— Locally administered investigational therapeutic designed to increase muscle mass in treated muscles —
— Fourth internally discovered drug expands Acceleron’s clinical pipeline —

CAMBRIDGE, MA, USA I October 14, 2014 I Acceleron Pharma Inc. (NASDAQ:XLRN), a clinical stage biopharmaceutical company focused on the discovery, development and commercialization of novel protein therapeutics for cancer and rare diseases, today announced it has initiated a phase 1 clinical trial of its novel muscle drug, ACE-083. ACE-083 is designed to selectively increase muscle mass and strength in the muscles in which the drug is administered by blocking proteins in the Transforming Growth Factor-Beta (TGF-β) protein superfamily that modulate muscle growth.

“Acceleron has built a highly productive drug discovery platform based on our deep understanding of the biology of the TGF-β protein superfamily, and we are proud to bring another first-in-class protein therapeutic into human clinical trials,” said John Knopf, Ph.D., Chief Executive Officer of Acceleron. “There is enormous unmet medical need to treat patients suffering from muscular and neuromuscular diseases, such as some forms of muscular dystrophy, and we believe that ACE-083 has the potential to treat a wide array of diseases in which patients have lost muscle mass and strength in specific muscles or muscle groups.”

About ACE-083

ACE-083 is an investigational protein therapeutic that acts as a ligand trap for members in the Transforming Growth Factor-Beta (TGF-β) superfamily involved in the regulation of muscle mass and strength. ACE-083 has been designed to increase muscle mass and strength selectively in the muscles into which the drug is administered. Acceleron is developing ACE-083 for diseases in which improved muscle strength in a specific set of muscles may provide a clinical benefit, such as inclusion body myositis and certain forms of muscular dystrophy. For more information, please visit www.clinicaltrials.gov, identifier NCT02257489.

About Acceleron

Acceleron is a clinical stage biopharmaceutical company focused on the discovery, development and commercialization of novel protein therapeutics for cancer and rare diseases. The company is a leader in understanding the biology of the Transforming Growth Factor-Beta (TGF-β) protein superfamily, a large and diverse group of molecules that are key regulators in the growth and repair of tissues throughout the human body, and in targeting these pathways to develop important new medicines. Acceleron has built a highly productive R&D platform that has generated innovative clinical and preclinical protein therapeutic candidates with novel mechanisms of action. These protein therapeutic candidates have the potential to significantly improve clinical outcomes for patients with cancer and rare diseases.

SOURCE: Acceleron