Results from a pooled analysis of two phase III randomized, controlled trials suggest that treatment with gefapixant reduced cough frequency by nearly 20% in patients with chronic cough. Jacky Smith, MBChB, FRCP, PhD, from Manchester University NHS Foundation Trust, presented the findings of this analysis at the 2021 American Thoracic Society’s International Conference.
Chronic cough is often associated with conditions such as reflux disease or upper airway cough syndrome, Dr. Smith explained, and is often refractory to treatment or has an unexplained cause. The COUGH-1 and COUGH-2 trials compared the P2X3 receptor antagonist gefapixant at two dose levels (15 mg or 45 mg twice-daily) versus placebo, finding that the drug led to significant reductions in 24-hour cough frequency. Participants had chronic cough for at least one year, had refractory or unexplained chronic cough, and screening and baseline cough severity visual analogue scales scores of ≥40 mm.
Objective cough frequency endpoints included 24-hour cough frequency (coughs/hour over 24 hours) and Awake Cough Frequency (coughs/hour during waking hours), and these measures were assessed over 12 weeks (COUGH-1) and 24 weeks (COUGH-2).
More than 2,000 patients with refractory or unexplained chronic cough were enrolled in the COUGH trials and were pooled for this analysis. The estimated relative reductions observed in patients treated with gefapixant 45 mg twice-daily were 18.59% for objective cough frequency and 17.38% for awake cough frequency. No serious adverse events were observed with greater incidence than placebo.
“This is the largest prospective analysis of clinical trial data in chronic cough to date,” the study authors concluded. “Gefapixant 45 mg provided clinically important reduction in cough frequency versus placebo and was not associated with an increase in serious adverse events although taste-related adverse events were observed.”