Merck Releases Data on Rare Blood Vessel Disorder Treatment

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Sotatercept, a drug candidate acquired by Merck in an $11.5 billion acquisition, showed statistically significant improvements in various measures.

Merck, known as MSD outside of the United States and Canada, announced full results from a Phase III clinical trial (STELLAR) on March 6, 2023. The trial evaluated sotatercept, an investigational activin-signaling inhibitor biologic, in combination with stable background therapy for the treatment of adult patients with pulmonary arterial hypertension (PAH).

According to a company press release, the trial’s primary endpoint—increasing six-minute walk distance—showed a statistically significant improvement of 40.8 meters. Additionally, eight of the nine secondary measures, including World Health Organization functional class and pulmonary vascular resistance, also demonstrated clinically meaningful improvements.

“PAH is a rare, rapidly progressive, debilitating, and ultimately life-threatening condition with a five-year mortality rate of 43 percent,” said Marius Hoeper, Hannover Medical School, Germany, and lead investigator, in the release. “Sotatercept demonstrated profound improvements across the primary endpoint of six-minute walk distance and multiple secondary endpoints. These landmark results show the potential of sotatercept and the approach of targeting cellular signaling associated with vascular hyperproliferation and pathological remodeling for the treatment of PAH.”

“The results from the Phase III STELLAR trial are immensely important to physicians and patients and highlight the critical role sotatercept may play in improving exercise capacity and other meaningful clinical outcome measures for patients with PAH,” said Dean Y. Li, president, Merck Research Laboratories, in the release. “These findings are compelling given the profound reduction in the risk of clinical worsening or death in patients treated with sotatercept on top of background therapy. We look forward to discussing these pivotal data with health authorities and are working with urgency to bring this potential new treatment option to patients.”


Merck acquired the rights to sotatercept in an $11.5 billion acquisition of Acceleron in 2021. The drug has been granted Breakthrough Therapy designation and Orphan Drug designation by FDA, as well as Priority Medicines designation and Orphan Drug designation by the European Medicines Agency for the treatment of PAH.

Source: Merck