Capecitabine Plus Pyrotinib Versus Capecitabine Plus Trastuzumab and Pertuzumab in the First-line Treatment of HER2-positive Metastatic Breast Cancer

Exclusion Criteria

• •History of anti-cancer therapy for MBC（with the exception of one prior hormonal regimen for MBC）.
• •History of HER tyrosine kinase inhibitors or monoclonal antibody for breast cancer in any treatment setting，except trastuzumab used in the neo-adjuvant or adjuvant setting.
• •Assessed by the investigator to be unable receive systemic chemotherapy.
• •History of other malignancy within the last 5 years，except for carcinoma in situ of cervix，basal cell carcinoma or squamous cell carcinoma of the skin that has been previously treated with curative intent.
• •Pregnant or lactating women，or for women of childbearing potential unwilling to use a highly-effective contraception during of the study treatment and for at least 7 months after the last dose of study treatment.