Fig. 2.

Generations of CARTs. The first generation of CAR-T cells is used as a template to construct later generations and its signaling is based on the presence of the intracellular CD3ζ domain. The second generation CAR-T cells (CARTs) incorporate a costimulatory domain, most often CD28. Third generation CARTs incorporate additional costimulatory domains, such as CD28, ICOS, 4-1BB or OX40. Fourth generation CARTs, also called TRUCKs, are based off second generation CARTs with an additional gene cassette, which induces cytokine expression. scFv single-chain variable fragment, NFAT nuclear factor of activated T cells