Abstract 2342: Profiling microRNAs in fecal immunochemical test leftover buffer to improve colorectal cancer screening

Abstract Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide, but large screening programs can effectively reduce both incidence and mortality. Fecal immunochemical test (FIT) is widely used in CRC screening programs and cost-effective. However, FIT test shows a low sensitivity for advanced adenomas (AA) and is also prone to false positive results, resulting in unnecessary total colonoscopies (TC). Leftover from FIT samples after hemoglobin measurement may offer unique opportunity to study alternative biomarkers, which may allow adopting a tailored screening approach. Altered miRNA profiles can be detected non-invasively in fecal samples. Our group studying the whole miRNome in stool recently contributed to the identification of a miRNA signature that accurately discriminates sporadic CRC at diagnosis (Pardini et al, Gastroenterology 2023) and demonstrated the feasibility of miRNA profiling in FIT leftovers (Birkeland et al. Mol Cancer 2023). However, a potential implementation of miRNA markers in FIT-based screening has not been fully explored. The aim of the study was to investigate the association of miRNA expression profiles with CRC or adenomas as well as the predictivity of miRNA signatures for outcomes at the subsequent screening round among screens examined within the population-based screening program in Turin, Italy. Small RNA sequencing was performed on leftover FIT samples of 438 subjects: 183 FIT positive (FIT+) detected with colorectal neoplasm (45 early adenomas, 110 AA, and 28 CRC), 93 with FIT+ and negative TC and 162 FIT negative (FIT-) controls. We compared the miRNA expression profiles of FIT+ screens with a negative TC and of those detected with neoplasia. For a subset of 213 subjects with a negative FIT at the previous round, we compared the miRNA profile at the first sample among screens with persistent negative results with those with a positive FIT and neoplasms. An average of 691 miRNAs were detected and 198 among them identified in more than 90% of the samples. Differential expression analyses between FIT+ and FIT- samples showed 379 miRNAs with significantly different levels (adj. p<0.05), mainly in AA or CRC. Notably, the previously identified 5-miRNA signature in stool was confirmed able to distinguish in FIT+ subjects with AA or CRC with respect to FIT-. miR-1246 was able to distinguish also subjects with neoplasm from those with negative TC. An increase of miR-1246 levels was observed in leftover samples of subjects at first round of screening who were detected AA or CRC following a positive FIT result at second round with respect to those with FIT- test. The previously identified miRNA signature shows a good performance in discriminating subject with neoplasm within FIT+ subjects. Further analyses to investigate the performance of various miRNA sets according to different FIT levels or screening rounds are ongoing. Citation Format: Barbara Pardini, Giulio Ferrero, Sara Bulfamante, Sonia Tarallo, Giulia Francescato, Davide Ricupero, Gianluigi Ferrante, Carlo Senore, Alessio Naccarati. Profiling microRNAs in fecal immunochemical test leftover buffer to improve colorectal cancer screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2342.