Fibroblast growth factor 19-fibroblast growth factor receptor 4 axis: From oncogenesis to targeted-immunotherapy in advanced hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality globally, with limited therapeutic progress for advanced stages. The aberrant fibroblast growth factor 19 (FGF19)-fibroblast growth factor receptor 4 (FGFR4) axis promotes oncogenesis and is linked to targeted-immunotherapy of HCC. Multi-kinase inhibitors (MKIs) enhance anti-tumor effects by targeting this axis and FGF19 overexpression upregulates programmed cell death ligand 1 in tumor microenvironment. Clinical studies have demonstrated the efficacy of selective FGFR4 inhibitors in HCC treatment, with enhanced anti-tumor effects when combined with MKIs or immune checkpoint inhibitors. Phase I clinical trials of Irpagratinib (ABSK-011) demonstrated an objective response rate of 43.5%, which increased to 55.6% combined with atezolizumab. FGF19 also serves as a biomarker for HCC. This review systematically summarizes the literature retrieved from PubMed and other databases using search terms "HCC", "fibroblast growth factor 19", "fibroblast growth factor receptor 4", "FGFR4 inhibitor", "targeted therapy", "multi-kinase inhibitor", "immunotherapy", "immune checkpoint inhibitor", and "biomarker". It also firstly synthesizes combination strategies and underlying mechanisms between FGFR4 inhibitors and targeted-immunotherapy, addressing critical gaps in existing reviews. Additionally, we discuss the potential of FGF19 as a predictive biomarker, integrating mechanistic and clinical evidence to advance precision HCC therapeutics.