• Provision of signed and dated Informed Consent Form (ICF).

• Stated willingness to comply with all study procedures and availability for the duration of the study.

• Age ≥ 18.

• Triple negative breast cancer; to fulfill the requirement of triple negative disease, a breast cancer must express (≤ 10%), by immunohistochemistry (IHC), of the hormone receptors (estrogen receptor \[ER\] and progesterone receptor \[PR\]).

• Breast cancer as documented by extracranial tumor biopsy with brain metastases documented from MRI brain imaging or intracranial surgical pathology.

• Eligible for Stereotactic radiosurgery (SRS) to brain metastases or to the post-operative bed.

• Measurable brain disease per RANO-BM criteria1 that can be measured in at least one dimension as ≥ 0.5 cm for both intact brain metastases and post-operative cavities.

• Maximum diameter of the largest intact brain metastases ≤ 4 cm.

• Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2.

• Symptomatic patients having undergone surgery or on stable doses of steroids ≤ 8 mg/day dexamethasone will be enrolled.

• Prior treatment with taxane based chemotherapy with anthracyclines.

• Individuals with prior SRS/fractioned stereotactic radiotherapy (FSRT) treatment will be allowed if active measurable disease has not previously been treated with radiation therapy.

• Women of childbearing potential (WOCBP) must have a negative serum or urine pregnancy test within 24 hours prior to the administration of each dose of study agent.

• Male and female patients of childbearing potential who engage in heterosexual intercourse must agree to use specified method(s) of contraception.