A Study to Evaluate the Safety and Efficacy of Gocatamig (MK-6070) and Ifinatamab Deruxtecan (I-DXd) in Participants With Relapsed/Refractory Extensive-Stage Small Cell Lung Cancer (MK-6070-002)

Eligibility Criteria

• * Has histologically or cytologically confirmed SCLC that is extensive stage (defined as Stage IV (T any, N any, M1a/b/c) following at least 1 prior line of systemic therapy that included platinum-based chemotherapy
• * Must be able to provide archival tissue sample or fresh biopsy tissue sample
• * Human immunodeficiency virus (HIV) infected participants must have well controlled HIV on antiretroviral therapy (ART)
• * Pleural effusion, pericardial effusion, or ascites requiring recurrent drainage procedure
• * History of (noninfectious) pneumonitis/interstitial lung disease (ILD) that required steroids or has current pneumonitis/ILD, and or suspected ILD/pneumonitis
• * Has clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses
• * History of clinically significant intracranial bleeding or spinal cord bleeding
• * Active neurologic paraneoplastic syndrome
• * Active or history of immune deficiency with the exception of HIV-infected participants with well controlled HIV on ART
• * History within 6 months before the first dose of study intervention 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) (New York Heart Association \> class II), and/or uncontrolled cardiac arrhythmia
• * Has other uncontrolled or significant protocol-specified cardiovascular disease
• * History of arterial thrombosis (eg, stroke or transient ischemic attack) within 6 months before the first dose of study intervention
• * Chronic liver disease, including liver cirrhosis of Child-Pugh class B or C
• * Active clinically significant infection requiring systemic therapy
• * History of allogeneic tissue/solid organ transplant
• * History of leptomeningeal disease
• * Received prior radiotherapy within 2 weeks of start of study intervention, or has radiation-related toxicities, requiring corticosteroids
• * Ongoing treatment with immunosuppressive medications, with protocol-specified exceptions
• * Known additional malignancy that is progressing or has required active treatment within the past 3 years
• * Untreated or symptomatic brain metastases
• * Active viral hepatitis, defined as hepatitis A (hepatitis A virus immunoglobulin M \[IgM\] positive in the setting of associated signs/symptoms), hepatitis B (hepatitis B virus surface antigen \[HbsAg\] positive and/or detectable hepatitis B virus (HBV) deoxyribonucleic acid \[DNA\]), or hepatitis C (hepatitis C virus \[HCV\] antibody positive and detectable HCV ribonucleic acid). Participants with HBV with undetectable viral load after treatment are eligible. Participants with HCV with undetectable virus after treatment are eligible.
• * Part 1 only: Radiation therapy to the lung \>30 Gy within 6 months before the start of study intervention
• * Part 1 only: Abdominal radiation within 4 weeks before start of study intervention
• * Part 1 only: Other anticancer therapy, including cytotoxic agents, targeted agents, immunotherapies, antibody, retinoid, transplant, or anticancer hormonal treatment (except luteinizing hormone-releasing hormone \[LHRH\]) within 2 weeks before start of study intervention
• * Part 1 only: Antibody-based cancer therapy within 3 weeks before start of study intervention
• * Part 1 only: Chloroquine/hydroxychloroquine within 2 weeks before start of study intervention
• * Part 1 only: Clinically significant corneal disease