Actelion has received some bad news as US regulators have told the Swiss firm that it needs to do further risk analysis before they will consider expanding use of the pulmonary arterial hypertension big-seller Tracleer.

The US Food and Drug Administration has issued a complete response letter regarding the supplemental New Drug Application Actelion filed in August 2007 for Tracleer (bosentan). The Allschwil/Basel-based group wants the indication on the drug to be expanded to include patients suffering from PAH but with a less severe form of the disease.

In the letter, the FDA informed Actelion that its risk evaluation and mitigation strategy submitted in September 2008 needs to be finalised and approved before the agency can conclude the review of the sNDA. Chief executive Jean-Paul Clozel said the firm “will continue to diligently work” with the FDA and the company noted that in August last year, Tracleer obtained an expanded label in the European Union for the treatment of patients with mildly symptomatic PAH.

Actelion’s revenues climbed 12% to 1.47 billion Swiss francs in 2008 and Tracleer contributed 1.29 billion francs, up 10% on 2007. That figure will rise dramatically if the company manages to get FDA approval for Tracleer as a treatment for idiopathic pulmonary fibrosis.