Tuesday, the FDA approved Merck ( MRK ) & Co Inc’s Winrevair (sotatercept-csrk), for injection, 45mg, 60mg for adults with pulmonary arterial hypertension (PAH) to increase exercise capacity, improve WHO functional class (FC), and reduce the risk of clinical worsening events. 

PAH is high blood pressure in your pulmonary arteries, which carry oxygen-poor blood from your heart to the lungs.

Merck ( MRK ) added sotatercept via its $11 billion acquisition of Acceleron Pharma Inc in 2021.

Winrevair is the first FDA-approved activin signaling inhibitor therapy for PAH, representing a new class of therapy that works by improving the balance between pro- and anti-proliferative signaling to regulate vascular cell proliferation underlying PAH.

The approval is based on the Phase 3 STELLAR trial, which compared Winrevair (n=163) to placebo (n=160), both in combination with background standard-of-care therapies.

Results showed that adding Winrevair to background therapy increased the six-minute walk distance from baseline by 41 meters at Week 24 and significantly improved multiple secondary outcome measures, including reducing the risk of death from any cause or PAH clinical worsening events by 84% versus background therapy alone (number of events: 9 vs. 42).

Healthcare providers should monitor hemoglobin and platelets before each dose of Winrevair for the first five doses, or longer if values are unstable, and periodically after that to determine if dose adjustments are required. 

Merck ( MRK ) estimates that Winrevair will be available at select specialty pharmacies in the U.S. by the end of April.

Winrevair is the subject of a licensing agreement with Bristol Myers Squibb & Co .

Reuters noted that Winrevair will carry a list price of $14,000 per vial. According to data from the company’s trial, most patients will use a single vial every three weeks, which would translate to $238,000 per year.

Citing J.P. Morgan analyst Reuters noted, “We see sotatercept having a strong initial launch and quickly becoming part of the standard of care for eligible PAH patients.”

Schott estimates the therapy to reach peak sales of about $5 billion by 2030.

Price Action: MRK shares are up 4.76% at $131.50 during the premarket session on the last check Wednesday.