Tracleer has shown positive long-term impact in treating pulmonary arterial hypertension (PAH) in patients with systemic sclerosis (scleroderma), the drug-maker Actelion said on Friday.

In abstracts presented at a European rheumatology conference, Actelion said that data showed that Tracleer, also known by its generic name bosentan, helped patients do better in physical performance tests over short and long periods.

“Over 12 or 16 weeks, patients treated with bosentan improved by 14.6 metres in the 6-minute walk test while patients in the placebo group deteriorated by 22.2 metres,” Actelion said.

The company said that as many as 15 percent of scleroderma patients develop PAH and the prognosis is extremely poor. Without treatment there is a median survival rate of just 12 months for scleroderma patients diagnosed with PAH, the Swiss biotech firm said.