Merck recently won FDA approval for its sotatercept-csrk Winrevair for treating adults with pulmonary arterial hypertension.

The drug was approved to increase exercise capacity and reduce the risk of clinical worsening events, according to the Rahway, N.J.-based company. It previously received FDA breakthrough designation and is the first FDA-approved action signaling inhibitor therapy for pulmonary arterial hypertension (PAH).

The new class of therapy works by improving the balance between pro- and anti-proliferative signaling to regulate vascular cell proliferation underlying PAH.

“Pulmonary arterial hypertension is a rare, progressive and ultimately life-threatening disease in which blood vessels in the lungs thicken and narrow, causing significant strain on the heart,” said Dr. Marc Humbert, Professor of Medicine and Director of the Pulmonary Hypertension Reference Center at the Université Paris-Saclay and investigator on the Phase 3 Stellar study. “Based on the Phase 3 Stellar trial, adding Winrevair to background PAH therapy demonstrated significant clinical benefits compared to background PAH therapy alone. This approval is an important milestone, as it offers healthcare providers a novel therapeutic option that targets a new PAH treatment pathway.”

Merck won approval based on the Phase 3 Stellar trial, which compared Winrevair to a placebo, both in combination with background standard-of-care therapies in adult patients with PAH. Results showed that adding Winrevair to background therapy increased the six-minute walk distance from baseline by 41 meters. It also improved multiple important secondary outcome measures, including reducing the risk of death from any cause or PAH clinical worsening events by 84% versus just background therapy.

The company recommends healthcare providers monitor hemoglobin and platelets before each dose of Winrevair for the first five doses or longer if values are unstable. They should also periodically measure them afterward to determine if dose adjustments are required.

“The Pulmonary Hypertension Association welcomes the development of new therapies for those with PAH,” Matt Granato, president and chief executive officer of Pulmonary Hypertension Association, said in a news release. “A diagnosis of PAH is a life-changing experience for patients and families due to its chronic, progressive nature. 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.”

Winrevair is administered once every three weeks by subcutaneous injection and can be administered by patients or caregivers with guidance, training and follow-up from a healthcare provider, Merck said. The company estimates that the drug will be available for dispensing by select specialty pharmacies in the U.S. by the end of April.

“PAH remains a debilitating disease with high morbidity and mortality,” said Dr. Eliav Barr, senior vice president and head of global clinical development, chief medical officer, Merck Research Laboratories. “This approval of Winrevair is an important milestone and a testament to our science-led strategy and focus on the development of innovations that can help people affected by rare diseases like PAH. We are proud to bring this novel medicine to patients.”