Description:
e15527 Background: Circulating epithelial tumor cells (CETCs) are an important link between primary tumors and metastases and provide a readily accessible source of tumor material from patients with solid cancer. Therefore, they are representative for primary and metastatic lesions to evaluate treatment response in real-time and to guide therapeutic modifications. Beyond enumeration, information on mutations is extremely important in the clinical setting to monitor the development of the disease over time and to guide drug selection. Isolating single CETCs with high recovery and purity from the high background of blood cells is an indispensable prerequisite to investigate cell heterogeneity and provides a tool for a personalized medicine approach. Methods: Blood from patients with non-small cell lung cancer, colon cancer and malignant melanoma was analysed for CETCs using the maintrac approach. Between 8-20 EpCAM positive cells from each patient were isolated individually using a semiautomated capillary approach and deposited one by one into micro cups. For mutational profiling, EGFR, KRAS and BRAF hotspot mutations were analysed in CETCs after whole genome amplification. Results: DNA could be amplified from all individually isolated cells. EGFR mutations were detected in 17% of isolated tumor cells from patients with non-small cell lung cancer; KRAS mutations were detectable in 28% of cells from patients with colon cancer and BRAF mutations in 50% of evaluable cells. A high heterogeneity in mutation status was observed among CETCs within a patient. Conclusions: Individually isolating CETCs from the peripheral blood from patients with non-small cell lung cancer, colon cancer and melanoma allows not only to detect driver mutations but also to determine genotypic heterogeneity between cells and changes over time. Mutations in the CETCs resemble those detected in primary tumors present only in part of the cells. They can be used to monitor the development of disease and its status over time, particularly for its impact in guiding drug selection.