Merck & Co. Inc., known as MSD outside the United States and Canada, has announced that the U.S. Food and Drug Administration (FDA) has granted priority review for a supplemental Biologics License Application (sBLA) to update the U.S. product label for WINREVAIR™ (sotatercept-csrk) based on results from the Phase 3 ZENITH trial. WINREVAIR, which was approved in 2024 for the treatment of adults with pulmonary arterial hypertension (PAH) to enhance exercise capacity, improve WHO functional class, and reduce clinical worsening events, is seeking an updated label to reflect its impressive trial results. The FDA has set a target action date of October 25, 2025, under the Prescription Drug User Fee Act. The ZENITH trial marked significant progress, showing a 76% reduction in the risk of major morbidity and mortality events compared to placebo, and it was the first PAH Phase 3 study halted early due to overwhelming efficacy. WINREVAIR is already approved in over 45 countries based on prior trial data.