What is the best dosage of Nab-Paclitaxel for chinese? This study would divide patients into two dosage groups: 1) 125mg/m2, 30 minutes intravenous injection, d1, 8, 21 days for a cycle(clinical use); 2) 125mg/m2 d1, 8, 15, 30 minutes intravenous injection, 28 days for a cycle(guideline recommand). Treatment to disease progression. The efficacy (CR, PR, SD, PD) is evaluated every 2-4 cycles.If the patient withdraws from the trial because he cannot tolerate the toxicity caused by one of the drugs, such as neurotoxicity or bone marrow toxicity, it is recommended to switch to other drugs and follow up to PFS and OS.Each group was planned to include 30 patients.

Inclusion criteria

• Female, aged≥ 18 years old;
• Histopathologically confirmed HER-2 negative (definition: immunohistochemical IHC 0, or 1+, or in situ hybridization ISH, defined as the ratio of HER2 gene copy number to CEP17 signal number less than 2.0, or for single probe detection, HER2 gene copy number less than 6) in patients with recurrent or metastatic breast cancer;
• Up to two previous lines of chemotherapy were permitted for recurrent and metastatic diseases. And for endocrine therapy, the number of treatment lines can be omitted;
• With measurable lesions;
• The physical condition score of the Eastern American Cancer Collaboration Group (ECOG) was less than 1;
• Expected survival period>3 months;

Exclusion Criteria

• New York Heart Association NYHA scores identify patients with congestive heart failure at grade II or above;Uncontrolled brain metastasis;
• Patients with severe systemic infection;Patients with peripheral nerve injury of degree II or above, or known drug allergy or intolerance within 4 weeks before admission;
• Important organ disorders or diseases: liver and kidney dysfunction, history of myocardial infarction, unstable heart disease, chronic active hepatitis,etc;There is a history of other malignant tumors within 5 years (except cured cervical cancer or skin basal cell carcinoma);
• Patients who had received other antineoplastic treatments or other experimental drugs within one month before treatment;
• Patients who also participated in other clinical trials;
• Researchers believe that patients are not suitable for any medical condition to enter the study.