Neuro/Sacituzumab Govitecan/Breast Brain Metastasis/Glioblastoma/Ph 0

Inclusion Criteria:

* At least 18 years of age
* Histologically or cytologically documented breast cancer (Cohort A) with known or suspected parenchymal brain metastases.
* Recurrent glioblastoma (Cohort B) with documented progression by RANO criteria following standard combined modality treatment with radiation and temozolomide.
* Plans to undergo craniotomy as part of standard of care. Patients emergently needing surgical debulking due to symptoms of their disease are not eligible.
* Recovered from toxicities of prior therapy to grade 0 or 1
* ECOG performance status ≤ 2.
* Life expectancy of at least 3 months.
* Acceptable liver function:
* Bilirubin ≤ 1.5 times upper limit of normal
* AST (SGOT) and ALT (SGPT) ≤ 3.0 times upper limit of normal (ULN);
* Adequate renal function: calculated creatinine clearance ≥30mL/minute according to the Cockcroft and Gault formula
* Acceptable hematologic status (without hematologic support)
* ANC ≥1500 cells/uL
* Platelet count ≥100,000/uL
* Hemoglobin ≥9.0 g/dL
* All women of childbearing potential must have a negative serum pregnancy test and male and female subjects must agree to use effective means of contraception (surgical sterilization or the use or barrier contraception with either a condom or diaphragm in conjunction with spermicidal gel or an IUD) with their partner from entry into the study through 6 months after the last dose.

Exclusion Criteria:

* The subject is receiving warfarin (or other coumarin derivatives) and is unable to switch to low molecular weight heparin (LMWH) before the first dose of study drug.
* The subject has evidence of acute intracranial or intratumoral hemorrhage either by MRI or computerized tomography (CT) scan. Subjects with resolving hemorrhage changes, punctate hemorrhage, or hemosiderin are eligible.
* The subject is unable to undergo MRI scan (eg, has pacemaker).
* The subject has received enzyme-inducing anti-epileptic agents within 14 days of study drug (eg, carbamazepine, phenytoin, phenobarbital, primidone).
* Patients whose only lesion undergoing resection has received stereotactic radiation within the past 3 months
* The subject has received any of the following prior anticancer therapy:

  * Biologic agents (antibodies, immune modulators, vaccines, cytokines) within 21 days prior to first dose of study drug
  * Prior treatment with Sacituzumab Govitecan
* Patients receiving UGT1A1 (Uridine diphosphate glucuronosyl transferase 1A1) inhibitors or inducers.
* History of significant cardiovascular disease, defined as:

  * Congestive heart failure greater than New York Heart Association (NYHA) Class II according to the NYHA Functional Classification.
  * Unstable angina or myocardial infarction within 6 months before enrollment.
  * Serious cardiac arrhythmia.
* Clinically significant ECG abnormality, including:

  * Marked Baseline prolonged QT/QTc interval (ie, a repeated demonstration of a QTc interval \>500 ms) demonstrated on ECG at Screening.
  * History of risk factors for torsade de pointes (eg, heart failure, hypokalemia, family history of long QT Syndrome).
* Any medical or other condition which, in the opinion of the Investigator, causes the subject to be medically unfit to receive Sacituzumab Govitecan, or unsuitable for any other reason.