An additional bispecific, humanized IgG1 antibody which is beneath investigation is zenocutuzumab (MCLA-128), which acts via two independent mechanisms of action: inhibition of HER2–HER3 signalling and elimination of tumour cells by means of ADCC. MCLA-128 functions by way of a ‘dock and block’ mechanism whereby one arm from the antibody https://www.directivepublications.org/journal-of-clinical-breast-cancer/