Merck’s (MRK) novel investigational activin signaling inhibitor, Sotatercept, is under priority review by the FDA, with a decision due on March 26, 2024.Sotatercept is proposed for the treatment of adult patients with pulmonary arterial hypertension (PAH) (WHO Group 1). Pulmonary arterial hypertension, a specific type of pulmonary hypertension, is a rare disease caused due to thickening and constriction of arteries in the lungs. It is characterized by high blood pressure in the lungs, compelling the heart to exert increased effort in pumping blood through the narrowed arteries.Merck acquired exclusive rights to Sotatercept in the pulmonary hypertension field through the acquisition of Acceleron Pharma Inc. Sotatercept is the subject of a licensing agreement with Bristol Myers Squibb.MRK closed Tuesday's (Feb.27, 2024) trading at $129.03, up 0.15%.