Abstract / Summary
Abstract Hepatocellular carcinoma (HCC) patients frequently fail to respond to combined anti-PD1 immunotherapy, though pre-existing neoantigen-specific CD8⁺ T cells within tumor microenvironment are reinvigorated upon PD1 blockaded. Tumor-intrinsic mechanisms driving the therapeutic resistance in HCC remain unclear. Here, we analyzed pretreatment tumor biopsies from 78 advanced HCC patients receiving lenvatinib plus anti-PD1, and found that activation of Wnt/β-catenin signaling was significantly enriched in non-responders (49/78) compared with responders (29/78). Further analyses in 114 NCC-HCCs and 358 TCGA-LIHCs, a paucity of CD4⁺ T cells and mononuclear phagocytes was detected specifically in tumors harboring CTNNB1 mutations affecting the β-TrCP binding motif, particularly D32 mutations, but not in tumors with other Wnt/β-catenin activating alterations. We constructed β-catenin mutants at D32 (D32-mutant), transducing SK-Hep1 HCC cells and inducing murine liver cancers via hydrodynamic tail-vein injection of oncogene vector mixtures. D32-mutant strongly suppressed HCC cell-intrinsic NF-κB activity to repress the production of multiple chemokines and inflammatory cytokines, demoting CD4 + T-cell-mediated antitumor immunity by restraining mononuclear phagocyte infiltration and maturation. In C57BL/6 mice bearing SC4.D32 tumor, deficient in MHC-I mediated CD8 + T-cell-recognition, E7386 addition improved anti-PD1 antitumor effect and augmented lenvatinib plus anti-PD1 efficacy, relating to the enhancement of CD4 + T-cell-mediated antitumor immunity by recovering tumor-intrinsic NF-κB activity to increase tumor infiltration of phagocytes and their communication with CD4⁺ T cells. Thus, potentiating tumor-intrinsic NF-κB activity in mutated CTNNB1 -driven “immune excluded” HCCs could advance anti-PD1 treatment efficacy.