FDA Grants Priority Review for WINREVAIR Label Update Following ZENITH Trial Results

Merck, known as MSD outside the U.S. and Canada, announced that the U.S. Food and Drug Administration (FDA) has accepted and granted priority review to a supplemental Biologics License Application (sBLA) for WINREVAIR (sotatercept-csrk). The submission seeks to update the U.S. product label to include new data from the Phase 3 ZENITH trial for the treatment of pulmonary arterial hypertension (PAH, Group 1 PH). A decision is expected by October 25, 2025, under the Prescription Drug User Fee Act (PDUFA).

Originally approved in 2024, WINREVAIR is used to increase exercise capacity, improve WHO functional class, and reduce the risk of clinical worsening in adults with PAH. The updated application is supported by data from ZENITH—the first Phase 3 PAH trial to use a primary endpoint composed solely of major morbidity and mortality events.

The ZENITH trial was stopped early due to overwhelming efficacy, as determined by an independent data monitoring committee. Results showed a 76% reduction in the risk of a composite outcome including all-cause death, lung transplantation, and PAH-related hospitalization (≥24 hours) in patients treated with WINREVAIR compared to placebo. Clinical benefits were observed early and continued to improve over the course of treatment. The drug’s safety profile remained consistent with earlier studies.

“These findings represent a major advance in PAH care,” said Dr. Joerg Koglin, senior vice president of global clinical development at Merck Research Laboratories. “The FDA’s priority review of our application underscores the importance of ZENITH’s data and WINREVAIR’s potential to benefit a broad range of PAH patients.”

WINREVAIR is already approved in over 45 countries, based on data from the STELLAR trial, and continues to expand its global impact in the treatment of this serious and progressive condition.