Neoadjuvant SBRT Followed by Nab-Paclitaxel Combined With Toripalimab in HR+/HER2- Breast Cancer

The goal of this clinical trial is to evaluate the efficacy and safety of neoadjuvant stereotactic body radiotherapy (SBRT) followed by nab-paclitaxel combined with toripalimab in patients with previously untreated HR+/HER2-negative breast cancer. Eligible patients include those with stage IIB-IIIC disease (cT3N0, cT2-4N1-3 or cT1N2-3) or stage IIA disease (cT2N0 or cT1N1) with at least two of the following high-risk factors: histologic grade 3, Ki-67 ≥50% or premenopausal with age \<50 years. A total of 27 enrolled patients will be assigned to receive the combination therapy. The primary question it aims to answer is whether this combination of radiotherapy, de-escalated chemotherapy, and immunotherapy can improve the total pathologic complete response (tpCR) rate (defined as ypT0/Tis ypN0).