CTLA4 and breast cancer: In the same optics of exploiting the immune-mediated mechanism of some HER2-blockers, preclinical studies have investigated their potential synergistic effect in association with the cytotoxic T lymphocyte-associated antigen 4 (CTLA4) block or with the programmed cell death protein 1 (PD1) inhibition, demonstrating a robust lymphocytic activation against BC cells [17, 18].