A Study of Sacituzumab Govitecan Given at an Alternative Dose and Schedule in Participants With Advanced Triple-Negative Breast Cancer

Key Inclusion Criteria:

• Individuals assigned male or female at birth, 18 years of age or older, able tounderstand and give written informed consent.

• Histologically or cytologically locally confirmed TNBC.

• Phase 1: Individuals with unresectable, locally advanced or metastatic TNBC who arerefractory to or relapsed after at least one prior standard-of-care chemotherapyregimen or systemic therapy given for locally advanced or metastatic disease.

• Phase 2: Individuals with unresectable, locally advanced or metastatic TNBC who havenot received previous systemic therapy for advanced disease.

• Phase 2: Tumors must be PD-L1 negative, defined as tumor PD-L1 combined positivescore (CPS) < 10 using the PD-L1 immunohistochemistry (IHC) 22C3 assay.Alternatively, individuals with tumor CPS ≥ 10 will be eligible if they received ananti-PD-(L)1 agent (ie, checkpoint inhibitor) in the adjuvant or neoadjuvant settingor if they cannot be treated with an anti-PD-(L)1 agent. due to a comorbidity.

• Uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) genotype status.

During Phase 1 safety run-in, individuals must be UGT1A1 wild-type.

After Phase 1 safety run-in, individuals with any UGT1A1 genotype may be eligible.

• Measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI)according to RECIST Version 1.1 criteria.

• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1.

• Adequate hematologic counts within 2 weeks prior to enrollment.

• Adequate hepatic and renal function.

Key Exclusion Criteria:

• Prior treatment with a topoisomerase 1 inhibitor or antibody-drug conjugate (ADC)containing a topoisomerase inhibitor.

• Prior treatment with a trophoblast cell-surface antigen 2 (Trop-2)-directed ADC.

Note: Other protocol defined Inclusion/Exclusion criteria will apply.