ERBB3 and metastatic melanoma: To provide an improved targeting approach, antibody drug conjugates (ADCs) have been designed, in which a cytotoxic payload is attached to an antibody via a chemical linker.54 This is exemplified, for instance, by the novel ADC EV20‐Sap that displayed promising antitumor activity in metastatic melanoma, obtained by chemically coupling the HER‐3 targeting antibody EV20 to the plant toxin saporin.55 This conjugate maintained the biological activity of the naked HER‐3 antibody.