Abstract 1452: Perioperative detection of circulating tumor cells in patients undergoing colorectal cancer liver and lung metastasectomy : Comparing CellSearch and FMSA technologies and investigating the role of EMT .

Abstract

Abstract Circulating tumor cells (CTCs) reflect disease burden in metastatic colorectal cancer (mCRC) and patients with resectable liver and lung metastases are potentially curable by surgery with a 5-year survival of 30% . Here we report a study where we are detecting CTCs from blood of such patients collected perioperatively, using simultaneously the FDA-approved Veridex CellSearch and the Flexible Micro Spring Array (FMSA) device developed by Penn State Bioengineering and have accrued 12 patients so far. 7.5 ml of blood is collected from the central venous catheter placed during surgery at incision, at the point of starting surgical resection of the mass, 30 minutes after complete removal of the mass and on the day after surgery. Variation in CTC counts between samples from the same patient is expected to provide valuable answers about the kinetics of tumor cell shedding and dissemination during surgery. Tissue from resected liver or lung is appropriately stored for benchtop studies to correlate molecular signatures with CTC counts. Preliminary results suggest a mean count of 36 cells per blood sample detected using FMSA technology, with counts varying between zero to 101 cells / 7.5 ml of blood, in contrast to only zero to 2 cells in similar samples detected using the CellSearch method. FMSA relies on size-based isolation of CTCs from blood which are identified as CK+, DAPI +, CD45- cells on further immunostaining .The trial provides an opportunity to compare the two technologies in an important clinical setting and understand the underlying molecular mechanisms for the difference in counts . Aggressive tumors have been hypothesized to shed cells that have undergone EMT and thus evade detection by the EpCAM-based CellSearch detection method . We have noted expression of the mesenchymal marker vimentin in the CTCs captured by FMSA device thus documenting EMT . We plan to do additional stem cell and prognostic marker analysis on FMSA-captured CTCs . Both liver and lung metastases are being studied to compare two organs with different vascular anatomies and divergent surgical techniques. Correlating cell counts with disease-free survival as well as relapse will be helpful in validating intra-operative CTC isolation technique as means of prognosticating post-surgical recovery and gain insights into link between possible vascular tumor cell shedding and the surgical and vascular ligation technique that is followed. Future directions include comparing results with a patient population undergoing hepatic or pulmonary surgical procedures for non-malignant disease as well as extend the trial to include patients who are candidates for adjuvant chemotherapy and explore the role of intraoperative CTC counts and marker expression in choice of regime and predicting response. Citation Format: Avisnata Das, David T. Dicker, Ramdane Harouaka, Siyang Zheng, Noel Warfel, Kevin F. Staveley-O'Carroll, Wafik S. El-Deiry, Jussuf T. Kaifi. Perioperative detection of circulating tumor cells in patients undergoing colorectal cancer liver and lung metastasectomy : Comparing CellSearch and FMSA technologies and investigating the role of EMT . [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 1452. doi:10.1158/1538-7445.AM2013-1452