EPIX Pharmaceuticals Inc has announced initiation of its Phase 2b right-heart catheter study of PRX-08066 in patients with chronic obstructive pulmonary disease (COPD) and moderate-to-severe pulmonary hypertension (PH). PRX-08066 is a novel serotonin type 2B receptor (5-HT2B) antagonist that may represent a new mechanism of action for treating PH.

This possible new mechanism would selectively dilate diseased pulmonary arteries without affecting systemic blood pressure. Expression of the 5-HT2B receptor is increased in the pulmonary arteries of patients with PH. It is thought that PRX-08066 could block the 5-HT2B receptor in patients with PH, possibly reducing or preventing the acute rise in pulmonary blood pressure, which occurs when patients increase activity. This mechanism means that the heart would do less work for a given level of activity, allowing for improvements in exercise tolerance.

“There is an undeniable need for safe and effective treatments for patients with PH associated with COPD,” says lead investigator Aaron Waxman MD, PhD, assistant professor of medicine, Harvard Medical School. “We believe this drug may be an important advance toward effective treatment for patients with this progressive lung disease, and hope to see reductions in pulmonary artery blood pressure and improvements in exercise capacity in this trial similar to those seen in previous trials with PRX-08066 using more rigorous techniques.”