Guided Treatment Based on Mini-PDX in Metastatic Triple Negative Breast Cancer

Inclusion Criteria:

• 1. Women aged 18-70 years;
• 2. an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1;
• 3. Estimated lifetime is ≥ 3 months;
• 4. Histopathologically confirmed recurrent (unresectable) or metastatictriple-negative breast cancer; ER and PR negative is defined as ER <1% positive, PR <1% positive. HER-2 negative is defined as HER-2 (-) or (1+) by immunohistochemistry,HER-2 (2+) must be tested by FISH with negative result, HER-2 (1+) (1+), FISH isoptional and negative;
• 5. Have at least one measurable target lesion according to RECIST 1.1 criteria;
• 6. Biopsy of the tumor lesion and the specimen passes laboratory quality control;
• 7. A minimum of 2 prior cytotoxic chemotherapy regimens (including at least one lineof platinum-containing regimen) in metastatic settings are required prior toenrollment in this trial;
• 8. Adequate organ function, i.e. meeting the following criteria.

1. Hb ≥ 90 g/L (no transfusion within 14 days); ANC ≥ 1.5 × 109 /L; PLT ≥ 75 × 109 /L.
2. Liver function: total bilirubin TBIL ≤ 1.5×ULN (upper limit of normal); ALT andAST ≤ 3×ULN.
3. serum Cr ≤ 1.5×ULN.

• 9. Subjects voluntarily joined the study, signed the informed consent form, werecompliant and cooperated with the follow-up.

Exclusion Criteria:

• 1）Pregnancy or lactation；
• 2）History of autoimmune disease；
• 3）Anticancer- and radiation therapy-related toxicities have not resolved or downgradedto Grade 1 or less;
• 4. Symptomatic central nervous system (CNS) disease;
• 5. Previous treatment of Immune checkpoint inhibitors;
• 6. History of other malignancies within the past five years, with the exception ofcured non-malignant melanoma of the skin and carcinoma in situ of the cervix.