
Additions	(653)
Deduction	3,222
Currency Translation and Other	217
Balance at December 31, 2022	(390)
Drug Product Revenue [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2021	(39,036)
Additions	(74,634)
Recognized as Revenue	619
Reclassified to accrued liability / accounts payable	72,748
Balance at December 31, 2022	(40,303)
Drug Product Revenue [Member] \| AstraZeneca Agreements [Member] \| U.S. [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2021	(11,171)
Additions	0
Recognized as Revenue	0
Reclassified to accrued liability / accounts payable	11,171
Balance at December 31, 2022	0
Drug Product Revenue [Member] \| Astellas Agreement \| Japan [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2021	(1,974)
Additions	(2,226)
Recognized as Revenue	0
Reclassified to accrued liability / accounts payable	4,200
Balance at December 31, 2022	0
Drug Product Revenue [Member] \| Astellas Agreement \| Europe [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2021	(25,891)
Additions	(72,408)
Recognized as Revenue	619
Reclassified to accrued liability / accounts payable	57,377
Balance at December 31, 2022	$ (40,303)

Collaboration Agreements,License Agreement and Revenues

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Collaboration Agreements,License Agreement and Revenues

Collaboration Agreements, License Agreement and Revenues

Astellas Agreements

Astellas Japan Agreement

Astellas Europe Agreement

Accounting for the Astellas Agreements

The promised services that were analyzed, along with their general timing of satisfaction and recognition as revenue, are as follows:

(1)

(2)

(3)

(4)

(5)

Committee service. This promise is satisfied throughout the course of the agreements as meetings are attended.

(6)

License Revenue and Development Revenue Recognized Under the Astellas Agreements

Amounts recognized as license revenue and development revenue under the Astellas Japan Agreement were as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021		2020
Astellas Japan Agreement	License revenue	$	—	$	—	$	14,323
	Development revenue	$	284	$	248	$	1,220


Astellas Japan Agreement	Cumulative Revenue Through December 31, 2022		Deferred Revenue at December 31, 2022		Total Consideration Through December 31, 2022
License	$	100,347	$	—	$	100,347
Development revenue		16,882		—		16,882
Total license and development revenue	$	117,229	$	—	$	117,229

Amounts recognized as license revenue and development revenue under the Astellas Europe Agreement were as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021		2020
Astellas Europe Agreement	License revenue	$	22,590	$	108,434	$	—
	Development revenue	$	9,624	$	21,679	$	17,954

The transaction price related to consideration received through December 31, 2022 and accounts receivable has been allocated to each of the following performance obligations under the Astellas Europe Agreement, along with any associated deferred revenue as follows (in thousands):


Astellas Europe Agreement	Cumulative Revenue Through December 31, 2022		Deferred Revenue at December 31, 2022		Total Consideration Through December 31, 2022
License	$	618,975	$	—	$	618,975
Development revenue		280,265		—		280,265
Total license and development revenue	$	899,240	$	—	$	899,240

AstraZeneca Agreements

AstraZeneca U.S./Rest of World (“RoW”) Agreement

AstraZeneca China Agreement

The aggregate amount of the considerations received for milestone and upfront payments under the AstraZeneca China Agreement through December 31, 2022 totals $77.2 million.

AstraZeneca China Amendment

As a result, the interim period during the year ended December 31, 2020 primarily included the following activities:

•

The related net product revenue recognized from the sales to Falikang and the sales directly to distributors are discussed under the Product Revenue, Net section below.

Accounting for the AstraZeneca Agreements

Promised services that were not distinct have been combined with other promised services to form a distinct bundle of promised services, with revenue being recognized on the bundle of services rather than the individual promised services. There are no right-of-return provisions for the delivered items in the AstraZeneca agreements.

AstraZeneca U.S./RoW Agreement:

The promised services that were analyzed, along with their general timing of satisfaction and recognition as revenue, are as follows:

(1)

(2)

(3)

(4)

Information sharing and committee service. These promises are satisfied throughout the course of the agreement as services are provided.

(5)

AstraZeneca China Agreement:

•

License Revenue and Development Revenue Recognized Under the AstraZeneca Agreements

Amounts recognized as license revenue and development revenue under the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement were as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021		2020
AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement	License revenue	$	—	$	—	$	—
	Development revenue		12,519		48,345		61,508
	China performance obligation	$	—	$	—	$	(90	)

The transaction price related to consideration received through December 31, 2022 and accounts receivable has been allocated to each of the following performance obligations under the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement, along with any associated deferred revenue as follows (in thousands):


AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement	Cumulative Revenue Through December 31, 2022		Deferred Revenue at December 31, 2022			Total Consideration Through December 31, 2022
License	$	341,844	$	—		$	341,844
Co-development, information sharing & committee services		615,639		—			615,639
China performance obligation *		106,734		175,646			282,380
Total license and development revenue	$	1,064,217	$	175,646	**	$	1,239,863

* China performance obligation revenue is recognized as product revenue, as described in details under Product Revenue, Net section below.

** Contract assets and liabilities related to rights and obligations in the same contract are recorded net on the consolidated balance sheets. As of December 31, 2022, deferred revenue included $158.2 million related to the AstraZeneca U.S./RoW and the AstraZeneca China Agreement, which represents the net of $175.6 million of deferred revenue presented above and a $17.5 million unbilled co-development revenue under the AstraZeneca China Amendment.

There was no license revenue or development revenue resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods for the year ended December 31, 2022. The remainder of the transaction price related to the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement includes $9.6 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period, except for amounts allocated to the China performance obligation. The amount allocated to the China performance obligation is expected to be recognized as the Company transfers control of the commercial drug product to Falikang, and is expected to continue through 2028, which reflects our best estimates.

Product Revenue, Net

Product revenue, net from the sales of roxadustat commercial product in China was as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


	Years Ended December 31,
	2022			2021			2020
Direct Sales:
Gross revenue	$	12,366		$	13,727			89,027
Price adjustment		242			(982	)		—
Non-key account hospital listing award		49			95			(9,325	)
Contractual sales rebate		(624	)		(832	)		(6,189	)
Other discounts and rebates		(332	)		(21	)		(923	)
Sales returns		1			83			(92	)
Direct sales revenue, net		11,702			12,070			72,498

Sales to Falikang:
Gross transaction price		112,544			97,531			—
Profit share		(43,716	)		(34,759	)		—
Net transaction price		68,828			62,772			—
Decrease (increase) in deferred revenue		2,339			(27,204	)		—
Sales to Falikang revenue, net		71,167			35,568			—
Total product revenue, net	$	82,869		$	47,638		$	72,498

Direct Sales


	Balance at December 31, 2021			Additions			Deduction		Currency Translation and Other		Balance at December 31, 2022
Product revenue - Direct sales - contract liabilities	$	(3,176	)	$	(653	)	$	3,222	$	217	$	(390	)

Sales to Falikang – China Performance Obligation

The following table includes a roll-forward of the related deferred revenue that is considered as a contract liability (in thousands):


	Balance at December 31, 2021			Additions			Recognized as Revenue		Currency Translation and Other		Balance at December 31, 2022
Product revenue - AstraZeneca China performance obligation - deferred revenue	$	(171,516	)	$	(77,195	)	$	71,167	$	1,898	$	(175,646	)

Drug Product Revenue

Drug product revenue from commercial-grade API or bulk drug product sales to Astellas and AstraZeneca was as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


	Years Ended December 31,
	2022		2021			2020
Astellas Japan Agreement	$	9,480	$	2,056		$	4,281
Astellas Europe Agreement		1,606		1,130			—
AstraZeneca U.S./RoW Agreement		—		(2,224	)		4,625
Drug product revenue	$	11,086	$	962		$	8,906

Astellas Japan Agreement

Astellas Europe Agreement

AstraZeneca U.S./RoW Agreement

The following table includes a roll-forward of the above-mentioned deferred revenues that are considered as contract liabilities related to drug product (in thousands):


	Balance at December 31, 2021			Additions			Recognized as Revenue		Reclassified to Accrued Liability / Accounts Payable		Balance at December 31, 2022
Astellas Japan Agreement	$	(1,974	)	$	(2,226	)	$	—	$	4,200	$	—
Astellas Europe Agreement		(25,891	)		(72,408	)		619		57,377		(40,303	)
AstraZeneca U.S./RoW Agreement		(11,171	)		—			—		11,171		—
Drug product revenue - deferred revenue	$	(39,036	)	$	(74,634	)	$	619	$	72,748	$	(40,303	)

Eluminex Agreements

In July 2021, FibroGen exclusively licensed to Eluminex Biosciences (Suzhou) Limited (“Eluminex”) global rights to its investigational biosynthetic cornea derived from recombinant human collagen Type III.

Under the terms of the agreement with Eluminex, as amended and restated on January 21, 2022, Eluminex made an $8.0 million upfront payment to FibroGen during the first quarter of 2022, which was recognized as license revenue for the performance obligation satisfied and included in license revenue in the consolidated statement of operations during the year ended December 31, 2021.

In addition, FibroGen may receive up to a total of $64.0 million in future manufacturing, clinical, regulatory, and commercial milestone payments for the biosynthetic cornea program, as well as $36.0 million in commercial milestones for the first recombinant collagen III product that is not the biosynthetic cornea. FibroGen will also be eligible to receive mid single-digit to low double-digit royalties based upon worldwide net sales of cornea products, and low single-digit to mid single-digit royalties based upon worldwide net sales of other recombinant human collagen type III products that are not cornea products.

The Company accounted for this agreement under ASC 606 and identified one performance obligation at inception of the agreement related to the granting of the license rights to the investigational biosynthetic cornea derived from recombinant human collagen Type III. The Company based its assessment on the determination that Eluminex can benefit from the granted license on its own by developing and commercializing the underlying product using its own resources. All components of the transaction price in the agreement were allocated to the single performance obligation. The remaining future variable consideration related to future manufacturing, clinical, regulatory milestone payments as described above were fully constrained because the Company cannot conclude that it is probable that a significant reversal of the amount of cumulative revenue recognized will not occur, given the inherent uncertainties of success with these future milestones. For commercial milestones and royalties, the Company determined that the license is the predominant item to which the royalties or sales-based milestones relate and revenue will be recognized when the corresponding milestones and royalties are earned.

During the first quarter of 2022, FibroGen and Eluminex entered into a separate contract manufacturing agreement, under which the Company is responsible for supplying the cornea product at cost plus 10% of its product manufacturing costs until its manufacturing technology is fully transferred to Eluminex. Supply of the cornea product will be managed by a separate agreement and is considered a separate performance obligation. The related contract manufacturing revenue was recorded as other revenue and included in development and other revenue in the consolidated statement of operations.

Amounts recognized as revenue under the agreements with Eluminex were as follows for the years ended December 31, 2022 and 2021 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021
Eluminex	License revenue	$	—	$	8,000
	Other revenue - contract manufacturing	$	1,761	$	—

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2019	$ 535,406	$ 877	$ 1,300,725	$ (747)	$ (784,720)	$ 19,271
Balance, Shares at Dec. 31, 2019		87,657,489
Net loss	(189,291)	$ 0	0	0	(189,291)	0
Change in unrealized gain or loss on investments	(545)	0	0	(545)	0	0
Foreign currency translation adjustments	(3,207)	0	0	(3,207)	0	0
Shares issued from stock plans, net of payroll taxes paid	26,366	$ 37	26,329	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		3,783,144
Stock-based compensation	72,720	$ 0	72,720	0	0	0
Balance at Dec. 31, 2020	441,449	$ 914	1,399,774	(4,499)	(974,011)	19,271
Balance, Shares at Dec. 31, 2020		91,440,633
Net loss	(290,023)	$ 0	0	0	(290,023)	0
Change in unrealized gain or loss on investments	(899)	0	0	(899)	0	0
Foreign currency translation adjustments	1,235	0	0	1,235	0	0
Shares issued from stock plans, net of payroll taxes paid	5,494	$ 15	5,479	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		1,439,900
Stock-based compensation	71,161	$ 0	71,161	0	0	0
Conversion of subsidiary's convertible note payable(Note 10)	696	0	0	0	0	696
Balance at Dec. 31, 2021	229,113	$ 929	1,476,414	(4,163)	(1,264,034)	19,967
Balance, Shares at Dec. 31, 2021		92,880,533
Net loss	(293,654)	$ 0	0	0	(293,654)	0
Change in unrealized gain or loss on investments	(1,632)	0	0	(1,632)	0	0
Foreign currency translation adjustments	75	0	0	75	0	0
Shares issued from stock plans, net of payroll taxes paid	(983)	$ 13	(996)	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		1,285,553
Stock-based compensation	65,601	$ 0	65,601	0	0	0
Balance at Dec. 31, 2022	$ (1,480)	$ 942	$ 1,541,019	$ (5,720)	$ (1,557,688)	$ 19,967
Balance, Shares at Dec. 31, 2022		94,166,086

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

+ References

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+ Details

Segment and Geographic Information (Tables)

12 Months Ended

Dec. 31, 2022

Segment Reporting [Abstract]

Schedule of Revenue by Geographic Area

Geographic revenues, which are based on the region that revenue is generated, are as follows (in thousands):


	Years Ended December 31,
	2022		2021		2020
China	$	84,631	$	55,640	$	73,361
Europe		33,820		131,243		17,954
Japan		9,764		2,305		19,824
United States		12,519		46,121		65,180
Total revenue	$	140,734	$	235,309	$	176,319

Schedule of Long Lived Assets by Geographic Area

Property and equipment, net by geographic location are as follows (in thousands):


	December 31,
	2022		2021
United States	$	10,094	$	15,002
China		10,511		13,275
Total property and equipment	$	20,605	$	28,277

Summary of Finance and Operating Lease Right of Use Assets by Geographical Location

Finance lease right-of-use assets and operating lease right-of-use assets, net by geographic location are as follows (in thousands):


	December 31,
	2022		2021
United States	$	424	$	730
China		11		31
Total finance lease right-of-use assets	$	435	$	761

United States	$	76,273	$	87,113
China		3,620		3,999
Total operating lease right-of-use assets	$	79,893	$	91,112

