Ifinatamab vs. TreatmentA Study of Ifinatamab Deruxtecan Versus Treatment of Physician's Choice in Subjects With Relapsed Small Cell Lung Cancer

Inclusion Criteria

Participants must meet all the following criteria to be eligible for randomization into the study:

1. Sign and date the informed consent form (ICF) prior to the start of any study-specific qualification procedures.
2. Adults greater than or equal to (≥)18 years or the minimum legal adult age (whichever is greater) at the time the ICF is signed.
3. Has histologically or cytologically documented extensive-stage small cell lung cancer (ES-SCLC).
4. The participant must provide adequate baseline tumor samples with sufficient quantity and quality of tumor tissue content.
5. Has received prior therapy with only one prior platinum-based line as systemic therapy for SCLC with at least 2 cycles of therapy and a chemotherapy free-interval \[CTFI\] (duration from stop date of the platinum agent in 1L therapy to radiological PD) of ≥30 days.
6. Has at least 1 measurable lesion according to RECIST v1.1 as assessed by the investigator.
7. Has documentation of radiological disease progression on or after the most recent systemic therapy.
8. Has ECOG PS of less than or equal to (≤)1 within 7 days prior to Cycle 1 Day 1 (C1D1).
9. Participants with brain metastasis/leptomeningeal disease are eligible if protocol specified criteria are met.

Exclusion Criteria

Participants who meet any of the following criteria will be disqualified from entering the study:

1. Has received prior treatment with orlotamab, enoblituzumab, or other B7 homologue 3 (B7-H3) targeted agents, including I-DXd.
2. Prior discontinuation of an antibody drug conjugate (ADC) that consists of an exatecan derivative (eg, trastuzumab deruxtecan) due to treatment-related toxicities.
3. Has received any of the comparators used in this study or any topoisomerase I inhibitor.
4. Has inadequate washout period before randomization as specified in the protocol.
5. Has any of the following conditions within the past 6 months: cerebrovascular accident, transient ischemic attack, or another arterial thromboembolic event.
6. Has uncontrolled or significant cardiovascular (CV) disease.
7. Has clinically significant corneal disease.
8. All of the following indicators of interstitial lung disease (ILD)/pneumonitis are excluded:

1. Any history of ILD/pneumonitis irrespective of steroid use, except for a history of radiation pneumonitis that did not require steroids.
2. Current diagnosis of ILD.
3. Clinical or radiographic suspicion of ILD for which the diagnosis of ILD cannot be ruled out. Radiographic findings may include presence of lung parenchymal fibrosis, combined fibrosis and emphysema (CPFE), and/or interstitial lung abnormalities such as reticular opacities, traction bronchiectasis, honeycombing, or extensive ground glass opacities. Screening computed tomography (CT) scans must be submitted for independent central radiology review and results before randomization.
9. Has clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses, including, but not limited to, any underlying pulmonary disorder and potential pulmonary involvement caused by any autoimmune, connective tissue, or inflammatory disorders, prior pneumonectomy, or requirement for supplemental oxygen.