FDA Accepts NDA for Gefapixant for Chronic Cough

The US Food and Drug Administration (FDA) has accepted Merck’s New Drug Application (NDA) for gefapixant—an investigational, orally administered, selective P2X3 receptor antagonist, for the treatment of refractory chronic cough (RCC) or unexplained chronic cough (UCC) in adults.

“This submission underscores our commitment to help patients with refractory or unexplained chronic cough who currently have limited treatment options,” said Dr. Roy Baynes, senior vice president and head of global clinical development, chief medical officer, Merck Research Laboratories in a statement.

“If approved by the FDA, gefapixant would be the first medicine approved specifically to help these patients, and we look forward to participating in the advisory committee meeting and working with the FDA as they review our application,” he continued.

Currently, no date for an advisory committee meeting has been scheduled, but the FDA has set a Prescription Drug User Fee Act (PDUFA), or target action date, of Dec. 21, 2021.

Clinical Trials

The NDA is based on results from the Phase 3 COUGH-1 and COUGH-2 clinical trials, which are the first dual studies to evaluate patients with RCC or UCC.

The multinational, randomized, double-blind, placebo-controlled studies assessed a combined total of 2044 participants (COUGH-1, n = 730; COUGH-2, n = 1314).

Patients were then randomly assigned to receive gefapixant 45 mg twice daily, gefapixant 15 mg twice daily, or placebo.

The primary efficacy outcome measures were 24-hour cough frequency at week 12 for COUGH-1 and 24-hour cough frequency at week 24 for COUGH-2. Frequency was measured using an ambulatory digital audio recording device.

As such, data presented at the Virtual European Respiratory Society (ERS) International Congress 2020 showed that gefapixant 45 mg significantly reduced 24-hour cough frequency versus placebo at 12 weeks (-18.45% [95% CI, -32.92 to -0.86, P = 0.041]) in COUGH-1.

This trend was also seen in COUGH-2. Gefapixant demonstrated a significant reduction at 24 weeks compared with placebo (-14.64% [95% CI, -26.07 to -1.43; P = 0.031]).

However, gexapixant 15 mg did not meant the primary efficacy endpoint in either Phase 3 study.