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Affymax and Takeda Announce Long-Term Hematide Safety and Effectiveness Data from Phase 2 Clinical Trials in Chronic Kidney Disease Patients with Anemia

May 12, 2008

-- Results from three studies presented at the 45th ERA-EDTA Congress --

Stockholm, Sweden, May 12, 2008 – Takeda Global Research & Development Center, Inc. and Affymax, Inc. (Nasdaq: AFFY) today reported positive 12 month data from their ongoing Phase 2 trial evaluating the safety and tolerability of Hematide™, an investigational drug in development for the treatment of anemia associated with chronic kidney disease (CKD). Preliminary data from the trial showed that Hematide administered once every four weeks was well tolerated and maintained mean hemoglobin levels between 11 and 12 g/dL in patients with CKD, both pre-dialysis and hemodialysis, over a 12 month period. The results were presented by Andrzej Wiecek, M.D., trial investigator and head of Nephrology, Medical University of Silesia, Katowice, Poland, at the 45th ERA-EDTA Congress taking place in Stockholm, Sweden.

In addition, the companies announced the results of two other studies. One study also assessed safety and tolerability of Hematide in CKD, but only for patients already on hemodialysis and a third presentation detailed data relating to the treatment with Hematide of CKD patients with Pure Red Cell Aplasia (PRCA), a rare but serious condition, where the body produces antibodies to erythropoiesis stimulating agents (ESAs) and the patient’s endogenous erythropoietin. Patients who develop PRCA are usually transfusion-dependent. In this study, treatment of these patients with Hematide resulted in maintenance of hemoglobin levels within target in the absence of transfusions.

Commenting on these results, Dr. Wiecek said, “Maintaining average hemoglobin levels within the desired target range with infrequent injections is an important step forward in the treatment of patients with anemia caused by chronic kidney disease. We are pleased that these trials show the potential for Hematide to be dosed on a once-monthly basis while maintaining stable hemoglobin levels.”

Anemia is a common complication for patients with CKD, which affects approximately 40 million people in Europe – nearly eight percent of the population. Treatment of anemia in patients with CKD is usually considered when hemoglobin levels fall to 11 g/dL or below.

Speaking about the partnership which led to the latest developments for Hematide, Dr. David Recker, senior vice president, Clinical Sciences at Takeda said, “The focus for Takeda and Affymax are the needs of patients, which is at the forefront of drug development. Together, we are working to bring this novel potential treatment option to patients with CKD-induced anemia and to the physicians who treat them.”

Presentation Results
In the first study1, long term safety and tolerability data were presented on 84 patients with CKD induced anemia. Patients entering this study had already received Hematide for at least 24 weeks. The study is following patients for up to 18 months where patients continue to receive Hematide on a once per month dosing schedule. The study was initially designed in 2006 to maintain hemoglobin levels between 10-13 g/dL. The protocol was later modified to target hemoglobin ranges between 10-12.5 g/dL to reflect KDOQI guidelines. Four patients (4.8%) had at least one adverse event considered possibly or probably related to Hematide, which included increased or elevated potassium (3.6%), arteriovenous fistula thrombosis (1.2%), and hypertension (1.2%). No serious adverse events were considered related to study drug.

The second presentation2 reported the preliminary data from an ongoing open-label, multi-centre dose finding study of the safety, pharmacodynamics, and pharmacokinetics of Hematide for the maintenance of anemia in hemodialysis patients previously treated with epoetin. Hematide administered once every four weeks either by IV injection or subcutaneously in dialysis patients was shown to maintain mean hemoglobin concentrations between 11 and 12 g/dL throughout the study. No adverse or serious adverse events were considered related to Hematide. Further assessment of intravenous and subcutaneous dosing is currently underway in a Phase 3 study.

The third presentation3 showed the benefit of Hematide for all ten patients with PRCA at the time of this interim analysis. The average baseline hemoglobin levels increased from 9.7g/dL (9 of 10 transfusion-dependent) prior to treatment, to an average of 11.6 g/dL by six months, with transfusion requirements eliminated in all but one patient by 6 months, and in all patients by 8 months. The four adverse events considered possibly related to Hematide were hypertension, bone pain, injection site hematoma and increased blood pressure. No Hematide-related serious adverse events were reported.

Generally, Hematide appeared to be well-tolerated in patients across the three studies.

About Hematide
Hematide, a novel, synthetic, peptide-based erythropoiesis-stimulating agent (ESA), is a product candidate that has demonstrated the ability to stimulate the production of red blood cells. If proven safe and effective in clinical trials, it may offer physicians and patients an alternative therapy to recombinant erythropoietin, a hormone that stimulates red blood cell formation.

Affymax and Takeda are collaborating on the development of Hematide. The product will be commercialized in the European Union by Takeda. Affymax is conducting Phase 3 clinical trials for Hematide to treat anemia in chronic renal failure indications. Takeda is also focusing on a recently initiated Phase 1 clinical trial to evaluate Hematide to treat chemotherapy-induced anemia in prostate, breast and non-small cell lung cancer patients.

About Takeda Global Research & Development Center, Inc
Based in Deerfield, Ill., Takeda Global Research & Development Center, Inc. is a wholly owned subsidiary of Takeda Pharmaceutical Company Limited, the largest pharmaceutical company in Japan. Takeda Global Research & Development Center, Inc. supports clinical and product development activity for Takeda commercial organizations. With a robust pipeline of compounds in development for diabetes, cardiovascular disease, oncology, gastroenterology, neurology and other conditions, Takeda rapidly brings innovative products to market to improve patient health and enhance the practice of medicine. To learn more about the company, visit www.tgrd.com .

About Affymax Inc
Affymax, Inc. (Nasdaq: AFFY) is a biopharmaceutical company developing novel drugs to improve the treatment of serious and often life-threatening conditions. For additional information, please visit www.affymax.com .

This release contains forward-looking statements, including statements regarding the success of the collaboration, timing, design and results of the Companies' clinical trials and drug development program and the timing and likelihood of the commercialization of Hematide. The Companies' 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, the timing of patient accrual in ongoing and planned clinical studies, regulatory requirements and approvals, research and development efforts, industry and competitive environment, intellectual property rights and disputes and other matters that are described in Affymax'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 Companies undertake no obligation to update any forward-looking statement in this press release.

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MacDougall I. et al, Interim evaluation of long-term safety and tolerability of Hematide during maintenance treatment of anaemia in patients with chronic kidney disease, presented on 12 May 2008 at the 45th ERA-EDTA congress, Stockholm, Sweden 

Covic A. et al, A Phase 2, open-label, multi-center, dose finding study of the safety, pharmacodynamics and pharmacokinetics of Hematide for the maintenance of anaemia in haemodialysis patients previously treated with epoetin, presented on 12 May 2008 at the 45th ERA-EDTA congress, Stockholm, Sweden
Eckardt K-U. et al, Successful treatment of anti-erythropoietin antibody-mediated Pure Red Cell Aplasia with Hematide, presented on 12 May 2008 at the 45th ERA-EDTA congress, Stockholm, Sweden
European Kidney Health Alliance, The Kidney in Health and Disease, available at: http://www.ekha.eu/CobraManagedFiles/FINAL_FACTSHEET.pdf , last accessed on 25/04/08
National Institute of Clinical Excellence, Anaemia management in people with chronic kidney disease, available at:
http://www.nice.org.uk/nicemedia/pdf/62113_NICE_QRG_FINAL%20new.pdf accessed on 25/04/08