Phase 3, Open-Label Multicenter Study of Sotatercept in Japanese Participants With Pulmonary Arterial Hypertension

BACKGROUND: Sotatercept is a first-in-class activin signaling inhibitor, developed for the treatment of pulmonary arterial hypertension (PAH). OBJECTIVES: This open-label single-arm, multicenter, phase 3 study was initiated to evaluate the efficacy and safety of sotatercept in Japanese participants with PAH. METHODS: Forty-six adult Japanese participants with PAH on stable background therapy were enrolled and received subcutaneous sotatercept starting at 0.3 mg/kg with a target dose of 0.7 mg/kg administered every 3 weeks. The primary efficacy endpoint was the change from baseline in pulmonary vascular resistance at 24 weeks. RESULTS: and, 6-minute walk distance (key secondary endpoint) increased 41.8 (95% CI: 27.8-55.5) meters. There were 6 (13%) serious adverse events (AEs) and no discontinuations due to AEs in the primary period. Safety was consistent with the known safety profile for sotatercept with AEs that were clinically manageable. CONCLUSIONS: In this study of Japanese participants with PAH, improvements in pulmonary vascular resistance and 6-minute walk distance were observed, consistent with the pivotal phase 3 STELLAR (A Study of Sotatercept for the Treatment of Pulmonary Arterial Hypertension [MK-7692-003/A011-11]) trial. These data suggest that sotatercept may be an important treatment option for Japanese patients with PAH. (A Study of Sotatercept in Japanese Pulmonary Arterial Hypertension [PAH] Participants [MK-7962-020], NCT05818137; Japan Registry of Clinical Trials, jRCT2031230046).