Merck's PAH Therapy WINREVAIR Nears EU Approval After Landmark Trial Success

Merck has announced a key step forward for its pulmonary arterial hypertension (PAH) treatment. The European Medicines Agency's CHMP has recommended approving WINREVAIR (sotatercept) for patients in WHO Functional Class II, III, and IV. This marks the first activin signalling inhibitor therapy for PAH to receive such backing in the EU.

The CHMP's recommendation follows strong results from the Phase 3 ZENITH trial. This study showed a 76% reduction in the risk of major morbidity and mortality for patients taking WINREVAIR compared to a placebo. Due to its clear success, the trial was halted early, and participants were offered continued treatment under an open-label follow-up.

The decision also considered data from the Phase 3 STELLAR trial, which further supported WINREVAIR's benefits. The therapy is intended for use alongside other PAH treatments, expanding options for patients with severe disease. In October 2025, the U.S. FDA had already updated WINREVAIR's indication based on the same ZENITH trial findings.

The European Commission is now expected to make a final approval decision in the first quarter of 2026. If granted, WINREVAIR will become the first and only activin signalling inhibitor available for PAH in over 50 countries worldwide. As of February 2026, no approvals outside the EU have been confirmed for this specific use.

The CHMP's positive opinion brings WINREVAIR closer to becoming a new standard in PAH care across Europe. Patients in advanced disease stages may soon gain access to a therapy shown to significantly cut morbidity and mortality risks. A final ruling from the European Commission will determine its availability in early 2026.