The Safety, Feasibility, and Repeatability of Inhaled ATP Cough Challenges

Launched by MCMASTER UNIVERSITY · Jul 17, 2025

Keywords

ClinConnect Summary

This clinical trial is studying a new way to better understand chronic cough and asthma by using a test called the “ATP cough challenge.” In this test, participants will inhale a special substance called ATP to trigger a cough. The goal is to see if this test is safe, easy to do, and gives consistent results when repeated. This information could help doctors identify patients who might benefit from new treatments that block ATP and reduce cough sensitivity.

The study is looking for two groups of adults aged 18 and older. The first group includes healthy individuals with no history of lung disease or chronic cough. The second group includes people who have had a long-lasting cough that hasn’t improved with treatment or those with mild asthma who have never used steroid medications. Participants will undergo breathing tests and the ATP inhalation to measure their cough response. Certain people won’t be eligible, such as those with recent infections, serious health problems, or who are pregnant. If you join, the study team will carefully monitor your health to make sure the test is safe and comfortable. This research is still not open for enrollment but aims to improve how chronic cough and asthma are understood and treated in the future.

Gender

ALL

Eligibility criteria

• • Phase 1: Healthy individuals
• Inclusion Criteria:
• Eligible participants in Phase 1 will include healthy adults (≥18 years old) with:
• • 1. Normal spirometry; and
• • 2. No current or past medical history of chronic cough or other respiratory diseases.
• Exclusion Criteria:
• We will exclude healthy individuals meeting the following:
• • (1) Are a current or former smoker with a \>5 pack-year history and abstinence ≤6 months;
• • 1. Unable to perform acceptable and reproducible spirometry;
• • 2. Have unresolved symptoms of upper respiratory tract infection within 6 weeks prior to the first study visit;
• • 3. Have had a lower respiratory tract infection or pneumonia within 6 weeks prior to the first study visit;
• • 4. Presence of other primary pulmonary disorders, including pulmonary embolism, pulmonary hypertension, lung cancer, cystic fibrosis, radiologically-proven emphysema, severe bronchiectasis, or severe interstitial lung disease; or
• • 5. History of psychiatric illness, drug, or alcohol abuse that could interfere with participation in the study.
• • 6. History of clinically-significant cardiovascular disease, including coronary artery disease, aortic aneurysm, or stroke in the last 3 months;
• • 7. Those with serious medical conditions or those who are not on stable medication(s) for their condition(s);
• • 8. Those with immune system disorders, severe allergy, or on allergy-specific immunotherapy;
• • 9. Any other condition, that, in the opinion of the qualified investigator, may adversely affect the participant's ability to complete the study or its measures or pose significant risk to the participant;
• • 10. Pregnant or breastfeeding;
• 11. Women of child-bearing potential who:
• • 1. Do not agree to use a medically approved method of birth control for the duration of the study. All hormonal birth control must have been in use for a minimum of 3 months. Acceptable methods of birth control include oral contraceptives, hormone birth control patch, vaginal contraceptive ring, injectable contraceptives, or hormone implant, double-barrier method, intrauterine devices, non-heterosexual lifestyle or agrees to use contraception if planning on changing to heterosexual partner(s), vasectomy of partner at least 6 months prior to screening. Females who are not of child-bearing potential will be defined as females who have undergone a sterilization procedure (e.g., hysterectomy, bilateral oophorectomy, bilateral tubal ligation, complete endometrial ablation) or have been post-menopausal for at least 1 year prior to screening.
• • Phase 2: Patients with RCC/UCC and mild-steroid naïve asthma
• Inclusion Criteria:
• Eligible participants will include adults (≥18 years old) with:
• 1. RCC/UCC for \>1 year, demonstrated by a normal chest radiograph and no airflow obstruction (FEV1/FVC\>0.7/LLN) with either:
• • 1. Insufficient improvement in cough despite treatment targeting any underlying condition(s) contributing to the cough (RCC); or
• • 2. Cough for which an underlying cause has not been determined despite thorough investigation (UCC).
• • 2. Mild steroid-naïve asthma who demonstrate evidence of a positive screening methacholine (PC20\<16 mg/mL); symptoms of cough, shortness of breath, chest tightness, and wheeze, that, in the opinion of the qualified investigator, are well-controlled; and those have not used inhaled or oral corticosteroids for the past month.
• Exclusion Criteria:
• Cohort-specific exclusion criteria include the following:
• For the RCC/UCC cohort:
• • (1) Current smoker or ex-smoker with ≥20 pack-year history and abstinence ≤6 months;
• For the mild steroid-naïve asthma cohort:
• • 1. Current smoker or ex-smoker with ≥20 pack-year history and abstinence ≤6 months;
• • 2. History or exacerbation or uncontrolled symptoms within the last month prior to the first study visit; and
• • 3. Use of inhaled or oral corticosteroids within the last month prior to the first study visit.
• We will exclude participants meeting any of the following criteria from the study:
• • 1. Unable to perform acceptable and reproducible spirometry;
• • 2. Unresolved symptoms of upper respiratory tract infection within 6 weeks prior to the first study visit;
• • 3. Lower respiratory tract infection or pneumonia within 6 weeks prior to the first study visit;
• • 4. Presence of other primary pulmonary disorders, including pulmonary embolism, pulmonary hypertension, lung cancer, cystic fibrosis, radiologically-proven emphysema, severe bronchiectasis, or severe interstitial lung disease;
• • 5. History of psychiatric illness, drug, or alcohol abuse that could interfere with participation in the study;
• • 6. History of clinically-significant cardiovascular disease, including coronary artery disease, aortic aneurysm, or stroke in the last 3 months;
• • 7. Those with serious medical conditions or those who are not on stable medication(s) for their condition(s);
• • 8. Those with immune system disorders, severe allergy, or on allergy-specific immunotherapy;
• • 9. Any other condition, that, in the opinion of the qualified investigator, may adversely affect the participant's ability to complete the study or its measures or pose significant risk to the participant;
• • 10. Pregnant or breastfeeding;
• 11. Female participants of child-bearing potential who:
• • 1. Do not agree to use a medically approved method of birth control for the duration of the study;
• • 2. Have not been using hormonal birth control for a minimum of 3 months prior to screening.