Anticancer drug response and expression of molecular markers in early-passage xenotransplanted colon carcinomas I. Fichtner a, *, W. Slisow b , J. Gill c , M. Becker d , B. Elbe d , T. Hillebrand e , M. Bibby c a Max-Delbru ¨ck-Center for Molecular Medicine, Experimantal Pharmacology, Robert-Roessle-Str. 10, D-13092 Berlin-Buch, Germany b Charite ´, Campus Berlin-Buch, Department for Surgery and Surgical Oncology, Robert- Ro ¨ssle-Hospital/HELIOS Kliniken Berlin, Robert-Roessle-Str. 10, D-13125 Berlin-Buch, Germany c Cancer Research Unit, Tom Conners Cancer Research Centre University of Bradford, Bradford BD7 1DP, UK d Experimental Pharmacology & Oncology GmbH, Berlin-Buch, Robert-Roessle-Str. 10, D-13122 Berlin-Buch, Germany e Invitek GmbH, Robert-Roessle-Str. 10, D-13122 Berlin-Buch, Germany Received 22 May 2003; received in revised form 29 July 2003; accepted 17 October 2003 Abstract Despite some success in the treatment of colorectal carcinomas, novel rational therapies targeting specific cancer-related mol- ecules are under development and urgently needed. These approaches need careful preclinical evaluation in models that closely mirror the clinical situation. Therefore, we established a panel of 15 xenotransplantable tumours directly from fresh surgical material. We showed that both the histology and expression of tumour-associated markers (Epithelial Cell Adhesion molecule (EpCAM), E-cadherin, carcinoembryonic antigen (CEA)) could be maintained during passaging in nude mice. Xenotransplanted tumours were characterised for chemosensitivity and revealed a response rate of 5/15 (33%) for 5-fluorouracil (5-FU), 15/15 (100%) for irinotecan and 8/14 (57%) for oxaliplatin. 5 patients out of 15 were treated with cytostatics because of synchronous metastases. The response to chemotherapy in these patients coincided very closely with the response of the individual xenografts. All of the xenografts expressed the proliferation marker Ki67 and the nuclear enzyme, Topoisomerase IIa (Topo IIa) at the protein level. Most of the xenografts also expressed the tumour suppressor, p53 (9/14) and the nuclear enzyme Topoisomerase Ia (Topo Ia) (13/ 14) at the protein level. Interestingly, the presence of a K-ras mutation in codon 12 (5/15 xenografts) coincided with a low response rate towards oxaliplatin. This observation needs further confirmation using a larger number of tumours. In conclusion, we were able to establish transplantable xenografts suitable to mimic the clinical situation. These well characterised models are useful tools for the preclinical development of novel therapeutic approaches and for investigating translational research aspects. # 2003 Elsevier Ltd. All rights reserved. Keywords: Apoptosis; Topoisomerase; Chemosensitivity; ras mutations; Cytostatics 1. Introduction Colorectal carcinomas represent the second most fre- quent cause of cancer deaths in the Western population. Treatment of colorectal cancers generally comprises a combination of the three classical strategies of oncol- ogy: Surgery accompanied by radio- and chemotherapy. Advanced colorectal disease is routinely treated with adjuvant therapy such as 5-fluorouracil (5-FU) combined with Leucovorin or Levamisole. Recently, novel, highly efficient compounds like oxaliplatin [1] or irinotecan [2] have been introduced into clinical treat- ment modalities. Many other molecular therapies are now under investigation including immunotherapeutic agents like Panorex [3] and molecular therapeutic approaches (for a review, see Ref. [4]). At present, the preclinical development of more effective therapeutic strategies to treat colorectal cancer is limited by the availability of well characterised clinically relevant models [5]. Cell lines used for such studies in vitro or as xenografts mainly represent poorly differentiated carci- nomas which lack similarity to the original tumour and therefore the clinical situation. To better bridge the gap between preclinical and clinical studies, we started a programme to establish colon cancer xenografts directly from surgical material. Serially transplantable tumours 0959-8049/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.ejca.2003.10.011 European Journal of Cancer 40 (2004) 298–307 www.ejconline.com * Corresponding author. Tel.: +49-30-9406-2295; fax: +49-30- 9406-3823. E-mail address: fichtner@mdc-berlin.de (I. Fichtner).