Systemic Inactivation of TREX1 Induces Selective Inflammation of the Tumor Microenvironment and Invigorated T-cell-Mediated Tumor Control.

UNLABELLED

Therapeutic innate immune-stimulation within the tumor microenvironment can potentiate endogenous antitumor T-cell immunity. Strategies for controlled activation of cGAS/STING signaling are currently under intense investigation. DNase 3'-repair exonuclease 1 (TREX1) is essential for cellular DNA disposal, which prevents autoimmunity ensuing from cGAS/STING activation by endogenous DNA. TREX1-deficient tumor cells elicit enhanced protective immunity in syngeneic models. In this study, we showed that induced inactivation of the Trex1 gene in host (noncancer) cells yields improved type I IFN- and T-cell-dependent control of established TREX1-competent tumors. Host TREX1 deficiency was well tolerated and triggered selective immune cell infiltration into tumors but not into other tissues. Induced systemic loss of TREX1 in tumor-bearing mice resulted in enhanced intratumoral T-cell proliferation and massive increase in numbers of effector and effector-like "exhausted" cells, enabling complete rejection in combination with checkpoint inhibition. To conclude, systemic TREX1 inhibition is a promising approach to boost antitumor immunity and to overcome immune evasion mediated by cancer cell-intrinsic cGAS/STING inactivation.

SIGNIFICANCE

Selective inflammation of tumor tissue and efficient tumor immune control by systemically induced loss of TREX1 support the potential efficacy and therapeutic window for treating cancer with TREX1 inhibitors.