CAMBRIDGE, Mass.--(BUSINESS WIRE)--Acceleron Pharma, Inc., a biopharmaceutical company developing novel therapeutics that modulate the growth of cells and tissues including muscle, bone, fat, red blood cells and the vasculature, today announced the initiation of a Phase 2 clinical trial with ACE-031 in patients with Duchenne Muscular Dystrophy (DMD), a fatal neuromuscular disease. ACE-031 is an investigational protein therapeutic that builds muscle and increases strength by inhibiting signaling of a cell surface receptor called the activin receptor type IIB (ActRIIB).