Sonaiya, Sneh

Atezolizumab-bevacizumab and durvalumab-tremelimumab have established immunotherapy as a first-line standard of care in advanced hepatocellular carcinoma (HCC). Yet, objective response rates (ORRs) remain confined to approximately 15-20%, and no validated predictive biomarker exists for patient selection. Unlike melanoma and lung cancer, conventional markers, including programmed death-ligand 1, microsatellite instability-high status, and tumor mutational burden, have not demonstrated reliable predictive value in HCC. Prior narrative reviews comprehensively catalogued the biomarker landscape through 2022 but predate a wave of clinically significant publications. This narrative review synthesizes evidence published between 2020 and 2026, with particular emphasis on 2023–2026 data, within a unified clinical framework not provided by prior reviews. We critically evaluate tissue-based biomarkers, including the AI-derived Atezolizumab-Bevacizumab Response Signature-Pathology model, spatial multiplex immunohistochemistry, and β-catenin mutational profiling; blood-based biomarkers encompassing circulating tumor DNA for minimal residual disease detection and peripheral immune phenotyping; and serum indices including the CRAFITY score and neutrophil-to-lymphocyte ratio. Hepatitis B virus etiology and non-alcoholic steatohepatitis are discussed as biological modifiers of biomarker performance. We propose an original biomarker-guided clinical algorithm, a comparative clinical readiness table, and a disease-continuum biomarker timeline as practical tools for clinicians and trialists. Prospective biomarker-enrichment trials represent the most critical next step toward clinical translation.