ERBB2 and neoplasm: Its antitumor properties reside not only on the blockade of the HER2 signaling pathway and ADCC induction by trastuzumab but also on the internalization of the cytotoxic moiety by HER2 expressing cells, therefore, having a more potent cytotoxic effect within tumor cells instead of on healthy tissues (i.e., a better therapeutic index than traditional cytotoxic drugs) [44].