ALLSCHWIL/BASEL, SWITZERLAND - 29 August 2011
Actelion announced today that the exploratory Phase II study with macitentan in patients with idiopathic pulmonary fibrosis (IPF) shows a promising safety and tolerability profile of macitentan, no difference being observed between placebo and macitentan with regard to liver enzyme elevations.
Jean-Paul Clozel, M.D. and Chief Executive Officer of Actelion commented: "I am very encouraged to observe that, in this patient population, macitentan displays an excellent safety and tolerability profile, particularly in terms of liver enzyme elevations that are no different from placebo."
The primary endpoint of the MUSIC study, forced vital capacity, was not met. The company will not initiate a Phase III IPF program.

About macitentan
Macitentan is a highly potent, tissue-targeting endothelin receptor antagonist discovered in an in-house research program. Through complete blockade of tissular endothelin, macitentan is expected to protect tissue from the damaging effect of elevated endothelin, specifically in the cardiovascular system. In preclinical studies, macitentan also exhibited effects suggesting that it maintains the integrity of the vascular wall and improves long-term outcome. Accordingly, macitentan may provide therapeutic benefit in a wide range of cardiovascular indications.

About macitentan in Pulmonary Arterial Hypertension (PAH)
Macitentan is also currently being investigated in SERAPHIN, a Phase III study designed to evaluate its safety and efficacy in patients with pulmonary arterial hypertension (PAH) through the primary endpoint of morbidity and all-cause mortality.This is the largest study in PAH patients, with the potential to demonstrate long-term morbidity / mortality outcomes. Global enrollment was completed in December 2009 with a total of 742 patients. The study is event-driven and, based on the progress observed, results should be available in the first half of 2012.

ALLSCHWIL/BASEL, SWITZERLAND - 02 August 2011
Actelion announced today that the primary endpoint - reduction in the number of new active inflammatory lesions in the brain - has been met with its selective S1P1 receptor agonist, ponesimod, in a Phase IIb dose-finding study in patients with relapsing-remitting multiple sclerosis.

With 464 patients enrolled, this is the largest ever dose-finding study conducted in this autoimmune disorder of the central nervous system.

Martine Clozel, M.D. and Chief Scientific Officer at Actelion commented: "This is the first report of a selective S1P1 receptor agonist reporting a statistically significant treatment effect in patients suffering from relapsing multiple sclerosis."

Guy Braunstein, M.D. and Head of Clinical Development at Actelion commented: "I am very pleased to observe that this large study shows a clear dose response relationship. This gives us confidence that we can identify the appropriate dosing regimen for the upcoming Phase III program."

Jean-Paul Clozel, M.D. and Chief Executive Officer commented: "This large Phase IIb study highlights the efficacy of ponesimod and provides us with key information on the potential differentiation of this agent from all other oral MS agents, either marketed or in development."

About the selective S1P1 agonist ponesimod
Ponesimod prevents lymphocytes from leaving lymph nodes, thereby reducing circulating blood lymphocyte counts and preventing infiltration of lymphocytes into target tissues. The lymphocyte count reduction is rapid, dose-responsive, is sustained with continued dosing and quickly reversed upon discontinuation. Ponesimod is therefore considered a promising new oral agent for the treatment of a variety of autoimmune disorders.