This study is trying to identify the right dose of a long-acting medicine called WIN378 for people with moderate - severe chronic obstructive pulmonary disease (COPD). WIN378 blocks the action of a protein called TSLP that causes inflammation in the lung and may contribute to COPD control and symptoms. The study will test how doses of WIN378 are handled by the body (pharmacokinetics) and assess the safety of the medicine and markers of COPD inflammation in exhaled breath and blood, lung function and COPD control (pharmacodynamics)

This is a Phase 2a, multicenter, randomized, double-blind, placebo-controlled, dose-ranging study to evaluate the safety, tolerability, and pharmacokinetics of WIN378 in adult participants with moderate - severe chronic obstructive pulmonary disease (COPD). Participants will continue their standard background COPD therapy. Eligible participants will receive doses of WIN378 or placebo over a 24-week treatment period.

Inclusion Criteria:

• Adults aged 40 to 80 years
• Post-BD spirometry at screening FEV1/FVC < 0.70 and FEV1 30-80% predicted
• On stable triple inhaled therapy (ICS/LABA/LAMA) for ≥ 3 months
• Former smoker (≥ 10 pack-year history) and abstinence from smoking for ≥ 6 months
• Elevated eosinophil count
• Weight/BMI within allowed range

Exclusion Criteria:

• Clinically significant pulmonary disease other than chronic obstructive pulmonary disease (COPD)
• Clinically significant comorbid medical conditions or infections that, in the investigator's judgment, could affect participant safety or interfere with study conduct
• Clinically significant cardiovascular disease
• Recent respiratory infection or COPD exacerbation
• Exposure to approved or experimental biologic therapies for COPD with less than 5 half-life washout period
• Pregnancy or breastfeeding
• Smoking or diagnosed substance use disorder
• Any condition or circumstance that, in the investigator's opinion, would make participation unsafe or compromise study integrity

Double-blind