- Gefapixant significantly reduces objectively measured 24-hour cough frequency in patients with refractory chronic cough (RCC) or unexplained chronic cough (UCC).
Why this matters
- Currently, RCC and UCC have no approved treatments and pose a significant health burden.
- Gefapixant, a novel P2X3 receptor antagonist, has shown a reduction in objective cough frequency earlier in phase 2 trials.
- COUGH-1 and COUGH-2 are phase 3 double-blind, randomized placebo-controlled trials.
- 730 adults in COUGH-1 and 1314 adults in COUGH-2 were randomly assigned to 1 of 3 groups: gefapixant 45 mg twice a day, gefapixant 15 mg twice a day, or placebo.
- Primary outcomes were 24-hour cough frequency at 12 weeks (COUGH-1) and 24 weeks (COUGH-2), along with safety and tolerability.
- Funding: Merck and Co., Inc.
- The estimated relative reduction in cough frequency over 24 hours with 45 mg dose vs placebo:
- at 12 weeks was −18.45 (95% CI, −32.92 to −0.86; P=.041); and
- at 24 weeks was −14.64 (95% CI, −26.07 to −1.43; P=.031).
- The reduction in cough frequency with 15 mg dose was not statistically significant in both COUGH-1 (P=.872) and COUGH-2 (P=.875).
- The most common adverse events (AEs) with 45 mg dose were taste-related, reported by 58.0% of participants in COUGH-1 and 68.6% in COUGH-2.
- Serious AEs were rare and had a similar incidence between treatment groups.