Merck's WINREVAIR Approved by FDA for Expanded PAH Treatment

FDA Approval

The U.S. FDA has approved an updated indication for WINREVAIR (sotatercept-csrk) for adults with pulmonary arterial hypertension (PAH), based on the Phase 3 ZENITH trial. This approval expands its use to improve exercise capacity, WHO functional class, and reduce risks of clinical worsening events, including hospitalization, lung transplantation, and death.

ZENITH Trial Results

In the ZENITH trial, involving 172 participants, WINREVAIR demonstrated a 76% reduction in the risk of major morbidity and mortality outcomes compared to placebo. The trial's primary endpoint, time to first occurrence of all-cause death, lung transplantation, or PAH-worsening hospitalization, showed significant improvement, leading to the trial's early termination due to overwhelming efficacy.

Safety Monitoring

Healthcare providers are advised to monitor hemoglobin and platelet levels before each dose of WINREVAIR for the first five doses, or longer if values are unstable. WINREVAIR may increase hemoglobin, potentially leading to erythrocytosis and thromboembolic events, and decrease platelet count, increasing bleeding risk. Treatment should not start if platelet count is below 50,000/mm3.

Adverse Reactions

Common adverse reactions in the ZENITH trial included infections, epistaxis, diarrhea, telangiectasia, increased hemoglobin, rash, erythema, and gingival bleeding. The median duration of exposure was longer for WINREVAIR (435 days) compared to placebo (268 days), with fewer discontinuations due to adverse events in the WINREVAIR group.