Study of Sacituzumab Govitecan-hziy Versus Treatment of Physician's Choice in Patients With Previously Untreated Locally Advanced Inoperable or Metastatic Triple-Negative Breast Cancer

Key Inclusion Criteria: * Individuals, regardless of race and ethnic group, with previously untreated locally advanced, inoperable or metastatic triple-negative breast cancer (TNBC) * Individuals whose tumors are programmed cell death ligand 1 (PD-L1) negative at screening or individuals whose tumors are PD-L1 positive at screening if they have received an anti-PD-(L)1 inhibitor in the (neo) adjuvant setting or if they cannot be treated with a checkpoint inhibitor due to a comorbidity * Centrally confirmed TNBC and PD-L1 status on fresh or archival tissue * Individuals must have completed treatment for Stage I-III breast cancer, if indicated, and ≥ 6 months must have elapsed (with the exception of endocrine therapy) between completion of treatment with curative intent and first documented local or distant disease recurrence * Individuals presenting with de novo metastatic TNBC are eligible * Measurable disease based on computed tomography (CT) or magnetic resonance imaging (MRI) in accordance with per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1. as evaluated locally * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Demonstrates adequate organ function * Male individuals and female individuals of childbearing potential who engage in heterosexual intercourse must agree to use protocol-specified method(s) of contraception * Individuals with human immunodeficiency virus (HIV) must be on antiretroviral therapy (ART) and have a well-controlled HIV infection/disease Key Exclusion Criteria: * Positive serum pregnancy test or women who are lactating * Received systemic anticancer treatment within the previous 6 months or radiation therapy within 2 weeks prior to enrollment * Have not recovered from adverse events (AEs) due to a previously administered agent at the time study entry * May not be participating in a study with an investigational agent or investigational device within 4 weeks prior to randomization. Individuals participating in observational studies are eligible * Previously received topoisomerase 1 inhibitors or antibody drug conjugates containing a topoisomerase inhibitor * Active second malignancy * Active serious infection requiring antibiotics * Positive for HIV-1 or 2 with a history of Kaposi sarcoma and/or Multicentric Castleman Disease * Active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection Note: Other protocol defined Inclusion/Exclusion criteria may apply.