Breast Cancer Clinical Trials

• Having provided written informed consent, and be able to follow clinical trial protocol.

• 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+), \*ISH: Fluorescence in situ hybridization (FISH) or dual in situ hybridization (DISH); ISH positivity is defined as a ratio of HER2 gene copy number to CEP17 signal number ≥2.0. When the immunohistochemical (IHC) result is 3+, ISH testing is not required. When the IHC result is 2+, ISH testing should be performed to confirm HER2 positivity.

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

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

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

• Having at least one measurable lesion according to RECIST 1.1.

• Previous exposure to taxanes.

• During the screening period and the first 7 days before treatment, the following indicators confirm appropriate organ functions:

∙ Hematology: WBC≥3.0×109/L；NE≥1.5×109/L；Hb≥90 g/L；Plt≥100×109/L;

‣ Liver function: Total bilirubin ≤ 1.5 x the upper limit of normal; AST and ALT ≤ 2.5 x the upper limit of normal, ≤ 5.0 x the upper limit of normal in the presence of liver metastases;

‣ Kidney function: Serum creatinine ≤1.5 x the upper limit of normal;

‣ Coagulation function: prothrombin time and activated partial thromboplastin time ≤1.5 x the upper limit of normal.

⁃ Adequate wash-out periods:

• Major surgery ≥4 weeks;

∙ Radiotherapy ≥4 weeks (Palliative stereotactic radiotherapy without abdominal involvement radiotherapy: ≥2 weeks);

∙ Autologous transplantation: ≥3 months

∙ targeted therapy or chemotherapy≥4 weeks;

∙ Radioactive particle therapy: ≥3 months

∙ Nuclide therapy: ≥3 months

∙ Hormone therapy: ≥2 weeks, or based on judgement on the breast cancer

∙ Participants from the investigators' judgment;

∙ Endocrine therapy: ≥4weeks;

• Chemotherapy or targeted therapy: 5-fluorouracil-based preparations, folinic acid preparations, and/or Weekly paclitaxel: ≥2 weeks;

• Tyrosine kinase inhibitor: ≥2 weeks (or 5 half-lives)

• In the case of a decline period, the longer one shall prevail;

• Nitrosoureas or mitomycin C: ≥6 weeks

• Immunotherapy ≥4 weeks;

• Potent CYP3A4 inhibitor≥3\*t1/2 weeks;

• Any investigational agents≥4 weeks.

⁃ Female subjects who are capable of bearing children must have negative urine or serum pregnancy test results within 7 days before randomization, and must commit to using contraception throughout the study period and continue to do so for 7 months after the study ends.