Pertuzumab, a humanized IgG1 mAb targeting HER2 in a different domain compared to trastuzumab, prevents HER2 homodimerization and heterodimerization.25 The addition of pertuzumab to trastuzumab therapy has been studied in vitro.26 Although both trastuzumab and pertuzumab effectively activate ADCC against human BC cells with equal potency, there was no observed synergistic induction of ADCC with the combination, so the clear synergism and high activity that these two monoclonal antibodies have may not be a consequence of a more potent immune activity. Here, ERBB2 is linked to breast cancer.