Abstract 190: Lenvatinib induced cell death of cultured human hepatocellular carcinoma (HCC) under nutrient-starved condition through inhibition of FGFR signaling pathway
Authors: Hoshi Taisuke , Miyano Saori Watanabe , Sonobe Regina Mikie Kanada , Watanabe Hideki , Seki Yuki , Ohta Etsuko , Nomoto Kenichi , Matsui Junji , Funahashi Yasuhiro 
Published: August 2019

Abstract
Introduction: HCC is a one of the leading cause of cancer death worldwide. However systemic therapeutic option for unrespectable HCC was limited. Lenvatinib (LEN) is a multi-targeted tyrosine kinase inhibitor that mainly inhibits VEGFR1-3 and FGFR1-4. In a recent phase 3 clinical trial in unresectable HCC (REFLECT study), LEN showed statistical non-inferiority of OS compared to sorafenib (SOR) and clinically meaningful outcome in ORR, PFS, and TTP. We previously showed LEN decreased in vitro proliferation of HCC cells with activated FGF signaling pathways, and inhibited tumor FGF signal and angiogenesis. However, it is largely still unknown that the contribution of FGFR inhibition on tumor cells to the antitumor activity of LEN in addition to antiangiogenic activity. In this study, we investigated the role of tumor FGF signaling pathway in human HCC cells under nutrient-poor condition to mimic tumor environment induced by anti-angiogenesis.
Methods: LEN, SOR or the corresponding vehicle were given orally to mice bearing Hep3B2.1-7 xenograft tumors for 7 days. The tumor sections were stained with H&E, and analyzed histologically. To evaluate the roles of FGF signaling pathway in cell deaths of HCC in vitro, HCC cells were treated with LEN, FGFR1-3 specific inhibitors E7090, or MEK inhibitor PD0325901 under nutrient-starved condition, and cell death induction was assessed. The phosphorylation status of downstream molecules of FGFRs and PARP cleavage were evaluated by Western blot analysis.
Results: LEN (10 and 30 mg/kg) and SOR (30mg/kg) significantly increased focal necrotic area compared to vehicle treated Hep3B2.1-7 xenograft tumors by histological analysis. LEN increased focal necrotic area in a dose dependent manner. 10 mg/kg LEN increased focal necrotic area more than 30 mg/kg SOR, although anti-angiogenic activity was not different. Under nutrient-starved condition in vitro, LEN and E7090 significantly increased death of Hep3B2.1-7 and HuH-7 cells, harboring FGF19 overexpression, but not SOR, which does not inhibit FGFR. LEN and E7090 clearly decreased the phosphorylation of downstream molecules (FRS2 and Erk) in HCC cell lines, and then LEN and E7090 also increased PARP cleavage under nutrient-starved condition. MEK inhibitor PD0325901 induced cell death and PARP cleavage in Hep3B2.1-7 and HuH-7 under nutrient-starved condition.
Conclusion: FGF signaling pathway plays a key role in survival of HCC cells under nutrient-starved condition, and inhibition of FGF signaling pathway by LEN or E7090 induced HCC cell death through FGFR-MAPK-PARP cleavage. The dual inhibition of VEGFR and FGFR by LEN may provide enhanced antitumor activity against HCC with activated FGF signaling pathways by induction of death of HCC cells, which escape from angiogenesis inhibition.
Citation Format: Taisuke Hoshi, Saori Watanabe Miyano, Regina Mikie Kanada Sonobe, Hideki Watanabe, Yuki Seki, Etsuko Ohta, Kenichi Nomoto, Junji Matsui, Yasuhiro Funahashi. Lenvatinib induced cell death of cultured human hepatocellular carcinoma (HCC) under nutrient-starved condition through inhibition of FGFR signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 190.