Acceleron Pharma

Acceleron Pharma works on 9 rare diseases tracked on Trial Friend, including Charcot-Marie-Tooth Disease, Duchenne Muscular Dystrophy, Facioscapulohumeral Muscular Dystrophy and 6 more, with 2 recruiting clinical trials.

Acceleron Pharma was a Boston biotech that bet for nearly two decades that a niche corner of biology called activin receptor signaling could produce drugs for diseases nobody had cracked. The company was founded in 2003 and went public on the NASDAQ in 2013, but the bigger story is what happened in 2021. Merck acquired Acceleron for $11.5 billion specifically to gain rights to a drug called sotatercept, which was in late-stage development for pulmonary arterial hypertension (PAH). The acquisition closed in November 2021, and Acceleron now operates as part of Merck.

Sotatercept, marketed by Merck as Winrevair, is the drug that justified the acquisition. The FDA approved Winrevair in March 2024 for adults with pulmonary arterial hypertension, a rare and progressive disease where the arteries between the heart and lungs become narrow and stiff, forcing the right side of the heart to work much harder than it should. Winrevair was the first new mechanism approved for PAH in over a decade, and it works by rebalancing growth and inflammatory signals in pulmonary artery walls so they can remodel back toward normal. In the Phase 3 STELLAR trial, patients on Winrevair plus standard background therapy walked significantly farther in 6 minutes after 24 weeks compared to placebo, and saw lower rates of clinical worsening events such as PAH-related hospitalization or death.

Acceleron also co-developed luspatercept with Celgene, which is now part of Bristol Myers Squibb and markets the drug as Reblozyl. Reblozyl is approved for anemia in patients with transfusion-dependent beta thalassemia and in lower-risk myelodysplastic syndromes (MDS). Beta thalassemia is an inherited blood disorder where patients cannot make enough functional hemoglobin and often require lifelong transfusions, and Reblozyl helps reduce how often those patients need transfusions. In MDS, the drug similarly addresses the chronic anemia that defines the lower-risk forms of the disease.

The legacy of the company is now spread across two of the largest pharmaceutical organizations in the world, but the underlying scientific bet is intact. Block or rebalance specific signaling pathways in tissues where current therapies only manage symptoms, and patients can get a meaningful disease-modifying benefit.