September 12, 2012

Acceleron Founder Dr. Tom Maniatis To Receive The 2012 Lasker Award in Medical Science

Cambridge, Mass. – September 12, 2012 – Acceleron Pharma, Inc., a biopharmaceutical company developing protein therapeutics for cancer and orphan diseases, announced that Tom Maniatis, Ph.D., an Acceleron co-founder and Professor and Chair of the Department of Biochemistry and Molecular Biophysics at the College of Physicians and Surgeons, is to be honored with the 2012 Lasker-Koshland Special Achievement Award in Medical Science. The Albert and Mary Lasker foundation award is considered to be one of the most prestigious scientific prizes and the Special Achievement Award recognizes its recipients for exceptional leadership and citizenship in biomedical science. Dr. Maniatis will be presented with the Lasker-Koshland Special Achievement Award in Medical Science on September 21st in New York City.

Dr. Maniatis is a pioneer in the development of gene cloning technology, and he has published extensively in the field of eukaryotic gene regulation. In particular, he identified numerous genetic defects that underlie the inherited human illness β- thalassemia. Dr. Maniatis is widely known for his seminal work developing gene cloning technologies and applying those methods to discovering the genetic bases of human diseases. His book, “The Cloning Manual,”has become a world-wide resource.

In addition to these scientific accomplishments, Dr. Maniatis has been instrumental in creating successful companies. He was a co-founder of Genetics Institute, where he chaired the scientific board and served on the board of directors for more than 17 years. During this time, Genetic Institute’s gained FDA approval for several protein-based drugs, including recombinant human , Factor VIII and Factor IX, as well as bone morphogenic proteins. Dr. Maniatis was also a co-founder of ProScript Inc., which discovered the drug Velcade® (bortezomib). Dr. Maniatis is currently a member of the board of directors at Acceleron.

Mark Ptashne, Ph.D., the Ludwig Chair of Molecular at Memorial Sloan-Kettering Cancer Center in New York, a co- founder of Genetics Institute and Acceleron, and a previous Lasker awardee said, “I’ve worked with Tom for many years in both basic science and biotechnology,he is simply the best.”

“Tom has had an enormous impact on the scientific community and an equally impressive contribution to the discovery and development of innovative medicines at several biotechnology companies,”said John Knopf, Ph.D., Chief Executive Officer of Acceleron. “I have had the distinct pleasure of knowing and working with Tom since I joined Genetics Institute 30 years ago. I personally continue to benefit significantly from his involvement at Acceleron as does our entire team of world-class scientists.

About Acceleron

Acceleron is a privately-held biopharmaceutical company committed to discover, develop, manufacture and commercialize novel protein therapeutics for orphan diseases and cancer. Acceleron’s scientific approach takes advantage of its unique insight to discover first-in-class therapies based on the TGF-β protein superfamily. Acceleron utilizes proven biotherapeutic technologies and capitalizes on the company’s internal GMP manufacturing capability to advance its therapeutic programs rapidly and efficiently. The investors in Acceleron include Advanced Technology Ventures, Alkermes, Avalon Ventures, Bessemer Ventures, Celgene, Flagship Ventures, MPM BioEquities, OrbiMed Advisors, Polaris Ventures, QVT Financial, Sutter Hill Ventures and Venrock. For further information on Acceleron, please visit www.acceleronpharma.com.

CONTACT:

Acceleron Pharma: Steven Ertel, 617-649-9234 Chief Business Officer

Maureen L. Suda (Media) Suda Communications LLC 585-387-9248