Merck & Co, Inc (NYSE: MRK), a research-intensive biopharmaceutical company, announced on Monday that its Phase 3 HYPERION study evaluating WINREVAIR (sotatercept-csrk) in adults recently diagnosed with pulmonary arterial hypertension (PAH) met its primary endpoint. WINREVAIR, added to standard background therapy, significantly reduced the risk of clinical worsening events compared to placebo.

HYPERION enrolled 320 patients with WHO Group 1 PAH, functional class II or III, within 12 months of diagnosis. Over 70% were on dual background therapy, and 83% were not receiving prostacyclin infusions. The trial showed a statistically significant reduction in time to first morbidity or mortality event, defined by a composite of all-cause death, PAH-related hospitalisation, lung transplantation, atrial septostomy, or PAH progression.

The trial, stopped early following interim data and findings from the related ZENITH study, is the third Phase 3 study to demonstrate efficacy for WINREVAIR, following STELLAR and ZENITH. All participants were offered continued access through the SOTERIA open-label extension.

Regulatory submissions based on HYPERION results are planned. WINREVAIR, an activin signalling inhibitor, is approved in over 45 countries and represents the first therapy in its class for PAH. It is licensed from Bristol Myers Squibb and has demonstrated improvements in exercise capacity, WHO functional class, and clinical outcomes.

Safety findings from HYPERION aligned with previous trials, with adverse events including headache, epistaxis, rash, and thrombocytopenia. WINREVAIR carries warnings for fetal harm, fertility impairment, bleeding risks, and elevated haemoglobin.

PAH remains a rare, progressive disease affecting around 40,000 people in the US, with high morbidity and mortality. Merck continues to focus on advancing therapies for life-threatening cardiopulmonary conditions.