Parallel CD19/CD20 CAR-Activated T-Cells Are More Effective for Refractory B-Cell Lymphoma In Vitro and In Vivo

Anti-CD19 chimeric antigen receptor (CAR) T-cells are an effective treatment for refractory B-cell lymphoma, but CD19 deletion is prone to relapse. We conducted this study to find more effective dual CAR19/20 T-cells to target B-cell lymphoma and prevent antigen loss leading to recurrence. In this study, we transduced CD19 and CD20 CARs into human T cells in parallel and compared parallel dual CAR19/20, single CAR, and tandem CAR19/20 in vitro and in vivo. After transduction with the corresponding vectors, CD19 and CD20 CARs were dually expressed in human T cells. It was observed that parallel CAR19/20 T-cells contained a substantial proportion of naive subpopulations and were able to proliferate in vitro. Treatment with parallel CAR19/20, single CAR, or tandem CAR19/20 T-cells sustainably induced complete lysis of leukemia cells in a 5 : 1 ratio. Compared with single or tandem CAR T-cell-transplanted mice, parallel CAR19/20 T-cell-transplanted mice exhibited smaller tumor volume, more stable body weight, and longer survival. This suggests that parallel CAR19/20 has superior antilymphoma activity in vivo. In addition, parallel CAR19/20 T-cells were also able to kill patients' lymphoma cells in vitro. Therefore, it can be considered that parallel CAR19/20 is equally effective against single CAR and tandem CAR19/20 in vitro but more effective against lymphoma cells in vivo. This is a promising treatment to prevent the recurrence of antigen loss following CD19-targeted therapy in B lymphoma.