Schematic representation highlighting (A) the conceptual structure of an ADC and a multifunctional antibody conjugated nanoparticle and (B) internalisation, breakdown, and drug release within the cell. The tumour-specific ligand of the ADC or nanoparticle interacts with and binds to the cell surface expressed antigen. Upon binding, the antigen–protein complex becomes internalised via receptor mediated endocytosis. The nanoparticle or ADC linker is degraded within the endo-lysosomal system, resulting in drug release within the cell. Illustrations not to scale. Image created with the use of Smart Servier Medical Art.