Canadian biopharmaceutical firm Bellus Health has commenced patient enrolment in the Phase II RELIEF clinical trial of BLU-5937 to treat refractory chronic cough.

BLU-5937 is a selective inhibitor of human P2X purinoceptor 3 (P2X3) receptors, which are associated with the cough reflex pathway.

The randomised, double-blind, placebo-controlled, crossover, dose-escalation study will evaluate the safety, efficacy, and tolerability of 25mg, 50mg, 100mg, and 200mg twice-daily doses of the compound.

RELIEF is designed to recruit around 65 patients at twelve clinical sites across the US and UK. Top-line results from the trial are expected next year.

The company will further study BLU-5937 in a separate Phase II study for treating patients with chronic pruritus caused by mild to moderate atopic dermatitis (AD).

This randomised, double-blind, placebo-controlled, parallel-group trial is set to launch next year and will involve 100 participants.

Findings from preclinical testing of BLU-5937 in pruritus will be presented at the European Society for Dermatological Research Conference on 21 September 2019.

Bellus Health president and CEO Roberto Bellini said: “The RELIEF study in chronic cough will build on the body of earlier clinical evidence, which showed for the first time that a highly selective P2X3 antagonist is associated with little to no impact on taste.

“The BLU-5937 P2X3 antagonist platform also extends to chronic pruritus, and we believe BLU-5937 has the potential to be an important treatment option for patients that suffer from either condition.”

The company expects the compound to have clinical benefit in additional afferent hypersensitisation-related conditions, including visceral pain, hypertension, and migraine.

In addition, Bellus Health is conducting research on how P2X3 activation is associated with irritation and pain, and how P2X3 receptors inhibition could be used in the treatment of related disorders.