BUILD-3 study with bosentan in idiopathic pulmonary fibrosis does not meet primary endpoint

03-02-2010: Actelion Ltd announced the initial results of BUILD-3, a clinical study evaluating the safety and efficacy of bosentan in patients suffering from idiopathic pulmonary fibrosis. While there was a consistent trend in favor of bosentan, the primary endpoint, reduction in morbidity/mortality, was not met (p=0.21). The well characterized safety profile of bosentan was confirmed.

Jean-Paul Clozel, M.D. and Chief Executive Officer of Actelion commented: "We are naturally disappointed with this outcome. While in BUILD-3 there is a consistent trend in favor of bosentan, these findings do not support initiating regulatory proceedings."

Jean-Paul Clozel continued: "We remain convinced that endothelin receptors are important targets for potential future treatments in this poorly understood and rapidly progressing form of pulmonary fibrosis. The results of BUILD-3 suggest that a more complete blockade of both endothelin receptors - as potentially achieved with macitentan - might be needed."

The 150 patient exploratory study with Actelion's highly potent, tissue-targeting endothelin receptor antagonist, macitentan, is currently enrolling patients with idiopathic pulmonary fibrosis. The study is expected to be fully enrolled later this year and report data in second half of 2011.

Bosentan, an orally available dual endothelin receptor antagonist, is already approved worldwide for the treatment of pulmonary arterial hypertension under the brand name Tracleer®. In the European Union and in other territories, Tracleer® is also approved for the reduction of new digital ulcers in patients with systemic scleroderma. Since market introduction in late 2001, more than 80'000 patients worldwide have been exposed to Tracleer®.