Actelion Pharmaceuticals has submitted a supplemental New Drug Application for Opsumit (macitentan) to expand the product’s indication to include treatment of adults with inoperable chronic thromboembolic pulmonary hypertension (CTEPH, WHO Group 4) in order to improve exercise capacity and pulmonary vascular resistance (PVR).

Opsumit is an endothelian receptor antagonist and is currently indicated to treat pulmonary arterial hypertension (PAH; WHO Group 1) to delay disease progression and hospitalization. The sNDA is accompanied by results from the MERIT-1 trial, a Phase 2 randomized, placebo-controlled, double-blind study which assessed the efficacy, safety and tolerability of macitentan 10mg in 80 patients with inoperable CTEPH. 

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Results showed that following 16 weeks of treatment, the Opsumit group had a significant mean reduction in PVR from baseline compared with placebo (-206 [450.4] dyn.s/cm5 vs -86 [301.5]; P=.041). This result was demonstrated across all subgroups, including patients receiving background PAH therapy at baseline. 

In addition, treatment with Opsumit was associated with a significant positive effect on exercise capacity (six-minute walk distance [6MWD] least squares mean increase at Week 24: 34.0 meters between macitentan and placebo [95%, Cl: 2.9, 65.2m; P=.03)

The safety profile was similar to previous studies of Opsumit, with the most frequently reported adverse event being peripheral edema (23%). Also, 15% of patients in the Opsumit group had a decrease in hemoglobin vs 0% in the placebo group. 

Study results were published in The Lancet Respiratory Medicine.

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