Pyrotinib, Trastuzumab And Abraxane in HER2-positive MBC With Brain Metastasis

Inclusion Criteria: * Aged \>18 years. * ECOG performance status ≤2. * Histologically or cytologic confirmed HER2 positive advanced breast cancer. * MRI confirmed brain metastases. According to RECIST 1.1, at least one measurable lesion exists. * No limit of previous chemotherapy lines. * Previously have not reveived capecitabine or disease progression of capecitabine after 6 months, or progression of capecitabine adjuvant therapy after one year; * Life expectancy of more than 3 months. * Required laboratory values including following parameters: ANC: ≥ 1.5 x 10\^9/L;Platelet count: ≥ 100 x 10\^9/L;Hemoglobin: ≥ 9.0 g/dL;Total bilirubin: ≤ 1.5 x upper limit of normal (ULN);ALT and AST: ≤ 1.5 x ULN (or ≤ 5×ULN in patients with liver metastases);BUN and creatine clearance rate: ≥ 50 mL/min;LVEF: ≥ 50%;QTcF: \< 470 ms for female and \< 450 ms for male. * Signed the informed consent form prior to patient entry. Exclusion Criteria: * Patients with brain metastases who have extensive meningeal metastases and are treated with hormone dehydration. * Subjects with third space fluid(such as a large amount of pleural effusion and ascites) that can not be controled by drainage or other methods. (such as pleural effusion and ascites). * Received whole brain radiotherapy, chemotherapy, surgery or target therapy within 2 weeks prior to randomization. Received hormone therapy within 1 weeks prior to randomization, Received the nitrosoureas or mitomycin chemotherapy within 6 weeks prior to randomization. * Participated in other clinical trial within 4 weeks prior to randomization. * Treated or treating with HER2 tyrosine kinase inhibitors (TKIs) (including Lapatinib, Neratinib and Pyrotinib). * Second malignancies within 5 years, except for cured carcinoma in-situ of uterine cervix, skin basal cell carcinomaand squamous-cell carcinoma. * Receiving any other anti-tumor therapies at time of study screening visit. * There are no other serious and/or uncontrolled diseases that may affect research participation, including any of the following: (1) unable to swallow, chronic diarrhea and intestinal obstruction and factors influencing the usage of oral administration; (2) has allergies or a known history of hypersensitivity to the drug components of this program; History of Immunodeficiency, acquired or congenital immunodeficiency (HIV positive) ,history of organ transplantation; (3) History of any kind of Heart disease, including 1) Myocardial infarction; 2) Heart failure; 3) Any other heart disease judged by researcher as not suitable for participating in this study, etc; (4) Infection. * All female patients in breastfeeding period or in child-bearing period or with positive pregnancy test result or refusing to take a reliable method of birth control during the study. * Any other situations judged by investigator as not suitable for participating in this study.