Characterization of CAR T Cells Manufactured using Genetically Engineered Artificial Antigen Presenting Cells

ObjectiveChimeric antigen receptor (CAR) T cell therapy has recently emerged as a promising approach for the treatment of different types of cancer. Improving CAR T cell manufacturing in terms of costs and product quality is an important concern for expanding the accessibility of this therapy. One proposed strategy for improving T cell expansion is to use genetically engineered artificial antigen presenting cells (aAPC) expressing a membrane-bound anti-CD3 for T cell activation. In this study, we characterized CAR T cells generated with this approach in terms of expansion efficiency, immunophenotype, and cytotoxicity. Materials and MethodsIn this experimental study, we generated an aAPC line by engineering K562 cells to express a membrane-bound anti-CD3 (mOKT3). T cell activation was performed by culturing PBMCs with either mitomycin C-treated aAPCs or surface-immobilized anti-CD3 and anti-CD28 antibodies. Untransduced and CD19-CAR-transduced T cells were characterized in terms of expansion, activation markers, IFN-{gamma} secretion, CD4/CD8 ratio, memory phenotype, and exhaustion markers. Cytotoxicity of CD19-CAR T cells generated by aAPCs and antibodies was also investigated using a bioluminescence-based co-culture assay. ResultsOur findings showed that the engineered aAPC line has the potential to expand CAR T cells similar to that of the antibody-based method. Although activation with aAPCs leads to a higher ratio of CD8+ and effector memory T cells in the final product, we did not observe a significant difference in IFN-{gamma} secretion cytotoxic activity or exhaustion between CAR T cells generated with aAPC or antibodies. ConclusionOur results show that despite the differences in the immunophenotypes of aAPC and antibody-based CAR T cells, both methods can be used to manufacture potent CAR T cells. These findings can be instrumental for the improvement of the T cell manufacturing process and future applications of aAPC-derived CAR T cells.