👤 Brandon M Lehrich

WNT-β-catenin activation is observed in around 50% of all patients with hepatocellular carcinoma (HCC), through either gain-of-function mutations in CTNNB1 (which encodes β-catenin) or loss-of-function mutations in AXIN1 or APC. Currently, first-line therapies for HCC are immune checkpoint inhibitor (ICI) combinations, and β-catenin-active HCCs have garnered increased attention due to their unique tumour immune microenvironment (TIME). This pathway is known to drive an immune-excluded TIME, but clinical investigations have provided a more nuanced perspective, with the emergence of a new 'immune-like' subclass of HCC that is paradoxically enriched for CTNNB1 mutations and has high levels of T cell infiltration. As such, patients and animal models with β-catenin activation treated with ICIs exhibit heterogeneous responses. Additionally, these tumours exhibit higher fatty acid oxidation to fuel tumour growth owing to a unique metabolic milieu shaped by zone 3 metabolism, which is a physiological function of WNT-β-catenin signalling in the liver lobule. Biomarkers to detect molecular subclasses of patients for targeted therapies are being developed. In this Review, we discuss advances in our understanding of the TIME and metabolism of β-catenin-active HCC, driven by in vitro and in vivo models and single-cell and spatial sequencing, and their implications for the treatment of a subset of HCCs using precision therapies against WNT-β-catenin signalling. Show less

First-line immune checkpoint inhibitor (ICI) combinations show responses in subsets of hepatocellular carcinoma (HCC) patients. Nearly half of HCCs are Wnt-active with mutations in CTNNB1 (encoding for β-catenin), AXIN1/2, or APC, and demonstrate heterogeneous and limited benefit to ICI due to an immune excluded tumor microenvironment. We show significant tumor responses in multiple β-catenin-mutated immunocompetent HCC models to a novel siRNA encapsulated in lipid nanoparticle targeting CTNNB1 (LNP-CTNNB1). Both single-cell and spatial transcriptomics reveal cellular and zonal reprogramming, along with activation of immune regulatory transcription factors IRF2 and POU2F1, re-engaged type I/II interferon signaling, and alterations in both innate and adaptive immunity upon β-catenin suppression with LNP-CTNNB1 at early- and advanced-stage disease. Moreover, ICI enhances response to LNP-CTNNB1 in advanced-stage disease by preventing T cell exhaustion and through formation of lymphoid aggregates (LA). In fact, expression of an LA-like gene signature prognosticates survival for patients receiving atezolizumab plus bevacizumab in the IMbrave150 phase III trial and inversely correlates with CTNNB1-mutatational status in this patient cohort. In conclusion, LNP-CTNNB1 is efficacious as monotherapy and in combination with ICI in CTNNB1-mutated HCCs through impacting tumor cell-intrinsic signaling and remodeling global immune surveillance, providing rationale for clinical investigations. Show less