Optimal pairing of binder and costimulatory domains improves dual CAR T cell efficacy

We explore whether introducing two chimeric antigen receptor (CAR) molecules with distinct signaling motifs into a single T cell improves CAR T cell (CART) efficacy against leukemia and lymphoma. RNA expression profiling demonstrated that T cells co-expressing two CARs that recognize the same target in which one CAR was linked to CD28 costimulation and the other was linked to 4-1BB costimulation augmented canonical NF-κB, non-canonical NF-κB, and Th17 differentiation pathways equivalently upon target engagement. Interestingly, multitargeted CARTs transcriptional profile favored the costimulatory domain linked to the binder of the more robustly expressed CD19 rather than one linked to the binder of the less expressed CD22 upon tumor engagement. In vivo and T cell exhaustion assays found that multitargeted T cells with distinct signaling domains led to greater durable control of B-ALL than single targeted Dual CAR T cells with T cells co-expressing CD19.BBζ and CD22.28ζ being the most potent. Together, this data indicates that optimal pairing of CAR binder domain with signaling cassette bolsters anti-tumor efficacy by improving both T cell durability and effector function.