Gefapixant Reduces Cough Frequency in Refractory and Unexplained Chronic Cough

Patients with refractory chronic cough (RCC) and unexplained chronic cough (UCC) who received the P2X3 receptor antagonist gefapixant had consistent reductions in cough frequency, according to researchers presenting at the American Association of Allergy, Asthma & Immunology (AAAAI) 2022 Annual Meeting, held in Phoenix, Arizona, from February 25 to 28.

Chronic cough (CC) is defined as cough that persists in spite of investigation and treatment, whereas RCC is cough that persists despite treatment of presumed contributing comorbidities. UCC is described as cough nonsuggestive of contributory comorbidities even after clinical evaluation. Such terms help identify comorbid conditions and allow subgroup comparisons of patients with and without comorbidities. In this study, pooled data from 2 gefapixant phase 3 trials, COUGH-1 and COUGH-2 (ClinicalTrials.gov Identifiers: NCT03449134 and NCT03449147), were used to evaluate subgroups of patients with RCC and UCC.

Both trials enrolled adults who had CC for l year or more, a guidelines-based diagnosis of RCC or UCC made by an enrolling physician, and cough severity greater than or equal to 40 mm/100 mm on the Visual Analog Scale. Baseline characteristics were reported for RCC and UCC subgroups. Efficacy, defined as 24-hour and awake cough frequency at week 12,  was evaluated through longitudinal analysis of covariance (ANCOVA) and was described as estimated relative reductions from baseline compared with placebo.

Of 1360 individuals receiving placebo or gefapixant 45 mg twice daily, 844 (62%) and 516 (38%) were classified as RCC or UCC, respectively. Comparable proportions of participants in both groups were female (RCC, 76%; UCC, 73 %) and 60 years of age or older (RCC, 54%; UCC, 49%). The mean cough duration was 11 years for both groups. Treatment with gefapixant 45 mg diminished placebo-adjusted 24-hour cough frequency in both subgroups, with an estimated relative reduction (95% CI) of -16% for RCC (-26%, -4%) and -22% for UCC (-36%, -5%). Treatment also reduced awake cough frequency for RCC by -16 % (-26%, -4%) and for UCC by -19% (-34%, -1%].

“In a guidelines-diagnosed population, patients with RCC or UCC had similar clinical features and experienced consistent cough frequency reductions with gefapixant,” the authors concluded.

Reference

Blaiss M, Dicpinigaitis, P, Birring  S, et al. Comparisons of Baseline Characteristics and Treatment Efficacy in Individuals With Refractory or Unexplained Chronic Cough Enrolled in Phase 3 Trials of Gefapixant. Presented at: American Academy of Allergy, Asthma & Immunology (AAAAI) 2022 Annual Meeting; February 25–28, 2022; Phoenix, AZ. Abstract 056.