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 antileukemia 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 IFNγ and other cytokines in recipient mice, especially with coadministration 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. Furthermore, they suggest that DGKζ targeting might decrease risks of antigen escape or resistance to immune checkpoint blockade. Cancer Res; 77(20); 5676–86. ©2017 AACR.

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