Purpose: Hepatocellular carcinoma (HCC) is the fifth most common primary neoplasm; surgery is the only curative option but 5-year survival rates are only 25% to 50%. Vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) are known to be involved in growth and neovascularization of HCC. Therefore, agents that target these pathways may be effective in the treatment of HCC. The aim of this study was to determine the antineoplastic activity of brivanib alaninate, a dual inhibitor of VEGF receptor (VEGFR) and FGF receptor (FGFR) signaling pathways.
Experimental design: Six different s.c. patient-derived HCC xenografts were implanted into mice. Tumor growth was evaluated in mice treated with brivanib compared with control. The effects of brivanib on apoptosis and cell proliferation were evaluated by immunohistochemistry. The SK-HEP1 and HepG2 cells were used to investigate the effects of brivanib on the VEGFR-2 and FGFR-1 signaling pathways in vitro. Western blotting was used to determine changes in proteins in these xenografts and cell lines.
Results: Brivanib significantly suppressed tumor growth in five of six xenograft lines. Furthermore, brivanib-induced growth inhibition was associated with a decrease in phosphorylated VEGFR-2 at Tyr(1054/1059), increased apoptosis, reduced microvessel density, inhibition of cell proliferation, and down-regulation of cell cycle regulators. The levels of FGFR-1 and FGFR-2 expression in these xenograft lines were positively correlated with its sensitivity to brivanib-induced growth inhibition. In VEGF-stimulated and basic FGF stimulated SK-HEP1 cells, brivanib significantly inhibited VEGFR-2, FGFR-1, extracellular signal-regulated kinase 1/2, and Akt phosphorylation.
Conclusion: This study provides a strong rationale for clinical investigation of brivanib in patients with HCC.