Studying a series of 111 consecutive HER2- and a series of 51 non-HER2-overexpressing breast cancer patients treated by neoadjuvant chemotherapy, it was observed that high CD8 and low FOXP3 cell infiltrates after chemotherapy were significantly associated with improved relapse free survival (p = 0.02) and OS (p = 0.002), and this predictive pair outperformed classical predictive factors in a multivariate analysis. Here, FOXP3 is linked to breast cancer.