Schedule of Customer Concentration by Collaboration Partners and Distribution Entity

The Company’s revenues to date have been generated from the following collaboration partners and distribution entity that individually accounted for 10% or more of the Company’s total revenue or accounts receivable:


	Percentage of Revenue									Percentage of Accounts Receivable
	Years Ended December 31,									December 31,
	2022			2021			2020			2022			2021
Falikang — Related party		51	%		15	%		—	%		65	%		—	%
Astellas — Related party		31	%		57	%		21	%		9	%		63	%
AstraZeneca		9	%		20	%		37	%		16	%		34	%

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Accounts receivable from related parties	$ 12,088	$ 10,930
Accrued and other current liabilities to related party	63,886	4
Deferred revenue current to related party	9,259	3,201
Deferred revenue non-current to related party	$ 31,044	$ 25,891
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	125,000,000	125,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	94,166,000	92,881,000
Common stock, shares outstanding	94,166,000	92,881,000

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes [Line Items]
Increase in valuation allowance	$ 68,200,000	$ 72,000,000.0	$ 124,000,000.0
Deferred tax asset for temporary difference			$ 78,700,000
Federal and state net operating loss carryforwards	166,708,000	167,135,000
Foreign net operating loss carryforwards	$ 49,990,000	38,117,000
Percentage of ownership changes	0.00%
Unrecognized tax benefits	$ 72,800,000
Accrued interest, unrecognized tax benefits	0	$ 0
Unrecognized tax benefits that would affect effective tax rate	$ 700,000
Unrecognized tax benefits description	The Company does not anticipate a material change to its unrecognized tax benefits over the next twelve months that would affect the Company’s effective tax rate.
Corporate alternative minimum tax percentage	15.00%
Percentage of excise tax on stock buyback	1.00%
Earliest Tax Year [Member]
Income Taxes [Line Items]
Foreign statute of limitation generally remains open in the year	2013
Latest Tax Year [Member]
Income Taxes [Line Items]
Foreign statute of limitation generally remains open in the year	2022
Foreign net operating loss [Member]
Income Taxes [Line Items]
Foreign net operating loss carryforwards	$ 242,600,000
Foreign net operating loss [Member] \| Minimum [Member]
Income Taxes [Line Items]
Operating loss carryforwards expiration year	2023
Foreign net operating loss [Member] \| Maximum [Member]
Income Taxes [Line Items]
Operating loss carryforwards expiration year	2032
Federal [Member]
Income Taxes [Line Items]
Federal and state net operating loss carryforwards	$ 758,300,000
Operating loss carryforwards expiration year	2026
Other tax credit carryforwards	$ 121,600,000
Other tax credit carryforwards expiration year	2023
State [Member]
Income Taxes [Line Items]
Federal and state net operating loss carryforwards	$ 140,100,000
Operating loss carryforwards expiration year	2028
State [Member] \| California [Member]
Income Taxes [Line Items]
Other tax credit carryforwards	$ 46,600,000

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

13.

Income Taxes

The components of loss before income taxes are as follows (in thousands):


	Years Ended December 31,
	2022			2021			2020
Domestic	$	(307,056	)	$	(268,499	)	$	(195,617	)
Foreign		12,187			(22,184	)		6,888
Loss before provision for income taxes	$	(294,869	)	$	(290,683	)	$	(188,729	)

The provision for income taxes consists of the following (in thousands):


	Years Ended December 31,
	2022		2021		2020
Current:
Federal	$	—	$	—	$	—
State		—		—		—
Foreign		358		347		360
Total current		358		347		360
Deferred:
Federal		—		—		—
State		—		—		—
Foreign		—		—		—
Total deferred		—		—		—
Total provision for income taxes	$	358	$	347	$	360

The following is the reconciliation between the statutory federal income tax rate and the Company’s effective tax rate:


	Years Ended December 31,
	2022			2021			2020
Tax at statutory federal rate		21.0	%		21.0	%		21.0	%
State tax		—	%		—	%		—	%
Stock-based compensation expense		(2.5	)%		(1.8	)%		2.4	%
Benefit due to intercompany transfer of assets		—	%		—	%		41.7	%
Valuation allowance on intercompany transfer of assets		—	%		—	%		(41.7	)%
Net operating losses not benefitted		(16.3	)%		(16.8	)%		(23.2	)%
Foreign net operating losses not benefitted		0.9	%		(1.6	)%		0.7	%
Deduction limitation on executive compensation		(0.2	)%		(0.3	)%		(0.8	)%
Global intangible low-taxed income		(2.8	)%		(0.4	)%		—	%
Other		(0.2	)%		(0.2	)%		(0.3	)%
Total		(0.1	)%		(0.1	)%		(0.2	)%

Significant components of the Company’s deferred tax assets are as follows (in thousands):


	December 31,
	2022			2021
Federal and state net operating loss carryforwards	$	166,708		$	167,135
Tax credit carryforwards		106,131			78,832
Foreign net operating loss carryforwards		49,990			38,117
Capitalized research and development expenses		45,125			—
Stock-based compensation		8,616			10,050
Lease obligations		18,442			20,415
Reserves and accruals		4,929			6,067
Deferred revenue		21,624			20,101
Intangible assets		69,159			84,625
Other		1,277			825
Subtotal		492,001			426,167
Less: Valuation allowance		(477,969	)		(409,810	)
Net deferred tax assets		14,032			16,357

Fixed assets		(13,101	)		(16,357	)
Non-deductibale accrued expenses		(931	)		—
Net deferred tax liabilities		(14,032	)		(16,357	)
Total net deferred tax assets	$	—		$	—

A valuation allowance has been provided to reduce the deferred tax assets to an amount management believes is more likely than not to be realized. Expected realization of the deferred tax assets for which a valuation allowance has not been recognized is based on upon the reversal of existing temporary differences and future taxable income.

The valuation allowance increased by $68.2 million, $72.0 million and $124.0 million for the years ended December 31, 2022, 2021 and 2020, respectively. Due to uncertainty surrounding the realization of the favorable tax attributes in the future tax returns, the Company has established a valuation allowance against its otherwise recognizable net deferred tax assets.

The Company intends to continue maintaining a full valuation allowance on its deferred tax assets until there is sufficient evidence to support the reversal of all or some portion of this allowance.

During 2020, the Company transferred certain intellectual property rights relating to its Chinese business between its wholly owned subsidiaries that are based in different tax jurisdictions. The transferor entity was not subject to income taxes in its local jurisdiction. The acquiring entity of the intellectual property is entitled to amortize the acquisition price of the intangible assets for tax purposes. In accordance with ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory, the Company recognized a deferred tax asset of $78.7 million for the temporary difference arising from the acquirer’s excess tax basis. Furthermore, based upon the weight of available evidence, the Company recognized a full valuation allowance against this deferred tax asset since it does not currently believe that realization of this gross deductible temporary difference is more likely than not. Accordingly, this inter-company transfer did not have a material impact to the Company’s consolidated financial statements.

At December 31, 2022, the Company had net operating loss carryforwards available to offset future taxable income of approximately $758.3 million and $140.1 million for federal and state tax purposes, respectively. These carryforwards will begin to expire in 2026 for federal and 2028 for state purposes, if not utilized before these dates. The Company also had foreign net operating loss carryforwards of approximately $242.6 million, which expire between 2023 and 2032 if not utilized.

At December 31, 2022, the Company had approximately $121.6 million of federal and $46.6 million of California research and development tax credit and other tax credit carryforwards available to offset future taxable income. The federal credits begin to expire in 2023 and the California research credits have no expiration dates.

Federal and state tax laws impose substantial restrictions on the utilization of net operating loss and credit carryforwards in the event of an “ownership change” for tax purposes, as defined in IRC Section 382. The Company reviewed its stock ownership for year ended December 31, 2022 and concluded no ownership changes occurred which would result in a reduction of its net operating loss or in its research and development credits expiring unused. If additional ownership change occurs, the utilization of net operating loss and credit carryforwards could be significantly reduced.

On August 16, 2022, the Inflation Reduction Act of 2022 (“IRA”) was signed into law. Among other changes to the Internal Revenue Code, the IRA imposes a 15% corporate alternative minimum tax on certain corporations and 1% excise tax on public company stock buybacks for tax years beginning after December 31, 2022. The Company does not expect these provisions to have a material impact on its consolidated financial statements and related disclosures.

Uncertain Tax Positions

The Company had unrecognized tax benefits of approximately $72.8 million as of December 31, 2022. Approximately $0.7 million of unrecognized tax benefits, if recognized, would affect the effective tax rate. The interest accrued as of December 31, 2022 and 2021 was immaterial.

A reconciliation of the beginning and ending amounts of unrecognized income tax benefits during the three years ended December 31, 2022 is as follows (in thousands):


	Federal and State
Balance as of December 31, 2019	$	32,263
Decrease due to prior positions		(137	)
Increase due to current year position		16,448
Balance as of December 31, 2020		48,574
Decrease due to prior positions		(245	)
Increase due to current year position		8,415
Foreign exchange rate differential		927
Balance as of December 31, 2021		57,671
Increase due to prior positions		6,954
Increase due to current year position		9,074
Foreign exchange rate differential		(908	)
Balance as of December 31, 2022	$	72,791

Unrecognized tax benefits may change during the next twelve months for items that arise in the ordinary course of business. The Company does not anticipate a material change to its unrecognized tax benefits over the next twelve months that would affect the Company’s effective tax rate.

The Company classifies interest and penalties as a component of tax expense, if any.

The Company files income tax returns in the U.S. federal jurisdiction, U.S. state and other foreign jurisdictions. The U.S. federal and U.S. state taxing authorities may choose to audit tax returns for tax years beyond the statute of limitation period due to significant tax attribute carryforwards from prior years, making adjustments only to carryforward attributes. The foreign statute of limitation generally remains open from 2013 to 2022. The Company is not currently under audit in any tax jurisdiction.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI https://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Collaboration Agreements, License Agreement and Revenues - Accounting for the Astellas Agreements - Additional Information 2 (Detail) - Astellas Agreement [Member]	12 Months Ended
	Dec. 31, 2022 USD ($)
Minimum [Member] \| Measurement Input Discount Rate [Member] \| Discounted Cash Flow [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Discount rate applied	17.5
Maximum [Member] \| Measurement Input Discount Rate [Member] \| Discounted Cash Flow [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Discount rate applied	20.0
Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-contingent upfront payments received	$ 40,100,000
Variable consideration related to payments for milestones considered probable of being achieved	65,000,000.0
Variable consideration related to co-development billings	12,100,000
Provision for co-development services	0
Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-contingent upfront payments received	320,000,000.0
Variable consideration related to payments for milestones considered probable of being achieved	365,000,000.0
Variable consideration related to co-development billings	$ 219,200,000

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Cash Flows [Abstract]
Accounts receivable from related parties	$ (1,158)	$ (6,803)	$ 718
Prepaid expenses and other current assets from related party	0	889	124,321
Accounts payable from related party	0	(1,118)	1,118
Accrued and other liabilities from related party	63,882	(20)	(36,859)
Deferred revenue from related parties	$ 11,211	$ 21,549	$ 7,169

Collaboration Agreements,License Agreement and Revenues - Summary of Amounts Recognized as Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	$ 140,734	$ 235,309	$ 176,319
License Revenue [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	22,590	116,434	14,323
License Revenue [Member] \| Eluminex Agreements [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue		8,000
Other Revenue - Contract Manufacturing [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	24,189	$ 70,275	$ 80,592
Other Revenue - Contract Manufacturing [Member] \| Eluminex Agreements [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	$ 1,761

- Definition

+ References

+ Details

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2022	Jan. 31, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Trading Symbol	FGEN
Entity Registrant Name	FIBROGEN, INC.
Entity Central Index Key	0000921299
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.01 par value
Security Exchange Name	NASDAQ
Entity File Number	001-36740
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0357827
Entity Address, Address Line One	409 Illinois Street
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	978-1200
Entity Common Stock, Shares Outstanding		94,182,915
Entity Public Float			$ 975.1
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	true
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	San Jose, California
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Items 10, 11, 12, 13 and 14 of Part III of this Annual Report on Form 10-K for the year ended December 31, 2022 (the “Annual Report”) incorporate information by reference from the definitive proxy statement for the registrant’s 2023 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than after 120 days after the end of the fiscal year covered by this Annual Report.

Collaboration Agreements,License Agreement and Revenues - Drug Product Revenue - Additional Information (Detail) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					$ 140,734,000	$ 235,309,000	$ 176,319,000
Deferred Revenue	$ 12,739,000				12,739,000	15,857,000
Prepaid Supplies	17,488,000				17,488,000	66,909,000
Astra Zeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Recognized as Revenue					71,167,000
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					11,086,000	962,000	8,906,000
Drug Product Revenue [Member] \| API Shipment [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					(4,000,000.0)	2,100,000
Drug Product Revenue [Member] \| Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					11,100,000
Drug Product Revenue [Member] \| Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	8,400,000		$ 9,800,000		8,200,000
Accrued liabilities	6,500,000				6,500,000
Drug Product Revenue [Member] \| Japan [Member] \| API Shipment [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					8,700,000
Drug Product Revenue [Member] \| Japan [Member] \| Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					9,480,000	2,056,000	4,281,000
Drug Product Revenue [Member] \| Europe [Member] \| Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					1,606,000	1,130,000	0
Drug Product Revenue [Member] \| Europe [Member] \| Astellas Europe Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Burdened manufacturing costs		$ 1,000,000.0		$ 1,000,000.0
Bulk Drug Product \| Astellas Europe Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue						8,300,000
Bulk Drug Product \| Astra Zeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					11,200,000	11,200,000
Accrued liabilities	11,200,000				11,200,000	2,200,000	4,600,000
Bulk Drug Product \| Europe [Member] \| Astellas Europe Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized					57,400,000
Deferred Revenue	23,200,000				23,200,000	11,800,000	$ 6,000,000.0
Prepaid Supplies						49,800,000
Billed Contracts Receivable	49,200,000				49,200,000
Accrued liabilities	$ 57,400,000				57,400,000
Bulk Drug Product \| Europe [Member] \| Astellas Europe Agreement [Member] \| Royalty Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Recognized as Revenue					$ 600	$ 200

Income Taxes - Reconciliation of the Beginning and Ending Amounts of Unrecognized Income Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Contingency [Line Items]
Ending Balance	$ 72,800
Federal and State [Member]
Income Tax Contingency [Line Items]
Beginning balance	57,671	$ 48,574	$ 32,263
Decrease due to prior positions		(245)	(137)
Increase due to prior positions	6,954
Increase due to current year position	9,074	8,415	16,448
Foreign exchange rate differential	(908)	927
Ending Balance	$ 72,791	$ 57,671	$ 48,574

Consolidated Statements of Operations (Parenthetical) - Astellas Agreement [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
License and milestone revenue from a related party	$ 22,590	$ 108,434	$ 14,323
Collaboration services and other revenue from a related party	9,908	21,928	19,174
Product revenue from a related party	71,167	35,568	0
Drug product revenue from a related party	$ 11,086	$ 3,186	$ 4,281

Collaboration Agreements, License Agreement and Revenues - Eluminex Agreement - Additional Information 2 (Detail) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2021 USD ($) PerformanceObligation	Mar. 31, 2022	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue			$ 140,734	$ 235,309	$ 176,319
Eluminex Agreements [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Upfront payment	$ 8,000			$ 8,000
Future manufacturing clinical regulatory and commercial milestone payments	64,000
Commercial milestone	$ 36,000
Eluminex Agreements [Member] \| ASC 606 [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Number of identified performance obligation at inception of agreement \| PerformanceObligation	1
Eluminex Agreements [Member] \| Cornea Products [Member] \| ASC 606 [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Percentage of product manufacturing costs until manufacturing technology fully transferred		10.00%

Segment and Geographic Information

12 Months Ended

Dec. 31, 2022

Segment Reporting [Abstract]

Segment and Geographic Information

15.

