The Impact of the Intracellular Domains of Chimeric Antigenic Receptors on the Properties of CAR T-cells.

The advent of the T-cell engineering technology using chimeric antigen receptors (CARs) has revolutionized the treatment of hematologic malignancies and reoriented the direction of research in the field of immune cell engineering and immunotherapy. Regrettably, the effectiveness of CAR T-cell therapy in specific instances of hematologic malignancies and solid tumors is limited by a number of factors. These include (1) an excessive or insufficient CAR T-cell response, possibly a result of both resistance within the tumor cells or the microenvironment and the suboptimal structural and functional organization of the chimeric receptor; (2) a less-than-optimal functional phenotype of the final CAR T-cell product, which is a direct consequence of the manufacturing and expansion processes used to produce CAR T-cells; and (3) the lack of an adequate CAR T-cell control system post-administration to the patient. Consequently, current research efforts focus on optimizing the CAR structure, improving production technologies, and further developing CAR T-cell modifications. Optimizing the CAR structure to enhance the function of modified cells is a primary strategy in improving the efficacy of CAR T-cell therapy. Since the emergence of the first CAR T-cells, five generations of CARs have been developed, employing both novel combinations of signaling and structural domains within a single molecule and new systems of multiple chimeric molecules presented simultaneously on the T-cell surface. A well thought-out combination of CAR components should ensure high receptor sensitivity to the antigen, the formation of a stable immune synapse (IS), effective costimulation, and productive CAR T-cell activation. Integrating cutting-edge technologies - specifically machine learning that helps predict the structure and properties of a three-dimensional biopolymer, combined with high-throughput sequencing and omics approaches - offers new possibilities for the targeted modification of the CAR structure. Of crucial importance is the selection of specific modifications and combinations of costimulatory and signaling domains to enhance CAR T-cell cytotoxicity, proliferation, and persistence. This review provides insights into recent advancements in CAR optimization, with particular emphasis on modifications designed to enhance the therapeutic functionality of CAR T-cells.