Decreasing affinity of CAR-T cells targeting HER2 to increase therapeutic out-come against tumors / 药学实践杂志

ABSTRACT

Objective To investigate whether decreasing affinity of CAR-T cells can increase their therapeutic outcome or not .Methods Moderate affinity La-G3HER2-CAR and high affinity Ha-G3HER2-CAR were constructed ,and electroporated to modify T cells .Western blot assay ,FCM assay and the RTCA DP cytotoxic equipment were applied to test the CAR expres-sion and cytotoxic function of CAR-T cells .Results 43000 and 58000 exogenous CD3ζfragments were expressed by both La-G3HER2-CAR-T cells and Ha-G3HER2-CAR-T cells with 58 .1% and 69 .0% transfection rate respectively .High affinity Ha-G3HER2-CAR-T cells effectively killed all target tumor cells by which HER2 was expressed at variable expression levels , while moderate affinity La-G3HER2-CAR-T cells specifically killed HER2 high-level expressing SK-OV-3 and BT474 cells ,and showed weaker cytotoxicity on HER2 moderate-level expressing MDA-MB-231 and HCC-202 cells ,and showed no cytotoxicity on HER2 low-level expressing MCF-7 and 293 cells .The underlying mechanic investigation found that La-G3HER2-CAR-T cells and Ha-G3HER2-CAR-T cells were differentially activated by co-culture with MDA-MB-231 (CD107a8 .2% vs 71 .6% , IFN-γ66 .3% vs 83 .4% ,TNF-α73 .4% vs 94 .1% ) .Conclusion Moderate affinity La-G3HER2-CAR-T cells have en-hanced specific cytotoxicity toward target tumor cells compared to high affinity Ha-G3HER2-CAR-T cells ,decreasing affinity of CAR-T cell is a promising strategy to increase the therapeutic outcome of CAR-T cell based immunotherapies .