Acceleron Pharma Receives Grant for ACE-011 from MMRF

Acceleron Pharma, Inc., a biopharmaceutical company developing novel therapeutics that modulate the growth of tissues including bone and muscle, today announced that it was selected to receive a Biotech Investment Award from the Multiple Myeloma Research Foundation to support the research and development of ACE-011, a novel bone forming agent, for the treatment of multiple myeloma. In addition, Acceleron announced that it began a randomized, double-blind, placebo-controlled multiple ascending dose study of ACE-011.

"We are proud to receive this highly-regarded grant from the Multiple Myeloma Research Foundation," said John Knopf, Ph.D., Chief Executive Officer of Acceleron. "With this grant, we will continue to aggressively pursue the development of ACE-011, which has shown encouraging preclinical and clinical effects on bone formation, to treat the complications of bone loss associated with multiple myeloma."

The multiple dose study will be conducted in healthy, post-menopausal women. Subjects will receive four monthly subcutaneous doses of either ACE-011 or placebo. The primary objective of the study is to assess the safety, tolerability and pharmacokinetics of ACE-011. The pharmacodynamic effects of ACE-011 on bone will also be measured.

"We are excited to start this study with ACE-011 and expect to begin additional studies with this compound later this year for the treatment of cancer and cancer-related bone loss," said Matthew L. Sherman, M.D., Chief Medical Officer of Acceleron. "Our product pipeline continues to make great progress and we look forward to announcing additional clinical milestones throughout 2008."

About ACE-011

ACE-011, a protein therapeutic based on the activin receptor type IIA, is a novel bone forming agent. In numerous preclinical models of bone loss, ACE-011 increased bone mineral density, improved bone architecture, increased the mineral apposition and bone formation rates and improved bone mechanical strength. These effects have been demonstrated in therapeutic models of bone loss in which ACE-011 stimulated bone formation - a significant unmet medical need that is underserved by current treatments for bone loss. ACE-011 is currently in a phase 1b study and Acceleron expects to begin a phase 2a study in multiple myeloma in the middle of 2008.

About Acceleron Pharma

Acceleron is a privately held biopharmaceutical company committed to discover, develop, manufacture and commercialize novel biotherapeutics that modulate the growth of bone, muscle, fat and the vasculature to treat musculoskeletal, metabolic and cancer-related diseases. Acceleron's scientific approach takes advantage of its unique insight into the regenerative powers of two protein families: the Growth and Differentiation Factors (GDFs) and Bone Morphogenetic Proteins (BMPs). ACE-011, a novel bone forming agent, is the company's lead program, and is being developed to reverse bone loss in diseases such as cancer-related bone loss. In addition, the company is advancing through preclinical development product candidates that increase muscle mass, control angiogenesis and inhibit fat accumulation. Acceleron utilizes proven biotherapeutic technologies and capitalizes on the company's internal GMP manufacturing capability to rapidly and efficiently advance its therapeutic programs. The investors in Acceleron are Advanced Technology Ventures, Bessemer Ventures, Flagship Ventures, MPM BioEquities, OrbiMed Advisors, Polaris Ventures, QVT Financial, Sutter Hill Ventures and Venrock. For more information, visit www.acceleronpharma.com.