Precision targeting of beta-catenin induces tumor reprogramming and immunity in hepatocellular cancers [Bulk RNA-seq CTNNB1/hMet/POU2F1]

First-line immune checkpoint inhibitor (ICI) combinations have shown responses in subsets of patients with advanced hepatocellular carcinoma (HCC). Nearly half of patients are Wnt active with mutations in CTNNB1 (encoding for beta-catenin), AXIN1/2, or APC, and demonstrate limited benefit to ICI due to an immunosuppressive tumor microenvironment. We investigated a novel siRNA encapsulated in lipid nanoparticle targeting CTNNB1 (LNP-CTNNB1) in multiple beta-catenin-mutated immunocompetent HCC mouse models, observing complete response. Integrated single-cell and spatial transcriptomics revealed complete cellular and zonal reprogramming of CTNNB1-mutated tumors, and a spatiotemporal shift in innate immune surveillance with intra-tumoral pro-inflammatory myeloid infiltration following LNP-CTNNB1 intervention. beta-catenin knockdown initiated tumor cell-intrinsic type I/II interferon signaling accompanied by IRF2 upregulation, which was suppressed in CTNNB1-mutated HCCs. IRF2 re-expression in beta-catenin-mutated HCC restored adaptive tumor immunity with increased CD4+ T cells and impaired recruitment of resident T regulatory cells. Finally, LNP-CTNNB1 synergized with ICI in advanced-stage disease through increasing intra-tumoral recruitment of cytotoxic T cells. In summary, RNAi-mediated inhibition of CTNNB1 is efficacious as monotherapy and in combination with ICI in CTNNB1-mutated HCCs through remodeling both tumor cell intrinsic signaling and global immune surveillance, thus providing rationale for clinical investigations.