Treatment of Persistent Cough in Subjects with Idiopathic Pulmonary Fibrosis (IPF) with Gefapixant, a P2X3 Antagonist, in a Randomized, Placebo-Controlled Clinical Trial

Pulm Ther. 2021 Dec;7(2):471-486. doi: 10.1007/s41030-021-00162-9. Epub 2021 Jun 21.


Introduction: Chronic cough is a highly problematic symptom for patients with idiopathic pulmonary fibrosis (IPF); limited therapeutic options are available. We evaluated gefapixant, a P2X3 receptor antagonist, for the treatment of chronic cough in IPF.

Methods: This randomized, double-blind, placebo-controlled, crossover study included subjects with IPF. Sequence A included gefapixant 50 mg BID (period 1; 14 days) followed by placebo (period 2; 14 days); sequence B had the opposite sequence of treatments. This regimen was specified in a protocol amendment that modified the original active treatment regimen of gefapixant 50 mg BID for 10 days and 150 mg BID for 4 days. Patients randomized to the original treatment regimen were excluded from efficacy analyses but included in safety assessments. The primary efficacy endpoint was change from baseline in awake cough frequency (coughs/hour) from periods 1 and 2 combined. Adverse events (AEs) were monitored throughout the study.

Results: A total of 51 subjects were randomized, 44 of whom were randomized to treatment sequences evaluated in the primary efficacy analysis (i.e., 22 subjects in sequence A and 22 subjects in sequence B); seven subjects received the treatment assigned before the protocol amendment and were excluded from efficacy analyses. The change from baseline in awake cough frequency from periods 1 and 2 combined (mixed model for repeated measures analysis) did not demonstrate a significant reduction versus placebo in cough at day 14 (p = 0.90); in a post hoc analysis of log-transformed data p value for reduction versus placebo at day 14 was 0.07. The most common AEs were related to taste (dysgeusia and ageusia).

Conclusions: Gefapixant was generally well tolerated but was not associated with a significant improvement in chronic cough in subjects with IPF as defined by the primary endpoint in this study.

Trial registration: NCT02502097.

Keywords: AF-219; Chronic cough; Gefapixant; Idiopathic pulmonary fibrosis; MK-7264; P2X3 receptor antagonist; Treatment-refractory chronic cough.

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