Tumor-intrinsic ETV5 expression promotes PMN-MDSC-mediated immune evasion and immune checkpoint inhibitor resistance by activating the JAK2/STAT3/CCL2 axis.

Immunotherapy remains ineffective for a wide variety of solid tumors due to the existence of tumor immune evasion. Although the transcription factor ETV5 is recognized for its oncogenic roles in tumor progression, its role in remodeling the immunosuppressive microenvironment remains largely unexplored. Here, we reveal that tumor-intrinsic ETV5 drives immune evasion and immune checkpoint inhibitor (ICI) resistance by enhancing the expansion and recruitment of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Genetic silencing of ETV5 in murine tumor models suppressed PMN-MDSCs differentiation from myeloid progenitors, reduced their tumor infiltration, and attenuated immunosuppressive function, resulting in enhanced cytotoxic T cell activity and delayed tumor progression. Mechanistically, ETV5 directly binds to the JH1 domain of JAK2, inducing its dimerization and phosphorylation, which activates STAT3 to transcriptionally upregulate CCL2 and recruit PMN-MDSCs. Therapeutically, ETV5 ablation synergized with anti-PD-L1 therapy to enhance tumor control, mirroring clinical observations where high ETV5 expression predicted immunotherapy resistance. Our study uncovers a non-canonical, transcription-independent role of ETV5 in orchestrating the JAK2/STAT3/CCL2 axis to sustain PMN-MDSC-mediated immune evasion, proposing ETV5 as a druggable target to overcome ICI resistance in solid tumors.