New-generation mAb structures. Because of biological engineering, multiple structures of antibodies exist today. Therapeutic mAb structures are increasingly humanized, some are only fragments (ScFv, nanobody), and others are combined with drugs such as toxins, enzymes, radioelements, or with chemicals like polyethylene glycol. There are also Abs able to bind 2 or 3 different targets at the same time named BiTE (bispecific T-cell engager), BiKE (bispecific NK-cell engager), TriKE (trispecific NK-cell engager), quadroma, Knob-into-hole, CrossMAbVH-VL, CrossMAbCH1-CL, CrossMAbFab, and dual variable domain IgG (DVD-IgG).