Acceleron Pharma Appoints Matthew L. Sherman, M.D. as Chief Medical Officer

Acceleron Pharma, Inc.

Acceleron Pharma Appoints Matthew L. Sherman, M.D. as Chief Medical Officer

May 16, 2006

Dr. Sherman's Expertise in Building a Clinical Development Organization and Advancing Programs Through Regulatory Approval a Key Addition to the Management Team

5/16/2006 - Acceleron Pharma, Inc., a biopharmaceutical company focused on developing and commercializing therapeutics based on its novel tissue growth factor platform, today announced the appointment of Matthew L. Sherman, M.D. as Senior Vice President and Chief Medical Officer.

"Acceleron has built a robust preclinical pipeline with several programs poised to enter clinical trials. Matt brings to Acceleron broad scientific and clinical research knowledge along with his experience and proven track record of building clinical development organizations. With Matt joining our team, we are positioned to rapidly and efficiently advance our wealth of product candidates into clinical development and ultimately deliver important new therapies to patients," said Glenn Batchelder, Chief Executive Officer of Acceleron.

"I am thrilled to join Acceleron and lead the clinical development of several exciting programs," said Dr. Sherman. "Our lead program, ACE-011, has demonstrated remarkable preclinical efficacy in treating serious bone diseases such as osteoporosis and cancer-related bone loss. The clinical potential of this compound is enormous. Furthermore, Acceleron has several other preclinical programs targeting neuromuscular, oncology and metabolic diseases with high unmet medical need. We expect 3 programs to be in clinical development over the next 18 months. This promising pipeline reflects the remarkable progress Acceleron has achieved since receiving its initial funding in 2004."

Dr. Sherman joins Acceleron from Synta Pharmaceuticals where he was Senior Vice President and Chief Medical Officer responsible for clinical research, clinical operations, biostatistics, data management, regulatory affairs, quality assurance and program management. From 1998 to 2004, Dr. Sherman worked at Wyeth Pharmaceuticals as the Therapeutic Area Director for Oncology in Clinical Research and Development. While at Wyeth, Dr. Sherman provided senior oncology and hematology leadership for worldwide clinical development of 12 development projects for both small molecule and biologic therapeutics, including the submission and approval of Mylotarg(R) (gemtuzumab ozogamicin for injection) by the FDA. From 1992 to 1997, he held various clinical development leadership positions at Genetics Institute. From 1983 to 2001, Dr. Sherman held clinical positions at Harvard Medical School with corresponding hospital appointments at the Dana-Farber Cancer Institute and Brigham and Women's Hospital. Dr. Sherman holds a B.S. in chemistry Phi Beta Kappa from the Massachusetts Institute of Technology and an M.D. with honors from Dartmouth Medical School. He is board certified in Medical Oncology and Internal Medicine, has published over 75 original papers, reviews and book chapters on laboratory and clinical development of novel drugs as well as in clinical and molecular pharmacology. Dr. Sherman is also the holder of several patents.

About Acceleron Pharma

Acceleron is a privately held biopharmaceutical company that is focused on developing and commercializing protein therapeutics. The company's scientific platform is based on its unique position to harness the clinical potential of naturally occurring tissue growth factors to treat diseases with significant unmet medical need. The company's lead program is being developed to reverse bone loss in diseases such as osteoporosis and cancer-related bone loss. Additionally, the company has several programs in each of the following areas: muscle growth, angiogenesis and metabolic diseases. Acceleron utilizes proven biotherapeutic technologies and capitalizes on the company's internal GMP production capability to rapidly and efficiently advance products emerging from its R&D platform into multiple important therapies. The investors in Acceleron are Advanced Technology Ventures, Flagship Ventures, Polaris Ventures, Sutter Hill Ventures and Venrock Associates.

Contact:

Steven Ertel
Acceleron Pharma
Senior Director Business Development
617-576-2220 x234