A Clinical Study of Gocatamig (MK-6070) and Infinatamab Deruxtecan (MK-2400) in People With Small Cell Lung Cancer (MK-6070-003)

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

• Has a histologically or cytologically confirmed diagnosis of extensive-stage smallcell lung cancer (ES-SCLC)

• For participants receiving gocatamig + ifinatamab deruxtecan (I-DXd) in maintenanceonly:

• Completed 3 to 4 cycles of platinum + etoposide chemotherapy with concurrentapproved anti-programmed cell death 1/Ligand 1 (anti PD-1/L1) as first line (1L) treatment of ES-SCLC within 6 weeks prior to enrollment

• No radiological disease progression per Response Evaluation Criteria In SolidTumors version 1.1 (RECIST 1.1)

• No other prior systemic ES-SCLC therapy allowed

• Rechallenge therapy counts as an additional line and leads to exclusion

• For participants receiving gocatamig + I-DXd in induction and maintenance, orgocatamig + I-DXd in induction followed by gocatamig + atezolizumab in maintenance,or carboplatin + etoposide + atezolizumab in induction followed by atezolizumab inmaintenance: No prior systemic ES-SCLC treatment allowed

• Applicable to all participants: prior limited-stage small cell lung cancer (SCLC) isallowed if > 6 months have passed since the end of previous therapy and progression

• Must be able to provide a pretreatment archival tumor tissue sample or newlyobtained core, incisional, or excisional biopsy of a tumor lesion not previouslyirradiated

• Measurable disease by RECIST 1.1 as assessed by the local siteinvestigator/radiology. Lesions situated in a previously irradiated area areconsidered measurable if growth has been shown in such lesions since the completionof radiation

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

• Has pleural effusion, pericardial effusion, or ascites requiring recurrent drainageprocedures

• Has any history of interstitial lung disease (ILD)/pneumonitis irrespective ofsteroid use, current ILD, ILD that cannot be ruled out by imaging at screening, orsuspected ILD

• Has clinically severe pulmonary compromise resulting from intercurrent pulmonaryillnesses

• Has history of clinically significant intracranial bleeding or spinal cord bleeding

• Has active neurologic paraneoplastic syndrome

• Has history of coronary/peripheral artery bypass graft and/or anycoronary/peripheral angioplasty or clinically significant cardiovascular diseasesuch as myocardial infarction, symptomatic congestive heart failure (CHF), and/oruncontrolled cardiac arrhythmia within 6 months before the first dose of studyintervention

• Has other uncontrolled or significant protocol specified cardiovascular disease

• Has history of arterial thrombosis within 6 months before the first dose of studyintervention

• Has chronic liver disease

• Has history of allogeneic tissue/solid organ transplant

• Has history of leptomeningeal disease

• Is infected with human immunodeficiency virus (HIV) and has a history of Kaposi'ssarcoma and/or Multicentric Castleman's Disease

• Has received prior therapy with an anti-programmed cell death protein 1 (anti-PD-1),anti-programmed cell death ligand 1 (anti-PD-L1), or anti-programmed cell deathligand 2 (anti-PD-L2) agent or with an agent directed to another stimulatory orcoinhibitory T-cell receptor

• Has received prior radiotherapy within 2 weeks of start of study intervention, orhas radiation-related toxicities, requiring corticosteroids

• Has known additional malignancy that is progressing or has required active treatmentwithin the past 3 years

• Has active autoimmune disease that has required systemic treatment in the past 2years except replacement therapy

• Has known active central nervous system (CNS) metastases and/or carcinomatousmeningitis

• Has major surgery within 4 weeks or minor surgery within 2 weeks ofallocation/randomization (or first dose), or is anticipated to require a majorsurgical procedure during the study