Strategic decision by Sponsor; not due to safety reasons

The purpose of the study is to evaluate the efficacy and safety of two doses of CHF6001 (Tanimilast), as add-on to maintenance triple therapy in the target patient population.

Inclusion Criteria:

• Adults aged ≥ 40 years with COPD and chronic bronchitis
• Current or ex-smokers (history ≥ 10 pack years).
• Post-bronchodilator FEV1 <60% of the subject predicted normal value and FEV1/FVC ratio < 0.7.
• At least, one moderate or severe COPD exacerbation in previous year.
• CAT score ≥ 10
• Subjects on regular maintenance triple therapy for at least 12 months prior to screening and receiving regular maintenance triple therapy for at least 3 months prior to screening visit

Exclusion Criteria:

• Subjects with current asthma.
• Subjects with moderate or severe COPD exacerbation 4 weeks prior to study entry and randomization.
• Subjects with known α-1 antitrypsin deficiency as the underlying cause of COPD.
• Subjects with COPD emphysema or mixed phenotypes.
• Subjects with known respiratory disorders other than COPD.
• Subjects with active cancer or a history of lung cancer with full recovery less than 1 year after completing cancer therapy.
• Subjects under Roflumilast treatment within 6 months before study entry.
• Subjects with a diagnosis of depression, generalised anxiety disorder, suicidal ideation.
• Subjects with clinically significant cardiovascular.
• Subjects with a significant neurological disease.
• Subjects with clinically significant laboratory abnormalities.
• Subjects with moderate or severe hepatic impairment