Results Reported at Annual Meeting of the American Society of Hematology

San Diego - (Business Wire) - Dec. 6, 2004 - FibroGen, Inc., today reported results of a Phase 1 study and early results of a Phase 2a study of FG-2216, the Company's investigational oral anemia therapy, at the 46th Annual Meeting of the American Society of Hematology (ASH). Results of the Phase 1 study demonstrate that FG-2216 is safe and well tolerated and stimulates production of erythropoietin (EPO) and reticulocytes in normal human subjects. The Company also presented new data from the first completely enrolled dose group of a Phase 2a study of FG-2216 in chronic kidney disease (CKD) patients with anemia, demonstrating for the first time that oral therapy with FG-2216 leads to significant increases in levels of circulating hemoglobin (the oxygen-carrying molecule in red blood cells) and providing proof of concept for using FG-2216 to treat anemia in a CKD clinical setting.

The Phase 1 results provide the first demonstration in humans of an erythropoietic response due to stabilization of Hypoxia-Inducible Factor (HIF) induced by FG-2216, a member of a novel class of small molecules that inhibit HIF-Prolyl Hydroxylase (HIF-PH). All doses of FG-2216 (0.3 to 20 mg/kg) administered orally to a total of 54 healthy male subjects were found to be well tolerated with no serious adverse events or dose-limiting toxicities observed. A dose-dependent elevation in the serum level of EPO, a naturally occurring hormone that stimulates red blood cell production, was observed in response to treatment with FG-2216. Repeated dosing (twice or three times weekly) for three weeks was associated with a consistent increase in EPO production and in the number of circulating reticulocytes (young red blood cells) compared to the control group with no evidence of desensitization to the study drug (also see Company press release of November 1, 2004).

Ongoing Phase 2a multi-center trials of FG-2216 include single-blind, placebo controlled studies designed to evaluate the safety and efficacy of FG-2216 in anemic CKD patients (protocol defined as hemoglobin less than 10 g/dL), who have not received dialysis. One study is enrolling CKD patients not receiving recombinant EPO therapy for anemia (recombinant EPO naive), and the second study is enrolling CKD patients who are currently treated with recombinant EPO therapy for anemia and switched to FG-2216 or placebo (recombinant EPO withdrawn). Patients in each study are randomized to either a treatment group, which receives FG-2216 (6 or 20 mg/kg) administered orally three times a week (Monday, Wednesday, and Friday) for four weeks, or to a placebo group, followed by two weeks of observation. In the recombinant EPO naive study, the ability of FG-2216 to stimulate increases in circulating levels of hemoglobin is being evaluated. In the recombinant EPO withdrawn study, the ability of FG-2216 to maintain hemoglobin levels is being evaluated.

Early results from the first completely enrolled dose group (6 mg/kg) of the recombinant EPO naive study demonstrate that after three weeks of oral therapy, patients who received FG-2216 (n=5 patients) experienced a mean increase in hemoglobin from baseline of 1.0 g/dL (range = 0.1 to 2.2 g/dL), and patients who received placebo (n=3 patients) experienced a mean decrease in hemoglobin from baseline of 0.6 g/dL (range = -0.3 to -1.0 g/dL). This difference between means is statistically significant (p = 0.036, Mann-Whitney rank sum test; p = 0.024, t-test). An analysis of hemoglobin levels from the last available measurement of the planned 42-day study period demonstrated a mean hemoglobin increase of 1.4 g/dL (range = 0.4 to 2.7 g/dL) for the FG-2216 group and a mean hemoglobin decrease of 0.5 g/dL (range = 0 to -1.0 g/dL) for the placebo group (p = 0.025, Mann-Whitney rank sum test; p = 0.025, t-test). The baseline hemoglobin was 9.6 g/dL and 9.8 g/dL for the FG-2216 and the control groups, respectively. No serious adverse events or dose-limiting toxicities related to the study drug were observed.

"We are encouraged by these preliminary data that suggest the magnitude and rate of hemoglobin increases observed in patients treated with FG-2216 are likely to provide clinical benefit in treating anemia associated with CKD. The results also indicate that there were no serious adverse events or dose-limiting toxicities associated with oral administration of FG-2216," said Pedro R. Urquilla, M.D., Vice President of Medical Affairs at FibroGen. "As an oral therapy, we believe FG-2216 could meet a large underserved need for anemia therapy, in particular, in the predialysis setting."

"These data provide clear proof of concept that an oral anemia therapy based on FibroGen HIF stabilization technology can be therapeutically useful in treating anemia associated with CKD," said Thomas B. Neff, Chief Executive Officer of FibroGen. "We will continue to explore the use of HIF-PH inhibitors in CKD as well as in other clinical settings, such as chemotherapy-induced anemia, anemias of chronic disease (ACD) in various settings, iron deficiency anemia, and anemia associated with congestive heart failure, senescence, and menstruation. We believe HIF stabilization technology can provide clinical benefit in such underserved therapeutic areas by directly addressing deficient iron utilization and inflammation, which are other important factors underlying the pathophysiology of anemia in addition to a deficiency in EPO production."

About FG-2216

FG-2216 is an orally active, small molecule inhibitor of Hypoxia-Inducible Factor-Prolyl Hydroxylase (HIF-PH), an enzyme that regulates the stability and activity of HIF. FG-2216 is designed to stabilize HIF and selectively activate the body's natural process of HIF-2-mediated erythropoiesis, including the induction of endogenous EPO, the mobilization and utilization of iron stores, and suppression of inflammatory cytokines essential to the formation of new oxygen-carrying red blood cells and the treatment of anemia.

In 2004, FibroGen entered an agreement to license FG-2216 (and other compounds) to Yamanouchi Pharmaceutical Co., Ltd., for development and sale in Japan for the treatment of anemia. FibroGen retains rights to FG-2216 for the rest of the world.

About FibroGen

FibroGen, Inc., is a biotechnology-based drug discovery company using its expertise in the fields of tissue fibrosis and Hypoxia-Inducible Factor (HIF) biology to discover, develop, and commercialize novel therapeutics for fibrotic disorders, anemia, ischemic disease, cancer, and other areas of unmet medical need. FibroGen also develops and produces recombinant human collagens and gelatins using unique production technology that provides the basis for FibroGen's proprietary cosmetic dermal filler and biomaterials supply business.

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

Contact:
Laura Hansen, Director of Corporate Communications,
Phone: 650-866-7828