Abstract
Hepatocellular carcinoma (HCC), a primary malignancy of the liver and leading cause of cancer-related mortality worldwide, poses substantial therapeutic challenges, particularly in advanced and unresectable stages. Immune checkpoint inhibitors (ICIs) have emerged as critical therapeutic agents, targeting immune checkpoint pathways to restore antitumor immune responses. Combinations such as atezolizumab (anti-programmed cell death ligand 1 with bevacizumab (anti-vascular endothelial growth factor), as well as antibodies directed against cytotoxic T-lymphocyte associated protein 4 and programmed cell death protein 1 (e.g., ipilimumab and nivolumab), have demonstrated improved clinical outcome in selected patients. However, the overall efficacy of ICIs remains hindered by variable response rate and primary or acquired resistance. Recent evidence suggests that the gut microbiome plays a pivotal role in modulating host immune responses and may significantly influence the therapeutic efficacy of ICIs. Dysbiosis within the gut-liver axis has been implicated not only in pathogenesis and progression of HCC but also diminishing immunotherapy effectiveness. Emerging studies highlight the potential of microbiome-targeted interventions including dietary modulation, prebiotics, probiotics, and fecal microbiota transplantation to enhance ICIs responsiveness. This review explores the evolving interplay between the gut microbiota and immunotherapy in HCC, with a focus on microbiome-based strategies aimed at optimizing clinical outcomes.