Neoadjuvant Toripalimab Plus SBRT for Chemo-Resistant Triple-Negative Breast Cancer

Inclusion Criteria: * Female, age 18-75 years, newly diagnosed invasive breast cancer. * Histologically confirmed triple-negative phenotype: ER \< 1 %, PR \< 1 % by IHC, HER2 negative (IHC 0/1+ or IHC 2+ with ISH negative). * Clinical stage II-III (T2-4 or N1-3, M0). * Completed 2 cycles of standard neoadjuvant chemotherapy (taxane ± anthracycline ± platinum) and assessed as non-responder: stable disease (SD) or progressive disease (PD) by RECIST 1.1. * ECOG performance status 0 or 1. * Radiation oncologist confirms suitability for SBRT and subsequent standard post-operative radiotherapy. * Adequate organ function within 14 days before enrollment: WBC ≥ 2 000/µL, ANC ≥ 1 500/µL, platelets ≥ 100 000/µL, Hb ≥ 9 g/dL; Serum creatinine ≤ 2 mg/dL or GFR ≥ 40 mL/min; AST/ALT ≤ 2.5 × ULN, total bilirubin ≤ ULN (≤ 3 mg/dL if Gilbert syndrome); INR ≤ 1.5 (on anticoagulation allowed if therapeutic range) * Negative HIV, HBV surface antigen, and HCV antibody (or HBV DNA / HCV RNA negative if false-positive). Exclusion Criteria: * Inflammatory breast cancer. * Any other malignancy requiring treatment within the past 3 years (except adequately treated basal-cell skin carcinoma or cervical CIS). * Active autoimmune disease, immunodeficiency, or systemic steroids \> 10 mg/day prednisone equivalent within 2 years. * Clinically significant cardiovascular disease (unstable angina, NYHA III/IV heart failure, recent MI). * Prior radiotherapy to the breast or chest wall. * Active infection requiring systemic therapy. * Known intolerance or hypersensitivity to toripalimab, paclitaxel, or carboplatin. * Pregnant or lactating women.