Study of Naxitamab and Sacituzumab Govitecan in Patients With Metastatic Triple-negative Breast Cancer (TNBC)

1. Primary Objectives * To determine the safety and tolerability and establish the maximum tolerated dose/recommended phase 2 dose (MTD/RP2D) of the combination of naxitamab and sacituzumab govitecan in participant s with metastatic TNBC. * To determine the objective response rate (ORR) of naxitamab in combination with sacituzumab govitecan per RECIST v1.1 criteria in participant s with metastatic TNBC at the MTD/RP2D. 2. Secondary Objectives * To determine the duration of response, progression-free survival, and overall survival for participant s with metastatic TNBC treated with the combination of naxitamab plus SG: * To identify GD2-related biomarkers of response and resistance to the combination of naxitamab and sacituzumab govitecan. 3. Exploratory/Correlative Objectives • Investigate potential resistance mechanisms to naxitamab and develop a pre-clinical rationale for future therapeutic strategies.