IDDF2024-ABS-0079 Targeting STING pathway as a therapeutic strategy against β-catenin driven immune escape and resistance to anti-PD1 therapy in hepatocellular carcinoma

<h3>Background</h3> β-catenin mutation occurs in around 40% of hepatocellular carcinoma (HCC) patients, and preliminary evidence showed that β-catenin mutation drives resistance to anti-PD1 immunotherapy. <h3>Methods</h3> We explored the molecular mechanisms underlying β-catenin driven immune escape that confers resistance to anti-PD-1 therapies and demonstrated a novel therapeutic strategy targeting β-Catenin-driven HCC. We analyzed the correlation between β-catenin mutation and resistance to anti-PD-1 therapy in specimens collected from 70 untreated patients and 19 treated patients with nivolumab. We investigated the mechanisms by analyzing data from the TCGA and HCC cell lines and performing CRISPRi screening, coculture, DNA methylation, and chromatin immunoprecipitation. We tested a novel therapeutic strategy using a genetically engineered mouse model. <h3>Results</h3> Firstly, we determined that low CD27+CD8+ T cell infiltration is associated with the β-catenin mutation-driven immune escape by analysis of high-dimension flow cytometry. Importantly, multiplex IHC staining showed low tumor infiltrating CD8+CD27+ T cells is predicted poor survival and response to HCC patients treated with nivolumab, demonstrating that β-catenin mutation drives resistance to anti-PD1 immunotherapy involved in defective CD8+CD27+ functions. Subsequently, we found that the interaction of β-Catenin with sirtuin 1 inhibiting Type I interferon (IFN-I) production by suppression of IRF3/IRF7 activity. By CRISPRi screening, we found that disruption of β-catenin-SIRT1 interaction via STING caused persistent high-level IFN-I response which increased the transcription of CD27 via IL10/STAT3/BATF signaling on infiltrated CD8+ T cells, emphasizing that STING signaling is a therapeutic target to overcome β-catenin driven immune escape. Further, using hydrodynamic tail-vein injection murine models and STING lockout mice, we found that the STING reconstitution inhibited β-catenin-SIRT1 activity and subsequently, restored IFN signaling to rescue T-cell cytotoxic capacities, and enhanced the anti-PD-1 therapy. <h3>Conclusions</h3> We revealed that loss of STING reprogrammed β-Catenin mutant HCC tumor microenvironment, and a combination of STING restoration with anti-PD-1 treatment represents an effective novel therapeutic strategy for β-Catenin mutant HCC patients.