S1137 Analytical Sensitivity of a Quantitative Immunochemical Fecal Occult Blood Test (FIT) in Screening for Colorectal Cancer

based on a nucleic acids multi-gene assay performed on peripheral blood mononuclear cells (PBMCs) that can detect early CRCs and adenomas.Methods: 116 patients (mean age: 55 years; range: 18 to 74 years; female/male ration 0.98) were included in this pilot, nonblinded, colonoscopy-controlled study.Colonoscopy revealed 21 patients with CRC, 30 patients with adenoma bigger than 1 cm, 24 patients with inflammatory bowel disease (IBD) and 41 patients had no neoplastic or inflammatory lesions.Blood samples were taken from each patient the day of the colonoscopy and PBMCs were purified.Total RNA was extracted following standard procedures.Multiplex RT-qPCR was applied on 92 different candidate biomarkers.Different univariate and multivariate statistical methods were applied on these candidates, and among them, 57 biomarkers with significant p values (<0.01,Wilcoxon test) were selected, including ADAMTS1, MMP9, CXCL10, CXCR4, VEGFA and CDH1.Two distinct biomarker signatures are used to separate patients without neoplastic lesion from those with cancer (named COLOX 1 test), respectively from those with adenoma (named COLOX 2 test).Result: COLOX 1 and 2 tests have successfully separated patients without neoplastic lesion from those with CRC (sensitivity 70%, specificity 90%, AUC 0.88), respectively from those with adenoma bigger than 1cm (sensitivity 61%, specificity 80%, AUC 0.80).6/24 patients in the IBD group have a positive COLOX 1 test.Conclusion: These two COLOX tests demonstrated an acceptable sensitivity and a high specificity to detect the presence of CRCs and adenomas bigger than 1 cm.The false positives COLOX 1 test in IBD patients could possibly be due to the chronic inflammatory state.A prospective, multicenter, pivotal study is underway in order to confirm these promising results in a larger cohort.