This concept is now validated following FDA approval of KadcyclaTM and AdcetrisTM, for the treatment of HER2-positive breast cancer and Hodgkin Lymphoma respectively.14,16 However, there is a recognised requirement for conjugation chemistries that yield more homogeneous ADC products and that facilitate release of the payload once the ADC has been internalised into its target cell. This evidence concerns the gene ERBB2 and breast cancer.