Targeting TCF19 sensitizes MSI endometrial cancer to anti-PD-1 therapy by alleviating CD8⁺ T cell exhaustion via TRIM14-IFN- axis

Immune checkpoint blockade (ICB) therapies display clinical efficacy in microsatellite instable (MSI) endome-trial cancer (EC) treatment, the key mechanism of which is reversing T cell exhaustion and restoration of anti-tumor immunity. Here, we demonstrate that transcription factor 19 (TCF19), one of the most significantly differentially expressed genes between MSI and microsatellite stable (MSS) patients in The Cancer Genome Atlas (TCGA)-EC cohort, is associated with poor prognosis and immune exhaustion signature. Specifically, TCF19 is significantly elevated in MSI EC, which in turn promotes tripartite motif-containing 14 (TRIM14) tran-scription and correlates with hyperactive signaling of the TANK-binding kinase 1 (TBK1)-interferon regulatory factor 3 (IRF3)-interferon 0 (IFN-0) pathway. The TCF19-TRIM14 axis promotes tumorigenicity under non -immunological background, and the enhanced downstream secretion of IFN-0 facilitates CD8+T cell exhaus-tion through cell differentiation reprogramming. Finally, using humanized models, we show that a combina-tion of TCF19 inhibition and ICB therapy demonstrates more effective anti-tumor responses. Together, our study indicates that targeting TCF19 is a potent strategy for alleviating CD8+ T cell exhaustion and synergiz-ing with ICB in tumor treatment.