A Study to Test How Well Different Doses of BI 3820768 Are Tolerated by People With Advanced Cancer (Solid Tumours)

1. Patient must be ≥18 years of age and at least at the legal age of consent in countries where it is older than 18 years at the time of signature on the informed consent forms (ICFs).
2. For patients with endometrial cancer (EC) and ovarian cancer (OVC), signed and dated written ICF1 for target testing.
3. Signed and dated ICF2 for all patients describing the study in accordance with International Council on Harmonisation Good Clinical Practice (ICH-GCP) and local legislation prior to any trial-specific procedures, sampling, or analyses.
4. Prior to Screening Visit 02, confirmed target-positivity for EC and OVC based on central laboratory testing of tumour tissue sample.
5. Patients with a histologically or cytologically confirmed diagnosis of germ cell tumour (GCT), EC, or OVC.
6. Patients with advanced, relapsed/refractory (r/r) GCT, EC, or OVC.
7. Patients with disease progression despite conventional treatment, intolerant to or not a candidate for conventional treatment, who have exhausted all established treatment options.
8. Patients with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

Further inclusion criteria apply.

Exclusion criteria:

1. Patient with a history of a major surgery within 28 days prior to the first dose of BI 3820768 (major according to the Investigator's and/or Sponsor's assessment).

2. Previous or concomitant malignancies other than the one treated in this trial within the past 3 years except:

   1. Effectively treated non-melanoma skin cancers
   2. Effectively treated carcinoma in situ of the cervix
   3. Effectively treated ductal carcinoma in situ
   4. Other effectively treated malignancy that is considered cured by local treatment
3. Patient with known leptomeningeal disease or spinal cord compression due to disease.
4. Presence of any infection requiring systemic antimicrobial treatment within 7 days prior to the first dose of trial medication. Patients who have any clinical signs of infection (e.g. fever or leukocytosis) within 48 h prior to the first dose of trial medication are not eligible.

5. Patients with Hepatitis-C-Virus (HCV) infection, defined as:

   1. Currently receiving curative antiviral treatment for HCV infection, and/or
   2. HCV viral load is above the limit of quantification (HCV RNA positive).
6. Patients with active hepatitis B virus (HBV) infection (chronic or acute); defined as having a positive hepatitis B surface antigen (HBsAg), and HBsAg test at screening.
7. Patient with past HBV infection or resolved HBV infection (defined as the presence of hepatitis B core antibody (HBcAb) and absence of HbsAg) are eligible. HBV DNA must be obtained in these patients prior study start.

Further exclusion criteria apply.