ERBB2 and breast cancer: 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.