This study tests a new medicine, CHF6001 (Tanimilast), to see if it helps people with Chronic Obstructive Pulmonary Disease (COPD) and chronic bronchitis. COPD is a lung disease that makes it hard to breathe, and chronic bronchitis is when you have a long-lasting cough with mucus. The study lasts for 52 weeks, about one year. It compares two doses of CHF6001 with a placebo (a fake treatment) and a medicine called Roflumilast (Daliresp® 500µg). Participants must be 40 years or older and have been on regular triple therapy (a combination of three medicines) for at least 12 months. They should also have had at least one serious COPD flare-up in the past year. The study excludes people with asthma, recent severe COPD flare-ups, certain lung diseases, active cancer, and other significant health problems.

• The study lasts for 52 weeks.
• Participants will receive either CHF6001, a placebo, or Roflumilast.
• It's important to not have other serious health issues to join.