The United States Food and Drug Administration (US FDA) has granted Orphan Drug designation to United States-based Acceleron Pharma's Sotatercept intended for the treatment of patients with pulmonary arterial hypertension (PAH) a rare and chronic, rapidly progressing disorder characterised by the constriction of small pulmonary arteries and elevated blood pressure in the pulmonary circulation, it was reported yesterday.

Orphan designation is granted by the US FDA Office of Orphan Products Development to advance the assessment and development of safe and effective therapies for the treatment of rare diseases or conditions affecting fewer than 200,000 people in the US. According to the Orphan Drug Act, the US FDA is likely to provide grant funding toward clinical trial costs, tax advantages, FDA user-fee benefits, and seven years of market exclusivity in the US following the FDA's marketing approval.

The product is being assessed in two Phase two trials in patients with PAH: the PULSAR trial, which completed its target enrolment in June 2019 and the SPECTRA exploratory trial, which is presently enrolling. The company expects to report top-line results from the PULSAR trial during the first quarter of 2020.