NEW ORLEANS — Interim data from the REPAIR study show significant improvement in right ventricular function, including reversal of RV remodeling and reduced pulmonary vascular resistance, at 26 weeks after treatment with macitentan in patients with pulmonary artery hypertension.
The 52-week, open-label, multicenter REPAIR study was conducted to evaluate the effect of macitentan (Opsumit, Actelion Pharmaceuticals), initiated as monotherapy or combined with a phosphodiesterase type 5 (PDE5) inhibitor, on RV remodeling and function as determined by cardiac MRI and right heart catheterization.
The prespecified interim analysis results that included 42 patients with PAH were presented by Stephan Rosenkranz, MD, head of the Pulmonary Hypertension Center and head of the Cologne Cardiovascular Research Center at the University of Cologne in Germany, at the American College of Cardiology Scientific Session.
From baseline to week 26, treatment with macitentan resulted in improvement in the two coprimary endpoints: a 15.2-mL increase in RV stroke volume (P < .0001) and a 37% reduction in pulmonary vascular resistance (P < .0001). Enrollment in the study was stopped after both primary endpoints were met, according to a company press release.
Among the 42 patients in the interim analysis, the mean age at baseline was 46 years, 31 were women, median 6-minute walk distance was 376 m and most were classified as WHO functional class II (n = 19) or III (n = 23).
REPAIR is the first PAH treatment study to use a primary endpoint measured by MRI, researcher Richard N. Channick, MD, professor of medicine and director of the Acute and Chronic Thromboembolic Disease Program at UCLA Medical Center, told Cardiology Today.
Measuring RV function in patients with PAH is helpful to monitor response to treatment, according to Channick.
“We now have many approved treatments for PAH that improve exercise capacity. One of the important effects of therapy that we’ve been interested in is the efficacy of these drugs on right ventricular function,” Channick told Cardiology Today. “The ability to look at RV function with detailed imaging such as cardiac MRI is, I believe, critical to understand the disease itself and the benefit of PAH drugs such as macitentan. Using MR as a primary endpoint is unique in the PAH field.”
Macitentan is a dual endothelin-receptor antagonist that was approved by the FDA in 2013 for treatment of PAH.
“We’re at the point now with PAH that we are treating it with a similar strategy to that of left heart failure, using combinations of drugs,” Channick said. “The finding that a medication — macitentan — either alone or in combination with other therapies, can improve RV function has substantial clinical implications. When PAH patients die, they don’t die of the PAH, they die of RV failure.
“This study also underscores that RV function, as determined by MRI, is a relevant endpoint that can used in the future to evaluate the benefit of other therapies for PAH,” he said.
All patients enrolled in REPAIR will remain in the study up to their 52-week assessments. A final analysis will be presented once results are available, according to a company press release. – by Katie Kalvaitis
Rosenkranz S, et al. Oral 902-06. Presented at: American College of Cardiology Scientific Session; March 16-18, 2019; New Orleans.
Disclosure s : Channick and Rosenkranz report receiving research support and serving as paid consultants for Actelion Pharmaceuticals.