BLU-5937, BELLUS Health's lead product candidate, is a potent, highly-selective, orally bioavailable small molecule antagonist of the P2X3 receptor, a clinically validated target for chronic cough.

In July 2019, the Company announced that the first patient had been enrolled in the RELIEF (A Randomized, Double-blind, Placebo-Controlled, Crossover, Dose Escalation Study of BLU-5937 in Subjects with Unexplained or Refractory Chronic Cough) Phase 2 study of BLU-5937 in chronic cough. The Phase 2 study will evaluate the efficacy of BLU-5937 and is expected to add to the Phase 1 evidence showing little to no impact on taste. Top-line results are expected in mid-2020.

Clinical Phase 2 RELIEF Study

The RELIEF study is a dose-escalation, placebo-controlled, and crossover design to assess the efficacy, safety, and tolerability of BLU-5937, a highly selective P2X3 antagonist, at four doses; 25, 50, 100 and 200 mg, administered orally, twice-daily (BID). Approximately 65 patients with refractory chronic cough are expected to be enrolled at twelve clinical sites in the United Kingdom and United States. The Company intends to present top-line data from the RELIEF study in mid-2020. Further details on BELLUS Health’s RELIEF study for BLU-5937 can be found at

Clinical Phase 1 Study Data

On November 19, 2018, BELLUS Health announced the positive top-line results from the clinical Phase 1 study for BLU-5937.

The Phase 1 data demonstrated that BLU-5937 has an excellent pharmacokinetic profile. Plasma half-life was established at 4 to 9 hours, supporting BID dosing. Based on pre-clinical efficacy studies and comparison with drug levels achieved with a clinically validated comparator, the Company anticipates that drug levels required for optimal inhibition of cough will be achieved at 50 mg or 100 mg BID.

The Phase 1 data also showed that BLU-5937 has a good safety and tolerability profile. The overall incidence of adverse events was comparable between placebo (50%) and BLU-5937 (44%).

At the anticipated therapeutic doses of 50 mg or 100 mg, BLU-5937 did not cause any loss of taste perception and only one subject out of 24 (4.2%) reported transient taste alteration. This taste effect was reported only on the first day out of seven days of dosing, by a subject receiving 100 mg BID. No subject reported total loss of taste at any dose levels.

There were no serious adverse events and no subjects withdrew prematurely due to an adverse event during the study.

Clinical Phase 1 Study

The clinical Phase 1 study was a randomized, double-blind, placebo-controlled study of orally administered BLU-5937 in 90 healthy adult subjects. The primary objectives of the clinical Phase 1 study were to assess the safety, tolerability (including taste perception) and pharmacokinetic profile of BLU-5937 in healthy subjects.

The study was divided in two parts:

Part 1: A single ascending dose (SAD) study was conducted in 60 healthy subjects. Subjects were randomized into 6 cohorts of 10 subjects (8 BLU-5937: 2 placebo). The study evaluated single oral doses of BLU-5937 from 50 to 1200 mg.

Part 2: A multiple ascending dose (MAD) study was conducted in 30 healthy subjects. Subjects were randomized into 3 cohorts of 10 subjects (8 BLU-5937: 2 placebo). The study evaluated multiple oral doses of BLU-5937 of 100, 200 and 400 mg administered twice-a-day (BID) for 7 consecutive days.

Disease and Market

Chronic cough is a cough lasting more than eight weeks and is associated with significant adverse physical, social and psychosocial effects on health and quality of life. It is estimated that approximately 26 million adults in the United States suffer from chronic cough with more than 2.6 million having refractory chronic cough lasting for more than a year. There is no specific therapy approved for refractory chronic cough and treatment options are limited.

Pathophysiology of Chronic Cough

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