Ifinatamab Deruxtecan (I-DXd) in Subjects With Pretreated Extensive-Stage Small Cell Lung Cancer (ES-SCLC)

Inclusion Criteria: Participants must meet all the following criteria to be eligible for enrollment into the study: * Sign and date the informed consent form (ICF) prior to the start of any study-specific qualification procedures. * Participant must have at least one lesion, not previously irradiated, amenable to core biopsy. * Male or female subjects aged ≥18 years (follow local regulatory requirements if the legal age of consent for study participation is \>18 years old). * Histologically or cytologically documented ES-SCLC. * At least one measurable lesion according to RECIST v1.1 as assessed by the investigator. * Prior therapy with at least one platinum-based line as systemic therapy for extensive-stage disease with at least two cycles of therapy (except in the case of early objective PD) and beginning with protocol version 3.0, a minimum of two previous lines of systemic therapy. * Documentation of radiological disease progression on or after most recent systemic therapy. * Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1. Exclusion Criteria: Participants who meet any of the following criteria will be disqualified from entering the study: * Prior treatment with orlotamab, enoblituzumab, or other B7-H3 targeted agents, including I-DXd. * Prior discontinuation of an antibody drug conjugate (ADC) that consists of an exatecan derivative (eg, trastuzumab deruxtecan) due to treatment-related toxicities. * Clinically active brain metastases, spi…