• Patients aged 18 to 70 years

• With histologically confirmed HER2 negative recurrent and metastatic breast cancer

• have at least one measurable lesion in the central nervous system (the longest diameter ≥ 10mm)

• ECOG score (PS) of 0-2

• According to screening brain MRI, patients with CNS must meet the following conditions:

‣ untreated brain metastases of breast cancer;

⁃ do not need immediate local treatment;

⁃ brain metastases of breast cancer which was treated in the past:

• There are no clinical manifestations that have progressed after the previous local treatment of the central nervous system and require immediate local treatment.

∙ All records related to the treatment of the central nervous system must be provided.

∙ All toxicities related to the previous anti-tumor treatment of patients who have not received chemotherapy, radiotherapy, surgical treatment, targeted therapy and immunotherapy within 4 weeks before enrollment must be restored to ≤ level 1 (CTCAE v50). However, patients with hair loss of any grade are allowed to be recruited.

• Blood routine examination was basically normal within 1 week before enrollment.

• White blood cell count (WBC) ≥ 30 × 109 /L

• Neutrophil counts (ANC) ≥ 15 × 109/L

• Platelet count (PLT) ≥ 100 × 109 /L

• Hemoglobin ≥ 90g/dl. Patients can receive blood transfusion or erythropoietin treatment to meet this standard.

• Within 1 week before enrollment, the liver and kidney function tests were basically normal (based on the normal value of the laboratory of each research center).

• Total bilirubin ≤ 15 × Upper limit of normal value (ULN)

• Alanine aminotransferase (SGPT / ALT) ≤ 25 x ULN (patients with liver metastasis ≤ 5 × ULN)

• Glutamic oxaloacetic transaminase (SGOT/AST) ≤ 25 × ULN (patients with liver metastasis ≤ 5 × ULN)

• Creatinine clearance rate (Ccr) ≥ 60ml/min patients

• With fertility must agree to use effective contraceptive methods during the study period and within 90 days of the last study medication. Before enrollment, the blood or urine pregnancy test must be negative and the

• Life expectancy \> 12 weeks.

• The patient must be able to participate in and follow the treatment and follow-up.