Abstract 4096: Stage-defined, transgenic immunocompetent mouse model (ASV-B) to investigate new drugs for hepatocellular carcinoma

Abstract

Abstract Background: Hepatocellular carcinoma (HCC) is a complex multistep malignancy in need of new therapeutic options often arising on underlying chronic liver disease. HCC animal models relevant to clinical situations are crucial to investigate new anticancer drugs, alone or in combination. Mice bearing xenografts and transgenic mice are the two main models used for preclinical drug development, but most of them fail to mimic the different step of HCC observed in patients. In this study, we aim to describe a stage-defined, transgenic immunocompetent HCC mouse model. Methods: ASV-B is a transgenic mouse model that spontaneously develops, upon SV40 T-Ag oncogene expression in hepatocytes, a reproducible stage-defined HCC. Hyperplasia at week(W)8 is followed by nodular stage at W12 (multiple well-delimited tumor nodules of about 1 mm, growing progressively up to 1 cm), then diffuse carcinoma stage at W16-20. HCC is restricted to male, backcrossed with C57BL/6J mice, the female littermates being used as controls. Results: Liver volume assessed by ultrasound at each step of carcinogenesis showed a 2.7-, 2.7-, 3.9-, and 5.8-fold increase (p<0.001) in transgenic mice compared to controls (CTRL) at W8, 12, 16, and 20, respectively. ASV-B model displays marked arterialization with intense arterial flow in liver tumor similar to human HCC. Sinusoids in tumor nodules are tortuous and dilated, surrounded by activated hepatic stellate cells (HSCs) expressing smooth muscle actin (SMA) while HSCs surrounding normal sinusoids only express desmin. In addition, ASV-B livers develop along carcinogenesis a mesenchymal phenotype (increased vimentin and decreased e-cadherin staining), mimicking certain clinical situations of acquired resistance to VEGFR inhibitors. Angiogenesis, monitored using Doppler assessing blood flow velocity (BFV) in the hepatic artery, is enhanced by 29%, 51% and 156% at W8, W12 and W16, respectively, in transgenic liver animals as compared to CTRL. Increased angiogenesis was confirmed by CD31 staining in tumor specimen showing increased number of vessels per field. ASV-B model has been used to investigate the toxicity and efficacy of new drugs (galunisertib, MET/AXL inhibitor), including antiangiogenic agents (sorafenib and ramucirumab) alone or in combination, and may be relevant to explore the effects of immunotherapy agents. At the conference, we will display further characterization of liver tumors regarding vascularization, and immune cells localization using IHC. Conclusion: ASV-B transgenic mouse model mimics several characteristics of human HCC developing on healthy liver including multinodular disease, vessel abnormalities, and dedifferentiation toward mesenchymal phenotype. Further steps will consist of characterizing the adjacent nontumor liver, and developing nonalcoolic steatohepatitis (NASH) on ASV-B model using specific diets. Citation Format: Annemilaï Tijeras-Raballand, Patricia Hainaud, Christian Hobeika, Clarisse Eveno, Marc Pocard, Philippe Bonnin, Valérie Paradis, Mohamed Bouattour, Eric Raymond, Armand de Gramont, Evelyne Dupuy, Sandrine Faivre. Stage-defined, transgenic immunocompetent mouse model (ASV-B) to investigate new drugs for hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4096.