Overexpression of SMAD7 improves the function of EGFR-targeted human CAR-T cells against non-small-cell lung cancer

Background and ObjectiveRecent advancements in immunotherapy led to the development of Chimeric antigen receptor (CAR) T-cell therapy. CAR-T cell therapy in non-small cell lung cancer (NSCLC) is hindered by overexpression of transforming growth factor (TGF & beta;) in the cancer cells that have a negative regulatory role on T-cells activity. This study characterized CAR-T with overexpression of mothers against decapentaplegic homologue 7 (SMAD), a negative regulator of TGF & beta; downstream signalling. MethodsWe have generated three types of CAR-T: epidermal growth factor receptor (EGFR)-CAR-T, EGFR-dominant-negative TGFbeta receptor 2 (DNR)-CAR-T, and EGFR-SMAD7-CAR-T by transducing human T-cells with the lentivirus constructs. We characterized the proliferation, expression of proinflammatory cytokines, activation profile, and lysis capacity in co-cultures with A549 lung carcinoma cells with and without TGF & beta; neutralizing antibodies. We also tested the therapeutic potential of EGFR-SMAD7-CAR-T in the A549 cells tumour-bearing mice model. ResultsBoth EGFR-DNR-CAR-T and EGFR-SMAD7-CAR-T demonstrated a higher proliferation rate and lysis capacity to A549 than traditional EGFR-CAR-T. Neutralization of TGF & beta; by the antibodies resulted in increased performance of EGFR-CAR-T. In vivo, both EGFR-DNR-CAR-T and EGFR-SMAD7-CAR-T resulted in complete tumour resorption by day 20, whereas conventional CAR-T only has a partial effect. ConclusionWe demonstrated the high efficacy and resistance to negative TGF & beta; regulation of EGFR-SMAD7-CAR-T comparable with EGFR-DNR-CAR-T and without the systemic effect of TGF & beta; inhibition.