Precision killing of T cells via targeting of T cell receptors using two novel chimeric antigen receptor designs

Abstract

Abstract Pathologic T cells drive T cell leukemia, solid organ transplant rejection, and many autoimmune diseases. Currently approved treatments have limited ability to target pathogenic vs non-pathogenic T cells. While pan-T cell treatments can be effective, they have significant risks such as infection and malignancy. Chimeric antigen receptors (CAR) are synthetic constructs that retarget T cells to a specific antigen of interest; we hypothesized that we could use this technology for targeted killing of T cells. We developed two novel CAR designs which target T cells via their T cell receptor (TCR). We opted to target OT1 T cells, a model system with a known antigenic epitope. The anti-Vβ5 CAR is a second-generation CAR with a traditional extracellular scFv domain that targets Vβ5 of the OT1 TCR. The H2Kb bait CAR instead has an extracellular H2Kb complex loaded with the SIINFEKL cognate epitope. Both anti-Vβ5 and H2Kb bait CAR T cells demonstrate degranulation, activation, and proliferation upon binding OT1 T cells. In vitro co-culture with OT1 T cells results in internalization of the OT1 TCR and specific killing of OT1 T cells. Interestingly, the changes induced by the H2Kb bait CAR were delayed relative to the anti-Vβ5 CAR. In vivo experiments show both CAR designs kill adoptively transferred OT1 T cells without significant effect on the other T cell populations. In conclusion, we report the development of two novel CAR designs which allow for the targeted killing of T cells via their T cell receptor. While the anti-Vβ5 CAR T cells generated a more rapid response, the H2Kb bait CAR offers the promise of more precisely targeting T cells. This work has the potential to transform the treatment of conditions where removal of pathogenic T cells is critical for cure. Supported by NIH HL152756