The US Food and Drug Administration (FDA) has approved sotatercept (Winrevair, Merck), for the treatment of adults with pulmonary arterial hypertension (PAH), World Health Organization (WHO) Group 1, to increase exercise capacity, improve WHO functional class, and reduce the risk for clinical worsening events.

Sotatercept, which had breakthrough therapy designation, is a first-in-class activin signaling inhibitor that works by improving the balance between pro- and antiproliferative signaling to regulate the vascular cell proliferation that underlies PAH.

“Sotatercept added to background therapy has the potential to become a new standard-of-care option for patients with pulmonary arterial hypertension,” added co-investigator Aaron Waxman, MD, PhD, executive director of the Center for Pulmonary Heart Diseases at Brigham and Women’s Hospital, Boston.

The approval was based on results of the phase 3 STELLAR study, a global, double-blind, placebo-controlled, multicenter, parallel-group clinical trial in which, 323 patients with PAH (WHO Group 1, Functional Class II or III) were randomly assigned 1:1 to add sotatercept or placebo to stable background therapy.

The results showed that sotatercept, administered subcutaneously every 3 weeks for 24 weeks, improved average 6-minute walk distance from baseline by a significant and clinically meaningful 40.8 meters compared with placebo for the trial’s primary efficacy endpoint (P < .001).

Sotatercept also led to significant improvement in multiple secondary outcome measures, including:

• Reduction in the risk for death from any cause or PAH clinical worsening events by 84% vs background therapy alone (number of events: 9 vs 42; hazard ratio [HR], 0.16; P < .001) 
• Improvement in FC from baseline at 24 weeks in 29% of patients compared with 14% of patients treated with placebo (P < .001) 
• Improvement in pulmonary vascular resistance (PVR), with an average 235 dyn/sec/cm⁵ reduction in PVR from baseline (P < .001) 
• Improvement from baseline in N-terminal pro–B-type natriuretic peptide (NT-proBNP) levels. The median treatment difference in NT-proBNP between sotatercept and placebo was -442 pg/mL (P < .001) 

The results were reported last year at the joint scientific sessions of the American College of Cardiology and the World Heart Federation, with simultaneous publication in The New England Journal of Medicine. 

Sotatercept injection may be administered by patients or caregivers with guidance, training, and follow-up from a healthcare provider. The recommended starting dose is 0.3 mg/kg. The recommended target dose is 0.7 mg/kg every 3 weeks.

Sotatercept may increase hemoglobin, may lead to erythrocytosis, and also may decrease platelet count and lead to severe thrombocytopenia. Treatment should not be initiated if platelet count is < 50,000/mm³. 

Hemoglobin and platelets should be monitored before each dose of sotatercept for the first five doses, or longer if values are unstable, and periodically thereafter to determine if dose adjustments are required. 

Full prescribing information is available online. 

Merck estimates that sotatercept will be available for dispensing by select specialty pharmacies in the United States by the end of April 2024.