Inclusion Criteria:
1. Women aged 1.18 years and above, diagnosed with triple-negative breast cancer (ER≤10%, PR≤10%, HER-2 negative) by pathology;
2. Patients must have tumor specimens (formalin-fixed, paraffin-embedded, or fresh pre-treated tumor tissue) available for PD-L1 expression testing;
3. Researchers assess indications for neoadjuvant chemotherapy, with staging from IIA to IIIC, based on imaging or pathological evaluation of cT1c, N1-3, or cT2\~cT4, cN0\~N3, and patients with no distant metastasis as evaluated by imaging;
4. Patients must not have received chemotherapy or targeted therapy for advanced breast cancer;
5. ECOG PS: 0-2;
6. Expected survival of ≥12 weeks;
7. Major organ function levels must meet the following criteria:
1\) Hematological examination standards must meet: ANC≥1.5×10\^9/L, PLT≥75×10\^9/L, Hb≥90g/L (no blood transfusions or blood products within 14 days, and no use of G-CSF or other hematopoietic growth factors for correction) 2) Biochemical examination must meet the following standards: TBIL\<1.5×ULN, ALT, AST\<2.5×ULN, for patients with liver metastasis, ALT, AST may be \<5×ULN, 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 undergone a pregnancy test (serum or urine) within 7 days prior to enrollment, with a negative result, and must be willing to use appropriate contraceptive methods during the trial and for 8 weeks after the last administration of the investigational drug.
9\. Participants voluntarily join this study, demonstrate good compliance, and cooperate with follow-up.
Exclusion Criteria:
1. There is a clear distant transfer;
2. A history of autoimmune diseases;
3. Acute or chronic active hepatitis B (defined as positive hepatitis B surface antigen and/or hepatitis B core antibody, with hepatitis B virus DNA copy number ≥1×10³ copies/ml or ≥200 IU/ml) or positive antibodies for acute or chronic active hepatitis C, with positive hepatitis C antibodies but negative RNA testing allowed for enrollment.
4. Previous treatment with immune checkpoint inhibitors;
5. Received systemic immunostimulants, systemic corticosteroids, or immunosuppressants within the last 4 weeks;
6. Any severe underlying disease, comorbidities, and active infections, or patients with severe metabolic disorders;
7. Currently receiving other antitumor treatments;
8. Known comorbidities (e.g., chronic diarrhea, inflammatory bowel disease, etc.) that, in the investigator's assessment, would increase the risk associated with the administration of the study drug or interfere with the interpretation of study results.
9. Currently using or planning to use probiotics, yogurt, or bacterial-enhanced foods during the treatment period.
10. A history of epilepsy or seizure-inducing states;
11. Pregnant or breastfeeding patients;
12. Poor compliance or inability to undergo normal follow-up;
13. Individuals allergic to the study drug;
14. Diagnosis of other malignancies within the past 5 years, with the exception of: surgically removed non-melanoma skin cancer, adequately treated cervical carcinoma in situ, locally curative prostate cancer, surgically treated ductal carcinoma in situ, or malignancies diagnosed 2 years prior to randomization without evidence of disease and untreated for ≤2 years;
15. The investigator's judgment on other conditions that may affect the conduct of the clinical study and the determination of study results.
