Predix Pharmaceuticals, which recently announced a definitive agreement to merge with Epix Pharmaceuticals, has initiated a phase II clinical trial to evaluate the short-term efficacy and safety of PRX-08066, a serotonin 5-HT2B antagonist, in patients with pulmonary hypertension (PH) associated with chronic obstructive pulmonary disease (COPD).

"We hope to build on the promising results seen in our recently completed phase Ib trial, where adults conditioned to exercise at high altitudes that were given PRX-08066 experienced a statistically significant reduction in systolic pulmonary blood pressure during exercise-induced hypoxia," said Michael G. Kauffman, M.D., Ph.D., president and CEO of Predix Pharmaceuticals. "There are currently no approved drugs to treat PH associated with COPD, and based on our promising Phase I data, we believe PRX-08066 may benefit patients suffering from this disease."

The randomized, double-blind, placebo-controlled phase II trial is expected to enrol approximately 72 patients with PH associated with COPD. The primary endpoint of the trial is to assess the effect of PRX-08066 compared to placebo on systolic pulmonary artery pressure in patients with PH associated with COPD following two weeks of treatment. The trial will also assess the safety and tolerability of PRX-08066 during the course of therapy.

Discovered and designed using its Predict proprietary G-protein coupled receptor (GPCR) modelling and optimization technology, Predix is developing PRX-08066 to provide both symptomatic improvement - through selective dilation of diseased pulmonary blood vessels - and to also slow disease progression - by inhibiting the thickening of the pulmonary artery vessels. Predix believes PRX-08066 is the first 5-HT2B selective antagonist under development for pulmonary arterial hypertension (PAH) and pulmonary hypertension (PH) associated with chronic obstructive pulmonary disease. The 5-HT2B receptor represents a novel target for the treatment of pulmonary hypertension, as it has been linked to both pulmonary vasoconstriction, as well as the smooth muscle hypertrophy found in pulmonary vessels during pulmonary hypertension of various types.

Predix has completed three phase I clinical trials of PRX-08066 in healthy volunteers, including a Phase Ib trial in athletes conditioned to exercise at high altitudes whose pulmonary artery pressures were increased by breathing a gas with a reduced oxygen level. The results of the Phase Ib trial indicated that PRX-08066 significantly reduced the increase in pulmonary artery blood pressure during hypoxic exercise, without affecting systemic blood pressure. Predix is also exploring other potential indications targeting the 5-HT2B receptor, such as the treatment of irritable bowel syndrome and other diseases in which this receptor may play a key role.