The goal of the study is to assess the safety and effectiveness of the combination of anti-PD1 immunotherapy (pembrolizumab) and radiotherapy in the preoperative treatment of HER2-negative breast cancer resistant to classical chemotherapy.
The subject of the intervention will be:
1. Randomly assigned in a 2:1 ratio and double-blinded addition of pre-operative immunotherapy with pembrolizumab or placebo to standard chemotherapy
2. Addition of preoperative radiotherapy boost delivered with a CyberKnife radiosurgery system concomitantly with the use of paclitaxel (+/- carboplatin) and pembrolizumab / placebo.