1493-0002

This study is open to adults who are at least 40 years old and have idiopathic pulmonary fibrosis (IPF). People can participate in the study if they have a forced vital capacity (FVC) greater than or equal to 45% of the predicted value and fibrosis of 20% or more confirmed by a high-resolution computed tomography (HRCT) scan. The purpose of this study is to find out if a medicine called BI 765423 can improve lung function in people with IPF. The study will compare BI 765423 with a placebo to see if there is a difference in lung capacity after 3-6 months of treatment and will also look at changes in certain markers related to lung health.

Participants are put into two groups randomly, which means by chance. One group receives the study medicine, and the other group receives a placebo. Placebo looks like BI 765423 but does not contain any study medicine. The study medicine is given as an infusion into a vein every four weeks.

Participants are in the study for up to 11 months. During the study, participants may continue their regular treatment for IPF. During the study they visit the study site several times for screening, treatment, and follow-up. Doctors regularly test lung function by measuring FVC and take blood samples to measure study endpoints. The results are compared between the two groups to see whether the treatment works. The doctors also check participants' health and take note of any unwanted effects.

Inclusion Criteria :

1. 40 years of age or older at the time of informed consent signature.

2. Signed and dated written informed consent in accordance with International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use * Good Clinical Practice (ICH-GCP) and local legislation prior to admission to the trial.

3. Male or female patients. Male patients must not donate sperm while taking part in this study and for a specific period after the last dose of the IMP. Male patients with woman of childbearing potential (WOCBP) sexual partners must use contraception (male condom) to avoid exposure via seminal fluid during treatment and for a specific period after last drug intake. Women can only be included if they are of non-childbearing potential, defined as meeting at least one of the below conditions:

   • Permanently surgically sterilised (hysterectomy, bilateral salpingectomy and/or bilateral oophorectomy)

   • Postmenopausal, defined as no menses for 12 months without an alternative medical cause. In questionable cases wherein the menopausal status is uncertain and cannot be clearly determined, the following should be taken into

Consideration by the investigator:

• Women not using sex hormone medication such as hormone replacement therapy may be included if a blood sample confirms levels of follicle stimulating hormone (FSH) > 40 U/L and estradiol < 30 ng/L"

1. Patients with a documented diagnosis of IPF prior to Visit 1, confirmed by the investigator as per the 2022 American Thoracic Society (ATS)/European Respiratory Society (ERS)/Japanese Respiratory Society (JRS)/Latin American Thoracic Association (ALAT) Guideline and, if available, surgical lung biopsy or transbronchial lung cryobiopsy histopathology report.

2. Patients with a high-resolution computed tomography (HRCT) taken within 12 months of Visit 1 (or during the screening period, if not available) confirming "UIP" or "probable UIP" HRCT pattern consistent with the clinical diagnosis of IPF by central review (prior to Visit 2).

   • Patients with an "indeterminate" HRCT finding are eligible if a clinical diagnosis of IPF can be confirmed based on an historical histopathology report of a surgical lung biopsy or cryobiopsy demonstrating a "UIP" or "Probable UIP" pattern or Multidisciplinary Discussion and Diagnosis as per ATS guidelines.

   • Patients with an "alternative diagnosis" HRCT finding are eligible if a clinical diagnosis of IPF can be confirmed based on an historical histopathology report of a surgical lung biopsy or cryobiopsy demonstrating a "UIP" pattern Multidisciplinary Discussion and Diagnosis as per ATS guidelines.

3. Patients with an extent of fibrosis ≥20% as per an HRCT of the chest performed within 12 months prior to Visit 1 or during the screening period (if not available) and confirmed by central review.

4. Patients with a Forced vital capacity (FVC) ≥45% predicted at Visit 1. Predicted normal values will be calculated according to Global Lung Initiative (GLI).

5. Patients with haemoglobin-corrected diffusing capacity of the lungs for carbon monoxide (DLCO) ≥20% predicted at Visit 1.

Further inclusion criteria apply.

Exclusion criteria:

1. Acute exacerbation of IPF within at least 12 weeks prior to Visit 1 and/or during the screening period (investigator-determined).

2. Relevant airways obstruction (pre-bronchodilator forced expiratory volume in 1 second (FEV1)/FVC