• Have histologically confirmed HER2-negative metastatic breast cancer. HER2-negative defined as immunohistochemical (IHC) score of 0 or 1+, or IHC2+ with negative HER2 expression on in situ hybridization (ISH). (According to the 2023 American Society of Clinical Oncology \[ASCO\]/ College of American Pathologists \[CAP\] guidelines).

• Based on screening contrast-enhanced brain MRI, patients must have at least one measurable intracranial lesion according to RECIST 1.1 (≥1.0 cm in size) and must have one of the following: A) Untreated brain metastases not needing immediate local therapy. B) Brain metastases progressing after prior local therapy.

• Male or female aged ≥18 years.

• ECOG PS 0 or 1.

• Have a life expectancy of at least 3 months.

• Have adequate baseline hematologic parameters.

• Have adequate hepatic and renal function.

• ≤ 3 prior lines of chemotherapy in advanced or metastatic setting.

• Women of childbearing potential, unless hysterectomy or oophorectomy or postmenopausal for at least 12 consecutive months, must use an effective method of avoiding pregnancy (including oral, transdermal, or implanted contraceptives \[any hormonal method in conjunction with a secondary method\], intrauterine device, female condom with spermicide, diaphragm with spermicide, absolute sexual abstinence, use of condom with spermicide by sexual partner or sterile \[at least 6 months prior to study drug administration\] sexual partner) for at least 4 weeks prior to study drug administration, during study and up to 6 months following the last dose of study drug. Cessation of birth control after this point should be discussed with a responsible physician. Investigator will discuss with patient on the above points and the patient agreement will be documented in the source document. The investigator should ensure that the patient is using an effective method of avoiding pregnancy as per protocol. In case of Male patients: Either patient partners or patients themselves must use an effective method of avoiding pregnancy for at least 4 weeks prior to study drug administration, during study and up to 6 months following the last dose.

⁃ Patients must be able to follow the study visit schedule, and must be able of sign and give informed consent in accordance with institutional review board.