A Study of TRB191 in Patients With Extensive-stage Small Cell Lung Cancer

Inclusion Criteria:

* Age ≥ 18 years old
* Histologically or cytologically confirmed and documented ES-SCLC
* Dose escalation: Patients with ES-SCLC and disease progression after one or more chemotherapy regimens (with or without PD-L1 inhibitor) according to the local standard of care (SOC). Prior treatment with a DLL3-targeted therapy is allowed, except in cohorts designed to evaluate TRB191 in patients who are naïve to prior DLL3-targeted therapy
* Dose expansion: Patients with ES-SCLC and disease progression after one or more chemotherapy regimens (with or without PD-L1 inhibitor), according to the local SOC. Patients must have received prior treatment with tarlatamab

Exclusion Criteria:

* Patients with inadequate bone marrow function and/or organ functions with out-of-range laboratory values
* Impaired cardiac function or clinically significant cardiac disease
* Presence of symptomatic central nervous system (CNS) metastases or CNS metastases requiring local therapy or increasing doses of corticosteroids within 2 weeks prior to study entry
* Treatment with anti-cancer therapies prior to the first dose of study treatment within the stated timeframes
* Pregnant or nursing woman, and women of child-bearing potential, defined as all women physiologically capable of becoming pregnant, unless they are using highly effective methods of contraception

Other protocol-defined inclusion/exclusion criteria may apply.