• Male and female participants aged 18 years or older and able to understand and give written informed consent - Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1 (for the phase I portion of the study) and ECOG performance status of 0-2 (for the phase II portion of the study) - Life expectancy of at least 3 months - Histologically confirmed metastatic TNBC. (Estrogen receptor [ER] ≤10%; Progesterone receptor [PgR] ≤10%, HER2-negative as per ASCO/CAP guidelines) - Willingness to provide archival tumor tissue for correlative studies associated with this trial. - Received at least 1 prior line of systemic chemotherapy for metastatic TNBC and/or meet criteria to receive sacituzumab govitecan as standard of care - Measurable disease by CT or MRI as per RECIST Version 1.1 criteria - Adequate organ and marrow function as defined below: 2.

Participants who meet any of the following exclusion criteria are not eligible to be enrolled in this study. - Positive serum pregnancy test or women who are lactating. - Known or severe (≥ Grade 3) hypersensitivity or allergy to naxitamab and/or sacituzumab govitecan, their metabolites, or formulation excipient. - Grade 3 or greater peripheral neuropathy - Have previously received treatment with an anti-GD2 antibody - Prior treatment with TROP2-targeting antibody drug conjugates in the metastatic setting. Participant s who have received TROP2-targeting antibody drug conjugates in the neoadjuvant setting or adjuvant setting are eligible if at least 6 months have elapsed since the last dose of TROP2-targeting antibody drug conjugate. - Have an active second malignancy. Participant s with a history of active cancer for 3 years prior to enrollment, or participant s with surgically cured tumors with low risk of recurrence (eg, nonmelanoma skin cancer, histologically confirmed complete excision of carcinoma in situ, or similar) are allowed to enroll. - Have known active central nervous system (CNS) metastases and/or carcinomatous meningitis. - Have undergone an allogenic tissue or solid organ transplant. - Uncontrolled hypertension, defined as a consistently elevated systolic blood pressure of >160 mmHg despite optimal medical management - Clinically significant cardiac disease - Inadequate pulmonary function - Active chronic inflammatory bowel disease (ulcerative colitis, Crohn's disease) or GI perforation within 6 months of enrollment. - Uncontrolled seizure disorders despite anticonvulsant therapy (defined as a seizure event within 3 months prior to enrollment) - Active serious infection requiring systemic antimicrobial therapy. - Participants positive for HIV-1 or 2 with a history of Kaposi sarcoma and/or Multicentric Castleman Disease. - Have active hepatitis B or C infection - Has a diagnosis of immunodeficiency or receiving systemic corticosteroid therapy (higher than physiologic doses) ≥ 10 mg of prednisone per day or equivalent] or any other form of immunosuppressive therapy within 14 days of initiation of study treatment. - Has received prior radiotherapy within 1 weeks of start of study intervention.