Enumeration of circulating tumor cells using a non–EpCAM-dependent device.

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e23064 Background: One component of the metastatic process is the circulation of tumor cells. Identification of these circulating tumor cells (CTCs) provides important insights into cancer biology. There is enormous heterogeneity among CTCs, necessitating capture of both epithelial and non-epithelial subtypes. Detection and monitoring of CTCs will provide a non-invasive biomarker for the detection of early progression and assessing therapeutic response. Methods: The AxonDx nCyte™ System is designed to detect rare circulating cells from peripheral blood without enrichment or selection. An epi-fluorescence microscope scans pathology glass slides on which a sample has been applied, and high-resolution images of potential CTCs are captured at four emission wavelengths. The proprietary Cancer Cell Detection Cocktail is designed to detect CTCs from numerous solid tumors, including various stages (e.g., mesenchymal-epithelial transformation) and stem cells. The software distinguishes cancer-derived material (nucleus+/cytokeratin+/WBC marker-/ > 4 µm); from leukocytes (nucleus+/cytokeratin-/WBC marker+). Vimentin is used to distinguish epithelial from mesenchymal CTCs. We obtained informed consent from 32 genitourinary cancer patients to participate in this IRB-approved study. Red blood cells from 6 mL of whole blood were lysed and removed from 32 patient samples. Nucleated cells from the blood sample were fixed, permeabilized, and stained with AxonDx’s Cancer Cell Detection Cocktail. The prepared cells were dispensed onto two microscope slides, cover-slipped, and analyzed. Results: We detected CTCs in 32 of 32 samples (100%), in a range of 0.6–64.3 CTCs/mL. Number of CTCs correlated with metastatic tumor burden. Conclusions: The AxonDx nCYTE™ system can reliably detect CTCs from genitourinary patient samples. The AxonDx nCyte™ System has also successfully detected CTCs in other tumor types, e.g., breast, lung, CRC, and HCC. Because the system is not EpCAM-dependent, it captures the heterogeneous population of CTCs. Prospective longitudinal studies are ongoing to determine trends in CTC counts.