More and more, as momentum builds for the soon-to-be-blockbuster Winrevair, Merck’s $11.5 billion buyout of Acceleron in 2021 is looking like a savvy move.
The FDA has signed off on a label update for the first-in-class activin signaling inhibitor, which was the key piece of the acquisition. The new approval adds language to the medicine's label about its ability to reduce patients' risk of hospitalization for pulmonary arterial hypertension (PAH), lung transplantation and death.
Paving the way for the label update were results from the phase 3 Zenith trial, which enrolled 172 PAH patients at the highest risk of mortality—those in the World Health Organization Functional Class (FC) III or IV—and achieved its primary endpoint of time to clinical worsening to first morbidity or mortality event.
Winrevair, added to maximum background therapy, reduced the risk of these events by 76% versus placebo. Patients in the trial's treatment cohort received a subcutaneous dose of Winrevair every three weeks, and the median follow-up with patients was 10.6 months.
The results were so conclusive that the trial was halted at an interim stage in November of last year at the urging of an independent data monitoring committee, which also advised Merck to offer Winrevair to all patients in the study.
“For patients with PAH, the risk of serious events such as hospitalization, transplantation or death remains unacceptably high despite being maximally treated with traditional therapies,” Vallerie McLaughlin, M.D., a professor of cardiovascular medicine at the University of Michigan, said in a release. “Results from the pivotal Zenith trial add to the growing body of data and support the potential for Winrevair as standard of care.”
PAH is a rare, rapidly progressing disease in which the blood vessels in the lungs become thickened and narrow due to a buildup of cells, leading to shortness of breath and difficulty in the heart’s ability to pump blood to the lungs. That increases blood pressure and can lead to heart failure. Winrevair works by rebalancing the cell signaling.
Roughly 40,000 people in the U.S. have the disorder. PAH strikes more women than men, and most patients are middle-aged. The condition begins as a more common disorder, pulmonary hypertension (PH), which then can progress into PAH.
Winrevair, which was originally approved in March 2024, is off to a successful launch. In the second quarter, it generated revenue of $336 million, which was up from $280 million in the first quarter.
After results from the Zenith trial were revealed, analysts from Citi jacked up their 2030 sales estimate for Winrevair to a range of $5.7 billion to $6.1 billion.