The major advance in pulmonary arterial hypertension (PAH) is a therapy that targets a fourth biological pathway. Sotatercept (Winrevair), a first-in-class activin signaling inhibitor, rebalances pro- and anti-proliferative signaling to reduce the vascular remodeling that drives PAH. In the pivotal STELLAR trial it markedly improved exercise capacity (a roughly 41-meter placebo-corrected gain in six-minute walk distance), leading to FDA approval in March 2024. Its role then deepened: the Phase 3 ZENITH trial in high-risk (WHO functional class III–IV) patients was stopped early after sotatercept reduced the composite of death, lung transplantation, and PAH hospitalization by 76%, and the label was expanded in October 2025 to include this reduction in clinical worsening. Common effects include epistaxis, telangiectasia, and rises in hemoglobin and platelet counts requiring monitoring.
Sotatercept adds to the established framework of upfront combination therapy across the three classical pathways — nitric oxide-cGMP (PDE5 inhibitors such as sildenafil and tadalafil, and riociguat), endothelin (bosentan, ambrisentan, macitentan), and prostacyclin (epoprostenol, treprostinil, selexipag) — an approach that has substantially improved survival over recent decades.
Further reading: STELLAR sotatercept (Hoeper et al., NEJM 2023) and ZENITH trial with 2024/2025 approvals; PAH diagnosis and treatment review (Ruopp & Cockrill, JAMA 2022).