This a phase 1 study to evaluate the safety and preliminary efficacy of cisplatin combined with bortezomib in patients with recurrent or metastatic breast cancer.

Inclusion Criteria:

1. Women aged 18 years and above with pathologically confirmed recurrent or metastatic advanced breast cancer ;
2. The patient has tumor specimens (formalin-fixed, paraffin-embedded or fresh pre-treated recurrent tumor tissue);
3. Patients who have failed standard treatment in the late stage;
4. At least one measurable lesion;
5. ECOG PS : 0-2 points;
6. Estimated survival period ≥12 weeks;
7. The function level of major organs meets the following standards:

1) The blood routine examination standards must meet: ANC ≥1.5×109/L, PLT ≥75×109/L, Hb ≥85g/L (no blood transfusion and blood products within 14 days, no use of G-CSF and other hematopoietic stimulating factors for correction) 2) Biochemical examinations must meet the following standards: TBIL <1.5×ULN, ALT, AST <2.5×ULN, ALT, AST <5×ULN for patients with liver metastasis, BUN and Cr ≤1×ULN or endogenous creatinine clearance ≥50ml/min (Cockcroft-Gault formula); 8. Women of childbearing age must have taken reliable contraceptive measures, or have undergone a pregnancy test (serum or urine) within 7 days before enrollment, with a negative result, and are willing to use appropriate contraceptive methods during the trial and 8 weeks after the last administration of the trial drug.

9. The subjects voluntarily join this study, have good compliance, and cooperate with follow-up.

Exclusion Criteria:

Any of the following will be considered as meeting the exclusion criteria of the study:

1. Patients with acute active hepatitis B or acute active hepatitis C;
2. Any serious underlying disease, comorbidity and active infection
3. Currently receiving other anti-tumor treatments;
4. History of epilepsy or epileptic-induced condition;
5. Patients who are pregnant or breastfeeding;
6. Those with poor compliance or unable to undergo normal follow-up;
7. Allergic to study drugs;
8. Patients diagnosed with other malignant tumors within 5 years, except for the following: surgically resected non-melanoma skin cancer, adequately treated cervical carcinoma in situ, surgically radically treated ductal carcinoma in situ, or malignant tumors diagnosed 2 years ago with no current evidence of disease and untreated ≤ 2 years before randomization;
9. The researcher determines other situations that may affect the conduct of the clinical study and the determination of the study results.

Individual participant data (IPD) will not be shared due to ethical and privacy concerns.