Refining neoadjuvant chemoimmunotherapy and establishing predictive biomarkers remain pivotal challenges in early TNBC. Although SG/I (sacituzumab govitecan/PD-1 inhibitor) shows clinical promise, validation of responder identification tools is warranted. This phase II trial aims to identify a precision TNBC population suitable for de-escalated neoadjuvant therapy with sacituzumab govitecan plus tislelizumab, based on differential Trop-2 expression (±) and PD-L1 status (CPS >10% vs. <10%). Primary endpoints include pCR rate and safety; exploratory biomarker analyses will assess mechanisms of response/resistance

Inclusion Criteria:

• 1. Age ≥ 18 years; 2. Histologically confirmed stage II or III primary invasive TNBC TNBC defined as: immunohistochemistry (IHC) ER and PR <1%; HER2-negative, IHC 0 or 1+, IHC 2+, ISH-; 3. ECOG performance status score 0-1; 4. Provision of an acceptable tumor sample prior to randomization; 5. Bone marrow hematopoietic and organ function must meet study requirements; Without growth factor support or blood transfusion, ANC ≥ 1.5 × 10⁹/L, platelets ≥ 100 × 10⁹/L, hemoglobin ≥ 9 g/dL; Bilirubin ≤ 1.5 × upper limit of normal (ULN); ALT and AST ≤ 2.5 × ULN; Creatinine ≤ 1.5 × ULN; Urinalysis showing proteinuria < 2+ or 24-hour urine protein < 1 g; Coagulation function must be normal, defined as: International Normalized Ratio (INR) and/or Prothrombin Time (PT) ≤ 1.5 × ULN and/or Activated Partial Thromboplastin Time (APTT) ≤ 1.5 × ULN. If anticoagulant therapy is ongoing, PT must remain within the therapeutic range for the anticoagulant used.

Serum amylase ≤ 1.5×ULN and serum lipase ≤ 1.5×ULN.

Exclusion Criteria:

• 1. Evidence of severe/uncontrolled systemic disease, including active infections requiring intravenous therapy, severe chronic gastrointestinal disease associated with diarrhea, active bleeding disorders, severe cardiac or psychiatric disorders, or history of allogeneic organ transplantation; 2. History of other primary malignancies with known active disease within 3 years prior to randomization and low potential for recurrence (excluding adequately excised non-melanoma skin cancers and treated carcinoma in situ); 3. Active or documented history of autoimmune or inflammatory diseases; 4. Presence of distant metastases; 5. Active or uncontrolled hepatitis B or C infection, uncontrolled HIV infection, or active tuberculosis; 6. History of interstitial lung disease, drug-induced interstitial lung disease, radiation pneumonitis requiring steroid therapy, any clinically active interstitial lung disease, or immune-related pneumonitis induced by immunotherapy; 7. Any prior or concurrent surgery, radiotherapy, or systemic anticancer therapy for TNBC; 8. Prior exposure to the following treatments: Immunosuppressive drug therapy within 14 days before the first study intervention Live attenuated vaccines within 30 days before the first study intervention