A Study to Test Whether Different Doses of BI 1291583 Help People With Bronchiectasis

This study is open to adults with bronchiectasis. People can join the study if they produce sputum and have a history of flare-ups (also called exacerbations). The purpose of this study is to find out whether a medicine called BI 1291583 helps people with bronchiectasis. Participants are put into 4 groups randomly, which means by chance. Participants in groups 1, 2, and 3 get different doses of BI 1291583. Participants in group 4 get placebo. Placebo tablets look like BI 1291583 tablets, but do not contain any medicine. Participants take the tablets once a day. Participants are in the study for between 6 months and 1 year. During this time, they visit the study site about 10 times and get about 5 phone calls from the site staff. The doctors document when participants experience flare-ups during the study. The time to the first flare-ups is compared between the treatment groups. Doctors also regularly check participants' health and take note of any unwanted effects.