Mature DCs significantly enhanced antigen‐specific CD8+ T‐cell activity against HER2 (4.5%; p < 0.005) and MUC1 (19%; p < 0.05), and induced a dose‐dependent cytotoxic T‐lymphocyte response (65%) capable of killing autologous BC cells in vitro, outperforming DCs loaded with autologous lysates (p < 0.005). Here, ERBB2 is linked to breast cancer.