Abstract 4946: Developing anti-angiogenic therapies for human hepatocellular cancer (HCC)- studies of suntinib in the woodchuck model of hepatitis B related HCC
Authors: Pomakov Alexander , Toshkov Ilia , Buitrago Sandra , Curtin Leslie , Trump Donald , Johnson Candace , Ashton Edward , Tennant Bud , Iyer Renuka 
Published: May 2015

Introduction: Better animal models that recapitulate the liver milieu of human HCC are needed. The eastern woodchuck is an established model of human hepatitis B viral infection and spontaneously develops HCC in the context of chronic woodchuck hepatitis viral infection (WHV). The translational relevance of this model for developing anti-angiogenic therapies was evaluated using sunitinib (S), a potent oral, anti-angiogenic agent.

Methods: Woodchucks were bred and inoculated at birth with titered infectious WHV pools obtained from chronic WHV carriers. By 12 months of age, the rate of chronic WHV infection was &gt;60%. Carriers were followed by USG, upon developing HCC, 12 animals were randomized 1:1 to S or placebo (P) given once orally daily for 30 days. From a single treatment S PK study at 4 dose levels, n=3/group, simulations showed 12mg/kg daily was expected to be optimal for achieving steady state serum concentrations between 50- 100 ng/ml in woodchucks. Tumor size and blood flow were assessed using dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) before treatment and on day 28 using standardized protocols. At study completion or when animals were humanely euthanized, tumors and any other small nodules were fixed overnight in 10% buffered formalin. After standard processing and embedding in paraffin, 4 μm sections were prepared, deparaffinized, stained with hematoxylin-eosin (H&E), studied with a Zeiss Axio Imager A1 microscope by a pathologist blinded to the treatment arm. Morphometric study of areas of necrosis were compared to the size of the tumor sections by counting view fields at medium objective magnification, and differences in percentages between the groups were compared by the Excel student's two tailed, two-sample unequal variance t-test.

Results: The median age was 30 months. Four animals died during the course of the study (1P, 3 S) and were replaced. Median therapy duration was 28 days. Morphologically, portal hepatitis and pre-neoplastic lesions (foci of altered hepatocytes [FAH]) and larger areas of altered hepatocytes (AAH) were seen in all livers. Areas of tumor necrosis of varying size (20-100%) adjacent to terminal hepatic venules seen in both high grade and in rare, low grade tumor sections of S treated woodchucks were rare in P animals. The difference was highly significant (p= 6.0 E-13) between the two groups. By DCE-MRI, median tumor volume change was + 17% and -13% and necrotic tumor volume change was +22% and +190% in P and S treated animals respectively. However all MRI parameters (k trans, AUC90, median tumor volume) were not statistically significantly different between the groups.

Conclusions: Angiogenic response across different stages of hepatocarcinogenesis can be studied in woodchucks. Histological necrosis in S treated woodchucks without significant DCE-MRI change and the toxicities seen with S have translational significance to human HCC.

Citation Format: Alexander Pomakov, Ilia Toshkov, Sandra Buitrago, Leslie Curtin, Donald Trump, Candace Johnson, Edward Ashton, Bud Tennant, Renuka Iyer. Developing anti-angiogenic therapies for human hepatocellular cancer (HCC)- studies of suntinib in the woodchuck model of hepatitis B related HCC. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4946. doi:10.1158/1538-7445.AM2014-4946