A Study to Find Out Whether BI 1015550 Improves Lung Function in People With Idiopathic Pulmonary Fibrosis (IPF)

Inclusion criteria

1. Patients ≥40 years old at the time of signed informed consent.

2. Signed and dated written informed consent in accordance with ICH-GCP and local legislation prior to admission to the trial.

3. Diagnosis of Idiopathic Pulmonary Fibrosis (IPF).

4. Patients may be either:

• on a stable therapy* with nintedanib or pirfenidone for at least 12 weeks prior to Visit 1 and during screening and are planning to stay on this background treatment after randomization. Combination of nintedanib plus pirfenidone is not allowed. (*stable therapy is defined as the individually and general tolerated regimen of either nintedanib or pirfenidone (no dose changes) for at least 12 weeks).

• not on a treatment with nintedanib or pirfenidone for at least 8 weeks prior to Visit 1 and during the screening period (e.g. either Antifibrotic (AF)-treatment naïve or previously discontinued) and do not plan to start or re-start antifibrotic treatment.

5. Forced Vital Capacity (FVC) ≥45% of predicted normal at Visit 1.

6. Diffusing Capacity (of Lung) for Carbon Monoxide (DLCO) ≥25% of predicted normal corrected for hemoglobin (Hb) at Visit 1.

7. Women of childbearing potential (WOCBP) must be ready and able to use highly effective methods of birth control. WOCBP taking oral contraceptives (OCs) also have to use one barrier method.

Exclusion criteria

1. Prebronchodilator Forced Expiratory Volume in 1 second (FEV1)/Forced vital capacity (FVC) <0.7 at Visit 1.

2. In the opinion of the Investigator, other clinically significant pulmonary abnormalities.

3. Acute Idiopathic Pulmonary Fibrosis (IPF) exacerbation within 3 months prior to Visit 1 and/or during the screening period (investigator-determined).

4. Relevant chronic or acute infections including human immunodeficiency virus (HIV) and viral hepatitis.

5. Confirmed infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) not fully recovered according to investigator judgement within the 4 weeks prior to randomization (Visit 2).

6. Major surgery (major according to the investigator's assessment) performed within 6 weeks prior to Visit 2 or planned during the trial period, e.g. hip replacement. Registration on lung transplantation list would not be considered as planned major surgery.

7. Any documented active or suspected malignancy or history of malignancy within 5 years prior to Visit 1, except appropriately treated basal cell carcinoma of the skin, in situ squamous cell carcinoma of the skin or in situ carcinoma of uterine cervix.

8. Aspartate aminotransferase (AST) or Alanine Aminotransferase (ALT) >2.5 x Upper limit of normal (ULN) or total Bilirubin >1.5 x ULN at Visit 1.

Further exclusion criteria apply.