T cell activation upon exposure to patient-derived tumor tissue: A functional assay to select patients for adoptive T cell therapy

Gene-engineered T cell therapy represents a promising strategy to treat cancers. To enable pre-selection of patients sensitive to this type of treatment we have setup and validated a T cell activation assay to test antigen expression on patient-derived tumor tissues. Chimeric antibody-based receptor (CAR) directed against CAIX, currently used in a clinical trial to treat RCC patients, was used as a model receptor. Primary human T cells expressing CAIX CAR were able to respond to CAIX-positive but not CAIX-negative tumor tissue and showed an increased production of IFNγ, TNFα, IL-10 and IL-4, but not IL-2 or IL-5. Tumor tissue driven responses of primary T cells were paralleled by NFAT activation measured in CAR-transduced Jurkat T cells, which was shown to be triggered in a CAR and antigen-specific manner. Next, the reporter gene assay was applied to two independent PSMA CARs, which both mediated NFAT activation in response to tumor tissue. Taken together, a sensitive and donor-independent assay was established to measure T cell activation upon exposure to patient-derived tumor tissue, which may facilitate pre-selection of patients for clinical adoptive T cell therapy.