Segment and Geographic Information

The Company has determined that the chief executive officer is the chief operating decision maker (“CODM”). The CODM reviews financial information presented for the Company’s various clinical trial programs as well as results on a consolidated basis. License revenues and development revenues received are not allocated to various programs for purposes of determining a profit measure and resource allocation decisions are made by the CODM based primarily on consolidated results. As such, the Company has concluded that it operates as one segment. Supplemental enterprise-wide information has been presented below.

Geographic Revenues

Geographic revenues, which are based on the region that revenue is generated, are as follows (in thousands):


	Years Ended December 31,
	2022		2021		2020
China	$	84,631	$	55,640	$	73,361
Europe		33,820		131,243		17,954
Japan		9,764		2,305		19,824
United States		12,519		46,121		65,180
Total revenue	$	140,734	$	235,309	$	176,319

Geographic Assets

Property and equipment, net by geographic location are as follows (in thousands):


	December 31,
	2022		2021
United States	$	10,094	$	15,002
China		10,511		13,275
Total property and equipment	$	20,605	$	28,277

Finance lease right-of-use assets and operating lease right-of-use assets, net by geographic location are as follows (in thousands):


	December 31,
	2022		2021
United States	$	424	$	730
China		11		31
Total finance lease right-of-use assets	$	435	$	761

United States	$	76,273	$	87,113
China		3,620		3,999
Total operating lease right-of-use assets	$	79,893	$	91,112

Customer Concentration


	Percentage of Revenue									Percentage of Accounts Receivable
	Years Ended December 31,									December 31,
	2022			2021			2020			2022			2021
Falikang — Related party		51	%		15	%		—	%		65	%		—	%
Astellas — Related party		31	%		57	%		21	%		9	%		63	%
AstraZeneca		9	%		20	%		37	%		16	%		34	%

In January 2021, Falikang became fully operational and substantially all direct product sales to distributors in China were made by Falikang, while FibroGen Beijing continued to sell roxadustat product directly through pharmaceutical distributors in one province in China during 2021 and in one province in 2022. No individual distributor represented over 10% of the total revenue for the years ended December 31, 2022 and 2021. The aggregate accounts receivable from direct sales to distributors as of December 31, 2022 and 2021 were immaterial.

For the year ended December 31, 2020, the aggregate revenue from distributors represented 42% of the consolidated revenue, with no individual distributor representing over 10% of the total revenue. As of December 31, 2020, the aggregate accounts receivable from distributors represented 64% of the consolidated accounts receivable, with no material balance from any individual distributor.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Collaboration Agreements,License Agreement and Revenues - Drug Product Revenue - Summary of Drug Product Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue			$ 140,734	$ 235,309	$ 176,319
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue			11,086	962	8,906
Drug Product Revenue [Member] \| Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue	$ 8,400	$ 9,800	8,200
Drug Product Revenue [Member] \| Astellas Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue			11,100
Drug Product Revenue [Member] \| Astellas Agreement \| Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue			9,480	2,056	4,281
Drug Product Revenue [Member] \| Astellas Agreement \| Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue			1,606	1,130	0
Drug Product Revenue [Member] \| AstraZeneca Agreements [Member] \| United States [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue			$ 0	$ (2,224)	$ 4,625

- Definition

+ References

+ Details

Balance Sheet Components - Additional Information (Detail) - USD ($)	12 Months Ended			36 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022	Jul. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Other-than-temporary impairment loss				$ 0
Net unbilled co-development revenue	$ 0	$ 8,000,000		0
Depreciation expense	10,017,000	10,170,000	$ 11,678,000
API and bulk drug product price true-up	75,055,000	0		75,055,000
Acquired in-process research and development asset	0	35,000,000		0
Cash and cash equivalents	155,700,000	171,223,000		155,700,000
Eluminex Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled upfront payment		8,000,000.0			$ 8,000,000.0
Astellas Japan Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
API and bulk drug product price true-up	6,500,000			6,500,000
Astellas Europe Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
API and bulk drug product price true-up	57,400,000			57,400,000
AstraZeneca Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Net unbilled co-development revenue	17,500,000	9,100,000		17,500,000
API and bulk drug product price true-up	11,200,000			11,200,000
HiFiBiO Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
Acquired in-process research and development asset		35,000,000.0
Europe [Member] \| Astellas Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
Transfer price true up		49,800,000
Foreign subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 92,500,000	$ 91,200,000		$ 92,500,000

Income Taxes - Schedule of Reconciliation Between Statutory Federal Income Tax Rate and Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Tax at statutory federal rate	21.00%	21.00%	21.00%
State tax	0.00%	0.00%	0.00%
Stock-based compensation expense	(2.50%)	(1.80%)	2.40%
Benefit due to intercompany transfer of assets	0.00%	0.00%	41.70%
Valuation allowance on intercompany transfer of assets	0.00%	0.00%	(41.70%)
Net operating losses not benefitted	(16.30%)	(16.80%)	(23.20%)
Foreign net operating losses not benefitted	0.90%	(1.60%)	0.70%
Deduction limitation on executive compensation	(0.20%)	(0.30%)	(0.80%)
Global intangible low-taxed income	(2.80%)	(0.40%)
Other	(0.20%)	(0.20%)	(0.30%)
Total	(0.10%)	(0.10%)	(0.20%)

Equity method investment - Variable Interest Entity - Summary of Equity Method Investment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Acquisition And Variable Interest Entity [Line Items]
Beginning balance	$ 3,825
Investment income (loss) in unconsolidated variable interest entity	1,573	$ 1,007	$ (202)
Ending balance	$ 5,061	3,825
Beijing Falikang Pharmaceutical Co. Ltd [Member]
Acquisition And Variable Interest Entity [Line Items]
Ownership Percentage	51.10%
Beginning balance	$ 3,825
Investment income (loss) in unconsolidated variable interest entity	1,573
Currency Translation	(337)
Ending balance	$ 5,061	$ 3,825

Equity and Stock-based Compensation - Stock-Based Compensation - Additional information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Stock Option Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs	$ 40.8
Non-vested stock option awards granted that will be recognized on a straight-line basis over the weighted-average period	2 years 5 months 4 days
RSUs, PRSUs and TSR Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested stock option awards granted that will be recognized on a straight-line basis over the weighted-average period	2 years 7 months 2 days
Unrecognized compensation costs	$ 46.9

Commitments and Contingencies - Summary of Outstanding Non-cancelable Purchase Obligations (Detail) $ in Thousands	Dec. 31, 2022 USD ($)
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations due 2023	$ 27,909
Purchase obligations due 2024	25,846
Total	53,755
Manufacture and Supply of Pamrevlumab [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations due 2023	85
Purchase obligations due 2024	22,310
Total	22,395
Manufacture and Supply of Roxadustat [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations due 2023	6,126
Purchase obligations due 2024	2,369
Total	8,495
Other Purchases and Programs [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations due 2023	21,698
Purchase obligations due 2024	1,167
Total	$ 22,865

Leases - Additional Information (Detail) $ in Thousands		3 Months Ended	12 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Jun. 01, 2021 USD ($) Option	Mar. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Lessee Lease Description [Line Items]
Finance lease right-of-use assets			$ 435	$ 761
Finance lease liability			173
Operating lease right-of-use assets			79,893	91,112
Operating lease liability			89,885
Cash payment related to lease			$ 15,497	10,022	$ 951
Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term			1 year
Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term			5 years
Office Spaces
Lessee Lease Description [Line Items]
Lessee, operating lease, expiration period			2025
Office Equipment [Member] \| Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term			1 year
Office Equipment [Member] \| Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term			5 years
ASC 842 [Member]
Lessee Lease Description [Line Items]
Finance lease right-of-use assets			$ 0	24,654	0
Operating lease right-of-use assets			$ 0	$ 93,222	$ 0
Shorenstein Properties LLC [Member]
Lessee Lease Description [Line Items]
Lessee, finance lease, initial lease term			15 years
Lessee, finance lease, expiration period			2023
Shorenstein Properties LLC [Member] \| Lease Amendment [Member]
Lessee Lease Description [Line Items]
Lessee, finance lease, option to extend the additional lease term	5 years
Lessee, finance lease, additional lease expiration period	2028
Percentage increases on each anniversary of rent commencement date 2023	2.00%
Lessee, finance lease, existence of option to extend	true
Lessee, finance lease, option to extend	Under the terms of the Lease Amendment, the Company has two optional rights to each extend the lease for an additional five years.
Optional rights to extend lease \| Option	2
Rent increase commencement year first option	2023
Percentage increases on each anniversary of rent commencement date 2028	3.00%
Rent increase commencement year second option	2028
Shorenstein Properties LLC [Member] \| Lease Amendment [Member] \| ASC 842 [Member]
Lessee Lease Description [Line Items]
Finance lease right-of-use assets	$ 24,600
Finance lease liability	32,600
Operating lease right-of-use assets	93,200
Operating lease liability	$ 101,200
Beijing Economic-Technological Development Area [Member]
Lessee Lease Description [Line Items]
Operating lease right-of-use assets		$ 3,400
Operating lease liability		$ 3,400
Lessee, operating lease, lease term		5 years
Lessee, operating lease, expiration period		2026

Equity method investment - Variable Interest Entity - Additional Information (Detail)	Dec. 31, 2022
Beijing Kangda Yongfu Pharmaceutical Co., LTD [Member] \| Beijing Falikang Pharmaceutical Co Ltd \| FibroGen Beijing [Member] \| AstraZenecaAB [Member]
Acquisition And Variable Interest Entity [Line Items]
Percentage of outstanding shares acquired	51.10%

Collaboration Agreements, License Agreement and Revenues - Accounting for the AstraZeneca Agreements - Additional Information 3 (Detail) - AstraZeneca Agreements [Member] $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty rate against projected net revenues	40.00%
Measurement Input Discount Rate [Member] \| Discounted Cash Flow [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Discount rate applied	17.5
U.S./RoW and China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-contingent upfront payments received	$ 402.2
Variable consideration related to payments for milestones considered probable of being achieved	114.0
Variable consideration related to co-development billings	610.5
Variable consideration related to profit share	$ 7.3

Equity and Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Common Stock Reserved for Future Issuance

Shares of Common Stock outstanding, shares of stock plans outstanding and shares reserved for future issuance related to stock options and RSU grants and the Company’s Employee Stock Purchase Plan (“ESPP”) purchases are as follows (in thousands):


	December 31,
	2022		2021
Common stock outstanding		94,166		92,881
Stock options outstanding		9,088		8,967
RSUs outstanding		3,669		2,304
Shares reserved for future stock options and RSUs grant		11,524		10,253
Shares reserved for future ESPP offering		5,373		4,771
Total shares of common stock reserved		123,820		119,176

Summary of Stock Option Transactions

Stock option transactions, including forfeited options granted under the 2014 Plan as well as prior plans, are summarized below:


	Shares (In thousands)			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life (In Years)		Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2021		8,967		$	34.84
Granted		2,902			14.72
Exercised		(179	)		8.24
Expired		(1,847	)		34.36
Forfeited		(755	)		32.89
Outstanding at December 31, 2022		9,088			29.19		7.03	$	6,232
Vested and expected to vest, December 31, 2022		8,614			29.61		6.93		5,770
Exercisable at December 31, 2022		4,730		$	35.07		5.45	$	1,438

Summary of RSU,PRSU and TSR Awards

The following table summarizes the activities of RSUs, PRSUs and TSR awards:


	Shares (In thousands)			Weighted Average Fair Value at Grant
Unvested at December 31, 2021		2,304		$	30.60
Granted		3,151			14.68
Vested		(1,142	)		27.72
Forfeited		(644	)		25.06
Unvested at December 31, 2022		3,669		$	18.80

Schedule of Recorded Stock-Based Compensation Expense

Stock-based compensation expense was recorded directly to research and development and selling, general and administrative expense for the years ended December 31, 2022, 2021 and 2020 was as follows (in thousands):


	Years Ended December 31,
	2022		2021		2020
Research and development	$	34,861	$	40,547	$	46,229
Selling, general and administrative		30,740		30,614		26,491
Total stock-based compensation expense	$	65,601	$	71,161	$	72,720

Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Employee Stock Purchase Plans

The assumptions used to estimate the fair value of stock options granted and ESPPs using the Black-Scholes option valuation model were as follows:


	Years Ended December 31,
	2022			2021			2020
Stock Options
Expected term (in years)		5.7			5.7			5.7
Expected volatility		66.8	%		61.9	%		67.1	%
Risk-free interest rate		2.2	%		0.8	%		0.8	%
Expected dividend yield		—			—			—
Weighted average estimated fair value	$	7.88		$	20.21		$	18.36

ESPPs
Expected term (in years)	0.5 - 2.0			0.5 - 2.0			0.5 - 2.0
Expected volatility	58.5 - 97.6		%	47.1 - 104.4		%	47.5 - 77.1		%
Risk-free interest rate	0.1 - 4.5		%	0.0 - 2.2		%	0.1 - 2.9		%
Expected dividend yield		—			—			—
Weighted average estimated fair value	$	8.60		$	12.40		$	17.53

Schedule of Assumptions used to Estimate Fair Value of TSR Awards

The assumptions used to estimate the fair value of the TSR awards using the Monte Carlo valuation model were as follows:


	Year Ended December 31,
	2022
TSR awards
Expected term (in years)		3.9
Expected volatility		69.0	%
Risk-free interest rate		1.8	%
Expected dividend yield		—
Weighted average estimated fair value	$	24.01

Fair Value Measurements

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

Level 1: Quoted prices in active markets for identical assets or liabilities.

