Summary

This phase II trial studies the effect of sacituzumab govitecan in treating patients with HER2-negative breast cancer that has spread to the brain (brain metastases). Sacituzumab govitecan is a monoclonal antibody, called sacituzumab, linked to a chemotherapy drug, called govitecan. Sacituzumab is a form of targeted therapy because it attaches to specific molecules on the surface of cancer cells, known as Trop-2 receptors, and delivers govitecan to kill them. Giving sacituzumab govitecan may shrink the cancer in the brain and/or extend the time until the cancer gets worse.

Objectives

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.

Eligibility

1. 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
2. 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
3. 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 scans done to document disease status at baseline. All extracranial disease must be assessed and documented on the Baseline Tumor Assessment Form (Response Evaluation Criteria in Solid Tumors [RECIST] 1.1). NOTE: Brain lesions should not be included on the Baseline Tumor Assessment Form (RECIST 1.1) for this study
4. Participants must have had CNS progression after previous CNS-directed therapy (radiation therapy, surgery, or any combination of therapy)
5. Participants must have resolution of adverse event(s) of the most recent prior systemic anti-cancer therapy to < grade 2, with the exception of alopecia and =< grade 2 neuropathy, which are allowed
6. Participants with a prior or concurrent malignancy whose natural history or treatment (in the opinion of the treating physician) does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial
7. Participants must be >= 18 years of age
8. Participants must have Zubrod performance status 0 or 1
9. Participants must have history and physical exam obtained within 21 days prior to registration
10. Absolute neutrophil count (ANC) >= 1,500/mcL (obtained within 21 days prior to registration)
11. Platelet count >= 100,000/mcL (obtained within 21 days prior to registration)
12. Hemoglobin >= 9.0 g/dL (obtained within 21 days prior to registration)
13. Total bilirubin =< 1.5 times institutional upper limit of normal (ULN) (obtained within 21 days prior to registration)
14. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) =< 3 x institutional ULN (obtained within 21 days prior to registration)
15. Participants must have a serum creatinine =< 1.5 times the institutional upper limit of normal (IULN) OR measured OR calculated creatinine clearance >= 30 mL/min using the following Cockcroft-Gault Formula. This specimen must have been drawn and processed within 21 days prior to registration
16. Participants must have adequate cardiac function. Participants with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, must have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification, and must be class 2B or better
17. Participants must be offered the opportunity to participate in specimen banking. With participant consent, specimens must be collected and submitted via the Southwest Oncology Group (SWOG) Specimen Tracking System
18. Participants must be informed of the investigational nature of this study and must sign and give informed consent in accordance with institutional and federal guidelines