A further bispecific, humanized IgG1 antibody which is under investigation is zenocutuzumab (MCLA-128), which acts through two impartial mechanisms of action: inhibition of HER2–HER3 signalling and elimination of tumour cells by using ADCC. MCLA-128 functions through a ‘dock and block’ system whereby a single arm on the antibody binds HER2 https://www.directivepublications.org/journal-of-clinical-breast-cancer/