MOY 2 MicroRNAs as Bile Based Biomarkers for Pancreaticobiliary Cancers (MIRABILE)

Abstract Aims MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at the post-transcriptional level. They are commonly deregulated in cancer and are incredibly stable molecules in tissues and biofluids. Accurate identification of a malignant biliary stricture can sometimes be challenging. We aimed to identify miRNAs in the bile that are able to differentiate between malignant (pancreatic ductal adenocarcinoma (PDAC) and cholangiocarcinoma (CCA)) and benign pancreaticobiliary disease. Methods There were 111 patients recruited prospectively at initial endoscopic retrograde cholangiopancreatography (ERCP) for obstructive jaundice and bile aspirated for analysis. Total cell-free RNA was extracted from the bile from a discovery cohort of patients (n=78: 27 PDAC, 14 CCA, and 37 benign disease) and small RNA sequencing was performed. LASSO regression analysis was used to define bile miRNA signatures, and NormFinder used to identify endogenous controls. A validation cohort was used (n=87: 34 PDAC, 14 CCA, and 39 benign disease) to confirm candidate miRNAs using TaqMan RT-qPCR. Results We identified 6 potential bile miRNAs, of which 4 were suitable for RT-qPCR validation. We found miR-340 and miR-182 were significantly differentially expressed (p=0.0268 and p=0.0004 respectively) in malignant vs. benign bile, with combined AUC of 0.80 (sensitivity 64.6%; specificity 82.1%) for predicting malignant pancreaticobiliary disease. Adding serum CA 19-9 to this bile miRNA model improved the diagnostic potential (AUC 0.85: sensitivity of 86.4%; specificity of 71.4%). Conclusions Bile obtained at ERCP contains miRNAs able to differentiate benign from malignant pancreaticobiliary disease. Our novel bile miRNAs can be used with serum CA 19-9 to rapidly detect CCA and PDAC in patients presenting with obstructive jaundice.