Brightline-4: A Study to Test How Well Brigimadlin is Tolerated by People With a Type of Cancer Called Dedifferentiated Liposarcoma

Inclusion Criteria:

1. Provision of signed and dated, written informed consent form (ICF) in accordancewith International Council for Harmonisation of Technical Requirements forPharmaceuticals for Human Use (ICH) - Good Clinical Practice (GCP) and locallegislation prior to any study-specific procedures, sampling, or analyses

2. Male or female patients ≥18 years old at the time of signature of the ICF

3. Women of childbearing potential (WOCBP) and men able to father a child must be readyand able to use two medically acceptable methods of birth control per ICH M3 (R2)that result in a low failure rate of <1% per year when used consistently andcorrectly beginning at screening, during study participation, and until 6 months and 12 days after last dose for women and 102 days after last dose for men. A list ofcontraception methods meeting these criteria is provided in the patient information

4. Histologically documented locally advanced or metastatic, unresectable (i.e. surgerymorbidity would outweigh potential benefits), progressive or recurrentDedifferentiated liposarcoma (DDLPS), meeting the criteria for an open study cohort:

• Cohort A: patient has not received prior systemic therapy for DDLPS in anysetting (including adjuvant, neoadjuvant, maintenance, palliative)

• Cohort B: patient has received any prior systemic therapy for DDLPS in anysetting (including adjuvant, neoadjuvant, maintenance, palliative)

5. Written pathology report indicating the diagnosis of DDLPS with positive MDM2immunohistochemistry or MDM2 amplification as demonstrated by fluorescence in situhybridisation (FISH) or next-generation sequencing (NGS)

6. Presence of at least 1 measurable target lesion according to RECIST version 1.1. Inpatients who only have 1 target lesion, the baseline imaging must be performed atleast 2 weeks after any biopsy of the target lesion

7. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

8. Life expectancy ≥3 months at the start of treatment in the opinion of theinvestigator Further inclusion criteria apply.

Exclusion Criteria:

1. Known mutation in the TP53 gene (screening for TP53 status is not required)

2. Major surgery (major according to the investigator's assessment) performed within 4weeks prior to start of study treatment or planned within 6 months after screening

3. Previous administration of brigimadlin or any other MDM2-p53 or MDM4 regulator ofp53 (MDM4/MDMX)-p53 antagonist

4. Previous treatment in study 1403-0008 (Brightline-1)

5. Having to receive, or intending to receive, restricted medications or any drugconsidered likely to interfere with the safe conduct of the study

6. Receiving treatment for brain metastases or leptomeningeal disease (LMD) which mayinterfere with safety and/or endpoint assessment

7. Unable to swallow the study treatment

8. Previous or concomitant malignancies other than the one treated in this study withinthe previous 2 years, except effectively treated non-melanoma skin cancers,carcinoma in situ of the cervix, ductal carcinoma in situ, or other malignancy thatis considered cured by local treatment Further exclusion criteria apply.