The primary objective of this trial is to evaluate the safety and tolerability of tarlatamab in combination with ZL-1310 with or without durvalumab and to determine the maximum tolerated combination dose (MTCD) and/or recommended phase 2 dose (RP2D) of ZL-1310 in combination with tarlatamab.

Inclusion Criteria:

• Age ≥ 18 years (or ≥ legal age within the country if it is older than 18 years) at the time of signing the informed consent.
• Participants with Histologically or cytologically confirmed SCLC:
• For Part 1, participants must have SCLC that has progressed or recurred following at least 1 line of platinum-based anti-cancer therapy.
• For Parts 1 and 2, participants must have progressed or recurred following at least 1 line of platinum-based therapy. No prior tarlatamab is allowed in Cohort 2-1.
• For Part 3, participants must have extensive-stage SCLC (ES-SCLC) with no prior systemic treatment other than 1 cycle of platinum-based chemotherapy.

Note: Participants with prior treatment for limited-stage SCLC (LS-SCLC) before diagnosis of ES SCLC are permitted.

• Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.
• At least 1 measurable lesion as defined per RECIST v1.1 within 21-day screening period, not previously irradiated.
• Adequate organ function (hematological, coagulation, renal, hepatic, pulmonary, and cardiac function).

Exclusion Criteria:

• Symptomatic CNS metastases. Participants with treated brain metastases are eligible provided they meet the criteria specified in the protocol.
• History of interstitial lung disease (ILD)/pneumonitis.
• Received thoracic radiation therapy within 90 days prior to first dose of trial intervention.
• Prior therapy with any delta-like ligand 3 (DLL3)-directed therapy.
• Prior exposure to topoisomerase I inhibitors or antibody-drug conjugate (ADC) with topoisomerase I inhibitor payload.
• Receiving strong CYP3A4 or CPY2D6 inhibitors within 14 days or 5 half-lives (whichever is longer) before the first dose of trial treatment.
• Enrollment in any tarlatamab clinical trial.

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.

Data sharing requests relating to this trial will be considered beginning 18 months after the trial has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this trial.

Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen trial/trials in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.