Abstract 5103: Development of detecting systems for circulating tumor cells in malignant pleural mesothelioma patients.

Abstract Background. To isolate and quantify of CTCs, the CellSearch system is the most commonly used techniques, approved by the FDA. But in this system, EpCAM negative CTCs are excluded. To detect CTCs in malignant pleural mesothelioma patients, we have developed two novel approaches, CTC-Chip and immunomagnetic beads which could be labeled with any type of antibodies. Methods. To evaluate the accuracy of the number of CTCs, we used the peripheral blood samples collected from healthy donors, spiked definite number of tumor cell lines, ACC-MESO1 and ACC-MESO4. Both tumor cell lines (obtained from ATCC) were derived from malingnant pleural mesothelioma, positive of mesothelin and podoplanin. The recovery rate was evaluated with two methods, the CTC-Chip and immunomagnetic beads, coated with antibodies specific for mesothelin and podoplanin. In addition, an 8 ml sample of peripheral blood was collected from a patient with malignant pleural mesothelioma, and was served for the immunomagnetic beads. To identify the captured cells as tumor cells, immunocytochemistry was performed using with the cocktail of two human cytokeratin-specific antibodies. Results. To confirm the efficacy of tumor isolation by two methods, we used tumor cell suspicion as samples. In CTC-Chip coated with anti-mesothelin and podoplanin, the recovery rate of captured ACC-MESO1 was 99%, 97%, respectively. The recovery efficiency of ACC-MESO1-spiked blood samples using CTC-Chip coated with anti-mesothelin and podoplanin, was 45%, 80%, respectively. In immunomagnetic beads coated with anti-mesothelin and podoplanin, the recovery rate of captured ACC-MESO4 was 80%, 25%, respectively. The recovery efficiency of ACC-MESO4-spiked blood samples using immunomagnetic beads coated with anti-mesothelin and podoplanin, was 33%, 15%, respectively. The CTCs from a patient was detected using with immunomagnetic beads coated with anti-mesothelin antibody and CTC count was 440 per 8 ml of peripheral blood. Conclusions. Both CTC-Chip and immunomagnetic beads could capture CTCs, using antibodies specific for mesothelin and podoplanin. Detection of CTCs from a patient with malignant pleural mesothelioma was performed by labeling of mesothelin-coated immunomagnetic beads. But the recovery rate of tumor cells in spiked samples were less than 30%. The step of deletion of red blood cells is necessary to be improved. Citation Format: Chikaishi Yasuhiro, Tomoko So, Soichi Oka, Masaru Takenaka, Makoto Nakagawa, Hidehiko Shimokawa, Teruo Iwata, Yoshika Nagata, Hidetaka Uramoto, Takeshi Hanagiri, Takeshi Ohnaga, Fumihiro Tanaka. Development of detecting systems for circulating tumor cells in malignant pleural mesothelioma patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5103. doi:10.1158/1538-7445.AM2013-5103