A Study of [177Lu]Lu-DOTA-TATE in Newly Diagnosed ES-SCLC Patients in Combination With Carboplatin, Etoposide and Atezolizumab

Prior treatment

• Participant has received prior therapy with an antibody or drug against immune checkpoint pathways
• Severe chronic or active infections (including active tuberculosis, HBV, or HCV infection) requiring systemic antibacterial, antifungal or antiviral therapy within 2 weeks before Cycle 1 Day 1
• Any major surgical procedure requiring general anesthesia =\< 28 days before Cycle 1 Day 1
• Concurrent participation in another therapeutic clinical study

Other illness

• Active autoimmune diseases or history of autoimmune diseases that may relapse
• Known hypersensitivity to the active substances or any of the excipients of the study drugs

Other

• History or current diagnosis of electrocardiogram (ECG) abnormalities indicating significant risk of safety for participants participating in the study

• Participant is \>= 18 years on the day of signing informed consent form
• Histologically or cytologically confirmed ES-SCLC
• Presence of measurable disease
• No prior systemic treatment for ES-SCLC (except the first cycle of chemotherapy with or without atezolizumab of the induction period
• ECOG status =\< 1
• Provision of tumor tissue to support exploratory biomarker analysis
• Life expectancy of \>= 6 months