Consistently with an enhanced immunogenicity of HER2-positive BC, patients with HER2-overexpressing tumors achieving a pCR showed an increased number of IFN-γ producing T cells after stimulation with peptides derived from a broader range of TAAs, which included in addition to HER2, Mammaglobin-A, and Survivin, also Muc-1, Trag3, and Bcl-XL. This evidence concerns the gene MUC1 and breast cancer.