NEW ORLEANS – An investigational, first-in class agent that delivers a completely new type of intervention to patients with pulmonary arterial hypertension (PAH) scored a clear win in the STELLAR trial, the first to complete among three phase 3 trials that are testing this agent.
Sotatercept, administered subcutaneously every 3 weeks for 24 weeks, improved from baseline average 6-minute walk distance (6MWD) by a significant and clinically meaningful 40.8 meters, compared with placebo, for the trial’s primary efficacy endpoint (P < .001). The treatment also “delivered broad clinical benefit across multiple domains including hemodynamics, World Health Organization functional class, disease biomarkers, risk scores and patient-reported outcomes,” Marius M. Hoeper, MD, said at the joint scientific sessions of the American College of Cardiology and the World Heart Federation.
“These results establish the clinical utility of sotatercept, administered in combination with approved PAH therapies, as a new treatment for PAH,” added Dr. Hoeper, professor and deputy director of the department of respiratory medicine at Hannover (Germany) Medical School,
“The most important aspect was the hemodynamic improvement,” with sotatercept treatment, which led to an average 235 dyn/sec per cm−5 reduction in pulmonary vascular resistance from baseline and an average cut in pulmonary artery pressure of 13.9 mm Hg from baseline, compared with placebo, a result that’s “unheard of,” Dr. Hoeper said in a press conference during the meeting.
“With other tested agents we usually see very little improvement in pulmonary artery pressure. This is a signal that we achieved some reversing of the pathological changes in the pulmonary vessels that lead to” PAH, he added.
Simultaneously with his report the findings also appeared online in the New England Journal of Medicine.
‘A new hope’ for patients with PAH
Based on the reported findings, sotatercept is a “very exciting boutique molecule” that will “offer patients with PAH a very exciting new treatment,” commented Rhonda Cooper-DeHoff, PharmD, a designated discussant and a researcher at the University of Florida, Gainesville.
“This study is a new hope for patients with PAH. Until now, they’ve had really bad outcomes, but [in this study] we see significant differences in 6MWD, hemodynamics, and risk factors. Overall, I think the benefit is greater than the risk” it may pose to patients through potential adverse effects, commented Julia Grapsa, MD, PhD, a cardiologist at St. Thomas Hospital in London, and another discussant at the meeting.
“The results are impressive” and “encouraging,” and “suggest that sotatercept may represent a new and clinically consequential addition to current medications for PAH,” wrote three clinicians from Canyons Region Intermountain Medical Center in Murray, Utah, in an editorial that accompanied the published report.
But the authors of the editorial also raised several cautions and concerns. They questioned the generalizability of the findings, noting that the patients with PAH enrolled in the study were all adults who were clinically stable and an average of more than 8 years out from their initial PAH diagnosis, and more than 90% were on stable treatment for PAH with two or three agents specific for treating the disorder. The study cohort also had a disproportionately high enrollment of patients with idiopathic (59%) or heritable (18%) forms of PAH, and the 15% of patients in the trial with connective tissue disease represented a disproportionately low prevalence of this PAH subtype.
The editorialists also called for “ongoing vigilance” for adverse effects from sotatercept treatment, although they acknowledged that the adverse effects reported to date from sotatercept are “largely reassuring.”