Macitentan

Merck's PAH treatment Winrevair is poised for strong uptake in 2025, according to Leerink Partners based on its survey of physicians prescribing the treatment. Based on a survey of cardiologist and pulmonologists treating patients for pulmonary arterial hypertension (PAH), analysts at Leerink Partners believe that Merck’s Winrevair “should have strong uptake growth” in 2025.The treatment, which was the primary target in Merck’s $11.5 billion acquisition of Acceleron in 2021, logged $149 million in sales in the third quarter. It was a solid but underwhelming performance for the long-awaited drug that Merck has projected will reach $3 billion in peak sales.But the Leerink survey indicates that the risk of patients bleeding as a side effect of Winrevair is lower than that portrayed in a registrational trial that set the drug up for its FDA nod in March 2024.“The real-world safety is better than expected,” Leerink wrote while cknowledging that the data need to mature.“In 2024 we believe sentiment regarding bleeding risk and early market access challenges likely contributed to a slower Winrevair ramp, as many respondents expressed caution given the high bleed rate reported in clinical trials and were quick to discontinue or pause therapy,” Leerink wrote.The survey included 51 cardiologists and 53 pulmonologists who are treating 11,699 PAH patients, which is roughly a third of the patient population in the indication in the U.S.Prescribers said that 10% of their PAH patients were on Winrevair, indicating “large headroom for Winrevair growth,” Leerink added. There was investor concern last month when Keros Therapeutics halted dosing in two of three arms of a trial of its PAH candidate, which has the same mechanism of action as Winrevair. The pause was initiated because of pericardial effusion events.But prior to the Keros report, none of the physicians in the survey who had prescribed Winrevair had paused or discontinued treatment for pericardial events.According to the survey, most respondents agreed that earlier Winrevair use will reduce risk. “If bleeding risk indeed proves lower for patients treated earlier in their disease course, real-world bleeding rates will likely decline as physicians extend their Winrevair prescription to this patient group,” Leerink wrote. “We foresee opinions on bleeding risk converging in favor of Winrevair over time as physicians gain more personal experience and/or Merck better characterizes the risk.”On the flip side, Leerink analysts believe that Merck’s estimate that one-third of patients will need a two-vial dosage is “likely overly optimistic,” as many survey respondents said that adverse events were reduced by dosing pauses or reductions. In PAH, blood vessels narrow in the lungs, which causes blood pressure to increase, leading to heart failure. The disorder often leads to death and strikes more women than men.Winrevair competes with Johnson & Johnson’s prostacyclin receptor agonist blockbuster Uptravi, as well as J&J’s endothelin receptor agonist Opsumit, which garnered $2 billion in 2023 revenue.Meanwhile, just a few days before Merck’s green light, the FDA approved a new combination tablet in Opsynvi, which weds Opsumit with United Therapeutics’ Adcirca.