Investors and Media

Results support use of recombinant gelatin as a vaccine and biologic stabilizer

South San Francisco, CA - July 21, 2003

FibroGen, Inc., today announced positive results from the first clinical safety study of recombinant human gelatin, finding the study material safe and well tolerated at all doses tested. The data support the use of FibroGen's proprietary 8.5 kD gelatin fragment as a safe and fully characterized alternative to animal- and plasma-derived proteins currently used as stabilizing components in formulations of vaccines and biological therapeutics.

Products containing animal- or plasma-derived proteins, such as gelatin and albumin, respectively, have the potential to induce harmful inflammatory or immune responses in humans and pose risk of contamination with potentially life-threatening pathogens, such as viruses or prions. In addition, the current process of making gelatin by denaturing collagen (a protein extracted from the skin, bones, and tissues of animal carcasses) yields a highly variable material that is not easily traced to its source once incorporated into consumer products.

""FibroGen's recombinant gelatin stabilizer is expected to provide safer delivery and improved performance of vaccines and biologics,"" said James W. Polarek, Ph.D., Vice President, Collagen and Gelatin Development. ""Our recombinant gelatin is produced in a yeast system, eliminating the risk of contamination with transmissible pathogens that is associated with proteins derived from animal tissues or human plasma. FibroGen's proprietary technology also enables the consistent production of highly purified and fully characterized recombinant gelatin fragments that can be tailored for specific customer applications.""

The safety of FibroGen's 8.5 kD recombinant gelatin fragment was examined in human volunteers at doses similar to, or significantly greater than, the dosage of animal-derived gelatin found in marketed vaccines. Healthy volunteers received a total of three doses of either 1 mg, 15 mg, or 60 mg of recombinant gelatin administered intramuscularly at two-week intervals. The subjects were followed for 56 days after administration of the last dose, and no adverse events related to the study material were reported in any of the three dose groups. Serum was analyzed by ELISA for antibody production against recombinant gelatin or potential yeast host cell contaminants. No significant changes in antibody titers against recombinant gelatin or yeast-derived mannan and protein were seen over the course of the study. Finally, no significant changes related to study material were observed for the standard serum chemistry parameters measured over the course of the study.

""FibroGen is working closely with several leading vaccine companies in the evaluation of our recombinant gelatins as stabilizers for new vaccine products and replacements in existing vaccines,"" said Thomas B. Neff, Chief Executive Officer. ""We believe the successful demonstration of tolerability in this clinical safety study will support our commercialization process. Our next objective is to complete a Master File with the U.S. Food and Drug Administration, which will facilitate the registration of products that incorporate our recombinant gelatins.""

About FibroGen's Recombinant Human Gelatin

FibroGen's recombinant human gelatins are engineered from specific segments of human collagen genes. No animal- or human-derived materials are used in the entire production process. FibroGen's proprietary technology enables the production of discrete, reproducible batches of gelatin fragments having specific molecular weights (e.g., 8.5 kD, 25 kD, 50 kD), providing customers with the ability to select a product optimized for specific applications. For example, FibroGen's recombinant gelatin fragments can be used as excipients that are completely reproducible, traceable, and characterizable. The development of yeast production strains with high productivity, coupled with highly efficient purification processes, enables competitive production costs.

About FibroGen, Inc.

FibroGen, Inc., is a privately held biopharmaceutical company focused on the discovery, development, and commercialization of therapeutics and biomaterials to address unmet needs in the medical, pharmaceutical, and consumer markets. FibroGen's therapeutic target areas include fibrosis, anemia, and ischemia, and the Company develops and manufactures recombinant human collagen and gelatin biomaterials. FibroGen is headquartered in South San Francisco, California, with additional operations at FibroGen Europe Corp., the Company's subsidiary located in Helsinki, Finland.

For more information about FibroGen, Inc., please visit www.fibrogen.com.

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