325 Novel Multi-Target Stool DNA Marker Panel Yields Highly Accurate Detection of Colorectal Cancer and Premalignant Neoplasia

INTRODUCTION: Despite the demonstrated effectiveness of average-risk screening, colorectal cancer (CRC) remains the 2 nd leading cause of cancer death in the US. For optimal prevention, CRC screening tools should be highly accurate, user-friendly, and broadly accessible. Patient and provider adoption of the FDA-approved, guideline-endorsed multi-target stool DNA (mt-sDNA) test has grown exponentially since its launch in 2014. Toward ongoing improvement in CRC screening effectiveness, we conducted a blinded case-control study to assess the detection accuracy of a mt-sDNA panel of novel, highly discriminant methylated DNA markers (MDMs). METHODS: We selected 12 candidate MDMs from prior whole methylome discovery and validation in tissue. Stool was obtained as part of previous large, multicenter studies and collected prior to or 7 days post-colonoscopy (prior to any clinically-indicated treatment). CRC, advanced adenoma (AA; size ≥1 cm, high-grade dysplasia, or ≥25% villous morphology), non-AA, or control (no neoplasia) status was defined by colonoscopy and histopathology. Samples were blinded to operators and randomized by characterization to balance the test sets prior to assessment. MDMs were quantified by target-specific DNA capture and Long-probe Quantitative Amplified Signal assay on bisulfite-converted DNA; fecal hemoglobin was quantified by immunoassay. Bootstrapping methods were used to select a panel of 3 MDMs, which was then 10-fold cross-validated; hemoglobin was also included, as was a colon epithelium-specific MDM to normalize stool MDM levels. RESULTS: Participant samples included 117 CRC, 120 AA, 161 non-AA, and 327 controls. Median age was 67 (IQR 61, 75) years; 51% were men. The AUC with best-fit was 0.97 for CRC and 0.84 for AA, and these high AUCs held up tightly on cross-validation (Figure 1). At 92% (95% CI 88-94%) specificity, sensitivity of the panel was 92% (95% CI 86-96%) for CRC. Neither CRC stage (Figure 2) nor CRC site significantly affected performance. At the same 92% specificity, sensitivity was 65% (95% CI 56-73%) for AAs overall, 67% (38-88%) for sessile serrated polyps ≥1 cm, and 71% (57-82%) for adenomas with villous features (Figure 3). CONCLUSION: These data support highly accurate performance of a novel panel of mt-sDNA markers for detecting both CRC (including early stage lesions) and AAs at greatest risk of progression. Prospective comparative studies are warranted to further establish the clinical potential of this novel screening tool.