Abstract
Abstract Peritoneal metastasis (PM) represents a terminal tumor stage with limited therapy options for patients with colorectal cancer (CRC). To improve therapeutic efficacy and overall survival, availability of appropriate in vivo models of PM could improve the evaluation of chemosensitivity as well as identification of novel biomarkers and therapeutic targets to improve the therapeutic outcome of PM patients. In this context, we generated the first patient-derived xenograft (PDX) models of PM from CRC as platform to test chemotherapy response and to potentially analyze biomarkers. For the PDX establishment colorectal surgical specimens were subcutaneously (s.c.) transplanted onto immunocompromised NOG mice. The engrafted tumors were transferred to NMRI nu/nu mice for further passaging. They were characterized by histopathology, immunohistochemistry, and gene expression analyses using real-time RT-PCR. Chemosensitivity of PDX models was evaluated in vivo by application of a panel of conventional chemotherapeutic and of targeted drugs. For PDX establishment 68 CRC surgical specimens (taken from peritoneum and omentum) were transplanted, from which 22 PDX have engrafted. From those, 13 models of 10 patients have been analyzed. Their tumor doubling times ranged between 4 to 28 days. The histopathologic evaluation revealed maintenance of the original CRC histology in the PDX. The chemosensitivity testing of conventional and of targeted drugs in the 13 PM PDX models revealed the individual, diverging response of the PDX, such as for 5-FU, irinotecan, oxaliplatin, cetuximab, and erlotinib. More interestingly, different responses were observed in PDX of the omentum vs. peritoneum, which were derived from the same patient. Our results demonstrate that this novel panel of PDX maintains the morphology of the patient tumor in early passages, reflect heterogeneous response rates, and can be used as a preclinical in vivo platform for translational studies of potential clinical use. In conclusion, this PDX panel of PM of the CRC can be used for further studies to evaluate new biomarkers and to test novel therapies or combinations for PM of CRC. Citation Format: Wolfgang Walther, Eva Pachmayr, Bernadette Brzezicha, Britta Büttner, Beate Rau, Ulrike Stein. Novel patient-derived xenograft (PDX) models from peritoneal metastasis of colorectal carcinoma for drug testing and biomarker analysis [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr A17.
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