Derivatives of trastuzumab such as trastuzumab-emtansine (T-DM1) or trastuzumab-deruxtecan, two drugs that belong to the antibody-drug conjugates class of antitumorals, have also been approved as a second or third-line treatment for metastatic HER2 positive breast cancer patients [13–15]. This evidence concerns the gene ERBB2 and breast carcinoma.