Ensifentrine (MK-5884) Study for the Prevention of Chronic Obstructive Pulmonary Disease (COPD) Exacerbations in Adults With a History of Moderate or Severe Exacerbations While Receiving Standard of Care (SOC) (MK-5884-031/RPL554/ENHANCE-3)

The purpose of this study is to evaluate the efficacy and safety of ensifentrine (MK-5884) compared with placebo for the prevention of moderate and severe COPD exacerbation in adults with COPD and a history of exacerbations while receiving SOC treatment. The study will also evaluate the efficacy of ensifentrine compared with placebo in improving lung function, improving health related quality of life, and preventing severe exacerbations.

Inclusion Criteria: Inclusion Criteria include but are not limited to: * Has a diagnosis of Chronic Obstructive Pulmonary Disease (COPD) that was made ≥12 months prior to randomization * Has been on the stable treatment with the same standard of care (SOC) with long-acting muscarinic antagonist (LAMA)/long-acting beta-2 agonist (LABA)/inhaled corticosteroid (ICS) or LAMA/LABA (if ICS is not appropriate), for at least 2 months prior to Screening * Has a documented history of ≥1 moderate or severe COPD exacerbation while on standard of care (SOC) within 1 year of Screening * Is a current or former cigarette smoker with a history of cigarette smoking ≥10 packyears at Screening (number of pack-years = \[number of cigarettes per day/20\] × number of years smoked \[e.g., 20 cigarettes per day for 10 years, or 10 cigarettes per day for 20 years\]). Pipe, cigar, and/or e-cigarette/vape use cannot be used to calculate pack-year history. * Has post-bronchodilator forced expiratory volume 1 (FEV1) ≥25% and \15 hours per day * Uses chronic bilevel positive airway pressure for treatment of respiratory condition unless for treatment of sleep apnea at a stable pressure for at least 3 months * Is currently using or has used a biologic therapy (e.g., dupilumab, mepolizumab, or tozorakimab) within 6 months prior to Screening Visit * Has history of or current malignancy of any organ system, treated or untreated within the past 5 years, except for localized basal or squamous cell carcinoma of the skin.