ERBB2 and breast cancer: Currently two ADCs, brentuximab vedotin (Adcetris®, Seattle Genetics, directed against the CD30 antigen expressed in some lymphocytes) and trastuzumab emtansine (Kadcyla®, Genentech, targeted against the HER2/neu antigen that is overexpressed by some breast cancers) are approved for use in refractory Hodgkin’s lymphoma and metastatic breast cancer, respectively, and more than 30 other compounds are being tested in human clinical trials [38].