Actelion has received some disappointing news regarding its attempts to develop the dual endothelin receptor antagonist Tracleer as a skin cancer treatment.

The Swiss company noted that it will not be pursuing studies of Tracleer (bosentan) in metastatic melanoma after preliminary efficacy data generated in the proof-of-concept study evaluating the drug for that indication did not support a full clinical development programme. Actelion added that the safety profile was consistent with earlier findings in studies that led to the approval of Tracleer as a treatment for pulmonary arterial hypertension.

The company said it will fully analyse the data which involved 90 or so patients and discuss the findings “with key medical experts in the field”. Research will also continue to evaluate the potential use of endothelin receptor antagonism in pre-clinical cancer models, it added.

Tracleer, in the PAH indication, is responsible for pretty much all of Actelion’s revenues and nine-month 2007 sales of the drug were up 30% to 846.5 million Swiss francs or around $736 million. That figure could well be boosted in the future if Tracleer gets approved for treatment of a broader range of diseases involving the endothelium, including systemic sclerosis and fibrosis, as well as cancer.