Actelion has pulled the plug on a late-stage trial looking at its recently-approved pulmonary arterial hypertension drug Opsumit as a treatment for digital ulcers in patients with systemic sclerosis.

The Swiss biotech major says an independent data monitoring committee has recommended that the Phase III DUAL-2 study should be terminated. The DMC noted that there were no unexpected safety findings but that additional data "are unlikely to result in a positive primary outcome measure".

Both DUAL-1 and DUAL-2 were comparing Opsumit (macitentan) to placebo on the reduction of the number of new and ongoing digital ulcers in patients with SSc. The latter is a chronic autoimmune connective tissue disease characterised by excessive collagen deposition in the skin and internal organs. Around 40%–50% of SSc patients suffer from digital ulcers, difficult-to-heal open sores on fingers and toes.

Actelion noted that there are no more patients in DUAL-1 receiving treatment and this study will be completed as planned. It will now collect and analyse data from both trials and make it available in the future.

Opsumit is Actelion's follow-up to its blockbuster Tracleer (bosentan). Approved in the USA in October, the oral endothelin receptor antagonist recently got a positive opinion from the European Medicines Agency's Committee for Human Medicinal Products for PAH.