Actelion Ltd said the preliminary efficacy data generated in the proof-of-concept study evaluating bosentan (500mg bid) in the indication metastatic melanoma (stage 4) do not support the initiation of a full clinical development programme in this indication.

The observed safety profile was consistent with earlier findings in clinical studies that led to the approval of bosentan (Tracleer 125mg bid) in pulmonary arterial hypertension (PAH).

The company said it will fully analyse the data generated in the study with close to 90 patients and discuss the detailed findings with key medical experts in the field. The company will also continue to evaluate the potential use of endothelin receptor antagonism in pre-clinical cancer models.

Actelion Ltd is a biopharmaceutical company with its corporate headquarters in Allschwil/Basel, Switzerland. The company's first drug Tracleer, an orally available dual endothelin receptor antagonist, has been approved as a therapy for pulmonary arterial hypertension. Actelion, founded in late 1997, is a leading player in innovative science related to the endothelium - the single layer of cells separating every blood vessel from the blood stream. Actelion's over 1,500 employees focus on the discovery, development and marketing of innovative drugs for significant unmet medical needs.