Actelion's novel CRTH2 antagonist meets primary endpoint in Phase II study in patients with seasonal allergic rhinitis

The study assessed the efficacy and tolerability of various doses of this novel CRTH2 antagonist in adult patients with seasonal allergic rhinitis ("hay fever") due to mountain cedar pollen. Treatment in this study was well tolerated across all treatment groups and no serious adverse events were reported.

Jean-Paul Clozel, M.D. and Chief Executive Officer of Actelion commented: "We are very pleased with the results of this study since, for the first time, we now have proof that CRTH2 antagonists can bring clinically relevant benefit to patients suffering from allergic rhinitis. This study complements the positive proof-of-mechanism study in asthma reported in 2009. Together, these studies provide substantial information that will guide us in the further development of this compound and our follow-up molecules in allergic disorders."

Jean-Paul concluded: "We will now fully analyze the data and plan our next steps, taking into account the ongoing development program in asthma. We are very confident that, with these promising results, CRTH2 antagonists can play an important role in expanding Actelion's portfolio beyond specialty products."

Following full analysis of the study, results will be made available through scientific publication.

About the study design
The study was a prospective, multi-center, double-blind, placebo-controlled, active- reference, multiple-dose levels, randomized, parallel-group Phase II study. The study enrolled 579 patients, who were treated for two weeks, with the primary outcome measure to demonstrate efficacy versus placebo being the mean change from baseline in Daytime Nasal Symptom Score over the entire treatment period.

About Actelion's CRTH2 antagonist
Actelion's CRTH2 antagonist blocks some of the effects of prostaglandin D2 (PGD2) on inflammation and, as a consequence, the amplification and maintenance of allergic reactions. It targets allergic inflammation, with the potential of being used as therapy in both asthma and/or allergic rhinitis as well as in many other potential indications that are based on allergic inflammation.

Positive data have previously been obtained in a proof-of-mechanism study with Actelion's orally-active CRTH2 antagonist in mild-to-moderate allergic asthma. In the 18- patient 2-period crossover double-blind placebo-controlled study, the compound was well tolerated and demonstrates efficacy versus placebo on the primary endpoint (FEV1) during the late allergic reaction (3-10 hours) after a bronchial allergen challenge.

A Phase II dose-finding study in asthma is currently enrolling and is expected to report results mid-2012.


Contact:
Roland Haefeli Vice President, Head of Investor Relations & Public Affairs Actelion Pharmaceuticals Ltd Gewerbestrasse 16 CH-4123 Allschwil +41 61 565 62 62