Level 2: Observable inputs other than quoted prices in active markets for identical assets or liabilities.

Level 3: Unobservable inputs.

The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands):


	December 31, 2022
	Level 1		Level 2		Level 3		Total
Money market funds	$	19,881	$	—	$	—	$	19,881
Corporate bonds		—		82,008		—		82,008
Commercial paper		—		57,381		—		57,381
U.S. government bonds		98,972		12,373		—		111,345
Agency bonds		—		11,468		—		11,468
Asset-backed securities		—		2,474		—		2,474
Foreign government bonds		—		4,980		—		4,980
Convertible promissory note		—		—		1,000		1,000
Total	$	118,853	$	170,684	$	1,000	$	290,537

	December 31, 2021
	Level 1		Level 2		Level 3		Total
Money market funds	$	58,801	$	—	$	—	$	58,801
Corporate bonds		—		182,646		—		182,646
Commercial paper		—		69,079		—		69,079
U.S. government bonds		91,522		—		—		91,522
Agency bonds		—		23,275		—		23,275
Asset-backed securities		—		27,087		—		27,087
Foreign government bonds		—		9,154		—		9,154
Total	$	150,323	$	311,241	$	—	$	461,564

The Company’s Level 2 investments are valued using third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar investments, issuer credit spreads, benchmark investments, prepayment/default projections based on historical data and other observable inputs. During the year ended December 31, 2022, the transfers of assets between levels was a total of $10.5 million transfer from Level 1 to Level 2 as such US treasury notes and bills were changed to off-the-run when they were issued before the most recent issue and were still outstanding at measurement day. There were no transfers of assets between levels for the years ended December 31, 2021 and 2020.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Transfers of assets from level 1 to 2	$ 0	$ 0	$ 10,500,000
Transfers of assets from level 2 to 1	0	0
Transfers of assets into level 3	0	0
Transfers of assets out of level 3	$ 0	$ 0

Equity and Stock-based Compensation - Common Stock - Additional information (Detail)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Common stock voting rights	one vote

Income Taxes - Components of Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Domestic	$ (307,056)	$ (268,499)	$ (195,617)
Foreign	12,187	(22,184)	6,888
Loss before provision for income taxes	$ (294,869)	$ (290,683)	$ (188,729)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 32
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-SubTopic 10
-Section 50
-Paragraph 31
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8924-108599

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

Segment and Geographic Information - Schedule of Customer Concentration by Collaboration Partners and Distribution Entity (Detail) - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Percentage of Revenue [Member] \| Falikang—Related party
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	51.00%	15.00%	0.00%
Percentage of Revenue [Member] \| Astellas-Related party [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	31.00%	57.00%	21.00%
Percentage of Revenue [Member] \| AstraZeneca [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	9.00%	20.00%	37.00%
Percentage of Accounts Receivable [Member] \| Falikang—Related party
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	65.00%	0.00%
Percentage of Accounts Receivable [Member] \| Astellas-Related party [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	9.00%	63.00%
Percentage of Accounts Receivable [Member] \| AstraZeneca [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	16.00%	34.00%

Balance Sheet Components - Summary of Available for Sale Securities in Unrealized Loss Position, Fair Value and Gross Unrealized Loss By Length of Time Security in Continual Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	$ 31,538	$ 328,162
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(170)	(903)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	159,627	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(2,368)	0
Available for sale securities in continual unrealized loss position, estimated fair value	191,165	328,162
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(2,538)	(903)
Corporate bonds [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	6,738	177,124
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(147)	(492)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	75,270	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(925)	0
Available for sale securities in continual unrealized loss position, estimated fair value	82,008	177,124
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(1,072)	(492)
U.S. government bonds [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	22,326	91,522
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(13)	(318)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	67,909	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(1,194)	0
Available for sale securities in continual unrealized loss position, estimated fair value	90,235	91,522
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(1,207)	(318)
Agency bonds [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	0	23,274
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	0	(64)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	11,468	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(222)	0
Available for sale securities in continual unrealized loss position, estimated fair value	11,468	23,274
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(222)	(64)
Asset-backed securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	2,474	27,087
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(10)	(18)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	0	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	0	0
Available for sale securities in continual unrealized loss position, estimated fair value	2,474	27,087
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(10)	(18)
Foreign government bonds [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	0	9,155
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	0	(11)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	4,980	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(27)	0
Available for sale securities in continual unrealized loss position, estimated fair value	4,980	9,155
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	$ (27)	$ (11)

Segment and Geographic Information - Schedule of Long Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	$ 20,605	$ 28,277
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	10,094	15,002
China [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	$ 10,511	$ 13,275

Equity and Stock-based Compensation - Summary of RSU,PRSU and TSR Awards (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested, Shares, Beginning Balance	2,304
Unvested, Shares, Ending Balance	3,669	2,304
Granted, Weighted Average Fair value at Grant	$ 14.68	$ 30.19	$ 29.99
RSUs, PRSUs and TSR awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested, Shares, Beginning Balance	2,304
Granted, Shares	3,151
Vested, Shares	(1,142)
Forfeited, Shares	(644)
Unvested, Shares, Ending Balance	3,669	2,304
Unvested, Weighted Average Fair value at Grant, Beginning Balance	$ 30.60
Granted, Weighted Average Fair value at Grant	14.68
Vested, Weighted Average Fair value at Grant	27.72
Forfeited, Weighted Average Fair value at Grant	25.06
Unvested, Weighted Average Fair value at Grant, Ending Balance	$ 18.80	$ 30.60

Equity Method Investment - Variable Interest Entity (Tables)

12 Months Ended

Dec. 31, 2022

Acquisition And Variable Interest Entity [Abstract]

Summary of Equity Method Investment

The Company’s equity method investment in Falikang was as follows for the year ended December 31, 2022 (in thousands):


Entity	Ownership Percentage			Balance at December 31, 2021		Share of Net Income		Currency Translation			Balance at December 31, 2022
Falikang		51.1	%	$	3,825	$	1,573	$	(337	)	$	5,061

Summary of Significant Accounting Policies - Schedule of Significant Balance of Accounts Receivable (Detail) - Accounts Receivable [Member] - Credit Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Falikang - Related Party [Member]
Accounting Policy [Line Items]
Concentration risk, percentage	65.00%	0.00%
Astellas Agreement [Member]
Accounting Policy [Line Items]
Concentration risk, percentage	9.00%	63.00%
AstraZeneca Agreements [Member]
Accounting Policy [Line Items]
Concentration risk, percentage	16.00%	34.00%

Collaboration Agreements,License Agreement and Revenues - Product Revenue, Net - Additional Information 1 (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	$ 140,734	$ 235,309	$ 176,319
Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	82,869	47,638	72,498
Product Revenue, Net [Member] \| Beijing Falikang Pharmaceutical Co Ltd
Contract with Customer, Liability [Abstract]
Reductions to gross accounts receivable	500	13,400
China [Member]
Contract with Customer, Liability [Abstract]
Recognized as Revenue	2,300
China [Member] \| Product Revenue, Net [Member]
Contract with Customer, Liability [Abstract]
Contract with customer liability increase decrease in revenue due to changes to estimated variable consideration	1,400
AstraZeneca Agreements [Member]
Contract with Customer, Liability [Abstract]
Deferred Revenue	175,646	171,516
Recognized as Revenue	71,167
AstraZeneca Agreements [Member] \| China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	0	0	(90)
Contract with Customer, Liability [Abstract]
Deferred Revenue	21,000
Contractual Sales Rebate [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	600	800	6,200
Discounts And Rebates
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	700	1,700	16,400
Discounts And Rebates Current
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		1,000
Non-key Account Hospital Listing Award [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			$ 9,300
Rebates and Discounts [Member] \| Gross Accounts Receivable [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	$ 900	1,100
Constrained for Future Recognition [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		$ 27,200

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net loss	$ (293,654)	$ (290,023)	$ (189,291)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	10,017	10,170	11,678
Amortization of finance lease right-of-use assets	587	4,639	10,369
Net accretion of premium and discount on investments	1,619	2,482	103
Unrealized loss on equity investments	0	30	0
Investment income in unconsolidated variable interest entity	(1,573)	(1,007)	202
(Gain) / loss on disposal of property and equipment	(1)	233	933
Stock-based compensation	65,601	71,161	72,720
Expense for acquired in-process research and development asset	0	60,000	0
Non-cash interest expense related to sale of future revenues	1,036
Realized loss on sales of available-for-sale securities	5	0	258
Changes in operating assets and liabilities:
Accounts receivable, net ($(1,158), $(6,803) and $718 from related parties)	765	25,180	(11,973)
Inventories	(10,999)	(14,158)	(9,175)
Prepaid expenses and other current assets ($0, $889 and $124,321 from a related party)	4,916	(9,854)	123,492
Operating lease right-of-use assets	10,908	4,209	(24)
Other assets	263	(4,412)	5,843
Accounts payable ($0, $(1,118) and $1,118 from a related party)	5,909	805	17,731
Accrued and other liabilities ($63,882, $(20) and $(36,859) from a related party)	90,556	16,380	30,914
Operating lease liabilities, current	(547)	503	134
Deferred revenue ($11,211, $21,549 and $7,169 from related parties)	(4,130)	57,637	45,077
Accrued interest for finance lease liabilities	33	(75)	(177)
Operating lease liabilities, non-current	(8,994)	(4,043)	(143)
Other long-term liabilities	(18,250)	(12,089)	(27,069)
Net cash provided by (used in) operating activities	(145,933)	(82,232)	81,602
Investing activities
Purchases of property and equipment	(3,741)	(5,186)	(3,994)
Payment made for acquired in-process research and development asset	(35,000)	(25,000)	0
Payment made for investment in unconsolidated variable interest entity	0	0	(3,896)
Proceeds from equity transfer of unconsolidated variable interest entity	0	0	1,063
Proceeds from sale of property and equipment	6	0	0
Purchases of available-for-sale securities	(164,023)	(484,144)	(8,192)
Proceeds from sales of available-for-sale securities	7,382	4,214	10,606
Proceeds from maturities of investments	284,492	83,144	456,900
Net cash provided by (used in) investing activities	89,116	(426,972)	452,487
Financing activities
Repayments of finance lease liabilities	(135)	(5,489)	(12,620)
Repayments of lease obligations	(403)	(403)	(403)
Cash paid for payroll taxes on restricted stock unit releases	(5,167)	(7,372)	(11,463)
Proceeds from sale of future revenues, net of issuance costs	49,750
Cash paid for transaction costs related to sale of future revenues	(1,453)
Proceeds from issuance of common stock	4,184	12,701	37,829
Net cash provided by (used in) financing activities	46,776	(563)	13,343
Effect of exchange rate change on cash and cash equivalents	(5,482)	2,597	4,695
Net increase (decrease) in cash and cash equivalents	(15,523)	(507,170)	552,127
Total cash and cash equivalents at beginning of period	171,223	678,393	126,266
Total cash and cash equivalents at end of period	155,700	171,223	678,393
Supplemental Cash Flow Information [Abstract]
Interest payments	104	94	135
Balance in accounts payable and accrued liabilities related to purchases of property and equipment	428	1,009	884
Balance in accrued liabilities related to acquired in-process research and development asset	0	35,000	0
Balance in other receivables related to stock option exercise	0	165	0
Conversion of subsidiary's convertible note payable to non-controlling interests	$ 0	$ 696	$ 0

Equity and Stock-based Compensation - Schedule of Recorded Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 65,601	$ 71,161	$ 72,720
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	34,861	40,547	46,229
Selling, general and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 30,740	$ 30,614	$ 26,491

Income Taxes - Schedule of Components of Provision For Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ 0	$ 0	$ 0
State	0	0	0
Foreign	358	347	360
Total current	358	347	360
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	0	0	0
Total deferred	0	0	0
Total provision for income taxes	$ 358	$ 347	$ 360

Balance Sheet Components - Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 273,189	$ 402,664
Gross Unrealized Holding Gains	5	2
Gross Unrealized Holding Losses	(2,538)	(903)
Estimated Fair Value	270,656	401,763
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	83,080	183,136
Gross Unrealized Holding Gains	0	2
Gross Unrealized Holding Losses	(1,072)	(492)
Estimated Fair Value	82,008	182,646
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	57,381	68,079
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	57,381	68,079
U.S. government bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	112,547	91,840
Gross Unrealized Holding Gains	5	0
Gross Unrealized Holding Losses	(1,207)	(318)
Estimated Fair Value	111,345	91,522
Agency bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,690	23,339
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(222)	(64)
Estimated Fair Value	11,468	23,275
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,484	27,105
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(10)	(18)
Estimated Fair Value	2,474	27,087
Foreign government bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,007	9,165
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(27)	(11)
Estimated Fair Value	4,980	$ 9,154
Convertible promissory note [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,000
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Estimated Fair Value	$ 1,000

