Sacituzumab Govitecan +/- Pembrolizumab in Metastatic TNBC

Required: ESR1 expression ≤ 5% (≤ 5% by IHC)

Estrogen-receptor and progesterone-receptor expression both ≤ 5% by immunohistochemistry (IHC)

Required: PR (PGR) expression ≤ 5% (≤ 5% by IHC)

Estrogen-receptor and progesterone-receptor expression both ≤ 5% by immunohistochemistry (IHC)

Required: HER2 (ERBB2) negative (HER2-negative status as determined by the current ASCO/CAP guidelines)

HER2-negative status as determined by the current ASCO/CAP guidelines

Required: PD-L1 (CD274) negative (PD-L1-negative metastatic breast cancer defined as less than 1% expression of PD-L1 on tumor-infiltrating immune cells (IC) by the PD-L1 IHC SP142 assay or a Combined Positive Score (CPS) less than 10 by the PD-L1 IHC 22C3 assay)

Participants must have PD-L1-negative metastatic breast cancer defined as less than 1% expression of PD-L1 on tumor-infiltrating immune cells (IC) by the PD-L1 IHC SP142 assay or a Combined Positive Score (CPS) less than 10 by the PD-L1 IHC 22C3 assay

Excluded: UGT1A1 *28 homozygosity

Known history of UDP-glucuronosyltransferase 1A1 (UGT1A1) *28 allele homozygosity, which is associated with increased risk for neutropenia and diarrhea related to irinotecan

Cannot have received: chemotherapy

Exception: no prior chemotherapy for metastatic breast cancer; prior chemotherapy in other settings allowed if discontinued ≥ 28 days before study treatment

Participants must have received no prior chemotherapy for metastatic breast cancer and must have discontinued all chemotherapy at least 28 days prior to study treatment initiation

Cannot have received: biologic therapy

Exception: no prior biologic therapy for metastatic breast cancer; prior biologic therapy in other settings allowed if discontinued ≥ 28 days before study treatment

Patients must have received no prior biologic therapy for metastatic breast cancer and discontinued all biologic therapy at least 28 days prior to study treatment initiation

Cannot have received: anti-PD-1 therapy

Prior therapy with any anti-PD-1, PD-L1, or PD-L2 agent

Cannot have received: topoisomerase I-containing antibody drug conjugate (sacituzumab govitecan, irinotecan)

Prior therapy with sacituzumab govitecan (IMMU-132). Prior therapy with irinotecan or topoisomerase I-containing antibody drug conjugates at any time for early stage or metastatic disease