Enhancing the effectiveness of γδ T cells by mRNA transfection of chimeric antigen receptors or bispecific T cell engagers

Abstract

Adoptive cell therapy (ACT) utilizing γδ Tcells is becoming a promising option for the treatment of cancer, because it offers an off-the-shelf allogeneic product that is safe, potent, and clinically effective. Approaches to engineer or enhance immune-competent cells for ACT, like expression of chimeric antigen receptors (CARs) or combination treatments with bispecific Tcell engagers, have improved the specificity and cytotoxic potential of ACTs and have shown great promise in preclinical and clinical settings. Here, we test whether electroporation of γδ Tcells with CAR or secreted bispecific Tcell engager (sBite) mRNA is an effective approach to improve the cytotoxicity of γδ Tcells. Using a CD19-specific CAR, approximately 60% of γδ Tcells are modified after mRNA electroporation and these cells show potent anticancer activity invitro and invivo against two CD19-positive cancer cell lines. In addition, expression and secretion of a CD19 sBite enhances γδ Tcell cytotoxicity, both invitro and invivo, and promotes killing of target cells by modified and unmodified γδ Tcells. Taken together, we show that transient transfection of γδ Tcells with CAR or sBite mRNA by electroporation can be an effective treatment platform as a cancer therapeutic.