The U.S. Food and Drug Administration has approved an updated label for Winrevair (sotatercept-csrk), Merck’s (MRK) investigational treatment for pulmonary arterial hypertension (PAH), based on results from the Phase 3 HYPERION trial. The expanded approval reflects data demonstrating a 76% reduction in the risk of clinical worsening events when Winrevair is added to existing background therapies, compared with placebo. Merck’s stock closed at $146.87 on September 21, down 0.19%, before falling further to $146.45 after hours, reflecting market reaction to the regulatory milestone.
The HYPERION trial enrolled 320 adults newly diagnosed with PAH within 12 months of screening, with a mean time since diagnosis of 7.2 months. Seventy-two percent of participants were on double background therapies, while 28% received triple therapy. The trial’s primary endpoint was a 50% reduction in the risk of clinical worsening events, which Winrevair achieved with a hazard ratio of 0.24 (95% CI: 0.14–0.41; p < 0.0001). The incidence of first clinical worsening events dropped from 36.9% in the placebo group to 10.6% in the Winrevair cohort.
The updated label also highlights safety considerations, including contraindications for patients with serious hypersensitivity to sotatercept-csrk or its excipients. The most common adverse reactions in the Winrevair group—compared with placebo—were epistaxis (31.9% vs. 6.9%), telangiectasia (26.3% vs. 11.3%), and increased hemoglobin levels (11.3% vs. 1.3%). Treatment discontinuation due to adverse events occurred in 3% of Winrevair patients versus none in the placebo group. The European Respiratory Society published clinical guidelines earlier this month, aligning with the FDA’s approval.
Winrevair is now authorized for use in adults with PAH to improve exercise capacity, functional class, and reduce the risk of clinical deterioration. The approval follows Merck’s commitment to advancing treatments for rare diseases, where PAH affects approximately 15,000 Americans and 10,000 Europeans, according to the European Respiratory Society.
