 CAMBRIDGE, Mass.--BUSINESS WIRE--Acceleron Pharma Inc. Nasdaq: XLRN, a biopharmaceutical company dedicated to the discovery, development, and commercialization of TGF-beta superfamily therapeutics to treat serious and rare diseases, today announced that the European Commission EC has granted orphan designation to sotatercept for the treatment of patients with pulmonary arterial hypertension PAH. Were thrilled at the European Commissions decision to grant orphan designation to sotater 