T cells deficient in diacylglycerol kinase-{zeta} are resistant to PD-1 inhibition and help create persistent host immunity to leukemia

Efforts to improve the efficacy of adoptive T cell therapies and immune checkpoint therapies in myelogenous leukemia are desired. In this study, we evaluated the anti-leukemia activity of adoptively transferred polyclonal cancer antigen-reactive T cells deficient in the regulator diacylglycerol kinase-zeta (DGKζ) with or without PD-1/PD-L1 blockade. In the C1498 mouse model of myeloid leukemia, we showed that leukemia was eradicated more effectively in DGKζ-deficient (DGKζ-/-) mice than wild-type mice. T cells transferred from DGKζ-deficient mice to wild-type tumor-bearing recipients conferred this benefit. Leukemia clearance was similar to mice treated with anti-PD-L1. Strikingly, we found that the activity of adoptively transferred DGKζ-/- T cells relied partly on induction of sustainable host T cell immunity. Transferring DGKζ-deficient T cells increased the levels of IFN-γ and other cytokines in recipient mice, especially with co-administration of anti-PD-L1. Overall, our results offered evidence that targeting DGKζ may leverage the efficacy of adoptive T cell and immune checkpoint therapies in leukemia treatment. Further, they suggest that DGKζ targeting might decrease risks of antigen escape or resistance to immune checkpoint blockade.

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