Merck, known as MSD outside the United States and Canada, announced that the U.S. Food and Drug Administration (FDA) has expanded the approval of WINREVAIR™ (sotatercept-csrk) for the treatment of adults with pulmonary arterial hypertension (PAH, WHO Group 1). The updated label now includes evidence showing that WINREVAIR reduces the risk of hospitalization, lung transplantation, and death in addition to improving exercise capacity and WHO functional class.
The approval is based on results from the Phase 3 ZENITH trial, which demonstrated that adding WINREVAIR to background PAH therapy resulted in a 76% reduction in the risk of major morbidity and mortality events compared to placebo. Among 172 participants with WHO functional class III or IV PAH, only 17% of those receiving WINREVAIR experienced a clinical worsening event versus 55% in the placebo group. The trial was stopped early due to the overwhelming efficacy of the treatment, and participants were offered access to WINREVAIR through an open-label follow-up study.
“For patients with PAH, the risk of serious events such as hospitalization, transplantation, or death remains unacceptably high despite current therapies,” said Dr. Vallerie McLaughlin, Director of the Pulmonary Hypertension Program at the University of Michigan. “The ZENITH trial results support WINREVAIR’s potential as a new standard of care.”
Merck emphasized that patients treated with WINREVAIR should be monitored for hemoglobin and platelet levels, as the therapy may increase the risk of thromboembolic events, hyperviscosity syndrome, or thrombocytopenia, particularly when combined with prostacyclin infusions. The most common side effects observed in the ZENITH trial included infections, nosebleeds, diarrhea, skin telangiectasia, rash, and gingival bleeding.
“Merck’s leadership in PAH research is anchored in a comprehensive clinical program that continues to advance science and deliver meaningful evidence for physicians and patients,” said Dr. Joerg Koglin, senior vice president of global clinical development at Merck Research Laboratories. “This approval underscores WINREVAIR’s ability to significantly reduce the risk of clinical worsening events, including death, for adults living with PAH.”
WINREVAIR was first approved in March 2024 following the pivotal STELLAR study, and this latest FDA decision broadens its indication based on ZENITH’s compelling results. The drug represents a major advance in the management of PAH, a progressive and life-threatening condition with limited treatment options.