In 11/16 patients, we found a positive signal to at least one of the aforementioned antigens (patients no. 1, 4, 8, 10, 12, 13, 15, and 21 showed survivin-specific T cells, patients no. 12 and 20 mammaglobin-specific T cells, patients no. 4, 5, and 9 HER2-specific T cells), already before RT treatment, thus confirming the presence of spontaneous T-cell responses in BC patients elicited by the tumor itself (Figures 1A–C; Figure S2 in Supplementary Material). Here, BIRC5 is linked to breast cancer.