The AIRTIVITY™ Study: A Study to Find Out Whether BI 1291583 Helps People With Bronchiectasis

Inclusion criteria:

• Male or female participants. Woman of childbearing potential (WOCBP) must be readyand able to use highly effective methods of birth control per International Councilof Harmonisation (ICH) M3 (R2) that result in a low failure rate of less than 1 %per year when used consistently and correctly. A list of contraception methodsmeeting these criteria is provided in the participant information.

• Signed and dated written informed consent and assent, if applicable, prior toadmission to the study, in accordance with GCP and local legislation.

• Age of participants when signing the informed consent/assent ≥12 years.

-- Adolescents need to weigh at least 35 kg at Visit 1.

• Clinical history consistent with bronchiectasis (e.g. cough, chronic sputumproduction, recurrent respiratory infections) and investigator confirmed diagnosisof bronchiectasis by CT scan where bronchiectasis has been documented by aradiologist.

Participants whose past CT scan image records are not available will undergo a chest CT scan during Screening. Historical scans must not be older than five years.

• Adult participants should be able to produce sputum for Pseudomonas aeruginosaassessment during the screening period.

• History of documented pulmonary exacerbations (assessed and recorded by theinvestigator) requiring antibiotic treatment. In the 12 months before Visit 1,participants must have had either:

• at least 2 exacerbations, or

• at least 1 exacerbation and an St. George's Respiratory Questionnaire (SGRQ)Symptoms score of >40 at screening Visit 1 (adults only)

• at least 1 exacerbation and high symptom burden according to the investigator'sjudgement (adolescents only) For participants on oral or inhaled antibiotics aschronic treatment for bronchiectasis and participants on Cystic FibrosisTransmembrane Conductance Regulator Modulator Therapy (CFTR-MT), at least oneexacerbation must have occurred since initiation of antibiotics or CFTR-MT.

Exclusion criteria:

• Any new or newly diagnosed condition of primary or secondary immunodeficiency within 1 year before randomisation.

• Allergic bronchopulmonary aspergillosis being treated or requiring treatment.

• Tuberculosis or non-tuberculosis mycobacterial infection being treated or requiringtreatment

• Any findings in the medical examination and/or laboratory value assessed atScreening Visit 1 or during screening period, that in the opinion of theinvestigator may put the participant at risk by participating in the trial.

• Any clinically relevant (at the discretion of the investigator) acute respiratoryinfection or ongoing pulmonary exacerbation at screening visit or during thescreening unless recovered in the opinion of the investigator prior to Visit 2.

• Any relevant pulmonary, gastrointestinal, hepatic, renal, cardiovascular, metabolic,immunological, hormonal, or other disorder that, in the opinion of the investigator,may put the participant at risk by participating in the study.

• Major surgery (major according to the investigator's assessment) performed within 6weeks prior to randomisation or scheduled during trial period.

• Any documented active or suspected malignancy or history of malignancy within 5years prior to screening, except appropriately treated in situ non-melanoma skincancers or in situ carcinoma of uterine cervix.

• Evidence or medical history of moderate or severe liver disease (Child-Pugh score Bor C hepatic impairment).

• estimated Glomerular Filtration Rate (eGFR) according to Chronic Kidney DiseaseEpidemiology Collaboration (CKD-EPI) formula (adults) or Chronic Kidney DiseaseUnder 25 (CKiD-U25) (adolescents) <30 mL/min at Visit 1.

• Previous treatment with a dipeptidyl peptidase-1 (DPP1) (Cathepsin C (CatC))inhibitor. (Note: Participants that were randomised and only received placebo instudies with DPP1 (CatC) inhibitor are allowed.) Further exclusion criteria apply.