Abstract B048: Neutrophil extracellular traps-targeting DNase I enhances the therapeutic efficacy of CAR-T cell adoptive immunotherapy in a syngeneic murine metastasis model

Abstract In recent years, chimeric antigen receptor (CAR) T cell therapy has emerged as a promising approach for treating various malignancies, most notably in hematologic cancers. However, its efficacy in solid tumors is often hindered by an immunosuppressive tumor microenvironment (TME), which, in particular, is frequently characterized by the presence of tumor-associated cell-free DNA (cfDNA), especially in the form of neutrophil extracellular traps (NETs). In adoptive immunotherapies NETs, composed primarily of neutrophil-derived DNA, histones and neutrophil granule enzymes (e.g., MPO, NE), act as physical barriers and induce the secretion of immunosuppressive factors that impair CAR T cell function. This study investigates the potential of co-administration of deoxyribonuclease I (DNase I) with CAR T cells in a syngeneic B16 melanoma murine model of lung metastasis. Bioluminescent imaging of melanoma metastatic processes has shown that a single injection of DNase I (10 mg/kg) suppresses B16-EGFR lung metastasis at early stages in comparison to the vehicle control group but does not improve survival. However, co-administration of DNase I with murine EGFR-CAR T cells significantly suppresses tumor burden, decreases the number of metastatic foci, and substantially prolongs survival compared to the CAR T cell monotherapy group. Degrading of NETs [RB1] by DNase I increases the amount of tumor-infiltrating T and CAR T cells and reduces the immunosuppressive effects of the TME. This is reflected in the CD8 population of tumor-infiltrating CAR T cells from the DNase I treated group, which have lower expression of PD-1 and TIM-3 exhaustion markers. This research highlights the critical role of the NETs in modulating CAR T cell efficacy and provides a compelling rationale for incorporating DNase I as an adjunctive treatment to improve therapeutic responses in patients undergoing CAR T cell therapy. However, further clinical studies are warranted to validate these findings and explore the translational potential of this combinatorial approach in enhancing cancer treatment. [RB1]Again - this takes the emphasis and the reader away from NETs and into the cfDNA universe. Citation Format: Alexey Stepanov, Wenjian Wang, Yingqin Hou, Ivan Chernikov Ivan Chernikov, Reid Bissonnette, George Tetz, Grigory Borisenko, Dmitry Genkin. Neutrophil extracellular traps-targeting DNase I enhances the therapeutic efficacy of CAR-T cell adoptive immunotherapy in a syngeneic murine metastasis model [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B048.