Swiss biotechnology firm Actelion has unveiled interesting data from a proof-of-concept/dose-ranging study of almorexant, the first of a new class of drugs developed to aid insomniacs.

In data presented at the World Sleep Congress in Cairns, Australia, almorexant, an orexin receptor antagonist, was tested on 147 patients (39 at 400mg, 38 at 200mg, 38 at 100mg and 32 at 50mg) at 24 centres in Europe and Israel. The study achieved its primary endpoint demonstrating that almorexant significantly increased sleep efficiency in adults in the first three doses, but the results at 50 mg did not reach statistical significance.

Principal author Jasper Dingemanse, head of clinical pharmacology at Actelion, said the findings confirm “the pivotal role of the highly specific orexin system in controlling the sleep-wake cycle”. The data also indicate that almorexant assists patients in falling and staying asleep “in a non-sedative fashion, while at the same time not exhibiting any negative effects on next-day performance”, as is commonly observed with traditional sleep drugs which target benzodiazepine receptors.

Dr Dingemanse added that almorexant has demonstrated its potential to restore to normal levels time spent in REM (rapid-eye-movement) sleep, or dream phase, which “is thought to be of key importance for our ability to store and process information”. This means the drug “has the unique potential to restore normal physiological sleep”.

Almorexant 100mg and 200mg will now move into a Phase III programme, called RESTORA, and Actelion chief executive Jean-Paul Clozel, said that the firm will put “all required intellectual and material resources” behind this “highly innovative compound”. The Allschwil-based company is hoping to get to market ahead of GlaxoSmithKline, which began Phase II trials of an orexin drug at the end of last year.

The insomnia market is still dominated by Sanofi-Aventis’ Stilnox/Ambien (zolpidem) and, since the second quarter, generic versions of the latter. Sanofi also has a new drug in Phase III development called eplivanserin, a serotonin antagonist.

Data supports wider use of Tracleer

Meantime, Actelion has also presented positive data at the European Society of Cardiology congress in Vienna, Austria from a Phase IIIb trial of its biggest earner Tracleer (bosentan). The 185-patient EARLY trial showed that six months of treatment with the drug in patients with class II pulmonary arterial hypertension significantly delayed time to clinical worsening and reduced the number of patients worsening to classes III and IV of the disease. Tracleer is currently only approved for treating life-threatening Class III or IV PAH.

The data revealed that just 3% of patients on Tracleer saw their condition worsen significantly against 14% on placebo, a 77% risk reduction, while Actelion also noted that the treated group had a 22.6% percent improvement in pulmonary vascular resistance. The data is being used as a basis for regulatory submissions worldwide and approvals for earlier use of Tracleer would provide a major boost to the drug’s sales, which reached almost 560 million Swiss francs, or $465 million, in the first six months of 2007.