Effect of dendritic cells (DC) transduced with chimeric antigen receptor (CAR) on CAR T-cell cytotoxicity.

144Background: T cells interacting DC could be superior in T cell cytotoxicity. CD141+/Cleg9a+ intra-tumoral DC play a critical role in tumor cytotoxicity. Therefore, combining intra-tumoral DC in CAR T cell would safely increase localized CAR T cell cytotoxicity. We hypothesized that bioengineered DC compartment could be an excellent source for enhanced CAR T cell cytotoxicity. Methods: DC precursors and T cells of PBMC were transduced with a CAR (pCCL-anti-CD33-4-1BB-CD3z-T2A-GFP; CAR-DC or CAR T). For comparison, additional DC were transduced with 4-1BB cDNA (pCCL-4-1BB-T2A-GFP; 4-1BB-DC) or mock control (pCCL-eGFP). In addition to lentivirus transduction, differentiation of DC in vitro employed Flt3L/GM-CSF/IL-4. Transduced CAR T and CAR-DC were sorted by GFP expression at day 5. After further 10 days of culture, cells were harvested and analyzed for phenotype. An acute myeloid leukemia (AML) cell line (Kasumi-1) was treated with CAR T +/- CAR-DC, 4-1BB-DC, or mock control for functional assays. Resul...