The Efficacy and Safety of Gefapixant in a Phase 3b Trial of Patients with Recent-Onset Chronic Cough.

PURPOSE: We evaluated gefapixant, a P2X3 receptor antagonist, in participants with recent-onset (≤ 12 months) refractory chronic cough (RCC) or unexplained chronic cough (UCC).

METHODS

Participants (≥ 18 years of age; ≥ 40 mm on a 100-mm cough severity visual analog scale [VAS] at screening and randomization) with chronic cough for < 12 months were enrolled in this phase 3b, double-blind, placebo-controlled, parallel group, multicenter study (NCT04193202). Participants were randomized 1:1 to gefapixant 45 mg BID or placebo for 12 weeks with a 2-week follow-up. The primary efficacy endpoint was change from baseline at Week 12 in Leicester Cough Questionnaire (LCQ) total score. Adverse events were monitored and evaluated.

RESULTS

There were 415 participants randomized and treated (mean age 52.5 years; median [range] duration 7.5 [1-12] months): 209 received placebo and 206 received gefapixant 45 mg BID. A statistically significant treatment difference of 0.75 (95% CI: 0.06, 1.44; p = 0.034) for gefapixant vs. placebo was observed for change from baseline in LCQ total score at Week 12. The most common AE was dysgeusia (32% gefapixant vs. 3% placebo participants); serious AEs were rare (1.5% gefapixant vs. 1.9% placebo participants).

CONCLUSION

Gefapixant 45 mg BID demonstrated significantly greater improvement in cough-specific health status from baseline compared to placebo, in participants with recent-onset chronic cough. The most common AEs were related to taste and serious AEs were rare.