The condition occurs when the small blood vessels in the lungs become narrowed. This leads to high blood pressure in the arteries that carry blood from the heart to the lungs, which can damage the heart and lead to limited physical activity. From diagnosis, the patient mortality rate is 43% over five years, according to Merck.
Merck estimates that Winrevair will be available in select U.S. specialty pharmacies by the end of April, according to a company news release. The drug is an injection administered every three weeks and is distributed in kits of one or two vials.
It will be priced at $14,000 per vial before insurance, a Merck spokesman said in a statement. But the company has a program that offers eligible patients help with out-of-pocket costs and co-pays.
Winrevair is designed to be used alongside existing therapies for the condition to increase exercise capacity, reduce the severity of PAH, and reduce the risk of the disease worsening.
The approval is critical for Merck, which is working to diversify its revenue stream as top-selling cancer immunotherapy Keytruda moves closer to losing market exclusivity in 2028.
In a note this month, JPMorgan analyst Chris Schott estimated that Winrevair would reach annual global sales of about $5 billion by 2030 and become one of Merck’s “biggest growth drivers.”
Merck Chief Medical Officer Eliav Barr told CNBC that “this is a really great opportunity for the company, but really, more importantly, a very important opportunity for patients.” He noted that the drug would be a “paradigm change” for patients living with PAH.
The company obtained the rights to Winrevair through the $11.5 billion acquisition of Acceleron Pharma in 2021. At the time, Merck estimated that the PAH market would be approximately $7.5 billion by 2026.
The FDA approval was based on data from a late-stage study that followed more than 300 patients with moderate PAH who were already taking another drug for the blood vessel condition.
The study found that Winrevair combined with existing therapy helped patients with the disease walk about 40.8 meters further in six minutes than those who received a placebo, 24 weeks after the trial began.
“There’s been a huge improvement in people’s ability to exercise and move,” Barr said. “Because this disease makes people very, very housebound. They’re short of breath, they can’t move.”
Winrevair in addition to an existing drug also significantly improved eight of nine secondary endpoints in the study. This includes reducing the risk of death or worsening of the condition by 84% compared to an existing drug alone.
Severe and serious side effects were less common in the group of patients taking Winrevair than those receiving placebo, according to the study. Side effects that occur more often include nosebleeds, headaches, and rashes, among others.
One notable advantage of Winrevair is that patients or caregivers can inject it subcutaneously with proper training from a healthcare provider. Meanwhile, some existing treatments for PAH must be administered by medical professionals in an infusion center.
“One of the things we heard very loud and very clear from both patients and doctors is that they want something that you can get at home,” Barr said.
Merck continues to study Winrevair in other phase two and phase three trials.
These trials included late-stage studies of patients with more advanced BAH disease and those within the first year of diagnosis. Merck said it expects these trials to be completed around 2025 and 2026.