Gilead Sciences in collaboration with GlaxoSmithKline (GSK) has announced plans for a new clinical trial to study combination therapy vs monotherapy in a first-line treatment setting for pulmonary arterial hypertension (PAH).

The randomised, double-blind, multicentre Ambition study will evaluate first-line combination use of ambrisentan, an endothelin receptor antagonist (ERA) and tadalafil, a PDE5 inhibitor, in patients with PAH.

Ambrisentan is approved under the tradename Letairis, as a once-daily treatment for PAH in patients with WHO functional class II or III symptoms to improve exercise capacity and delay clinical worsening.

University of California professor of medicine Lewis J Rubin said that the question of first-line combination therapy versus monotherapy is one of the most important outstanding clinical questions in PAH.

“As the first large randomised clinical trial to address the efficacy of initial combination therapy in PAH, Ambition has the potential to be a landmark study,” Rubin said.

Gilead and GSK are working with regulatory agencies and the PAH research community to finalise details of the study and plan to begin enrollment in 2010.