Inclusion Criteria:

- Signed informed consent.

- Female, ≥ 18 years.

- Histologically confirmed invasive breast cancer.

- Metastatic breast cancer.

- Karnofsky Performance Status ≥60.

- Life expectancy of more than 3 months.

- Subject must have adequate organ function.

- Normal laboratory values: hemoglobin > 80g/dl, neutrophils > 2.0×10^9/L, platelets >
80×10^9/L, serum creatinine < upper limit of normal (ULN), serum bilirubin < ULN, ALT
and AST < 2.5×ULN, AKP < 5×ULN.

- Negative serum pregnancy test for women with childbearing potential.

- Good conditions for infusion and willing to have phlebotomy throughout whole study.

- Have ceased anti-tumor treatments including endocrinotherapy and bio-targeted therapy
for more than 28 days.

- Have at least one target lesion according to the Response Evaluation Criteria in
Solid Tumors (RECIST) criteria.

- No prior use of docetaxel or has used docetaxel in adjuvant/neo-adjuvant chemotherapy
and has a relapse free survival of at least 12 months.

Exclusion Criteria:

- Pregnant or lactating females.

- History of other malignancy. However, subjects who have been disease-free for 5
years, or subjects with a history of completely resected non-melanoma skin cancer or
successfully treated in situ carcinoma are eligible.

- Concurrent disease or condition that would make the subject inappropriate for study
participation, or any serious medical disorder that would interfere with the
subject's safety.

- Active or uncontrolled infection.

- Known history of uncontrolled or symptomatic angina, arrhythmias, or congestive heart
failure.

- Concomitant with brain metastases.

- Have received chemotherapy after metastasis.