Study of Gefapixant (MK-7264) in Adult Japanese Participants With Unexplained or Refractory Chronic Cough (MK-7264-033)

Study Overview
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Brief Summary
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This estimation study (no hypotheses) will evaluate the safety, tolerability, and efficacy of gefapixant (MK-7264) in Japanese adult participants with unexplained or refractory chronic cough.

Official Title
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Phase II Study, Randomized, Double-Blind, Placebo-Controlled 4-Week Clinical Study, to Evaluate the Efficacy and Safety of MK-7264 in Adult Japanese Participants With Unexplained or Refractory Chronic Cough

Conditions
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Chronic Cough

Intervention / Treatment
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* Drug: Gefapixant 45 mg
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Chest radiograph or computed tomography scan of the thorax (within 5 years of Screening/Visit 1 and after the onset of chronic cough) not demonstrating any abnormality considered to be significantly contributing to the chronic cough or any other clinically significant lung disease in the opinion of the principal investigator or the sub-investigator. Has had chronic cough for ≥ 1 year and a diagnosis of refractory chronic cough or unexplained chronic cough. For female participants, is a female who is not pregnant, not breastfeeding, not of childbearing potential, or agrees to follow contraceptive guidance Provides written informed consent and is willing and able to comply with the study protocol (including use of the digital cough recording device and completion of study questionnaires) Exclusion Criteria: Is a current smoker or has given up smoking within 12 months of Screening, or is a former smoker with a pack-year history >20 pack-years Has a history of upper or lower respiratory tract infection or recent clinically significant change in pulmonary status Has a history of chronic bronchitis Is currently taking an angiotensin converting enzyme inhibitor (ACEI), or has used an ACEI within 3 months of Screening Has a history of malignancy ≤5 years Has a screening systolic blood pressure >160 millimeters of mercury (mmHg) or a diastolic blood pressure >90 mm Hg Has a history of cutaneous adverse drug reaction to sulfonamides with or without systemic symptoms or history of anaphylaxis to sulfonamides Is a user of recreational or illicit drugs or has had a recent history of drug or alcohol abuse or dependence Has a known allergy/sensitivity or contraindication to gefapixant Has donated or lost ≥1 unit of blood within 8 weeks prior to the first dose of gefapixant Has previously received gefapixant or is currently participating in or has participated in an interventional clinical study

Ages Eligible for Study
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Minimum Age: 20 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Japanese adult participants with refractory or unexplained chronic cough will be randomized to 1 of 2 treatment groups: gefapixant 45 mg twice daily (BID), or placebo BID.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Gefapixant 45 mg<br>Participants will receive a gefapixant 45 mg film-coated tablet BID for 28 days. | Drug: Gefapixant 45 mg<br>* Gefapixant 45 mg (film-coated tablet) to be administered orally BID<br>* Other names: MK-7264;|
| Placebo Comparator: Placebo<br>Participants will receive a film-coated placebo tablet matching gefapixant BID for 28 days. | Drug: Placebo<br>* Placebo (film-coated tablet) matching gefapixant to be administered orally BID<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants Who Experienced an Adverse Event | An adverse event is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. | Up to 6 weeks | 
| Number of Participants Who Discontinued Study Treatment Due to an Adverse Event | An adverse event is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. | Up to 4 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline at Week 4 in Log-transformed 24-hour Coughs Per Hour | Cough frequency will be evaluated using a digital recording device which records sounds from the lungs and trachea through a chest contact sensor, as well as ambient sounds through a lapel microphone. Change from baseline in log-transformed 24-hour coughs per hour = log (24-hour coughs per hour at post-baseline) - log (24-hour coughs per hour at baseline). The denominators may be different if the recording period is actually <24 hours but ≥20 hours). | Baseline and Week 4 | 
| Change From Baseline at Week 4 in Log-transformed Awake Coughs Per Hour | Change from baseline at Week 4 in awake coughs per hour is the average hourly cough frequency (based on sound recordings) during the 24-hour monitoring period while the participant is awake. Change from baseline in log-transformed awake coughs per hour = log (awake coughs per hour at post-baseline) - log (awake coughs per hour at baseline) for the monitoring period the participant is awake. | Baseline and Week 4 |