Phase Ⅱ Study of Pegylated Liposomal Doxorubicin（PLD）Plus Trastuzumab in HER-2 Positive Metastatic Breast Cancer

Inclusion Criteria: * Ability to understand and voluntarily receive the research procedures according to protocol,willingness to sign the written informed consent document; * Female patients aged from 18 to 70 years old； * Histologically confirmed as invasive breast cancer； * HER-2 Positive（defined by: IHC 3+ or ISH positive）, regardless of HR status; * Recurrence after adjuvant therapy or metastatic breast cancer，and chemotherapy naïve in the metastatic setting or had one prior regimen for metastatic breast cancer； * Patients must have measurable disease according to RECIST criteria Version 1.1（Brain metastases lesions and bone metastases lesions were excluded）; * The adverse event caused by prior therapy has recovered, or stabilized, or does not affect the study administration according to the investigator's judgment； * Performance status 0-1； * Life expectancy of at least 3 months； * Left ventricular ejection fraction (LVEF)≥55%； * Brain natriuretic peptide (BNP) and cardiac troponin T (cTnT) were in the normal range； * Patients must have normal ECG； * Bone marrow function: absolute neutrophil count (ANC)≥1.5×109/L，platelets≥100×109/L，hemoglobin ≥90g/L； * Hepatic function：alanine aminotransferase(ALT) and aspartate aminotransferase(AST) ≤2.5×ULN，serum total bilirubin≤ 1.5×ULN，or ≤2.5×ULN who has Gilbert's syndrome; * Renal function：serum creatinine≤1.5×ULN； * Coagulation function：the international standardized ratio (INR) ≤1.5×ULN, prothrombin time (PT) or the activated partial thrombin time (APTT) ≤1.5×ULN. Exclusion Criteria: * Patients with symptomatic brain metastases. * Patients who are known or suspected to be allergic to the active ingredient or excipients of the investigational drug. * Prior cumulative dose of 240 mg/m2 for doxorubicin and 400 mg/m2 for epirubicin. * Prior treatment with anthracyclines has caused cardiotoxicity, or failed (disease progression during therapy or recurrence and metastasis within 12 months after adjuvant therapy). * Prior mediastinal radiotherapy. * Participation in other clinical trials within 4 weeks before enrollment. * Severe cardiovascular disease, including history of congestive heart failure, acute myocardial infarction within 6 months before enrollment, transmural myocardial infarction measured by ECG, uncontrolled arrhythmia, angina requiring therapy, clinically significant valvular heart disease, uncontrolled hypertension. * Severe or uncontrolled infection. * Positivity for HIV, Hepatitis B or C. * Active malignancy in the past 5 years (other than carcinoma in situ of the cervix or basal cell carcinoma of the skin). * Patients who are pregnant , breastfeeding ,or refuse to use adequate contraception during the course of participation. * Need to concurrent other cancer therapy(other than palliative care for non-target lesions). * Other ineligible conditions according to the researcher's judgment.