This study is open to adults with extensive stage small cell lung cancer. The study is in people with advanced cancer that are eligible for standard of care including chemotherapy and anti-PD-L1 (Programmed Cell Death Ligand 1) immunotherapy.

The purpose of this study is to find out the highest dose of BI 764532 (also called obrixtamig) that people can tolerate when taken together with standard of care. BI 764532 is an antibody-like molecule that may help the immune system fight cancer. Participants get BI 764532 and different standard treatments as infusions into a vein.

If there is benefit for the participants and if they can tolerate it, the treatment is given for the entire duration of the study. During this time, participants visit the study site regularly. The visits also depend on the response to the treatment. At the study visits, the doctors check the health of the participants, take necessary laboratory tests, and note any health problems that could have been caused by the study treatment.

Inclusion Criteria:

• Male or female participants ≥18 years old and at least at the legal age of consent in countries where it is greater than 18 years at the time of signature of the informed consent form (ICF)

• Signed and dated written informed consent in accordance with International Council for Harmonisation-Good Clinical Practice (ICH-GCP) and local legislation prior to admission to the trial

• Histologically or cytologically confirmed extensive-stage small cell lung carcinoma (ES-SCLC)

• Availability of archival tumour tissue

• Patients must be eligible for platinum+etoposide+anti-Programmed Cell Death Ligand 1 (PD-L1) regimen as first line standard of care (SoC) treatment:

  • In Part A, patients must be eligible to receive carboplatin + etoposide + atezolizumab
  • In Part B, patients must be eligible to receive etoposide, carboplatin or cisplatin, and atezolizumab or durvalumab

• No prior systemic treatment for ES-SCLC

• Prior systematic anti-cancer treatment for limited-stage small cell lung cancer (SCLC) must have been complete at least 6 months prior to the diagnosis of ES-SCLC

• Eastern Cooperative Oncology Group (ECOG) performance status of 0-1 Further inclusion criteria apply.

Exclusion Criteria:

• Previous treatment in this trial
• Treatment with a systemic anti-cancer therapy or investigational drug within 28 days or 5 half-lives (whichever is longer) of the first administration of trial medication
• Presence of leptomeningeal carcinomatosis
• Previous treatment with Delta-like ligand 3 (DLL3)-targeting T cell engagers and cell therapies
• Patients who have been treated with extensive field radiotherapy including whole brain irradiation within 2 weeks prior to first administration of BI 764532
• Persistent toxicity from previous treatments that has not resolved to ≤ Common Terminology Criteria for Adverse Events (CTCAE) Grade 1 (except for alopecia, asthenia/fatigue, CTCAE Grade 2 neuropathy, or Grade 2 endocrinopathies controlled by replacement therapy)
• Major surgery (major according to the investigator's assessment) within 28 days prior to first administration of BI 764532 or planned during treatment period, e.g. hip replacement
• Any documented active or suspected malignancy or history of malignancy within 5 years prior to Screening (other than the target indication), except for appropriately treated basal cell carcinoma of the skin or in situ carcinoma of uterine cervix Further exclusion criteria apply.

Once the criteria in section "Time Frame" are fulfilled, researchers can use the following link https://www.clinicalstudies.boehringer-ingelheim.com/msw/datasharing to request access to the clinical study documents regarding this study, and upon a signed "Document Sharing Agreement".

Furthermore, researchers can request access to the clinical study data, for this and other listed studies, after the submission of a research proposal and according to the terms outlined in the website.

After structured results have been posted, all regulatory activities are completed in the US and EU for the product and indication, and after the primary manuscript has been accepted for publication.

For study documents - upon signing of a 'Document Sharing Agreement'. For study data - 1. after the submission and approval of the research proposal (checks will be performed by the sponsor and/or the independent review panel, including checking that the planned analysis does not compete with sponsor's publication plan); 2. and upon signing of a legal agreement.