Abstract B095: Antitumor activity of lenvatinib mesilate (LEN) via angiogenesis inhibition and tumor FGF signaling pathway in the human hepatocellular carcinoma models
Authors: Hoshi Taisuke , Matsuki Masahiro , Yamamoto Yuji , Minoshima Yukinori , Matsui Junji , Funahashi Yasuhiro 
Published: August 2018

Abstract
Background: LEN is an oral multi-targeted tyrosine kinase inhibitor that selectively inhibits vascular endothelial growth factor receptor (VEGFR)1-3, fibroblast growth factor receptor (FGFR)1-4, platelet-derived growth factor receptor α, RET, and KIT. LEN was noninferior to sorafenib (SOR) in overall survival (OS) in a phase 3 study in patients with unresectable hepatocellular carcinoma (HCC) (medians: LEN, 13.6 vs SOR, 12.3 months; hazard ratio: 0.92; 95% confidence interval, 0.79-1.06) and statistically superior to SOR in progression-free survival (PFS), time to progression (TTP), and objective response rate (ORR). We previously reported that LEN showed antitumor activity in multiple HCC xenograft models including patient-derived xenograft (PDx) models. Here, we investigated the mode of action of LEN in preclinical human HCC models to examine antitumor angiogenesis activity in vivo and the effects on FGF signaling pathways both in vitro and in vivo in the preclinical HCC models. Methods: Antiproliferative activity of LEN and SOR was examined using human HCC cells (Hep 3B2.1-7, HuH-7, SNU398, and PLC/PRF/5) in vitro, and antitumor and anti-angiogenesis activity were examined using these HCC cell lines and PDx models. The effect on the FGF signaling pathway was evaluated by determining the phosphorylation of FRS2, a direct substrate of FGFRs, with immunoblotting analysis in both cultured cells and tumor xenografts. Anti-angiogenesis activity was evaluated by determining microvessel density (MVD) within tumor xenografts by immunohistochemical analysis using anti-CD31 antibody. Result: LEN decreased the phosphorylation of FRS2 in FGF19-overexpressing Hep3B2.1-7 and HuH-7 cells at 0.03 to 3 μmol/L in a concentration-dependent manner. LEN showed selective antiproliferative activity against these cells with half-maximal inhibitory concentration (IC50) values of 0.23 and 0.42 μmol/L, respectively, and those concentrations were consistent with ones for inhibitions of the phosphorylation of FRS2. In tumor xenografts, LEN also decreased the phosphorylation of FRS2 by the single administration of LEN between 3 and 30 mg/kg. SNU398 cells are known to have a relatively weak dependence on the FGF signaling pathway without FGF19 expression. LEN inhibited in vitro proliferation of SNU398 cells, and the phosphorylation of FRS2 both in vitro and in vivo at higher doses than in Hep 3B2.1-7 and HuH-7 cells. SOR did not selectively inhibit in vitro proliferation or the phosphorylation of FRS2 in HCC cells with FGF activation in vitro and in vivo. In HCC PDx and PLC/PRF/5 xenograft models, LEN significantly decreased the MVD in a dose-dependent manner between 3 and 30 mg/kg, and it was correlated with tumor growth inhibition in each models. SOR showed clear anti-angiogenesis activity at 30 mg/kg, but not at 10 mg/kg. Conclusion: These results suggest that inhibition of the FGF signaling pathway via FGFR with LEN affects proliferation of HCC cells with activation of the FGF signaling pathway, and the potent anti-angiogenic activity underlies the antitumor activity of LEN in preclinical HCC xenograft models.
Citation Format: Taisuke Hoshi, Masahiro Matsuki, Yuji Yamamoto, Yukinori Minoshima, Junji Matsui, Yasuhiro Funahashi. Antitumor activity of lenvatinib mesilate (LEN) via angiogenesis inhibition and tumor FGF signaling pathway in the human hepatocellular carcinoma models [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B095.