Merck receives FDA label update for WINREVAIR based on Phase 3 HYPERION trial

• Merck (NYSE:MRK) received FDA approval for an updated U.S. label for WINREVAIR (sotatercept-csrk) based on Phase 3 HYPERION trial data.
• The update adds efficacy and safety information for newly diagnosed pulmonary arterial hypertension (PAH) patients receiving background therapy.
• HYPERION showed a 76% reduction in clinical worsening events compared with placebo.

Merck (NYSE:MRK), known as MSD outside the United States and Canada, announced that the U.S. Food and Drug Administration (FDA) approved an update to the U.S. prescribing information for WINREVAIR™ (sotatercept-csrk).

The updated label incorporates data from the Phase 3 HYPERION trial, expanding clinical information on WINREVAIR use in adults with pulmonary arterial hypertension (PAH, WHO Group 1 pulmonary hypertension).

WINREVAIR is approved to improve exercise capacity and WHO functional class while reducing the risk of clinical worsening events, including PAH-related hospitalization, lung transplantation and death.

The HYPERION trial evaluated adults newly diagnosed with PAH within 12 months of study screening who had WHO functional class II or III disease and intermediate to high risk of progression.

The randomized Phase 3 study enrolled 320 patients, with 160 receiving WINREVAIR plus background therapy and 160 receiving placebo plus background therapy.

Adding WINREVAIR reduced the risk of clinical worsening events by 76% compared with placebo, with a hazard ratio of 0.24 (95% confidence interval: 0.14 to 0.41; p<0.0001).

A first clinical worsening event occurred in 10.6% of patients receiving WINREVAIR compared with 36.9% of patients receiving placebo.

Participants in HYPERION reflected a broad PAH population, with an average diagnosis duration of 7.2 months.

Approximately 72% of patients were receiving double background therapy, while 28% were receiving triple therapy.

The safety findings were generally consistent with previous WINREVAIR studies.

The most common adverse reactions in HYPERION included nosebleeds (epistaxis), telangiectasia and increased hemoglobin levels.

Merck updated safety information to include warnings regarding serious hypersensitivity reactions, increased hemoglobin levels that may contribute to erythrocytosis, and reductions in platelet counts that may increase bleeding risk.

Healthcare providers are advised to monitor hemoglobin and platelet levels before dosing during the initial treatment period and periodically afterward.

Earlier in 2026, the European Respiratory Society included WINREVAIR in updated PAH treatment guidelines, providing a strong recommendation for its use in certain adult PAH patients receiving background therapy who have not achieved low-risk status.

Merck said the combination of clinical trial evidence and updated treatment guidelines supports the continued evaluation of WINREVAIR as an important therapy option for people living with PAH.