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

In Part A, participants will be allocated to Arm 1 or Arm 2 per investigator's discretion. In Part B, participants will be allocated to Arm 1 per investigator's discretion and randomized to Arms 2, 3, and 4.

Inclusion criteria

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

• Has a histologically or cytologically confirmed diagnosis of extensive-stage small cell lung cancer (ES-SCLC)
• For participants receiving gocatamig + ifinatamab deruxtecan (I-DXd) in maintenance only:

• Completed 3 to 4 cycles of platinum + etoposide chemotherapy with concurrent approved 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 Solid Tumors 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, or gocatamig + I-DXd in induction followed by gocatamig + atezolizumab in maintenance, or carboplatin + etoposide + atezolizumab in induction followed by atezolizumab in maintenance: No prior systemic ES-SCLC treatment allowed
• Applicable to all participants: prior limited-stage small cell lung cancer (SCLC) is allowed 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 newly obtained core, incisional, or excisional biopsy of a tumor lesion not previously irradiated
• Measurable disease by RECIST 1.1 as assessed by the local site investigator/radiology. Lesions situated in a previously irradiated area are considered measurable if growth has been shown in such lesions since the completion of radiation

Exclusion criteria

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

• Has pleural effusion, pericardial effusion, or ascites requiring recurrent drainage procedures
• Has any history of interstitial lung disease (ILD)/pneumonitis irrespective of steroid use, current ILD, ILD that cannot be ruled out by imaging at screening, or suspected ILD
• Has clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses
• 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 any coronary/peripheral angioplasty or clinically significant cardiovascular disease such as myocardial infarction, symptomatic congestive heart failure (CHF), and/or uncontrolled cardiac arrhythmia within 6 months before the first dose of study intervention
• Has other uncontrolled or significant protocol specified cardiovascular disease
• Has history of arterial thrombosis within 6 months before the first dose of study intervention
• 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's sarcoma 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 death ligand 2 (anti-PD-L2) agent or with an agent directed to another stimulatory or coinhibitory T-cell receptor
• Has received prior radiotherapy within 2 weeks of start of study intervention, or has radiation-related toxicities, requiring corticosteroids
• Has known additional malignancy that is progressing or has required active treatment within the past 3 years
• Has active autoimmune disease that has required systemic treatment in the past 2 years except replacement therapy
• Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis
• Has major surgery within 4 weeks or minor surgery within 2 weeks of allocation/randomization (or first dose), or is anticipated to require a major surgical procedure during the study