Affymax® Announces Hematide™ Successfully Restores Hemoglobin in Patients with Pure Red Cell Aplasia (PRCA)
-- Phase 2 Study Findings Presented at American Society of Nephrology Renal Week 2007 --

PALO ALTO, Calif. & OSAKA, Japan, Nov 05, 2007 (BUSINESS WIRE) -- Affymax, Inc. (Nasdaq: AFFY) and Takeda Pharmaceutical Company Limited (TOKYO:4502) today announced results from a Phase 2 clinical trial of Hematide™ to treat anemia in dialysis and predialysis chronic kidney disease (CKD) patients with pure red cell aplasia (PRCA, Anti-erythropoietin antibody-mediated). Results showed that Hematide could restore hemoglobin to the target range in these patients and eliminate the need for red blood cell transfusions in the patients studied.

The data were presented yesterday by Iain C. Macdougall, M.D., Hematide clinical trial investigator, consultant nephrologist and honorary senior lecturer at King's College Hospital in London during an oral presentation at the American Society of Nephrology Renal Week 2007 in San Francisco. In addition, Phase 2 clinical trial results of Hematide in patients with anemia due to CKD were presented during the poster session.

PRCA, a rare autoimmune disorder, occurs when the body produces neutralizing antibodies to the currently marketed recombinant human erythropoietin (EPO), thus suppressing the production of red blood cells by the bone marrow. In contrast, Hematide, Affymax's lead drug in development for the treatment of anemia, is a novel synthetic, pegylated peptidic compound with no structural homology with human EPO.

"PRCA is a treatment complication resulting when a patient develops antibodies to recombinant EPO products. While rare, PRCA is a serious disease that prohibits further treatment with recombinant EPO and requires patients undergo regular blood transfusions and immunosuppressive therapy to suppress antibody production in an attempt to correct anemia and manage hemoglobin levels," said Dr. Macdougall, consultant nephrologist in the Department of Renal Medicine at King's College Hospital in London, U.K. "These trial results provide important information about the safety profile of Hematide."

"Hematide is immunologically distinct from EPO. In preclinical studies, Hematide addressed hemoglobin deficiencies caused by EPO-specific antibodies, and antibodies generated to recombinant EPO have not been shown to cross-react with Hematide," added Robert B. Naso, Ph.D., executive vice president of research and development at Affymax. "The PRCA data presented at ASN are intriguing findings which support the differentiation of Hematide. At some point in the future, Affymax and Takeda may decide to pursue further development of the product in the area of PRCA, but for now our development priorities are focused on anemia in chronic renal failure and chemotherapy-induced anemia."

"We are pleased with this data presentation, which suggests the difference of Hematide," said Masaomi Miyamoto, Ph.D., general manager of pharmaceutical development division at Takeda. "With our partner Affymax, we will vigorously continue development activities of this scientifically interesting product as a potential new treatment option for patients with anemia in both chronic renal failure and chemotherapy-induced anemia."

PRCA Study Results
The open-label, multi-center trial in 10 dialysis and predialysis CKD patients with PRCA evaluated the effectiveness and safety of Hematide administered subcutaneously every four weeks. The primary endpoint was the change in hemoglobin from baseline over time. Secondary endpoints included safety and the effectiveness of Hematide in reducing the frequency of red blood cell transfusions over time.

Results showed that by six months of treatment, median hemoglobin had increased from 9.7 g/dL to 11.6 g/dL and transfusion requirements were eliminated. Three patients, who had their hemoglobin levels increased with Hematide, improved sufficiently to undergo kidney transplant surgery. Hematide was generally well tolerated. Some adverse events, including bone pain, hypertension, injection site hematoma, and increased blood pressure, were considered possibly related to Hematide.

Hematide Phase 2 Trial Results Also Presented at ASN Conference
In addition to the oral presentation on PRCA trial results, two posters from two separate Phase 2 clinical trials of Hematide in dialysis and predialysis CKD patients were presented at the ASN conference. These data showed that Hematide increased hemoglobin in treatment-naive, predialysis patients when administered monthly at an appropriate dose. Similarly, the data in dialysis patients previously treated with three-times weekly Epoetin alfa demonstrated that mean hemoglobin levels were maintained at target levels following a switch to once-monthly dosing of Hematide at an appropriate dose.

