FDA Grants Priority Review for WINREVAIR™ (sotatercept-csrk) to Update Label Based on Results From ZENITH Trial

RAHWAY, N.J.--(BUSINESS WIRE)-- Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced that the U.S. Food and Drug Administration (FDA) has accepted and granted priority review for a new supplemental Biologics License Application (sBLA) seeking approval to update the U.S. product label based on the Phase 3 ZENITH trial for WINREVAIR™ (sotatercept-csrk). In 2024, WINREVAIR was approved for the treatment of adults with pulmonary arterial hypertension (PAH, Group 1 PH) to increase exercise capacity, improve WHO* functional class (FC), and reduce the risk of clinical worsening events. The FDA has set a Prescription Drug User Fee Act (PDUFA), or target action date, of Oct. 25, 2025.

The sBLA is based on data from the Phase 3 ZENITH trial. The ZENITH trial was the first PAH Phase 3 outcome study to use a primary endpoint comprised entirely of major morbidity and mortality events. It was also the first PAH Phase 3 study stopped early by an independent data monitoring committee for overwhelming efficacy. In ZENITH, WINREVAIR demonstrated a 76% reduction in the risk of a composite of all-cause death, lung transplantation, and hospitalization for PAH ≥24 hours compared to placebo. Improvement was observed early in treatment with increasing benefit throughout the study. The safety profile of WINREVAIR in ZENITH was generally consistent with that observed in previous studies. These results were published in the New England Journal of Medicine.

“We are pleased that the FDA has accepted our sBLA for WINREVAIR and granted a priority review to consider an update to labeling for WINREVAIR to include the impressive results of ZENITH. There remains a significant unmet medical need for patients living with PAH who, despite being on background therapy, remain at higher risk of morbidity and mortality,” said Dr. Joerg Koglin, senior vice president, global clinical development, Merck Research Laboratories. “The FDA’s Priority Review designation acceptance of our sBLA reinforces our confidence in WINREVAIR for a broad range of patients and represents a critical step toward advancing the treatment of PAH.”

WINREVAIR is currently approved in more than 45 countries based on the results from the STELLAR trial.

*World Health Organization
About ZENITH
The ZENITH study (NCT04896008) is a global, double-blind, placebo-controlled clinical trial to evaluate WINREVAIR when added to maximum tolerated background PAH therapy on time to first event of all-cause death, lung transplantation, or PAH worsening related hospitalization of ≥ 24 hours, in adult participants with WHO functional class III or IV PAH at high risk of mortality. ZENITH study inclusion criteria required Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL) Lite 2.0 risk score of ≥9.

The study enrolled 172 participants, who were randomized in a 1:1 ratio to either WINREVAIR plus background PAH therapy or placebo plus background PAH therapy. The primary composite outcome measure was time to first confirmed major morbidity or mortality event. Events were defined as all-cause death, lung transplantation, or PAH worsening-related hospitalization of ≥ 24 hours. Secondary outcome measures included overall survival, transplant-free survival and several additional measures. The study excluded patients with PAH Group 1 subtypes: human immunodeficiency virus (HIV)-associated PAH and PAH associated with portal hypertension as well as diagnosis of pulmonary veno-occlusive diseases, pulmonary capillary hemangiomatosis or overt signs of capillary and/or venous involvement.

Participants who completed the ZENITH trial were offered the opportunity to receive WINREVAIR as part of the open-label, long-term extension study, SOTERIA (NCT04796337), consistent with that study’s eligibility criteria.

About WINREVAIR™ (sotatercept-csrk) for injection, for subcutaneous use, 45 mg, 60 mg

WINREVAIR is FDA-approved for the treatment of adults with pulmonary arterial hypertension (PAH, WHO Group 1) to increase exercise capacity, improve WHO functional class (FC) and reduce the risk of clinical worsening events. WINREVAIR is the first activin signaling inhibitor therapy approved to treat PAH. WINREVAIR improves the balance between pro-proliferative and anti-proliferative signaling to modulate vascular proliferation. In preclinical models, WINREVAIR induced cellular changes that were associated with thinner vessel walls, partial reversal of right ventricular remodeling, and improved hemodynamics.