• Ability to understand and the willingness to provide written informed consent.

• Men or women aged 18-75.

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

• Life expectancy greater than 3 months.

• Left ventricular ejection fraction (LVEF) ≥50%.

• Histopathological and/or cytological confirmed Her2-positive locally advanced or metastatic breast cancer (IHC3+, or IHC2+ and ISH+)

• Failure for at least 1 line of standard systemic treatment for metastatic disease. Meet one of the following conditions:

⁃ 1\) Recurrent within 12 months after completing or during neoadjuvant/ adjuvant therapy (the regimens contain trastuzumab or its biosimilar with pertuzumab or not).

⁃ 2\) Received at least one treatment with trastuzumab or its biosimilar ±pertuzumab (monotherapy or in combination with other drugs) for recurrent or metastatic disease.

⁃ 8\. Previous exposure to taxanes. 9. Having at least one measurable lesion according to RECIST 1.1 . 10. Having sufficient bone marrow, liver and kidney functions: white blood cell count≥ 3×109/L; Absolute neutrophil count ≥ 1.5×109/L; Platelet count ≥ 100×109/L; Hemoglobin ≥ 9.0 g/dL with no blood transfusion in the past 28 days; Total bilirubin ≤ 1.5 x the upper limit of normal (ULN); AST and ALT ≤ 3.0 x ULN (or ≤ 5.0 x ULN in the presence of liver metastases); Serum creatinine ≤1.5 x ULN; Coagulation function (prothrombin time and activated partial thromboplastin time ≤1.5 x ULN); 11. Adequate wash-out periods: Major surgery ≥4 weeks; radiotherapy ≥4 weeks; targeted therapy or chemotherapy≥4 weeks; endocrine therapy≥2 weeks; targeted therapy and endocrine therapy≥2 weeks; mAbs and immunotherapy ≥4 weeks; Any investigational agents≥4 weeks; potent CYP3A4 inhibitor≥3\*t1/2 weeks.

⁃ 12\. Female subjects must meet the following conditions: infertility or fertility and use high-efficiency contraceptive measures during the study and for 6 months following the last dose of the study drug infusion.