US pharma powerhouse Merck has said the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) has recommended approving an expanded indication for WINREVAIR (sotatercept), significantly broadening the drug’s use in pulmonary arterial hypertension (PAH).

 

The recommendation would allow WINREVAIR, used in combination with other PAH therapies, to treat adult patients across WHO Functional Class II, III and IV — including the sickest patients — based on results from the Phase 3 ZENITH study. WINREVAIR is currently approved in the European Union only for adults with WHO Functional Class II to III disease to improve exercise capacity.

 

The CHMP opinion now moves to the European Commission, which will decide whether to amend the drug’s marketing authorization across the EU, Iceland, Liechtenstein and Norway. A final ruling is expected in the first quarter of 2026.

 

"If approved, this broader indication would recognize the impact of WINREVAIR on morbidity and mortality in adult patients with PAH, extending the overall use of WINREVAIR to be inclusive of WHO FC II, III and now IV patients, with a treatment objective beyond the improvement of exercise capacity,” said Dr. Joerg Koglin, senior vice president and head of general medicine, global clinical development, Merck Research Laboratories. 

 

“We look forward to the EC's decision as we work to ensure broad patient access to the first and only activin signaling inhibitor therapy approved in Europe and continue to deliver meaningful evidence to support treatment decisions.”

 

The recommendation is anchored in data from the Phase 3 ZENITH trial, which showed that adding WINREVAIR to standard background therapy cut the risk of major morbidity and mortality events by 76% compared with placebo in adults with WHO Functional Class III or IV PAH.

 

The trial’s primary composite endpoint — time to first occurrence of all-cause death, lung transplantation or PAH-related hospitalization lasting at least 24 hours — occurred in just 15 patients (17%) receiving WINREVAIR, versus 47 patients (55%) on placebo. The study was halted early at an interim analysis due to overwhelming efficacy, and patients were offered continued access to WINREVAIR in an open-label extension. Results were published in The New England Journal of Medicine.

 

CHMP reviewers also considered morbidity and mortality data from the secondary endpoint of Merck’s pivotal Phase 3 STELLAR trial in reaching their decision.

 

WINREVAIR is currently the first and only activin signalling inhibitor approved for PAH across all 27 EU member states, as well as Iceland, Liechtenstein and Norway, and is authorized in more than 50 countries worldwide. In October 2025, the U.S. Food and Drug Administration approved an expanded U.S. label based on the ZENITH data.