Trastuzumab is the FDA-approved treatment for HER2-positive breast cancer, which decreases HER2 overactivation by multiple mechanisms, such as preventing HER2 dimerization, downregulating the HER2 receptor through endocytic destruction, and inhibiting the constitutive HER2 cleavage mediated by metalloproteases [2]. This evidence concerns the gene ERBB2 and breast cancer.