Abstract B113: Establishment of a clinically relevant orthotopic xenograft model for human liver cancer.
Authors: Klingner Kerstin , Giesemann Torsten , Baltes Steffen , Fiebig Heinz Herbert , Schueler Julia B. 
Published: June 2012

Abstract
In order to allow a better understanding of liver carcinoma, the establishment of functional and reproducible in vivo models is widely pursued. Of available model systems, orthotopically growing xenografts in immunodeficient mice reflect well the clinical situation. In the present study, the growth behaviour and sensitivity towards the multikinase inhibitor sorafenib of human liver carcinoma cells implanted orthotopically into NMRI nude mice was investigated. Liver carcinoma cell line SKHEP1 was injected orthotopically into nude mice. Three days after inoculation of 5 Mio. tumor cells, mice were subdivided into two groups, and treatment was started either with vehicle (control) or sorafenib (100 mg/kg/d, po, days 3–36). Tumor growth was monitored via a) fluorescence-based in vivo imaging (IVI, using Alexa750 labeled anti-human CD10 antibody) once weekly, b) macroscopic examination at the end of the experiment, and c) histological examination of murine liver tissue. IVI pictures were merged with x-ray for an optimal localization of the fluorescent tissue. Antitumoral and antimetastatic capacity was determined by comparing the fluorescent intensity as well as the fluorescent area for primary tumors and metastasized organs over the time.
Seven days after implantation, SKHEP1-derived tumors could be detected in the liver in all animals via IVI. Weekly follow-up analyses confirmed, that liver engraftment was prominent and observed in all animals (16/16). Lymphnode metastases (6/9 control mice and 3/7 Sorafenib-treated mice) could be determined 14 days after tumor cell inoculation. Beyond that bone marrow metastases (4/9) could be detected exclusively in the untreated control group. The detection limit of the investigated model was about 5×104 cells within one region of interest. Signal to noise ratio was excellent due to a highly specific antibody, the use of a near-infrared fluorophore combined with the absence of auto-fluorescense of murine hair. IVI produced very bright and reproducible pictures optimal for exact quantification of the tumor load. Sorafenib showed a strong antitumoral and antimetastastatic activity, inducing optimal T/C values as low as 2.7% for the primary tumor and 40% for the lymphnode metastases on day 56. In addition, the total number of metastasized animals was reduced in comparison to the untreated animals. The occurrence of bone marrow metastases was almost completely reduced by sorafenib treatment. Tolerability of the test compound was very high as no marked body weight losses or drug related toxicities could be observed.
Our xenografts show a close resemblance to the liver cancer disease regarding the growth behaviour of primary tumor and metastatic involvement of other organs. Collection of whole-body IVI data proved to be a time- and animal-saving analysis that allows to closely monitor hepato-carcinoma growth. Quantification and localization of tumor load was determined in a very exact and prompt manner. Thus, orthotopically implanted liver xenografts monitored by a fluorescent-based in vivo imaging system will be a useful tool in the development of new therapies against human liver carcinoma.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B113.