Endocrine Abstracts

Only a few cell lines are available for endocrine tumors which furthermore do not reflect heterogenous functional properties and specific therapeutic response rates of individual tumors. To facilitate patient individual treatments and thereby to optimize therapeutic efficacy, we are aiming at the development and characterisation of patient-individual tumor models. Pieces of surgical tumor specimen from four adrenocortical carcinomas, one aldosterone producing adenoma, one pheochromocytoma (pheo), one metastasis of a malignant pheo, one pheo and medullary thyroid carcinoma associated with multiple endocrine neoplasia type 2 and 9 neuroendocrine tumors (NETs, seven NETs of the gastroenteropancreatic system including one metastasis as well as one primary tumor and one metastasis of Merkel cell carcinoma) were implanted subcutaneously in athymic NMRI nude mice at this time. To investigate whether morphological and functional characteristics between tumor samples after mouse engraftment in comparison to the original tumor would be comparable, we started examination of implanted material and original patient tumor by histology and immunohistochemistry. Twelve weeks after engraftment tumors were explanted and investigated for vitality (HE), proliferation (Ki67) and endocrine differentiation marker (SF-1, Chromogranin A). HE stainings revealed successful engraftment with maintained vitality of the implanted tumor tissues. Ki67 stainings exhibited furthermore proliferating tumor cells in the implanted material. In addition, depending on the entity tumors expressed SF-1 or Chromogranin A. First comparisons indicate that the implanted tumors keep the characteristics of the original tumor material in the murine host. These findings need to be further substantiated and additional endpoints such as vascularization and endocrine potential need to be examined. Nevertheless, these tumor models have the potential to evaluate individualized treatment modalities in the future.