Fig. 3
Components and structures of mAb, CAR, BiKE and TriKE. A Taking anti-CD16 antibody for example, it can be divided into several components including Fab, Fab’, scFv and Fc. B CAR contains an antigen recognition domain, a transmembrane domain and a signal domain providing activating signal to NK cell. As above figure shows, extracellular scFv domain of a CD33 CAR molecule is composed of VH and VL anchored to the transmembrane domain by a flexible hinge, and intracellular part includes two signal domains. C A BiKE consists of two scFvs, and a short flexible polypeptide linker joins to prevent dissociation. Take CD16/CD33 BiKE for example, it constructs from VH and VL of anti-CD16 and anti-CD33 antibodies which make it capable of binding both tumor cells and NK cells. AFM is a bispecific, tetravalent chimeric antibody construct that specifically recruits NK cells by two binding sites exclusively for each antigen. D Compared to BiKE, CD16/IL-15/CD33 TriKE adds a novel modified human IL-15 crosslinker which can assist in improvement of NK cell cytotoxicity. TriKE can be also designed with a scFv fragment of anti-CD16 mAb and two scFvs of tumor specific antigens. BiKE, bispecific killer cell engager; CAR, chimeric antigen receptor; CD, cluster of differentiation; Fab, fragment of antigen binding; IL-15, interleukin 15; CH, constant heavy chain; CL, constant light chain; mAb, monoclonal antibody; scFv, single-chain variable fragment; VH, variable heavy chain; VL, variable light chain; TriKE, trispecific killer cell engage