About Hematide
Hematide is a novel synthetic, pegylated peptidic compound that binds to and activates the erythropoietin receptor and thus acts as an erythropoiesis stimulating agent. The investigational product is being evaluated in a Phase 3 program for the treatment of anemia in patients with dialysis and predialysis chronic renal failure (CRF) and earlier stage clinical trials in cancer patients receiving chemotherapy.

About PRCA
Dialysis and non-dialysis patients with CKD frequently develop anemia because of a reduction in native EPO production by dysfunctional kidneys. Since the late 1980s, recombinant EPO has been used successfully to treat anemia-associated EPO deficiency. A small number of CKD patients develop antibody-mediated PRCA, a type of anemia that develops when patients mount a neutralizing antibody response to recombinant EPO used to treat the anemia associated with CKD. These antibodies neutralize not only the recombinant EPO but also cross-neutralize natural EPO produced by the patients, leading to a state of absolute EPO resistance and transfusion dependence. While the incidence of PRCA has decreased, there continues to be sporadic reports of antibody-mediated PRCA associated with commercially available EPO products. Concern over PRCA prompted the addition of warnings in the prescribing information of all EPO-based products marketed in the U.S.

About Affymax, Inc.
Affymax, Inc. is a biopharmaceutical company developing novel drugs to improve the treatment of serious and often life-threatening conditions. Affymax's lead product candidate, Hematide™, is currently in Phase 3 clinical trial stage for the treatment of anemia associated with chronic renal failure and in clinical trials for the treatment of anemia in cancer patients. For additional information, please visit www.affymax.com.

About Takeda
Located in Osaka, Japan, Takeda (TOKYO:4502) is a research-based global company with its main focus on pharmaceuticals. As the largest pharmaceutical company in Japan and one of the global leaders of the industry, Takeda is committed to striving toward better health for individuals and progress in medicine by developing superior pharmaceutical products. Additional information about Takeda is available through its corporate website, www.takeda.com.

This release contains forward-looking statements, including statements regarding the timing, design and results of the Company's clinical trials and drug development program and the timing and likelihood of the commercialization of Hematide. The Company's actual results may differ materially from those indicated in these forward-looking statements due to risks and uncertainties, including risks relating to the continued safety and efficacy of Hematide in clinical development, the potential for once per month dosing, regulatory requirements and approvals, research and development efforts, industry and competitive environment, intellectual property rights and disputes and other matters that are described in the Company's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission. Investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this release. The Company undertakes no obligation to update any forward-looking statement in this press release.

ASN Abstract #SU-FC061: Treatment of Erythropoietin Antibody-Mediated Pure Red Cell Aplasia with a Novel Synthetic Peptide-based Erythropoietin Receptor Agonist. Presented in an oral session at the American Society of Nephrology Renal Week 2007, Sunday, November 4, 4:00-6:00 p.m.

ASN Abstract #SU-PO783: Comparison of Monthly Dosing Schemes Using Hematide, a Synthetic Peptide-based Erythropoiesis Stimulating Agent (ESA), to Maintain Hemoglobin (Hb) in Hemodialysis (HD) Patients Previously Treated with Epoetin Alfa (EPO). Presented in a poster presentation at the American Society of Nephrology Renal Week 2007, Saturday, November 3, 11:00 a.m. - 12:00 p.m.

ASN Abstract #SA-PO777: Comparison of Monthly Dosing Schemes Using Hematide, a Synthetic Peptide-based Erythropoiesis Stimulating Agent (ESA), to Correct Anemia in Patients with Chronic Kidney Disease (CKD) not on Dialysis. Presented in a poster presentation at the American Society of Nephrology Renal Week 2007, Sunday, November 4, 11:00 a.m. - 12:00 p.m.

Source
Affymax, Inc.

Contact
Affymax, Inc.
Sylvia Wheeler, 650-812-8700
Executive Director, Corporate Communications
or
Takeda Pharmaceutical Company Limited
Seizo Masuda, +81-3-3278-2037
Coordinator, Corporate Communications

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