Canadian biopharmaceutical firm BELLUS Health has completed patient enrolment for its dose-escalation, placebo-controlled Phase II RELIEF trial of BLU-5937 in patients with refractory chronic cough.

BLU-5937 is a highly selective P2X3 antagonist for human P2X3 receptors. It has the potential to treat chronic cough, chronic pruritus and other hypersensitisation-related disorders.

The two-arm, dose-escalation, placebo-controlled, and crossover RELIEF trial is designed to assess the efficacy, safety, and tolerability of BLU-5937 at 25mg, 50mg, 100mg and 200mg doses. It will be administered orally twice a day.

A total of 68 patients with refractory chronic cough have been enrolled at 16 clinical sites in the UK and the US, with 75% having already completed dosing.

BELLUS Health president and CEO Roberto Bellini said: “Completing patient enrolment for the RELIEF trial is an important achievement in the BLU-5937 development programme.

“BLU-5937 has the potential to address a significant unmet medical need in chronic cough, and we believe our compound may be better tolerated than competitor candidates due to its high selectivity, potentially reducing cough frequency with little to no taste alteration.”

Top-line data from the trial are expected to be available in the middle of this year.

The P2X3 receptor in the cough reflex pathway is a rational target for treating chronic cough. Multiple clinical trials have validated it using different P2X3 antagonists.

BLU-5937 is claimed to be the most selective of the P2X3 antagonists currently being studied.

In addition to chronic cough and chronic pruritus, the company also anticipates its applicability across other afferent hypersensitisation-related disorders.

Bellus Health started patient enrolment in the Phase II RELIEF clinical trial in July last year.