Phase II Exploratory Study of Toripalimab Combined With SBRT in HER2-Negative Breast Cancer Patients With Insensitivity to Neoadjuvant Chemotherapy

The goal of this clinical trial is to evaluate the efficacy and safety of toripalimab combined with radiochemotherapy as perioperative therapy in HER2-negative breast cancer patients insensitive to neoadjuvant chemotherapy. This was a multicohort, single-center exploratory clinical study. Eligible patients were initially administered standard neoadjuvant chemotherapy (TAC or TE regimen). Efficacy assessment was performed after 2 cycles of neoadjuvant chemotherapy, and only those evaluated as stable disease (SD) were formally enrolled. Enrolled patients were stratified into the HR-positive group and the triple-negative breast cancer (TNBC) group, with each group further divided into 3 arms receiving the following treatments respectively: * Cohort 1: Continued the original neoadjuvant chemotherapy for 4 cycles, followed by surgical treatment within 5 weeks for eligible patients. * Cohort 2: Received the original neoadjuvant chemotherapy regimen plus toripalimab for 4 cycles, followed by surgery within 5 weeks; toripalimab monotherapy was continued for an additional 13 cycles postoperatively. * Cohort 3: Received the original neoadjuvant chemotherapy regimen plus toripalimab for 4 cycles combined with concurrent stereotactic body radiation therapy (SBRT, 25Gy/5f), followed by surgery within 5 weeks; toripalimab monotherapy was continued for an additional 13 cycles postoperatively.