Segment and Geographic Information - Schedule of Revenue by Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenue recognized	$ 140,734	$ 235,309	$ 176,319
China [Member]
Segment Reporting Information [Line Items]
Revenue recognized	84,631	55,640	73,361
Europe [Member]
Segment Reporting Information [Line Items]
Revenue recognized	33,820	131,243	17,954
Japan [Member]
Segment Reporting Information [Line Items]
Revenue recognized	9,764	2,305	19,824
United States [Member]
Segment Reporting Information [Line Items]
Revenue recognized	$ 12,519	$ 46,121	$ 65,180

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
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-Section 50
-Paragraph 3
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-URI https://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 825
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-Section 50
-Paragraph 28
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=123596393&loc=d3e14064-108612

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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-Section S99
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-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442552-122756

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
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-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442552-122756

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442552-122756

Reference 22: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(ii))
-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442526-122756

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI https://asc.fasb.org/extlink&oid=126953954&loc=SL114868664-224227

+ Details

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Accounts receivable from related parties	$ 12,088	$ 10,930
Accrued liabilities to related party	63,886	4
Investment income (loss)	1,573	1,007	$ (202)
Equity method investment in unconsolidated variable interest entity	5,061	3,825
Astellas [Member]
Related Party Transaction [Line Items]
Drug product revenue from a related party	11,100	3,200	4,300
Astellas [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Accounts receivable from related parties	1,500	10,900
Deferred revenue	40,300	27,900
Accrued liabilities to related party	63,900
Falikang
Related Party Transaction [Line Items]
Accounts receivable from related parties	10,500	0
Deferred revenue	$ 0	1,200
Percentage of outstanding shares owned	51.10%
Investment income (loss)	$ 1,600	1,000	(200)
Equity method investment in unconsolidated variable interest entity	5,100	3,800
Falikang \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenue related to collaboration agreements	71,200	35,600
License and Development [Member] \| Astellas [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenue related to collaboration agreements	$ 32,500	$ 130,400	$ 33,500

Collaboration Agreements, License Agreement and Revenues (Tables)

12 Months Ended

Dec. 31, 2022

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue and Product Revenue Net

Product revenue, net from the sales of roxadustat commercial product in China was as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


	Years Ended December 31,
	2022			2021			2020
Direct Sales:
Gross revenue	$	12,366		$	13,727			89,027
Price adjustment		242			(982	)		—
Non-key account hospital listing award		49			95			(9,325	)
Contractual sales rebate		(624	)		(832	)		(6,189	)
Other discounts and rebates		(332	)		(21	)		(923	)
Sales returns		1			83			(92	)
Direct sales revenue, net		11,702			12,070			72,498

Sales to Falikang:
Gross transaction price		112,544			97,531			—
Profit share		(43,716	)		(34,759	)		—
Net transaction price		68,828			62,772			—
Decrease (increase) in deferred revenue		2,339			(27,204	)		—
Sales to Falikang revenue, net		71,167			35,568			—
Total product revenue, net	$	82,869		$	47,638		$	72,498

Roll-forward of Related Contract Liabilities

The following table includes a roll-forward of the related contract liabilities (in thousands):


	Balance at December 31, 2021			Additions			Deduction		Currency Translation and Other		Balance at December 31, 2022
Product revenue - Direct sales - contract liabilities	$	(3,176	)	$	(653	)	$	3,222	$	217	$	(390	)

Schedule of Drug Product Revenue

Drug product revenue from commercial-grade API or bulk drug product sales to Astellas and AstraZeneca was as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


	Years Ended December 31,
	2022		2021			2020
Astellas Japan Agreement	$	9,480	$	2,056		$	4,281
Astellas Europe Agreement		1,606		1,130			—
AstraZeneca U.S./RoW Agreement		—		(2,224	)		4,625
Drug product revenue	$	11,086	$	962		$	8,906

Summary of Amounts Recognized as Revenue

Amounts recognized as revenue under the agreements with Eluminex were as follows for the years ended December 31, 2022 and 2021 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021
Eluminex	License revenue	$	—	$	8,000
	Other revenue - contract manufacturing	$	1,761	$	—

AstraZeneca Agreements [Member]

Roll-forward of Related Contract Liabilities

The following table includes a roll-forward of the related deferred revenue that is considered as a contract liability (in thousands):


	Balance at December 31, 2021			Additions			Recognized as Revenue		Currency Translation and Other		Balance at December 31, 2022
Product revenue - AstraZeneca China performance obligation - deferred revenue	$	(171,516	)	$	(77,195	)	$	71,167	$	1,898	$	(175,646	)

Drug Product Revenue [Member]

Roll-forward of Related Contract Liabilities

The following table includes a roll-forward of the above-mentioned deferred revenues that are considered as contract liabilities related to drug product (in thousands):


	Balance at December 31, 2021			Additions			Recognized as Revenue		Reclassified to Accrued Liability / Accounts Payable		Balance at December 31, 2022
Astellas Japan Agreement	$	(1,974	)	$	(2,226	)	$	—	$	4,200	$	—
Astellas Europe Agreement		(25,891	)		(72,408	)		619		57,377		(40,303	)
AstraZeneca U.S./RoW Agreement		(11,171	)		—			—		11,171		—
Drug product revenue - deferred revenue	$	(39,036	)	$	(74,634	)	$	619	$	72,748	$	(40,303	)

Japan [Member]

Summary of License Revenue and Development Revenue Recognized under Agreement

Amounts recognized as license revenue and development revenue under the Astellas Japan Agreement were as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021		2020
Astellas Japan Agreement	License revenue	$	—	$	—	$	14,323
	Development revenue	$	284	$	248	$	1,220

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue and Product Revenue Net


Astellas Japan Agreement	Cumulative Revenue Through December 31, 2022		Deferred Revenue at December 31, 2022		Total Consideration Through December 31, 2022
License	$	100,347	$	—	$	100,347
Development revenue		16,882		—		16,882
Total license and development revenue	$	117,229	$	—	$	117,229

Europe [Member]

Summary of License Revenue and Development Revenue Recognized under Agreement

Amounts recognized as license revenue and development revenue under the Astellas Europe Agreement were as follows for the years ended December 31, 2022, 2021 and 2020 (in thousands):


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021		2020
Astellas Europe Agreement	License revenue	$	22,590	$	108,434	$	—
	Development revenue	$	9,624	$	21,679	$	17,954

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue and Product Revenue Net

The transaction price related to consideration received through December 31, 2022 and accounts receivable has been allocated to each of the following performance obligations under the Astellas Europe Agreement, along with any associated deferred revenue as follows (in thousands):


Astellas Europe Agreement	Cumulative Revenue Through December 31, 2022		Deferred Revenue at December 31, 2022		Total Consideration Through December 31, 2022
License	$	618,975	$	—	$	618,975
Development revenue		280,265		—		280,265
Total license and development revenue	$	899,240	$	—	$	899,240

U.S./RoW and China [Member]

Summary of License Revenue and Development Revenue Recognized under Agreement


		Years Ended December 31,
Agreement	Performance Obligation	2022		2021		2020
AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement	License revenue	$	—	$	—	$	—
	Development revenue		12,519		48,345		61,508
	China performance obligation	$	—	$	—	$	(90	)

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue and Product Revenue Net

The transaction price related to consideration received through December 31, 2022 and accounts receivable has been allocated to each of the following performance obligations under the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement, along with any associated deferred revenue as follows (in thousands):


AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement	Cumulative Revenue Through December 31, 2022		Deferred Revenue at December 31, 2022			Total Consideration Through December 31, 2022
License	$	341,844	$	—		$	341,844
Co-development, information sharing & committee services		615,639		—			615,639
China performance obligation *		106,734		175,646			282,380
Total license and development revenue	$	1,064,217	$	175,646	**	$	1,239,863

* China performance obligation revenue is recognized as product revenue, as described in details under Product Revenue, Net section below.

Liability Related to Sale of Future Royalties - Additional Information (Detail) - USD ($)				12 Months Ended
	Nov. 30, 2022	Nov. 17, 2022	Nov. 04, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Transaction costs related to sale of future revenues				$ 1,453,000
Total revenue				140,734,000	235,309,000	176,319,000
Drug Product Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue				$ 11,086,000	962,000	8,906,000
NovaQuest [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Transaction costs related to sale of future revenues			$ 1,700,000
Effective annual interest rate related to sale of future revenues				19.67%
NovaQuest [Member] \| Payment Cap Date on or before December 31, 2028 [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum payment cap amount			100,000,000.0
NovaQuest [Member] \| Payment Cap Date on or after January 1, 2029 [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum payment cap amount			112,500,000
NovaQuest [Member] \| Payment Cap Date after January 1, 2030 [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum payment cap amount			125,000,000.0
Minimum [Member] \| NovaQuest [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Prepayment amount of 2024 to 2030			80,000,000.0
Minimum [Member] \| NovaQuest [Member] \| Before December 31, 2028 [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue interest payment			62,500,000
Minimum [Member] \| NovaQuest [Member] \| No Later Than December 31, 2030 [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue interest payment			125,000,000.0
Maximum [Member] \| NovaQuest [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Prepayment amount of 2024 to 2030			125,000,000.0
Product [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue				$ 82,869,000	47,638,000	72,498,000
Product [Member] \| NovaQuest [Member] \| RIFA [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue interest payment			10,000,000.0
License Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue				22,590,000	116,434,000	14,323,000
Development Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue				24,189,000	$ 70,275,000	$ 80,592,000
Astellas Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Future revenue granted			$ 50,000,000.0
Percentage of revenue interest on global net sales			100.00%
Received from sale of revenue		$ 49,800,000
Gross proceeds received from sale of revenue		$ 50,000,000.0
Astellas Agreement [Member] \| Regulatory Milestone [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue				25,000,000.0
Astellas Agreement [Member] \| Drug Product Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue				11,100,000
Non-cash interest expense related to drug product revenue				1,000,000.0
Astellas Agreement [Member] \| Maximum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue payment cap amount				125,000,000.0
Astellas Agreement [Member] \| Product [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of revenue sold	22.50%
Astellas Agreement [Member] \| Milestone Payments [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of revenue sold	10.00%
Astellas Agreement [Member] \| Milestone Payments [Member] \| Before December 31, 2028 [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of revenue sold	20.00%
Astellas Agreement [Member] \| License Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue				22,600,000
Astellas Agreement [Member] \| Development Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue				$ 2,400,000

Collaboration Agreements, License Agreement and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations Deferred Revenue (Detail) - AstraZeneca Agreements [Member] - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Contract with Customer, Liability	$ 175,646	$ 171,516
U.S./RoW and China [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	1,064,217
Contract with Customer, Liability	175,646
Total Consideration	1,239,863
U.S./RoW and China [Member] \| License Revenue [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	341,844
Contract with Customer, Liability	0
Total Consideration	341,844
U.S./RoW and China [Member] \| Co-development, information sharing & committee services [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	615,639
Contract with Customer, Liability	0
Total Consideration	615,639
U.S./RoW and China [Member] \| China performance obligation [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative Revenue	106,734
Contract with Customer, Liability	175,646
Total Consideration	$ 282,380

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):


	December 31,
	2022		2021
Cash	$	135,819	$	111,422
Commercial paper		—		1,000
Money market funds		19,881		58,801
Total cash and cash equivalents	$	155,700	$	171,223

Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Investments


	December 31, 2022
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Corporate bonds	$	83,080	$	—	$	(1,072	)	$	82,008
Commercial paper		57,381		—		—			57,381
U.S. government bonds		112,547		5		(1,207	)		111,345
Agency bonds		11,690		—		(222	)		11,468
Asset-backed securities		2,484		—		(10	)		2,474
Foreign government bonds		5,007		—		(27	)		4,980
Convertible promissory note		1,000		—		—			1,000
Total investments	$	273,189	$	5	$	(2,538	)	$	270,656

	December 31, 2021
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Corporate bonds	$	183,136	$	2	$	(492	)	$	182,646
Commercial paper		68,079		—		—			68,079
U.S. government bonds		91,840		—		(318	)		91,522
Agency bonds		23,339		—		(64	)		23,275
Asset-backed securities		27,105		—		(18	)		27,087
Foreign government bonds		9,165		—		(11	)		9,154
Total investments	$	402,664	$	2	$	(903	)	$	401,763

Summary of Available for Sale Securities in Unrealized Loss Position, Fair Value and Gross Unrealized Loss By Length of Time Security in Continual Unrealized Loss Position


	December 31, 2022
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses
Corporate bonds	$	6,738	$	(147	)	$	75,270	$	(925	)	$	82,008	$	(1,072	)
U.S. government bonds		22,326		(13	)		67,909		(1,194	)		90,235		(1,207	)
Agency bonds		—		—			11,468		(222	)		11,468		(222	)
Asset-backed securities		2,474		(10	)		—		—			2,474		(10	)
Foreign government bonds		—		—			4,980		(27	)		4,980		(27	)
Total	$	31,538	$	(170	)	$	159,627	$	(2,368	)	$	191,165	$	(2,538	)

	December 31, 2021
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses
Corporate bonds	$	177,124	$	(492	)	$	—	$	—		$	177,124	$	(492	)
U.S. government bonds		91,522		(318	)		—		—			91,522		(318	)
Agency bonds		23,274		(64	)		—		—			23,274		(64	)
Asset-backed securities		27,087		(18	)		—		—			27,087		(18	)
Foreign government bonds		9,155		(11	)		—		—			9,155		(11	)
Total	$	328,162	$	(903	)	$	—	$	—		$	328,162	$	(903	)

Summary of Contractual Maturities of Available-for-Sale Investments

The contractual maturities of the available-for-sale investments were as follows (in thousands):


	December 31, 2022
	Amortized Cost		Estimated Fair Value
Within one year - Bond and mutual funds	$	268,709	$	266,308
After one year through three years		4,480		4,348
Total investments	$	273,189	$	270,656

Schedule of Inventory

Inventories consisted of the following (in thousands):


	December 31,
	2022		2021
Raw materials	$	1,241	$	1,363
Work-in-progress		36,003		21,499
Finished goods		3,192		8,153
Total inventories	$	40,436	$	31,015

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	December 31,
	2022			2021
Contract assets	$	17,488		$	66,909
Deferred revenues from associated contracts		(17,488	)		(58,909	)
Net unbilled contract assets		—			8,000
Prepaid assets		9,730			7,383
Other current assets		4,353			5,070
Total prepaid expenses and other current assets	$	14,083		$	20,453

Schedule of Property and Equipment

Property and equipment consisted of the following (in thousands):


	December 31,
	2022			2021
Leasehold improvements	$	102,580		$	103,352
Laboratory equipment		21,175			19,300
Machinery		9,642			8,339
Computer equipment		9,486			9,670
Furniture and fixtures		6,200			6,201
Construction in progress		204			2,423
Total property and equipment	$	149,287		$	149,285
Less: accumulated depreciation		(128,682	)		(121,008	)
Property and equipment, net	$	20,605		$	28,277

Schedule of Accrued and Other Current Liabilities

Accrued and other current liabilities consisted of the following (in thousands):


	December 31,
	2022		2021
Preclinical and clinical trial accruals	$	57,780	$	56,283
API and bulk drug product price true-up		75,055		—
Acquired in-process research and development asset		—		35,000
Payroll and related accruals		22,562		20,909
Accrued co-promotion expenses - current		36,677		25,746
Contract liabilities to pharmaceutical distributors		390		3,176
Roxadustat profit share to AstraZeneca		7,280		7,895
Property taxes and other taxes		7,691		12,610
Professional services		5,480		6,074
Other		6,858		4,906
Total accrued and other current liabilities	$	219,773	$	172,599

Leases - Schedule of Maturities of Lease Liabilities (Detail) $ in Thousands	Dec. 31, 2022 USD ($)
Finance Leases
2023	$ 44
2024	41
2025	40
2026	39
2027	36
Beyond 2027	0
Total future lease payments	200
Less: Interest	(27)
Present value of lease liabilities	173
Operating Leases
2023	13,915
2024	17,302
2025	18,448
2026	18,000
2027	18,476
Beyond 2027	17,400
Total future lease payments	103,541
Less: Interest	(13,656)
Present value of lease liabilities	$ 89,885

Commitments and Contingencies

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

10.

