A Study in Healthy Men to Measure the Amount of BI 425809 in the Blood When Taken as a Tablet

Inclusion Criteria: * Healthy male subjects according to the assessment of the investigator, based on a complete medical history including a physical examination, vital signs (Blood Pressure (BP), Pulse Rate (PR)), 12-lead Electrocardiogram (ECG), and clinical laboratory tests * Age of 18 to 65 years (incl.) * Body mass index (BMI) of 18.5 to 29.9 kg/m2 (incl.) * Signed and dated written informed consent prior to admission to the study in accordance with Good Clinical Practice (GCP) and local legislation * Subjects who are sexually active must use, with their partner, highly effective contraception from the time of administration of trial medication until 4 months after administration of trial medication. Adequate methods are: * Condoms plus use of hormonal contraception by the female partner that started at least 2 months prior to administration of trial medication (e.g., implants, injectables, combined oral or vaginal contraceptives, intrauterine device) or * Condoms plus surgical sterilization (vasectomy at least 1 year prior to enrolment) or * Condoms plus surgically sterilised partner (including hysterectomy) or * Condoms plus intrauterine device or * Condoms plus partner of non-childbearing potential (including homosexual men) Subjects are required to use condoms to prevent unintended exposure of the partner to the study drug via seminal fluid. * Alternatively, true abstinence is acceptable when it is in line with the subject's preferred and usual lifestyle. If a subject is usually not sexually active but becomes active, with their partner, they must comply with the contraceptive requirements detailed above. Exclusion Criteria: * Any finding in the medical examination (including Blood Pressure (BP), Pulse Rate (PR) or Electrocardiogram (ECG)) is deviating from normal and judged as clinically relevant by the investigator * Repeated measurement of systolic blood pressure outside the range of 90 to 139 mmHg, diastolic blood pressure outside the range of 45 to 89 mmHg, or pulse rate outside the range of 40 to 100 bpm * Any laboratory value outside the reference range that the investigator considers to be of clinical relevance * Any evidence of a concomitant disease judged as clinically relevant by the investigator * Clinically significant gastrointestinal, hepatic, renal, respiratory (including but not limited to interstitial lung disease), cardiovascular, metabolic, immunological or hormonal disorders * Further exclusion criteria apply