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

PRIMARY OBJECTIVE: I. To evaluate the intracranial objective response rate (ORR) (complete response \[CR\] or partial response \[PR\] by Response Assessment in Neuro-Oncology Brain Metastases \[RANO-BM\]) with sacituzumab govitecan (IMMU-132) in patients with HER2-negative metastatic breast cancer with brain involvement. SECONDARY OBJECTIVES: I. To evaluate bi-compartmental progression-free survival in this population. II. To evaluate overall survival in this population. III. To assess safety and tolerability of sacituzumab govitecan (IMMU-132) treatment in this population. IV. To evaluate ORR by hormone-receptor (HR) subgroup (HR+, HR-). BANKING OBJECTIVE: I. To bank specimens for future correlative studies. OUTLINE: Patients receive sacituzumab govitecan intravenously (IV) over 1-3 hours on days 1 and 8. Cycles repeat every 21 days for up to 2 years in the absence of disease progression or unacceptable toxicity. After completion of study registration, patients are followed up every 3 months for 1 year and then every 6 months for 1 year.