Commitments and Contingencies

Contract Obligations

As of December 31, 2022, the Company had the following outstanding non-cancelable purchase obligations (in thousands):


	Purchase Obligations Due In The Year Ending December 31,
	2023		2024		Total
Manufacture and supply of pamrevlumab	$	85	$	22,310	$	22,395
Manufacture and supply of roxadustat		6,126		2,369		8,495
Other purchases and programs		21,698		1,167		22,865
Total	$	27,909	$	25,846	$	53,755

The Company expects to fulfill its commitments under these agreements in the normal course of business, and as such, no liability has been recorded.

See Note 6, Leases, for details of the Company's operating and finance lease payment obligations. See Note 8, Liability Related to Sale of Future Revenues, and Note 9, Product Development Obligations for details of the respective obligations.

Some of the Company’s license agreements provide for periodic maintenance fees over specified time periods, as well as payments by the Company upon the achievement of development, regulatory and commercial milestones. As of December 31, 2022, future milestone payments for research and preclinical stage development programs consisted of up to approximately $697.9 million in total potential future milestone payments under the Company’s license agreements with HiFiBiO (for Gal-9 and CCR8), Medarex, Inc. and others. These milestone payments generally become due and payable only upon the achievement of certain developmental, clinical, regulatory and/or commercial milestones. The event triggering such payment or obligation has not yet occurred.

Legal Proceedings and Other Matters

From time to time, the Company is a party to various legal actions, both inside and outside the U.S., arising in the ordinary course of its business or otherwise. The Company accrues amounts, to the extent they can be reasonably estimated, that the Company believes will result in a probable loss (including, among other things, probable settlement value) to adequately address any liabilities related to legal proceedings and other loss contingencies. A loss or a range of loss is disclosed when it is reasonably possible that a material loss will incur and can be estimated, or when it is reasonably possible that the amount of a loss, when material, will exceed the recorded provision. The Company did not have any material accruals for any active legal action in its consolidated balance sheet as of December 31, 2022, as the Company could not predict the ultimate outcome of these matters, or reasonably estimate the potential exposure.

Between April 2021 and May 2021, five putative securities class action complaints were filed against FibroGen and certain of its current and former executive officers (collectively, the “Defendants”) in the U.S. District Court for the Northern District of California. The lawsuits allege that Defendants violated the Securities Exchange Act of 1934 by making materially false and misleading statements regarding FibroGen’s Phase 3 clinical studies data and prospects for U.S. Food and Drug Administration approval. On August 30, 2021, the Court consolidated the actions and appointed a group of lead plaintiffs. Plaintiffs filed their consolidated amended complaint on October 29, 2021 and a corrected consolidated amended complaint on November 19, 2021 (the “Complaint”). The Complaint alleges false and misleading statements between December 2018 and June 2021 and seeks to represent a class of persons or entities that purchased FibroGen securities between December 20, 2018 and July 15, 2021. On July 15, 2022, the court issued an order denying Defendants’ motions to dismiss. Defendants answered the Complaint on September 13, 2022 and discovery is ongoing. On January 27, 2023, Plaintiffs filed a motion for class certification. Defendants’ opposition is due April 28, 2023.

On July 30, 2021, a purported shareholder derivative (the “California Federal Derivative”) complaint was filed in the U.S. District Court for the Northern District of California. The California Federal Derivative complaint names as defendants FibroGen’s current and former officers and directors, as well as FibroGen as nominal defendant, and asserts state and federal claims based on some of the same alleged misstatements as the securities class action complaint. The California Federal Derivative complaint seeks unspecified damages, attorneys’ fees, and other costs. On December 23, 2022, Plaintiff filed an amended complaint. On February 21, 2023, Defendants filed a motion to dismiss on the basis that the lawsuit was brought in the improper forum. Plaintiffs’ opposition is due April 7, 2023. On December 27, 2021, a second purported shareholder derivative (the “Delaware Federal Derivative”) complaint was filed in the U.S. District Court for the District of Delaware. The Delaware Federal Derivative complaint names FibroGen’s current and former officers and directors as defendants, as well as FibroGen as nominal defendant, and asserts state and federal claims based on some of the same alleged misstatements as the securities class action complaint, as well as allegations of insider trading against certain defendants. The Delaware Federal Derivative complaint seeks unspecified damages, attorneys’ fees, and other costs. The Delaware Federal Derivative action has been stayed pending resolution of any motions for summary judgment in the securities class action. On April 14, 2022, a third purported shareholder derivative (the “Delaware Chancery Derivative”) complaint was filed in the Delaware Court of Chancery. The Delaware Chancery Derivative complaint names substantially the same defendants as the other purported shareholder derivative actions and asserts similar claims based upon similar allegations. The Delaware Chancery Derivative complaint seeks unspecified damages, attorneys’ fees, and other costs. On January 17, 2023, Defendants moved to dismiss on the basis of demand futility. Plaintiffs’ opposition is due on March 17, 2023.

The Company believes that the claims are without merit and it intends to vigorously defend against them. However, any litigation is inherently uncertain, and any judgment or injunctive relief entered against FibroGen or any adverse settlement could materially and adversely impact its business, results of operations, financial condition, and prospects.

In the fourth quarter of 2021, the Company received a subpoena from the SEC requesting documents related to roxadustat’s pooled cardiovascular safety data. The Company is fully cooperating with the SEC. The Company cannot predict with any degree of certainty the outcome of the SEC’s investigation or determine the extent of any potential liabilities. The Company also cannot predict whether there will be any loss as a result of the investigation nor can it provide an estimate of the possible loss or range of loss. Any adverse outcome in this matter or any related proceeding could expose the Company to substantial damages, penalties, or reputational harm that may have a material adverse impact on the Company’s business, results of operations, financial condition, growth prospects, and price of its common stock.

Between August 3, 2022 and August 4, 2022, the Company’s Board of Directors received three litigation demands from purported shareholders of the Company, asking the Board of Directors to investigate and take action against certain current and former officers and directors of the Company for alleged wrongdoing based on the same allegations in the pending derivative and securities class action lawsuits. The Company may in the future receive such additional demands.

Starting in October 2021, certain challenges have been filed with the China National Intellectual Property Administration against patents which claim a crystalline form of roxadustat. Final resolution of such proceedings will take time and the Company could not predict the ultimate outcome, or reasonably estimate the potential exposure.

Indemnification Agreements

The Company enters into standard indemnification arrangements in the ordinary course of business, including for example, service, manufacturing and collaboration agreements. Pursuant to these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, including in connection with intellectual property infringement claims by any third party with respect to its technology. The term of these indemnification agreements is generally perpetual any time after the execution of the agreement. The Company has entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the extent permissible under applicable law. The maximum potential amount of future payments the Company could be required to make under these arrangements is not determinable. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company believes the estimated fair value of these arrangements is minimal.

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 155,700	$ 171,223
Short-term investments	266,308	233,967
Accounts receivable, net ($12,088 and $10,930 from related parties)	16,299	17,401
Inventories	40,436	31,015
Prepaid expenses and other current assets	14,083	20,453
Total current assets	492,826	474,059
Restricted time deposits	2,072	2,072
Long-term investments	4,348	167,796
Property and equipment, net	20,605	28,277
Equity method investment in unconsolidated variable interest entity	5,061	3,825
Operating lease right-of-use assets	79,893	91,112
Other assets	5,282	6,680
Total assets	610,087	773,821
Current liabilities:
Accounts payable	30,758	26,097
Accrued and other current liabilities ($63,886 and $4 to a related party)	219,773	172,599
Deferred revenue ($9,259 and $3,201 to related parties)	12,739	15,857
Operating lease liabilities, current	10,292	10,944
Total current liabilities	273,562	225,497
Product development obligations	16,917	17,613
Deferred revenue, net of current ($31,044 and $25,891 to a related party)	185,722	186,801
Operating lease liabilities, non-current	79,593	88,776
Liability related to sale of future revenues, non-current	49,333
Other long-term liabilities	6,440	26,021
Total liabilities	611,567	544,708
Commitments and Contingencies (Note 10)
Stockholders' equity (deficit);
Preferred stock, $0.01 par value; 125,000 shares authorized; no shares issued and outstanding at December 31, 2022 and 2021
Common stock, $0.01 par value; 225,000 shares authorized at December 31, 2022 and 2021; 94,166 and 92,881 shares issued and outstanding at December 31, 2022 and 2021	942	929
Additional paid-in capital	1,541,019	1,476,414
Accumulated other comprehensive loss	(5,720)	(4,163)
Accumulated deficit	(1,557,688)	(1,264,034)
Total stockholders' equity (deficit)	(21,447)	209,146
Non-controlling interests	19,967	19,967
Total equity (deficit)	(1,480)	229,113
Total liabilities, stockholders' equity (deficit) and non-controlling interests	$ 610,087	$ 773,821

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 15,497	$ 10,022	$ 951
Operating cash flows from finance leases	2	629	1,896
Financing cash flows from finance leases	135	5,489	12,620
Non-cash: Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases	261	450	662
Operating leases	1,704	3,585	1,072
Non-cash: Increase (decrease) resulting from lease modification:
Finance lease right-of-use assets	(435)	(761)
Operating lease right-of-use assets	79,893	91,112
Finance lease liabilities, current	(36)	(11)
Operating lease liabilities, current	10,292	10,944
Finance lease liabilities, non-current	(137)	(3)
Operating lease liabilities, non-current	79,593	88,776
ASC 842 [Member]
Non-cash: Increase (decrease) resulting from lease modification:
Finance lease right-of-use assets	0	(24,654)	0
Operating lease right-of-use assets	0	93,222	0
Finance lease liabilities, current	0	(12,587)	0
Operating lease liabilities, current	0	9,221	0
Finance lease liabilities, non-current	0	(20,009)	0
Operating lease liabilities, non-current	$ 0	$ 91,943	$ 0

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Prepaid Expense and Other Assets, Current [Abstract]
Contract assets	$ 17,488	$ 66,909
Deferred revenues from associated contracts	(17,488)	(58,909)
Net unbilled contract assets	0	8,000
Prepaid assets	9,730	7,383
Other current assets	4,353	5,070
Total prepaid expenses and other current assets	$ 14,083	$ 20,453

Leases (Tables)

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Schedule of Lease Assets and Related Lease Liabilities

The Company’s lease assets and related lease liabilities were as follows (in thousands):


		December 31,
	Balance Sheet Line Item	2022			2021
Assets
Finance:
Right-of-use assets cost		$	2,367		$	2,165
Accumulated amortization			(1,932	)		(1,404	)
Finance lease right-of-use assets, net	Other assets		435			761
Operating:
Right-of-use assets cost			101,990			100,912
Accumulated amortization			(22,097	)		(9,800	)
Operating lease right-of-use assets, net	Operating lease right-of-use assets		79,893			91,112
Total lease assets		$	80,328		$	91,873

Liabilities
Current:
Finance lease liabilities	Accrued and other current liabilities	$	36		$	11
Operating lease liabilities	Operating lease liabilities, current		10,292			10,944
Non-current:
Finance lease liabilities	Other long-term liabilities		137			3
Operating lease liabilities	Operating lease liabilities, non-current		79,593			88,776
Total lease liabilities		$	90,058		$	99,734

Components of Lease Expense

The components of lease expense were as follows (in thousands):


		Years Ended December 31,
	Statement of Operations Line Item	2022			2021			2020
Finance lease cost:
Amortization of right-of-use assets	Cost of goods sold; Research and development; Selling, general and administrative expenses	$	587		$	4,639		$	10,369
Interest on lease liabilities	Interest expense		—			628			1,932
Operating lease cost	Cost of goods sold; Research and development; Selling, general and administrative expenses		17,125			10,722			1,151
Sublease income	Selling, general and administrative expenses		(3,373	)		(1,271	)		(1,201	)
Total lease cost		$	14,339		$	14,718		$	12,251

Schedule of Supplemental Cash Flow Information Related to Leases

Supplemental cash flow information related to leases were as follows (in thousands):


