Biopharmaceutical company Merck (NYSE: MRK) announced on Monday that its Phase 3 ZENITH trial evaluating WINREVAIR (sotatercept-csrk) for pulmonary arterial hypertension (PAH) met its primary endpoint at interim analysis, demonstrating a statistically significant reduction in morbidity or mortality events in patients with functional class III or IV PAH at high risk of death. The study will be stopped early based on the positive results, and all participants will be offered WINREVAIR in the SOTERIA extension study.

The trial, which included 172 participants, showed that WINREVAIR, when added to maximum background PAH therapy, significantly improved outcomes compared to placebo. Adverse events were balanced between groups. Results will be presented at an upcoming medical conference and submitted to regulators.

WINREVAIR, the first activin signaling inhibitor approved for PAH, addresses the disease's underlying cause by modulating vascular proliferation. It is FDA-approved in 36 countries and under review in Japan. PAH affects around 40,000 people in the US, with a five-year mortality rate of 43%.

Merck, operating as MSD outside the U.S. and Canada, continues its focus on research-driven innovations to combat life-threatening conditions like PAH.