MSD Korea said Thursday that its pulmonary arterial hypertension (PAH) drug Winrevair (sotatercept) has secured marketing approval in Korea, marking the first regulatory green light for an activin signaling inhibitor in the PAH space.

Winrevair is approved for use in adults with WHO Group I PAH, functional class II or III, alongside existing treatments to improve exercise capacity. The drug is administered via subcutaneous injection every three weeks and comes in 45 mg and 60 mg doses.

“This disease makes even simple breathing difficult, and curative treatments are still out of reach,” said Chung Wook-jin, president of the Korean Pulmonary Hypertension Society. “Winrevair, with its new mechanism that reverses vascular remodeling, is already recommended in global treatment guidelines for early combination use. Its approval broadens treatment options for Korean patients.”

The approval is backed by data from the phase 3 STELLAR trial, which enrolled 323 patients with PAH in the WHO functional class II or III. Patients received either Winrevair or placebo in addition to background therapy every three weeks for 24 weeks.

Winrevair improved six-minute walk distance by 40.8 meters compared to placebo and cut the risk of death or clinical worsening by 84 percent. It also showed significant gains across key secondary endpoints, including pulmonary vascular resistance and NT-proBNP levels.

The drug was designated a GIFT fast-track product by Korean regulators in 2024 and selected for a pilot program enabling simultaneous review, evaluation, and reimbursement discussions. 

“We’re proud to bring the first new class of PAH treatment in two decades,” said Myeong Hye-jin, MSD Korea’s pharma business unit director. “For patients struggling with poor quality of life, Winrevair may offer meaningful hope."