	Years Ended December 31,
	2022		2021			2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	15,497	$	10,022		$	951
Operating cash flows from finance leases		2		629			1,896
Financing cash flows from finance leases		135		5,489			12,620
Non-cash: Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases		261		450			662
Operating leases		1,704		3,585			1,072
Non-cash: Increase (decrease) resulting from lease modification:
Finance lease right-of-use assets		—		(24,654	)		—
Operating lease right-of-use assets		—		93,222			—
Finance lease liabilities, current		—		(12,587	)		—
Operating lease liabilities, current		—		9,221			—
Finance lease liabilities, non-current		—		(20,009	)		—
Operating lease liabilities, non-current	$	—	$	91,943		$	—

Schedule of Lease Term and Discount Rate

Lease term and discount rate were as follows:


	December 31,
	2022			2021
Weighted-average remaining lease term (years):
Finance leases		4.9			1.1
Operating leases		5.8			6.8
Weighted-average discount rate:
Finance leases		6.20	%		4.64	%
Operating leases		4.75	%		4.75	%

Schedule of Maturities of Finance and Operating Leases Liabilities

Maturities of lease liabilities as of December 31, 2022 are as follows (in thousands):


Year Ending December 31,	Finance Leases			Operating Leases
2023	$	44		$	13,915
2024		41			17,302
2025		40			18,448
2026		39			18,000
2027		36			18,476
Beyond 2027		—			17,400
Total future lease payments		200			103,541
Less: Interest		(27	)		(13,656	)
Present value of lease liabilities	$	173		$	89,885

Leases - Schedule of Lease Assets and Related Lease Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Right-of-use assets cost	$ 2,367	$ 2,165
Accumulated amortization	(1,932)	(1,404)
Finance lease right-of-use assets, net	$ 435	$ 761
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets, Noncurrent	Other Assets, Noncurrent
Right-of-use assets cost	$ 101,990	$ 100,912
Accumulated amortization	(22,097)	(9,800)
Operating lease right-of-use assets, net	79,893	91,112
Total lease assets	80,328	91,873
Finance lease liabilities	$ 36	$ 11
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Liabilities, Current	Liabilities, Current
Operating lease liabilities	$ 10,292	$ 10,944
Finance lease liabilities	$ 137	$ 3
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Operating lease liabilities	$ 79,593	$ 88,776
Total lease liabilities	$ 90,058	$ 99,734

Collaboration Agreements, License Agreement and Revenues - Summary of Revenue Recognized Under the Collaboration Agreements - Additional Information 4 (Detail)	12 Months Ended
	Dec. 31, 2022 USD ($)
Japan [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Transaction price, variable consideration from estimated future co-development billing	$ 0
Europe [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Transaction price, variable consideration from estimated future co-development billing	5,000,000.0
Europe [Member] \| Astellas Agreement [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	25,000,000.0
U.S./RoW and China [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	0
Transaction price, variable consideration from estimated future co-development billing	$ 9,600,000

Equity and Stock-based Compensation

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Equity and Stock-based Compensation

11.

Equity and Stock-based Compensation

Common Stock

Each share of Common Stock is entitled to one vote. The holders of Common Stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of stock outstanding.


	December 31,
	2022		2021
Common stock outstanding		94,166		92,881
Stock options outstanding		9,088		8,967
RSUs outstanding		3,669		2,304
Shares reserved for future stock options and RSUs grant		11,524		10,253
Shares reserved for future ESPP offering		5,373		4,771
Total shares of common stock reserved		123,820		119,176

Stock Plans

Stock Option and RSU Plans

Under the Company’s Amended and Restated 2005 Stock Plan (“2005 Stock Plan”), the Company may issue shares of Common Stock and options to purchase Common Stock and other forms of equity incentives to employees, directors and consultants. Options granted under the 2005 Stock Plan may be incentive stock options or nonqualified stock options. Incentive stock options may be granted only to employees and officers of the Company. Nonqualified stock options and stock purchase rights may be granted to employees, directors and consultants. The board of directors has the authority to determine to whom options will be granted, the number of options, the term and the exercise price. Options are to be granted at an exercise price not less than fair market value for an incentive stock option or a nonqualified stock option. Options generally vest over four years. Options expire no more than 10 years after the date of grant. Upon the effective date of the registration statement related to the Company’s initial public offering, the 2005 Plan was amended to cease the grant of any additional awards thereunder, although the Company will continue to issue common stock upon the exercise of previously granted stock options under the 2005 Plan.

In September 2014, the Company adopted a 2014 Equity Incentive Plan (the “2014 Plan”) which became effective on November 13, 2014. The 2014 Plan is the successor equity compensation plan to the 2005 Plan. The 2014 Plan will terminate on November 12, 2024. The 2014 Plan provides for the grant of incentive stock options, nonqualified stock options, restricted stock awards, stock appreciation rights, performance stock awards, performance cash awards, restricted stock units and other stock awards to employees, directors and consultants. Stock options granted must be at prices not less than 100% of the fair market value at date of grant. Option vesting schedules are determined by the Company at the time of issuance and generally have a four year vesting schedule (25% vesting on the first anniversary of the vesting base date and quarterly thereafter over the next 3 years). Options generally expire ten years from the date of grant unless the optionee is a 10% stockholder, in which case the term will be five years from the date of grant. Unvested options exercised are subject to the Company’s repurchase right. Shares reserved for issuance increases on January 1 of each year commencing on January 1, 2016 and ending on January 1, 2024 by the lesser of (i) the amount equal to 4% of the number of shares issued and outstanding on December 31 immediately prior to the date of increase or (ii) such lower number of shares as may be determined by the board of directors. As of December 31, 2022, the Company has reserved 11,523,829 shares of its common stock that remains unissued for issuance under the 2014 Plan.

Issuance of shares upon share option exercise or share unit conversion is made through issuance of new shares authorized under the plan.

Certain Common Stock option holders have the right to exercise unvested options, subject to a right held by the Company to repurchase the stock, at the original exercise price, in the event of voluntary or involuntary termination of employment of the stockholder. The shares are generally released from repurchase provisions ratably over four years. The Company accounts for the cash received in consideration for the early exercised options as a liability. At December 31, 2022 and 2021, no shares of Common Stock were subject to repurchase by the Company.

In February 2022, the Company granted 280,450 total shares of PRSUs to certain executives for the performance period beginning January 1, 2022 and ending December 31, 2025. The ultimate number of shares eligible to vest for PRSUs range from 0% to 200% of the target number of shares depending on achievement relative to the predefined clinical performance metrics and continued employment with the Company. As of December 31, 2022, all the PRSUs have not become vested.

In February 2022, the Company granted 280,450 total shares of TSR awards to certain executives for the performance period beginning January 1, 2022 and ending December 31, 2025. The ultimate number of shares eligible to vest for the TSR awards range from 0% to 200% of the target number of shares depending on the TSR of FibroGen’s common stock as compared to companies in the NBI index, and continued employment with the Company. As of December 31, 2022, all the TSR awards have not become vested.

Stock option transactions, including forfeited options granted under the 2014 Plan as well as prior plans, are summarized below:


	Shares (In thousands)			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life (In Years)		Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2021		8,967		$	34.84
Granted		2,902			14.72
Exercised		(179	)		8.24
Expired		(1,847	)		34.36
Forfeited		(755	)		32.89
Outstanding at December 31, 2022		9,088			29.19		7.03	$	6,232
Vested and expected to vest, December 31, 2022		8,614			29.61		6.93		5,770
Exercisable at December 31, 2022		4,730		$	35.07		5.45	$	1,438

The estimated weighted-average fair value of the stock options granted during the years ended December 31, 2022, 2021 and 2020 was $14.72, $35.58 and $31.55, respectively. The total intrinsic value of options exercised during the years ended December 31, 2022, 2021 and 2020 was $0.8 million, $13.1 million and $89.6 million, respectively.

The following table summarizes the activities of RSUs, PRSUs and TSR awards:


	Shares (In thousands)			Weighted Average Fair Value at Grant
Unvested at December 31, 2021		2,304		$	30.60
Granted		3,151			14.68
Vested		(1,142	)		27.72
Forfeited		(644	)		25.06
Unvested at December 31, 2022		3,669		$	18.80

The numbers of PRSUs and TSR awards granted included in the table above reflect the shares that could be eligible to vest at 100% of target number of shares.

Among the vested RSUs during the year ended December 31, 2022, 779,539 shares were released and issued, while the remaining was withheld for the related payroll taxes. The estimated weighted-average fair value of the awards granted during the years ended December 31, 2022, 2021 and 2020 was $14.68, $30.19 and $29.99, respectively.

ESPP

In September 2014, the Company adopted a 2014 ESPP that became effective on November 13, 2014. The 2014 ESPP is designed to enable eligible employees to periodically purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan or IRS limitations. At the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last day of the offering period. Purchases are accomplished through participation in discrete offering periods. The 2014 ESPP is intended to qualify as an ESPP under Section 423 of the Internal Revenue Code. The Company has reserved 1,600,000 shares of its common stock for issuance under the 2014 ESPP and shares reserved for issuance increases January 1 of each year, which commenced on January 1, 2016, by the lesser of (i) a number of shares equal to 1% of the total number of outstanding shares of common stock on December 31 immediately prior to the date of increase; (ii) 1,200,000 shares or (iii) such number of shares as may be determined by the board of directors. There were 327,298 shares, 213,505 shares and 143,876 shares purchased by employees under the 2014 Purchased Plan for the years ended December 31, 2022, 2021 and 2020, respectively.

Stock-Based Compensation


	Years Ended December 31,
	2022		2021		2020
Research and development	$	34,861	$	40,547	$	46,229
Selling, general and administrative		30,740		30,614		26,491
Total stock-based compensation expense	$	65,601	$	71,161	$	72,720

The fair value of employee stock-based compensation is estimated using the following assumptions:

•

Expected Dividend Yield. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future.

The assumptions used to estimate the fair value of stock options granted and ESPPs using the Black-Scholes option valuation model were as follows:


	Years Ended December 31,
	2022			2021			2020
Stock Options
Expected term (in years)		5.7			5.7			5.7
Expected volatility		66.8	%		61.9	%		67.1	%
Risk-free interest rate		2.2	%		0.8	%		0.8	%
Expected dividend yield		—			—			—
Weighted average estimated fair value	$	7.88		$	20.21		$	18.36

ESPPs
Expected term (in years)	0.5 - 2.0			0.5 - 2.0			0.5 - 2.0
Expected volatility	58.5 - 97.6		%	47.1 - 104.4		%	47.5 - 77.1		%
Risk-free interest rate	0.1 - 4.5		%	0.0 - 2.2		%	0.1 - 2.9		%
Expected dividend yield		—			—			—
Weighted average estimated fair value	$	8.60		$	12.40		$	17.53

The assumptions used to estimate the fair value of the TSR awards using the Monte Carlo valuation model were as follows:


	Year Ended December 31,
	2022
TSR awards
Expected term (in years)		3.9
Expected volatility		69.0	%
Risk-free interest rate		1.8	%
Expected dividend yield		—
Weighted average estimated fair value	$	24.01

As of December 31, 2022, there was $40.8 million of total unrecognized compensation costs, net of estimated forfeitures, related to non-vested stock option awards granted that will be recognized on a straight-line basis over the weighted-average period of 2.43 years. As of December 31, 2022, there was $46.9 million of total unrecognized compensation costs, net of estimated forfeitures, related to non-vested RSUs, PRSUs and TSR awards granted that will be recognized on a straight-line basis over the weighted-average period of 2.59 years.

Non-Controlling Interests and Subsidiary Stock

Non-Controlling Interests

Non-controlling interest positions related to the issuance of subsidiary stock as described below are reported as a separate component of consolidated equity from the equity attributable to the Company’s stockholders at December 31, 2022 and 2021. In addition, the Company does not allocate losses to the non-controlling interests as the outstanding shares representing the non-controlling interest do not represent a residual equity interest in the subsidiary.

In January 2013, FibroGen Cayman entered into a $0.6 million convertible promissory note. The note bears simple interest at a rate of two percent (2.00%) per annum, accrued on an annual basis in arrears. The outstanding principal balance and unpaid accrued interest on the note is due and payable upon the earlier of (a) the effectiveness of the initial public offering of FibroGen Cayman or (b) the eight year anniversary of the date of the note. During the year ended December 31, 2021, at the option of the lender, the $0.7 million total outstanding principal balance and unpaid accrued interest on the note were converted into Series A Preferred Stock of FibroGen Cayman, and was recorded as an addition to the non-controlling interest of the Company.

Upon the initial public offering and as described below, all eligible FibroGen Europe preferred shares were exchanged for 958,996 shares of FibroGen Common Stock. No other FibroGen Europe shares have the right to be exchanged for FibroGen, Inc. Common Stock.

FibroGen Europe

As of December 31, 2022 and 2021, respectively, FibroGen Europe had a total of 42,619,022 shares of Preferred Stock outstanding, of which there were 1,700,845 shares of Series A Preferred Stock, 1,875,000 shares of Series B Preferred Stock, 1,599,503 shares of Series C Preferred Stock, 1,520,141 shares of Series D Preferred Stock, 459,565 shares of Series E Preferred Stock, 5,714,332 shares of Series F Preferred Stock, 9,927,500 shares of Series G Preferred Stock and 19,822,136 shares of Series H Preferred Stock, all of which shares no longer have any right to be exchanged for FibroGen, Inc. Common Stock. The holders of FibroGen Europe’s shares of Preferred Stock (“Preferred Shares”) have the following rights, preferences and privileges:

Dividend Rights — When the assets of FibroGen Europe are distributed (except for distribution in a liquidation), Preferred Shares shall have the same rights to dividend or other forms of distribution as shares of Common Stock of FibroGen Europe. In the event of a merger, holders of Preferred Shares do not have the right to demand FibroGen Europe to redeem all or part of their Preferred Shares. FibroGen Europe may repurchase shares of Common Stock or Preferred Shares for consideration.

Pre-emptive Right — Preferred Shares shall have pre-emptive subscription right in accordance with the Finnish Limited Liability Companies Act if additional shares are issued, option rights are given, or convertible loan is taken, provided, however, that the foregoing pre-emptive right does not apply to a directed share issue, for which two thirds (2/3) of the voting shares represented at a general meeting of shareholders approve for an important legitimate cause.

