Study to Evaluate Sacituzumab Govitecan in Combination With Talazoparib in Patients With Metastatic Breast Cancer.

This research is studying the effect of Antibody-Drug Conjugate Sacituzumab Govitecan in Combination with the Poly (Adenosine Diphosphate \[ADP\]-Ribose) Polymerase (PARP) Inhibitor Talazoparib in Patients with Metastatic Triple-Negative Breast Cancer.

Inclusion Criteria: * Adult (≥ 18 years of age). * Histologically confirmed stage IV (metastatic) breast cancer. * Participants must have biopsy proven ER negative (ER-), PR negative (PR-), HER2 negative, invasive breast cancer, by AJCC 7th edition staging. ER, PR, and HER2 positivity would be determined per institutional (local) guidelines. * Pre- and postmenopausal women are eligible. * ECOG performance status = 0-1 * Measurable disease as per RECIST Version 1.1. * Ability to understand and the willingness to sign a written informed consent document. Patient has signed the Informed Consent (ICF) prior to any screening procedures being performed and is able to comply with protocol requirements. * At least 2 weeks beyond treatment (chemotherapy, targeted therapy, immunotherapy, and/or radiation therapy) or major surgery and recovered from all acute toxicities (adverse events from prior anti-cancer agents need to be grade 1 or lower; grade 2 alopecia or peripheral neuropathy is permitted). * At least 2 weeks beyond corticosteroids (however, low dose corticosteroids \