FDA Updates Merck Winrevair Label With Phase 3 HYPERION Data

The U.S. Food and Drug Administration approved an updated product label for Merck's pulmonary arterial hypertension therapy Winrevair (sotatercept-csrk), incorporating Phase 3 HYPERION trial data that supports its use earlier in the treatment process.

The regulatory update happens as Merck expands the clinical positioning of the biologic therapy, providing physicians with formal trial documentation for recently diagnosed patients receiving background therapies.

"The HYPERION study included people with PAH who closely reflect those we see in everyday clinical practice, including individuals who were recently diagnosed, older adults and people managing other health conditions," said Dr. Vallerie McLaughlin, Kim A Eagle MD Endowed Professor of Cardiovascular Medicine and Director, Pulmonary Hypertension Program, University of Michigan in Ann Arbor.

Trial Design and Clinical Worsening Risk Reduction

In the Phase 3 HYPERION trial of 320 participants, adding Winrevair on top of background therapy reduced the risk of clinical worsening events by 76% in adults with pulmonary arterial hypertension (PAH) WHO functional class II or III compared to placebo. The evaluation yielded a hazard ratio of 0.24 with a 95% confidence interval ranging from 0.14 to 0.41 and a p-value of less than 0.0001.

The study enrolled participants within their first year of diagnosis, reporting a mean time since PAH diagnosis of 7.2 months. Among the trial population, 72% of patients received double background therapy, while 28% were managed on triple background therapy.

"HYPERION is the third Phase 3 study of WINREVAIR in PAH and provides significant clinical evidence in adults with PAH when added to background therapy, including within the first year following a diagnosis," said Dr. Joerg Koglin, senior vice president, head of general and specialty medicine, global clinical development, Merck Research Laboratories.

Broader Regulatory and Guideline Context

The label expansion follows recent international recognition for the therapy. Earlier in September 2026, the European Respiratory Society published clinical guidelines that issued a strong recommendation for Winrevair in adult patients with PAH on background therapy who failed to achieve low-risk status at follow-up.

Pulmonary arterial hypertension is a progressive, life-threatening disorder characterized by constriction of small pulmonary blood vessels, leading to high blood pressure in the lungs and eventual right heart failure. The incorporation of HYPERION data into the official U.S. prescribing information gives healthcare providers empirical backing to introduce sotatercept-csrk earlier in patient care protocols.