In a widely expected decision, the Food and Drug Administration approved Merck’s Winrevair for injection, making it the first activin signaling inhibitor therapy for pulmonary arterial hypertension (PAH).

PAH is a form of high blood pressure that impacts the right side of the heart, leading to narrowed or blocked blood vessels in the lungs. Symptoms include shortness of breath, chest pain or pressure and dizziness.

The approval, which the pharma giant announced Wednesday evening, is the fruit of an $11.5 billion acquisition of Acceleron Pharma in 2021, which gave Merck access to sotatercept — the generic name for Winrevair. 

At the time, Merck said it was aiming to boost its cardiovascular pipeline with the acquisition, adding that it expected the PAH arena to be a $7.5 billion market by 2026.

The FDA’s approval of Winrevair will position the drug as a competitor to Johnson & Johnson’s Uptravi as well as other players in the space like Bayer, Gilead Sciences and GlaxoSmithKline.

The approval also reflects Merck’s efforts to focus on its cardiovascular pipeline to prepare for expected losses associated with its blockbuster drug Keytruda’s loss of exclusivity in 2028.

The agency granted Winrevair priority review last year after its Phase 3 STELLAR trial showed the drug was effective in improving exercise capacity in patients with PAH compared to placebo.

The latest approval reflects data from that trial, which tested the drug in combination with background standard of care therapies. 

Adding Winrevair to background therapy boosted patients’ six-minute walk distance by 41 meters and reduced the risk of death from any cause or PAH by 84% compared to background therapy alone.

Merck added that Winrevair may increase hemoglobin levels in patients and possibly lead to erythrocytosis — a high concentration of red blood cells. Healthcare providers, the pharma said, should monitor hemoglobin and platelet levels in patients before administering Winrevair for the first five doses.

The pharma said Winrevair will be available at select specialty pharmacies by the end of April. The wholesale acquisition price of Winrevair is $14,000 per vial.

Matt Granato, president and CEO of Pulmonary Hypertension Association, added in a statement that the organization welcomes the development of new therapies for patients living with PAH.

“A diagnosis of PAH is a life-changing experience for patients and families due to its chronic, progressive nature,” Granato said. “Patients with PAH experience limiting symptoms such as shortness of breath and fatigue. We are excited to see industry research leading to a better understanding of PAH and the development of a medicine in a novel treatment pathway that expands options for the patient community.”