Developing cell-free DNA (cfDNA) epigenetic signature (ep-Sig) for early detection of malignant transformation of intraductal papillary mucinous neoplasms (IPMN).

Abstract

616 Background: Pancreatic ductal adenocarcinoma (PDA) is one of the deadliest cancers with poor outcomes. Around 20% arise from premalignant lesions (PML) including IPMN. Current guidelines recommend risk stratifying IPMN based on the location, size, and imaging characteristics after first diagnosis, followed by endoscopic ultrasound (EUS) in high-risk populations, and annual or bi-annual imaging. This approach can be improved with cfDNA testing. Traditional mutation testing in cfDNA is not useful secondary to their poor prevalence/detection rates. We propose ep-Sig to improve surveillance and early detection of PDA transformation. Methods: We curated an 11-gene cfDNA ep-Sig from the literature with a proven role in the malignant transformation of IPMN. Evidence suggests that epigenetic changes in every gene of this panel have a role in carcinogenesis in IPMNs. We compared RNA and gene expression of the genes in this ep-Sig between normal (NT) and PDA tissues using a web-based tool, TNMplot.com that uses the data from the Gene Expression Omnibus of the National Center for Biotechnology Information (NCBI-GEO) or Cancer Genome Atlas (TCGA), Therapeutically Applicable Research to Generate Effective Treatments (TARGET), and The Genotype-Tissue Expression (GTEx) repositories was used create this tool. It uses Mann-Whitney or Kruskal-Wallis tests to compute statistical significance. We used cell-free epigenome atlas (CFEA) database to examine the prevalence of these markers in cfDNA of PDA patients. Results: RNA expression of all the genes from the ep-Sig combined was significantly lower in PDA than NT (0.45, p=3.13e-26). Gene expression was 8/11 genes was lower in PDA tissues than NT (0.44, p=3.13e-26). The other 2 genes were not detected in the tested samples. Prevalence of all the markers in ep-Sig was > 90%. Conclusions: Our proposed ep-Sig has a high prevalence in PDA patients and has reliable preliminary evidence in tissues suggesting its diagnostic value. This study is the first step in developing non-invasive cfDNA testing with the potential to improve the current surveillance strategies for IPMN pending larger prospective studies.