Clinical cases in which patients with HER2-positive breast cancer skin metastases were treated using (1) trastazumab alone, (2) trastazumab emtansine (TDM1), or (3) a combination of trastazumab and Ca2+ electroporation showed that although TDM1 was more effective on skin metastasis than trastazumab alone, the side effects associated with TDM1 were not well tolerated. This evidence concerns the gene ERBB2 and breast carcinoma.