Abstract 3963: Capture of EpCAM-negative mesothelioma cells with a “universal CTC-chip”: Sensitivity test and comparison with EpCAM-based standard method
Authors: Yoneda Kazue , Chikaishi Yasuhiro , Kawashima Eri , Ohnaga Takashi , Tanaka Fumihiro 
Published: July 2016

Backgrounds: Circulating tumor cells (CTCs), as a surrogate of distant metastasis, can be potentially useful in early diagnosis and monitoring therapeutic effects for patients with malignant tumors. Among a variety of systems for detection of CTCs, an epithelial cell adhesion molecule (EpCAM)-based immuno-magnetic separation system “CellSearch” is the only system approved for clinical use. Our previous study showed that CTC detected by CellSearch was useful in the diagnosis or the prognosis of epithelioid-type malignant pleural mesothelioma, however, the sensitivity was insufficient. Because EpCAM-negative tumor cells, such as those originating from non-epithelial cells and those undergoing epithelial-mesenchymal transition, cannot be captured using the “CellSearch”. Therefore, we have developed a novel polymeric microfluidic device system “universal CTC-chip” that can capture a variety of CTCs with or without EpCAM expression (AACR 2015). In the present study, we assessed its sensitivity for capturing mesothelioma cells and compare with CellSearch.

Methods: PC-9, human lung cancer cell line and ACC-MESO-4, human mesothelioma cell line were used in this study. Antibodies were coated on the chip in two steps, first with anti-mouse IgG antibody (“base-antibody”) and then as a “capture-antibody”, either mouse anti-human EpCAM antibody to capture EpCAM-positive cells (“EpCAM chip”) or mouse anti-human podoplanin antibody to capture podoplanin-positive mesothelioma cells (“podoplanin chip”). For sensitivity test, each cell line was suspended as concentration 500, 100, 50, 10cells/mL in phosphate buffered saline (PBS) or in blood. After 1ml of sample was flowed, we counted cells and calculated capture efficiency (number of capture cells /flowed cell). For comparison with CellSearch (CS), each cell line was suspended as concentration 50 or 10 cells /mL in blood and calculated detection efficiency (number of detected cells/ suspended cell).

Results: In sensitivity test, capture efficiency of PC-9 or ACC-MESO-4 was 101.1%, 90.7% (500 cells/mL), 94.8%, 95.9% (100 cells/mL), 104.7%, 97.9% (50 cells/mL), 114.3%, 113.75% (10 cells/mL), respectively in PBS. In the blood sample, capture efficiency of PC-9 or MESO-4 was 99.2%, 50% (50 cells/mL), 115.5%, 80.55% (10 cells/mL), respectively. On the other hand, detection efficiency of PC-9 (EpCAM chip, CS) was 110%, 121.3% at 50 cells/mL, 195%, 126% at 10 cells/mL in blood. In case of MESO-4, detection efficiency (podoplanin chip, CS) was 55%, 1.1% at 50 cells/mL, 70%, 0% at 10 cells/mL in blood.

Conclusion: The novel “universal CTC-chip” can be a promising CTC detection system.

Citation Format: Kazue Yoneda, Yasuhiro Chikaishi, Eri Kawashima, Takashi Ohnaga, Fumihiro Tanaka. Capture of EpCAM-negative mesothelioma cells with a “universal CTC-chip”: Sensitivity test and comparison with EpCAM-based standard method. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3963.