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

Inclusion criteria

• Provision of signed and dated, written informed consent form (ICF) in accordance with International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) - Good Clinical Practice (GCP) and local legislation prior to any study-specific procedures, sampling, or analyses
• Male or female patients ≥18 years old at the time of signature of the ICF
• Women of childbearing potential (WOCBP) and men able to father a child must be ready and 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 and correctly 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 of contraception methods meeting these criteria is provided in the patient information
• Histologically documented locally advanced or metastatic, unresectable (i.e. surgery morbidity would outweigh potential benefits), progressive or recurrent Dedifferentiated liposarcoma (DDLPS), meeting the criteria for an open study cohort:

• Cohort A: patient has not received prior systemic therapy for DDLPS in any setting (including adjuvant, neoadjuvant, maintenance, palliative)
• Cohort B: patient has received any prior systemic therapy for DDLPS in any setting (including adjuvant, neoadjuvant, maintenance, palliative)
• Written pathology report indicating the diagnosis of DDLPS with positive MDM2 immunohistochemistry or MDM2 amplification as demonstrated by fluorescence in situ hybridisation (FISH) or next-generation sequencing (NGS)
• Presence of at least 1 measurable target lesion according to RECIST version 1.1. In patients who only have 1 target lesion, the baseline imaging must be performed at least 2 weeks after any biopsy of the target lesion
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Life expectancy ≥3 months at the start of treatment in the opinion of the investigator Further inclusion criteria apply.

Exclusion criteria

• Known mutation in the TP53 gene (screening for TP53 status is not required)
• Major surgery (major according to the investigator's assessment) performed within 4 weeks prior to start of study treatment or planned within 6 months after screening
• Previous administration of brigimadlin or any other MDM2-p53 or MDM4 regulator of p53 (MDM4/MDMX)-p53 antagonist
• Previous treatment in study 1403-0008 (Brightline-1)
• Having to receive, or intending to receive, restricted medications or any drug considered likely to interfere with the safe conduct of the study
• Receiving treatment for brain metastases or leptomeningeal disease (LMD) which may interfere with safety and/or endpoint assessment
• Unable to swallow the study treatment
• Previous or concomitant malignancies other than the one treated in this study within the previous 2 years, except effectively treated non-melanoma skin cancers, carcinoma in situ of the cervix, ductal carcinoma in situ, or other malignancy that is considered cured by local treatment Further exclusion criteria apply.