Testing Sacituzumab Govitecan Therapy in Patients With HER2-Negative Breast Cancer and Brain Metastases

Inclusion Criteria: * Participants must have histologically confirmed HER2-negative (per 2018 American Society of Clinical Oncology \[ASCO\]/College of American Pathologists \[CAP\] joint guideline) invasive breast cancer that has metastasized to the brain. NOTE: Pathology report must confirm HER2-negative invasive breast cancer. Brain metastases must be confirmed by radiology report * Participants must have an magnetic resonance imaging (MRI) of the brain within 28 days prior to registration and must have central nervous system metastases with at least one measurable brain metastasis \>= 1.0 cm in size (per RANO-BM) that has not been irradiated, or has progressed despite prior radiation therapy (in the opinion of the treating physician). In the rare case that a previously irradiated brain metastasis is the sole target lesion and if there is concern about possible radiation necrosis, patient is eligible only if there is clear progression in the previously radiated lesion. Computed tomography (CT) of the head cannot substitute for brain MRI. All central nervous system (CNS) disease must be assessed and documented on the S2007 Brain Metastases Baseline Tumor Assessment Form * Participants may have measurable or non-measurable extracranial disease. All measurable disease must be assessed within 28 days prior to registration; all non-measurable disease must be assessed within 42 days prior to registration. Participants are NOT required to have extracranial disease, but must have…