Opsumit: Ph III MAESTRO data

Top-line data from the double-blind, international Phase III MAESTRO trial in 226 patients with PAH due to Eisenmenger syndrome in the intent-to-treat (ITT) population showed that once-daily 10 mg oral Opsumit missed the primary endpoint of improving mean 6MWD from baseline to week 16 vs. placebo (18.3 vs. 19.7 meters). The least squares mean difference in 6MWD between Opsumit and placebo was -4.7 meters (p=0.612). There were 3 patients with missing 6MWD results at week 16 in the Opsumit arm. In the per protocol (PP) population (n=200), Opsumit improved mean 6MWD from baseline to week 16 by 30.2 meters vs. 18.9 meters for placebo. The least squares mean difference in 6MWD between Opsumit and placebo in the PP population was 6.4 meters (p=0.347). Actelion said there was "an unexpected improvement" on the endpoint in the placebo arm...