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

Key Inclusion Criteria: * Individuals with locally advanced, inoperable, or metastatic triple-negative breast cancer (TNBC) who have not received previous systemic therapy for advanced disease and whose tumors are programmed cell death ligand 1 (PD-L1) positive at screening. * Individuals must have completed treatment for Stage I to III breast cancer, if indicated, and ≥ 6 months must have elapsed between completion of treatment with curative intent and first documented local or distant disease recurrence. * Individuals presenting with de novo metastatic TNBC are eligible for this study. * TNBC status and tumor PD-L1 combined positive score (CPS) will be confirmed centrally on a recent or archival tumor specimen. * Individuals must have measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) as per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1 criteria as evaluated locally. * Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1. * Demonstrates adequate organ function * Male and female individuals of childbearing potential who engage in heterosexual intercourse must agree to use protocol-specified method(s) of contraception. * Individuals with 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 prior therapy with an agent directed to another stimulatory or coin…