9 September 2019 - - The United States Food and Drug Administration has granted Orphan Drug designation to sotatercept for the treatment of patients with pulmonary arterial hypertension, US-based biopharmaceutical company Acceleron Pharma Inc. (NASDAQ: XLRN) said.

Orphan designation is granted by the FDA Office of Orphan Products Development to advance the evaluation and development of safe and effective therapies for the treatment of rare diseases or conditions affecting fewer than 200,000 people in the US.

Under the Orphan Drug Act, the FDA may provide grant funding toward clinical trial costs, tax advantages, FDA user-fee benefits, and seven years of market exclusivity in the United States following marketing approval by the FDA.

The granting of an orphan designation request does not alter the standard regulatory requirements and process for obtaining marketing approval.

Sotatercept is being evaluated in two Phase 2 trials in patients with PAH: the PULSAR trial, which completed its target enrollment in June of this year and the SPECTRA exploratory trial, which is currently enrolling. The company expects to report top-line results from the PULSAR trial during the first quarter of 2020.

Sotatercept is an investigational therapy that is not approved for any use in any country.

Sotatercept is an investigational agent designed to be a selective ligand trap for members of the TGF-beta superfamily to rebalance BMPR2 signaling, which is a key molecular driver of PAH.

In preclinical studies of PAH, sotatercept reversed pulmonary vessel muscularisation and improved indicators of right heart failure. Sotatercept is currently being evaluated in the PULSAR and SPECTRA Phase 2 trials in PAH.

PAH is a rare and chronic, rapidly progressing disorder characterized by the constriction of small pulmonary arteries and elevated blood pressure in the pulmonary circulation.

PAH results in significant strain on the heart, often leading to limited physical activity, heart failure, and reduced life expectancy.

The five-year survival rate for patients with PAH is approximately 57%. Available therapies generally act by promoting the dilation of pulmonary vessels without addressing the underlying cause of the disease. As a result, PAH often progresses rapidly for many patients despite standard of care treatment.

A growing body of research has implicated imbalances in BMP and TGF-beta signaling as a primary driver of PAH in familial, idiopathic, and acquired forms of the disease.

Acceleron is a clinical-stage biopharmaceutical company dedicated to the discovery, development, and commercialization of therapeutics to treat serious and rare diseases.

The company's leadership in the understanding of TGF-beta superfamily biology and protein engineering generates innovative compounds that engage the body's ability to regulate cellular growth and repair.

Acceleron focuses its research and development efforts in hematologic, neuromuscular, and pulmonary diseases. In hematology, the company and its global collaboration partner, Celgene, are developing luspatercept for the treatment of chronic anemia in myelodysplastic syndromes, beta-thalassemia, and myelofibrosis.

Acceleron is also advancing its neuromuscular program with ACE-083, a locally-acting Myostatin+ agent in Phase 2 development in facioscapulohumeral muscular dystrophy and Charcot-Marie-Tooth disease and is conducting a Phase 2 pulmonary program with sotatercept in pulmonary arterial hypertension.