Redemption Right — If a Preferred Share can be redeemed by a majority shareholder owning more than ninety percent (90%) of the shares of FibroGen Europe in accordance with the provisions of the Finnish Limited Liability Companies Act, the minority holders of Preferred Shares have the right to request redemption of their shares.

Voting Right — Each share has one vote. Preferred Shares have voting rights only in situations that are specifically provided in the Articles of Association, which include a merger transaction and directed share issue. In addition, Preferred Shares have right to vote in a general shareholder meeting for amending the Articles of Association if the amendment will affect the rights of Preferred Shares.

Conversion Right (1-for-1 basis into Common Stock of FibroGen Europe):

•

Voluntary conversion right: Preferred Shares can be converted into common shares upon the written request of a shareholder provided that the conversion is feasible within the maximum and minimum amounts of shares of classes of FibroGen Europe as set forth in its Articles of Association. Such request can be withdrawn before the notification of conversion is filed with the Finnish Trade Register.

•

Compulsory conversion right: Preferred Shares will be converted into common shares if (i) FibroGen Europe’s shares are listed in a stock exchange or other trading system in the European Economic Area, or (ii) FibroGen Europe’s recombinant collagen and gelatin production technology is being put into commercial use in the area of Europe and certain other European states. Commercial use means there is income generated from the first commercial sale of the products incorporating the above-mentioned technology and does not include license fees, development financing, milestone payments or income from test products or equipment used in research. The board of directors of FibroGen Europe shall notify the shareholders of the compulsory conversion in writing, and the shareholders shall request to convert their shares within the timeframe provided in the notification. Should the shareholders fail to make the conversion request within the time limit, FibroGen Europe may redeem the shares of such shareholders.

Liquidation Right — In the event of a dissolution of FibroGen Europe, holders of Preferred Shares are entitled to be paid in an amount equal to the subscription price of the shares before any distribution is made to holders of common shares. Among holders of Preferred Shares, holders of shares of Series F Preferred Stock are entitled to be paid in an amount equal to the subscription price of Series F Preferred Stock before any distribution is made to holders of other Preferred Shares.

FibroGen Cayman

FibroGen Cayman had 6,758,000 Series A Preference Shares outstanding as of December 31, 2022 and 2021, respectively. The holders of the FibroGen Cayman Series A Preference Shares have the following rights, preferences and privileges:

Liquidation — In the event of liquidation, dissolution, or winding up of the Company, either voluntary or involuntary, including by means of a merger, the holders of FibroGen Cayman Series A Preference Shares are entitled to be paid an amount equal to the product of the number of shares held by a holder of shares of FibroGen Cayman Series A Preference Shares and the original issue price of $1.00 (subject to equitable adjustment for any stock dividend, combination, split, reclassification, recapitalization) plus all declared and unpaid dividends thereon.

Conversion — Each share of FibroGen Cayman Series A Preference Shares is convertible into the number of fully paid and non-assessable shares of Common Stock of FibroGen Cayman that results from dividing the original issue price by the conversion price in effect at the time of the conversion, subject to adjustments for stock splits, stock dividends, reclassifications and like events. The FibroGen Cayman Series A Preference Shares have a conversion price that is equal to the original issuance price such that the conversion ratio to FibroGen Cayman Common Stock is 1:1 as of all periods presented.

Voting — The holders of FibroGen Cayman Series A Preference Shares are entitled to vote together with the FibroGen Cayman Common Stockholders on all matters submitted for a vote of the stockholders. The holder of each share of FibroGen Cayman Series A Preference Shares has the number of votes equal to the number of shares of FibroGen Cayman Common Stock into which it is convertible.

Dividends — The holders of FibroGen Cayman Series A Preference Shares are entitled to receive cash dividends when and if declared, at a rate of 6%.

Collaboration Agreements, License Agreement and Revenues - AstraZeneca Agreements - Additional Information 1 (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Jul. 30, 2013	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2015
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue			$ 12,739	$ 15,857
Aggregate considerations received			77,200
Deferred revenue ($9,259 and $3,201 to related parties)			12,739	15,857
Total revenue			140,734	235,309	$ 176,319
Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			82,869	47,638	72,498
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			11,086	962	8,906
China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payment received			2,300
AstraZeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payment received			71,167
AstraZeneca Agreements [Member] \| Selling, General and Administrative Expenses [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reversal of accrued co-promotion expenses		$ 84,400
Co-promotion expenses			$ 4,400	4,700	27,200
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent, non-refundable and time-based payments	$ 374,000
Potential milestone payments	875,000
Commercial sales milestone	325,000
Shared development costs						$ 233,000
Additional consideration based on net sales description			low 20% range
Aggregate considerations received excluding drug product revenue			$ 439,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| FibroGen, Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Shared development costs						$ 116,500
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	65,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	325,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Deferred Approval Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	160,000
AstraZeneca Agreements [Member] \| China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	348,500
Proceeds from upfront, non-contingent and non-refundable payments	28,200
Commercial sales and other events milestone	187,500
Total revenue			0	0	(90)
AstraZeneca Agreements [Member] \| China [Member] \| Accrued and Other Current Liabilities [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue			7,300	7,900
Deferred revenue ($9,259 and $3,201 to related parties)			7,300	7,900
AstraZeneca Agreements [Member] \| China [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	15,000
AstraZeneca Agreements [Member] \| China [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	$ 146,000
Direct Sales [Member] \| Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			$ 11,702	$ 12,070	$ 72,498

Product Development Obligations - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) DevelopmentObligation	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Number of product development obligations \| DevelopmentObligation	11
Accrued product development costs excluding interest	$ 10.1	$ 10.7
Accrued Interest	$ 6.8	$ 6.9
Bank of Finland Interest Rate [Member]
Debt Instrument [Line Items]
Percentage points deducted to reference rate to compute effective interest rate	1.00%
Minimum [Member]
Debt Instrument [Line Items]
Interest rate on product development advances	3.00%

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Schedule of Significant Balance of Accounts Receivable

The Company has not experienced any loss on its deposits of cash and cash equivalents. Included in current assets are significant balances of accounts receivable as follows:


	December 31,
	2022			2021
Falikang — Related party		65	%		—	%
Astellas — Related party		9	%		63	%
AstraZeneca		16	%		34	%

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue:
Total revenue	$ 140,734	$ 235,309	$ 176,319
Operating costs and expenses:
Cost of goods sold	$ 20,280	$ 12,871	$ 8,869
Cost, Product and Service [Extensible List]	Product Revenue, Net [Member]	Product Revenue, Net [Member]	Product Revenue, Net [Member]
Research and development	$ 296,791	$ 387,043	$ 252,924
Selling, general and administrative	124,688	123,925	106,406
Total operating costs and expenses	441,759	523,839	368,199
Loss from operations	(301,025)	(288,530)	(191,880)
Interest and other, net
Interest expense	(1,440)	(1,075)	(2,402)
Interest income and other income (expenses), net	7,596	(1,078)	5,553
Total interest and other, net	6,156	(2,153)	3,151
Loss before income taxes	(294,869)	(290,683)	(188,729)
Provision for income taxes	358	347	360
Investment income (loss) in unconsolidated variable interest entity	1,573	1,007	(202)
Net loss	$ (293,654)	$ (290,023)	$ (189,291)
Net loss per share - basic	$ (3.14)	$ (3.14)	$ (2.11)
Net loss per share - diluted	$ (3.14)	$ (3.14)	$ (2.11)
Weighted average number of common shares used to calculate net income (loss) per share:
Basic	93,582	92,349	89,854
Diluted	93,582	92,349	89,854
License Revenue [Member]
Revenue:
Total revenue	$ 22,590	$ 116,434	$ 14,323
Development and Other Revenue [Member]
Revenue:
Total revenue	24,189	70,275	80,592
Product Revenue, Net [Member]
Revenue:
Total revenue	82,869	47,638	72,498
Drug Product Revenue [Member]
Revenue:
Total revenue	$ 11,086	$ 962	$ 8,906

Leases - Schedule of Lease Term and Discount Rate (Detail)	Dec. 31, 2022	Dec. 31, 2021
Weighted-average remaining lease term (years):
Finance leases	4 years 10 months 24 days	1 year 1 month 6 days
Operating leases	5 years 9 months 18 days	6 years 9 months 18 days
Weighted-average discount rate:
Finance leases	6.20%	4.64%
Operating leases	4.75%	4.75%

Collaboration Agreements, License Agreement and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations Deferred Revenue (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Deferred revenue, net of current	$ 185,722	$ 186,801
Net unbilled co-development revenue	0	8,000
AstraZeneca Agreements [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Deferred Revenue	175,646	171,516
Net unbilled co-development revenue	17,500	$ 9,100
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Deferred revenue, net of current	158,200
Deferred Revenue	175,600
Net unbilled co-development revenue	$ 17,500

Collaboration Agreements, License Agreement and Revenues - Astellas Agreements - Additional Information (Detail) - USD ($)	1 Months Ended			3 Months Ended			12 Months Ended			35 Months Ended	45 Months Ended
	Dec. 31, 2020	Apr. 30, 2006	Jun. 30, 2005	Dec. 31, 2022	Mar. 31, 2022	Sep. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Feb. 28, 2009	Feb. 28, 2009
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue							$ 140,734,000	$ 235,309,000	$ 176,319,000
Unbilled contract asset				$ 17,488,000			17,488,000	66,909,000
Deferred Revenue				12,739,000			12,739,000	15,857,000
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue							11,086,000	$ 962,000	8,906,000
Japan [Member] \| Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue				8,400,000	$ 9,800,000		$ 8,200,000
Astellas Agreement [Member] \| Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received											$ 40,100,000
Potential milestone payments	$ 15,000,000.0		$ 132,500,000
Commercial sales milestone			15,000,000.0
Additional consideration based on net sales description							the low 20% range of the list price
Transaction price and allocated to performance obligations	$ 15,000,000.0								$ 15,000,000.0
Aggregate considerations received excluding drug product revenue				105,100,000			$ 105,100,000
Astellas Agreement [Member] \| Japan [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			22,500,000
Astellas Agreement [Member] \| Japan [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 95,000,000.0
Astellas Agreement [Member] \| Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received										$ 320,000,000.0
Potential milestone payments						$ 120,000.0
Additional consideration based on net sales description							low 20% range
Transaction price and allocated to performance obligations					$ 25,000,000.0	$ 120,000.0
Aggregate considerations received excluding drug product revenue				$ 685,000,000.0			$ 685,000,000.0
Development and regulatory approval milestones		$ 425,000,000.0
Percentage of joint development costs committed to fund		50.00%
Astellas Agreement [Member] \| Europe [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments		$ 90,000,000.0
Astellas Agreement [Member] \| Europe [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments		$ 335,000,000.0

Collaboration Agreements,License Agreement and Revenues - Summary of Product Revenue, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation Of Revenue [Line Items]
Total revenue	$ 140,734	$ 235,309	$ 176,319
Non-key Account Hospital Listing Award [Member]
Disaggregation Of Revenue [Line Items]
Total revenue			9,300
Contractual Sales Rebate [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	600	800	6,200
Discounts And Rebates [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	700	1,700	16,400
Product Revenue, Net [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	82,869	47,638	72,498
Product Revenue, Net [Member] \| Direct Sales [Member]
Disaggregation Of Revenue [Line Items]
Gross revenue	12,366	13,727	89,027
Total revenue	11,702	12,070	72,498
Product Revenue, Net [Member] \| Direct Sales [Member] \| Price Adjustment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	242	(982)
Product Revenue, Net [Member] \| Direct Sales [Member] \| Non-key Account Hospital Listing Award [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	49	95	(9,325)
Product Revenue, Net [Member] \| Direct Sales [Member] \| Contractual Sales Rebate [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(624)	(832)	(6,189)
Product Revenue, Net [Member] \| Direct Sales [Member] \| Other Discounts and Rebates [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(332)	(21)	(923)
Product Revenue, Net [Member] \| Direct Sales [Member] \| Sales Returns [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	1	83	(92)
Product Revenue, Net [Member] \| Sales To Falikang
Disaggregation Of Revenue [Line Items]
Total revenue	71,167	35,568	0
Gross transaction price	112,544	97,531	0
Product Revenue, Net [Member] \| Sales To Falikang \| Profit Share
Disaggregation Of Revenue [Line Items]
Total revenue	(43,716)	(34,759)	0
Product Revenue, Net [Member] \| Sales To Falikang \| Net Transfer Price
Disaggregation Of Revenue [Line Items]
Total revenue	68,828	62,772	0
Product Revenue, Net [Member] \| Sales To Falikang \| Decrease (Increase) in Deferred Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	$ 2,339	$ (27,204)	$ 0

Fair Value Measurements - Fair Values of Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	$ 270,656	$ 401,763
Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	82,008	182,646
Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	57,381	68,079
Asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	2,474	27,087
Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	4,980	9,154
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	290,537	461,564
Fair Value, Measurements, Recurring [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	19,881
Investments		58,801
Fair Value, Measurements, Recurring [Member] \| Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	82,008	182,646
Fair Value, Measurements, Recurring [Member] \| Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure		69,079
Investments	57,381
Fair Value, Measurements, Recurring [Member] \| U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	111,345	91,522
Fair Value, Measurements, Recurring [Member] \| Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	11,468	23,275
Fair Value, Measurements, Recurring [Member] \| Asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	2,474	27,087
Fair Value, Measurements, Recurring [Member] \| Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	4,980	9,154
Fair Value, Measurements, Recurring [Member] \| Convertible promissory note
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	1,000
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	118,853	150,323
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	19,881
Investments		58,801
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure		0
Investments	0
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	98,972	91,522
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Convertible promissory note
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	170,684	311,241
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	0
Investments		0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	82,008	182,646
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure		69,079
Investments	57,381
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	12,373	0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	11,468	23,275
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	2,474	27,087
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	4,980	9,154
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Convertible promissory note
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	1,000	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	0
Investments		0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure		0
Investments	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	$ 0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Convertible promissory note
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	$ 1,000