The study was terminated by Sponsor due to patient recruitment challenges.

This study will test whether daily use of azithromycin will reduce the rate of exacerbations and improve lung ventilation and perfusion assessed by XE-MRI. The sensitivity of XE-MRI to detect COPD progression will be compared with standard clinical assessment measures including standard lung function tests, 6 minute walk test, and patient reported quality of life.

Inclusion Criteria:

• Current or former smokers with years ≥ 10 pack years
• mMRC dyspnea score > 1
• Post-bronchodilator FEV-1/forced vital capacity (FVC) <0.70 at Visit 1 or Visit 2
• Cohort A: GOLD Stage 2-4 COPD with a history of ≥ 2 moderate/severe exacerbations within a 12-month period in the 24 months prior to screening
• Cohort B: GOLD Stage 1 COPD with a history of ≥1 moderate/severe exacerbations within a 12-month period in the 24 months prior to screening
• Receiving SOC background drug therapy as per GOLD or British Thoracic Society (BTS) guidance for COPD for 12 weeks prior to screening Visit 1
• On an eligible bronchodilator medication (LABA ± LAMA) ± ICS therapy for ≥12 weeks prior to Visit 1
• Chest X-ray or CT scan within 6 months prior to Visit 1, or during the screening period (prior to Visit 2), that confirms the absence of clinically significant lung disease besides COPD
• Use of contraceptive measures

Exclusion Criteria:

• Diagnosis of significant respiratory disease other than COPD
• Comorbid conditions that may interfere with the evaluation of an investigational medical product
• Known sensitivity or allergy to azithromycin
• A COPD exacerbation and or pneumonia within 4 weeks prior to Visit 1
• Use of systemic corticosteroids within 4 weeks (oral or intravenous) or within 12 weeks (intramuscular IM) prior to screening Visit 1
• MRI is contraindicated
• Any known arrhythmia, bradycardia or severe cardiac insufficiency
• Participant can not hold breath for 15 seconds
• Participant does not fit in the ¹²⁹XE vest coil used for MRI
• Pregnant, lactating, or intending to become pregnant during the study or within 4 weeks after the last dose of the investigational medical product
• History or evidence of substance abuse that would pose a risk to participants safety, interfere with the conduct of the study, or have an impact on the study results
• For participants in Cohort A: Known significant hearing impairment as indicated by a score of ≥ 26 on the Hearing Handicap Inventory in the Elderly-Screening Questionnaire or as determined by the investigator
• History of Clostridium difficile (C. difficile) diarrhea Clinically significant ECG changes, which in the opinion of investigator warrants further investigation or with a QTc interval > 450 ms