Fig. 5.

Redirection of UniCAR-expressing T cells using scFv-based, monovalent VHH-based, and bivalent VHH-based targeting modules targeting a particular target antigen. The UniCARs expressed on the surface of effector T cells are responsible for the signal transduction process and effector cell activation. The targeting modules only redirect UniCAR-expressing T cells against a particular cell surface antigen. As proposed by Albert et al., bivalent VHH-based targeting modules are capable of redirecting UniCAR-expressing T cells towards cancer cells expressing low levels of a target antigen (in this case, EGFR) [109]. scFv, single-chain fragment variable; TM, targeting module; UniCAR-T, UniCAR-expressing T cell; VHH, single variable domain on a heavy chain