Further data support Tracleer efficacy in PAH

Swiss biotechnology firm Actelion and US partner Genentech have reportedthe results of a Phase III trial which confirm the efficacy of their orally-active endothelin antagonist Tracleer (bosentan) in pulmonary arterial hypertension. The drug has already been filed for this indication in the USA and Europe, and the new data will also lead to additional submissions in Canada and Australia.

The new study, known as BREATHE-1, showed that Tracleer performed significantly better than placebo on the primary endpoint of exercise capacity. Patients receiving the endothelin antagonist were able to walk greater distances on a six-minute walk test after 16 weeks' treatment compared to those on placebo, with the improvement being statistically significant for both doses of Tracleer studied (125mg and 250mg given twice-daily).

The new findings provide a boost for Actelion and Genentech, which reported disappointing results from a Phase III trial of their other endothelin antagonist, Veletri (tezosentan), last month (Marketletter April 30). Veletri was being studied in acute heart failure, and analysts have suggested that this program could now be delayed by two-to-three years. Meantime, Tracleer is in Phase III trials for chronic heart failure, a much larger potential market than PAH.