QS117 - Evaluating circulating hybrid cells to identify disease evolution in colorectal cancer

Image or Table (Do Not add text here):

Purpose/Background: Despite the advent of FDA-approved blood screening tests for colorectal cancer (CRC), they still fall short to detect advanced adenomas, also called advanced precursor lesions (APL), which are at highest risk of progression to CRC. Colonoscopy is still the gold standard for addressing these lesions; however, compliance is poor and fails those persons with limited healthcare access. Circulating tumor cells (CTCs) are currently used in FDA-approved blood screening tests and represent cells shed from the primary tumor into the peripheral blood. Our team identified a novel disseminated neoplastic-immune cell in peripheral blood called circulating hybrid cells (CHC) that are present in peripheral blood at numbers which are an order of magnitude greater than conventionally defined CTC. These cells are identified not only in the blood of patients with CRC, but also in those with APL.

Methods/Interventions: Peripheral blood samples were collected from patients across the colorectal disease continuum from healthy patients to APL to CRC immediately prior to colonoscopy or surgical resection. Peripheral blood mononucleocytes (PBMC) were isolated utilizing Ficoll gradient centrifugation, processed onto glass slides, and stained via standard immunofluorescence methods. CHCs were identified by co-expression of CD45 as well as pancytokeratin (panCK), epithelial cell adhesion molecule (EpCAM), and/or epithelial cadherin (E-cad). After staining, we utilized QiTissue software to visualize images for enumeration of CHC and normalized values to 50,000 PBMC. CHC levels were compared between patient cohorts (healthy, APL, CRC) with Kruskal-Wallis testing. After enumerating CHC for each patient sample, we performed chart review for clinical correlation.

Results/Outcomes: Evaluation was completed on N=60 patients (N=21 healthy, N=20 APL, and N=19 CRC). Enumeration of CHCs revealed that there were significantly more CHCs in the peripheral blood of patients with APL compared to healthy individuals (healthy mean = 1.7, SD = 2.3; APL mean = 17.9, SD = 6.7, p< 0.001). Further, there were significantly more CHCs in patients with CRC compared to APL and healthy (mean = 39.8, SD = 25.8, p< 0.0001 compared to healthy, p=0.030 compared to APL).

Conclusion/Discussion: CHCs are present in the peripheral blood of patients with APL at significantly higher numbers than healthy individuals but lower numbers than patients with CRC. This indicates that CHC could represent a viable biomarker to identify individuals at high risk of developing CRC. Despite statistical significance between levels of CHC in APL compared to CRC, there is some overlap in enumeration between patients with CRC and APL. Utilizing phenotypic information as well as enumeration of CHC offers great potential to better understand the biology of malignant transformation and impact the early detection of CRC.