A post-marketing study of Actelion's Tracleer (bosentan) assessing its ability to delay death in patients with high blood pressure has failed to hit targets.

The Phase IV trial did not meet its primary endpoint of time to first morbidity or mortality event in patients taking sildenafil.

While Tracleer showed a 17% risk reduction versus placebo, this was not a statistically significant difference. The study was designed to show a relative risk reduction of 43%, the firm said.

Actelion did note that in an exploratory analysis, patients taking Tracleer and sildenafil showed a significant increase of 21.8m in the six minute walking distance test. 

“While the observed risk reduction of 17% did not reach statistical significance, I am convinced that this study provides important information for the scientific community and we are committed to perform all the necessary analyses to fully understand the outcome of the study," said Vallerie McLaughlin MD, University of Michigan, Ann Arbor, US, Chair of the COMPASS-2 Steering Committee commenting on the results.

Full data from the study will be made available at upcoming congresses and peer-reviewed publications, Actelion noted.