Abstract LB-363: Characterization of in vitro and in vivo models generated from disseminated tumor cells of patients without manifest metastasis

Abstract

Abstract We recently showed that dissemination of few melanoma cells to the lymph nodes is a quantitative risk factor for death from melanoma. However, the analysis of disseminated tumor cells (DTC) is limited by their extremely low frequency, resulting in a lack of in vitro/in vivo models for mechanistic studies of early systemic disease. Therefore, the objective of this study was to develop protocols to expand single DTC from lymph nodes of melanoma patients to establish better preclinical models for adjuvant cancer therapies. Sentinel lymph nodes from melanoma patients were cut in halves, disaggregated and analyzed for the presence of gp100-positive DTC. The other half was used for diagnostic assessment by histopathology. Single DTC within the lymph node-derived single cell suspension were then propagated under specific sphere forming conditions and expanded by transplantation in immunodeficient mice. DTC based pre-clinical in vitro/in vivo models were then characterized on molecular level and were used for functional analyses. To test drugs on DTC in presence of a human immune system we additionally generated humanized xenograft models. We successfully established cell lines and xenografts from DTCs of 17 melanoma patients. We confirmed the origin of the cells by genomic fingerprint and analyzed the genomic profile of the expanded cells over various culture and animal passages. DTC cell lines were used for functional analysis and for testing the efficacy of targeted therapies. In addition, we set up a novel preclinical mouse model based on expanded melanoma DTC. For this, we established a human immune system in immunodeficient mice, which were then transplanted with melanoma DTC-derived cells. Interestingly, the presence of a human immune system significantly induced tumor formation, as well as dissemination of melanoma cells and improved the response to a targeted therapy compared to mice without a humanized immune system. The development of DTC based pre-clinical in vitro/in vivo models enables mechanistic studies on DTCs and drug tests against the target cells of adjuvant therapies in the presence of human immune cells. These models may help to identify candidate adjuvant therapies targeting DTCs and to understand mechanisms of drug resistance of currently applied targeted therapies. Citation Format: Christian Werno, Kathrin Weidele, Steffi Treitschke, Catherine Botteron, Sebastian Scheitler, Bernhard Polzer, Melanie Werner-Klein, Christoph Andreas Klein. Characterization of in vitro and in vivo models generated from disseminated tumor cells of patients without manifest metastasis [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 LB-363.