Study of Sacituzumab Govitecan Versus Standard of Care in Participants With Previously Treated Extensive Stage Small Cell Lung Cancer

Key Inclusion Criteria: * Histologically confirmed diagnosis of SCLC. * Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1. * Measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) as assessed by investigator per RECIST v1.1 criteria. * Documentation of radiological disease progression after 1 prior line of platinum-containing chemotherapy (defined as at least 2 cycles of treatment) with or without therapy directed against programmed cell death protein 1 (PD-1) or programmed cell death ligand 1 (PD-L1; PD-1 and PD-L1 are hereafter referred to as PD-(L)1) for ES-SCLC. Key Exclusion Criteria: * Chemotherapy-free interval (CTFI) time from the last dose of first-line platinum-containing chemotherapy to the occurrence of progressive disease) \< 30 days (independent of the immunotherapy maintenance). * Received any prior treatment with irinotecan, topotecan, SG, SN-38, exatecan derivatives, and similar agents targeting topoisomerase I. * Untreated central nervous system (CNS) metastases and/or carcinomatous meningitis. Participants with previously treated brain metastases may participate provided they have stable CNS disease (ie, without evidence of progression) for at least 4 weeks prior to enrollment and all neurologic symptoms have returned to baseline, have no evidence of new or enlarging brain metastases, and are taking ≤ 10 mg/day of prednisone or its equivalent. Note: Other protocol defined Inclusion/Exclusion criteria may apply.