Abstract 1721: Detection of CTCs in thoracic malignant tumors with "universal" CTC-chip

Background: Circulating tumor cells (CTCs) are tumor cells shed from primary tumor and circulate in the peripheral blood. CTCs, as a surrogate of distant metastasis, can be potentially useful in diagnosis and monitoring therapeutic effects in malignant tumors. Among a variety of systems for detection of CTCs, the “Cellsearch” is the only approved system for clinical use. However, EpCAM-negative tumor cells, such as those originating from non-epithelial cells and those undergoing epithelial-mesenchymal transition (EMT) cannot be captured with the “CellSearch” that is an EpCAM-based isolation system. Therefore, we have developed a novel polymeric microfluidic device (“Universal” CTC-chip) that can capture CTCs with or without EpCAM expression (AACR 2015). In the present study, we examined CTCs-detection performance of the CTC-chip in patients with thoracic malignant tumors (lung cancer [LC] as an “EpCAM-positive” tumor and malignant pleural mesothelioma [MPM] as an “EpCAM-negative” tumor) in comparison with that of the CellSearch. Methods: Peripheral blood sampled from each patient was divided and subjected to quantitative evaluation of CTCs with the CTC-chip as well as with the “CellSearch”. The CTC-chip, coated with an anti-EpCAM antibody, was used to capture CTCs in the blood samples (n=19) from lung cancer patients. To capture CTCs in the samples (n=11) from MPM patients, the CTC-chip was coated with an antibody against podoplanin that is expressed on the mesothelioma. After immuno-staining for cytokeratin and CD45 on the chip, a captured cell containing Hoechst-positive nucleus and cytokeratin-positive/ CD45-negative cytoplasm was judged as a CTC. The CTC-count for each sample was represented as the number per 7.5mL of the blood. Results: The median CTC-count detected with the CTC-chip in LC was 50 (range, 0-270), which was significantly higher than that (the median CTC-count, 0; range, 0-47) with the CellSearch (p