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INTRODUCTION: Effective colorectal cancer (CRC) prevention and screening requires sensitive detection of all advanced neoplasias (CRC and advanced adenomas [AA]). However, existing noninvasive screening approaches cannot accurately detect adenomas with high sensitivity. METHODS: Here, we describe a multifactor assay (RNA-FIT test) that combines 8 stool-derived eukaryotic RNA biomarkers, patient demographic information (smoking status), and a fecal immunochemical test (FIT) to sensitively detect advanced colorectal neoplasias and other non-advanced adenomas in a 1,305-patient, average-risk, prospective cohort. This cohort was supplemented with a 22-patient retrospective cohort consisting of stool samples obtained from patients diagnosed with AA or CRC before treatment or resection. Participants within these cohorts were evaluated with the RNA-FIT assay and an optical colonoscopy. RNA-FIT test results were compared with colonoscopy findings. RESULTS: Model performance was assessed through 5-fold internal cross-validation of the training set (n = 939) and by using the model on a hold out testing set (n = 388). When used on the hold out testing set, the RNA-FIT test attained a 95% sensitivity for CRC (n = 22), 62% sensitivity for AA (n = 52), 25% sensitivity for other non-AA (n = 139), 80% specificity for hyperplastic polyps (n = 74), and 85% specificity for no findings on a colonoscopy (n = 101). DISCUSSION: The RNA-FIT assay demonstrated clinically relevant detection of all grades of colorectal neoplasia, including carcinomas, AAs, and ONAs. This assay could represent a noninvasive option to screen for both CRC and precancerous adenomas.

516 Background: Colorectal cancer (CRC) is the second leading cause of cancer related deaths in the United States. The high mortality rate is largely attributable to the high frequency of late-stage diagnoses, caused by low patient compliance with screening guidelines. A reliable and noninvasive screening alternative is needed for the 40 million noncompliant patients. The development of a novel nucleic acid extraction method to isolate stool-derived eukaryotic RNA (seRNA) permits reliable and noninvasive evaluation of biomarkers derived from the gastrointestinal (GI) epithelium. This method enables sequencing-based tools for the detection of patients with CRC and adenomas. Methods: Stool samples were obtained from 96 individuals prior to undergoing a screening colonoscopy. Fecal immunochemical tests (FITs) were obtained for each sample. RNA isolates underwent custom library preparation, next-generation sequencing, and somatic variant identification. An seRNA assay assessed the probability of CRC risk using results from the FIT, mutational burden of transcripts implicated in precancerous change (APC), and mutational burden of transcripts associated with malignant transformation (KRAS / TP53). Results: When compared to results from a colonoscopy and subsequent biopsy, the seRNA risk assessment attained a 100% sensitivity for CRC, a 71.4% sensitivity for advanced adenomas, and an 88.5% specificity for no neoplastic findings. Conclusions: A single-center, IRB-approved, prospective and blinded clinical study is being conducted in 450 patients to further develop this seRNA assay. Supplemental data will include expression from 408 seRNA transcripts. Preliminary analysis described herein indicates this assay could be the most sensitive noninvasive screening test for the detection of CRC and adenomas. [Table: see text]

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Abbreviations AUC area under the curve ANOVA analysis of variance CRC colorectal cancer DE differentially expressed FC fold-change FIT fecal immunochemical test HRA high-risk adenoma LRA low-risk adenoma MRA medium-risk adenoma NPV negative predictive value PPV positive predictive value ROC receiver operating characteristic seRNA stool-derived eukaryotic RNA AbstractBackground and aims: Colorectal cancer (CRC) is the second leading cause of cancer related deaths in the United States. Mortality is largely attributable to low patient compliance with screening and a subsequent high frequency of late-stage diagnoses. Noninvasive methods, such as stool-or blood-based diagnostics could improve patient compliance, however, existing techniques cannot adequately detect high-risk adenomas (HRAs) and early-stage CRC. Methods: Here we apply cancer profiling using amplicon sequencing of stool-derived eukaryotic RNA for 275 patients undergoing prospective CRC screening. A training set of 154 samples was used to build a random forest model that included 4 feature types (differentially expressed amplicons, total RNA expression, demographic information, and fecal immunochemical test results). An independent hold out test set of 121 patients was used to assess model performance. Results: When applied to the 121-patient hold out test set, the model attained a receiver operating characteristic (ROC) area under the curve (AUC) of 0.94 for CRC and a ROC AUC of 0.87 for CRC and HRAs. In aggregate, the model achieved a 91% sensitivity for CRC and a 73% sensitivity for HRAs at an 89% specificity for all other findings (medium-risk adenomas, low-risk adenomas, benign polyps, and no findings on a colonoscopy). Conclusion: Collectively, these results indicate that in addition to early CRC detection, stool-derived biomarkers can accurately and noninvasively identify HRAs, which could be harnessed to prevent CRC development for asymptomatic, average-risk patients.