Actelion's key experimental drug macitentan proved to be safe at a high dose even though it failed to reach its goal in a mid-stage trial in a potentially deadly lung disease, the Swiss biotech group said today.

Actelion has decided not to move the drug into late-stage clinical trials after it missed the primary endpoint of forced vital capacity in patients with idiopathic pulmonary fibrosis (IPF) in a phase II study.

But the trial did offer investors some relief as it showed macitentan, which is currently in late-stage trials for another disease, did not raise liver enzymes compared with the placebo.

Macitentan, by far the most important drug in Actelion's pipeline at the moment, is being billed as a successor to blockbuster Tracleer to treat the heart and lung disease pulmonary arterial hypertension (PAH).

Late-stage results in this setting are expected in the first half of next year. Investors were keenly awaiting the phase II trial in IPF for insight into how safe macitentan is.

"The first indication that macitentan is safe at the highest investigated dose (10mg) is comforting and should restore some confidence in the pipeline in Actelion," Vontobel analyst Andrew Weiss said.

Some traders said the fact that macitentan was not moving into late-stage trials was not a surprise and that many analysts had not included sales of macitentan to treat IPF in their models.

Actelion, Europe's largest pure-play biotech group, has faced fierce criticism this year from its largest shareholder, Elliott Advisors, which urged the group to consider putting itself up for sale after a string of product setbacks thwarted its efforts to reduce its dependency on Tracleer.

Reuters