Introduction

The identification and establishment of reliable biomarkers and early diagnostic system for pancreatic ductal adenocarcinoma (PDAC) are urgently needed. Although blood-based liquid biopsy for comprehensive genomic profiling is useful for cancer diagnosis, we have recently shown that driver gene mutations derived from PDAC can be detected at a higher rate in pancreatic juice (PJ) than blood. We have also reported that some RNAs are carried within extracellular vesicles (EVs) and EV-encapsulated RNAs circulating in body fluid are useful as biomarkers for PDAC diagnosis. We recently developed a unique immunoprecipitation method called EViSTEP™ that utilizes a chelating-based reagent and EV surface marker antibodies (CD9/CD63) to isolate EVs with high purity and high yield.

Aims & Methods

In this study, we aimed to evaluate the usefulness of multi-layer liquid biopsy system by DNA mutation and RNA expression in PJ for cancer diagnosis. PJ samples (n=83; 15 benign hepatopancreatobiliary diseases, 33 low-grade (LG) IPMN, 10 high-grade (HG) IPMN and 25 PDAC) were collected during ERCP examination from each patient in a multicenter study. Cell-free (cf) DNA/RNA and EV-derived RNA (EV RNA) were purified from 2 ml of each PJ. Digital PCR was performed for driver gene mutation analysis (4 types of KRAS and 2 types of GNAS), as well as expression analysis of 10 long non-coding RNAs (lncRNA, e.g., HEVEPA, LINC02280) in cfRNA and EV RNA. The diagnostic performance of pancreatic cancer (PDAC+HG-IPMN) was statistically analyzed after normalizing RNA expression with two reference genes (ACTB/B2M).

Results

Logistic regression analysis (objective variables; PDAC+HG IPMN and others) with the KRAS and GNAS variant allele frequency (VAF), and RNA expression as factors was performed. The Area Under Curves (AUC) in Receiver Operating Characteristic (ROC) curve analysis for PDAC+HG IPMN diagnosis were 0.490-0.74 for KRAS mutations, 0.475-0.554 for GNAS mutations, 0.451-0.654 for cfRNA expressions and 0.362-0.639 for EV RNA expressions. Among them, the factors with relatively high AUC were KRASG12V (0.728), KRASG12R (0.687), cfRNA RP11-750H9.5/ACTB(0.654), EV RNA CRNDE/ACTB(0.633). The AUC values of the combinations, [KRASG12V, KRASG12R, cfRNA RP11-750H9.5/ACTB and EV RNA CRNDE/ACTB] and [the aforementioned four factors and CA19-9], were 0.876 and 0.885, respectively in terms of discriminating PDAC+HG IPMN. Moreover, concerning the diagnosis of Stage 0/I PDAC, the AUC values of EV HEVEPA, CA19-9, and the combination [EV HEVEPA and CA19-9] were 0.693, 0.746 and 0.84, respectively, suggesting that EV HEVEPA would be reliable biomarker for early detection of PDAC.

Conclusion

By incorporating cell-free lncRNA and EV lncRNA expression analysis into DNA mutation analysis in PJ samples could be expected to improve the diagnostic performance of pancreatic cancer. Liquid biopsy using PJ would predict the presence of neoplastic lesions with high probability and has a powerful potential for early diagnosis. Establishing the multilayer gene panel using these DNA and RNA has the potential to improve the early diagnostic accuracy for pancreatic cancer, a disease that exhibits significant diversity.

Disclosure

Grants for commissioned/joint research: Hitachi High-Tech Corporation (KT, YM), H.U. Group Research Institute G.K. (KT)

Introduction

Defining pancreatic steatosis (PS) and establishing its association with pancreatic cancer has been a discussed theme in the last decade. However, no consensus guidelines have yet been published on the clinical relevance and management of PS. In this systematic review and meta-analysis, we investigated the association between PS and pancreatic ductal adenocarcinoma (PDAC).

Aims & Methods

Medical literature between 2007 and 2023 was reviewed for eligible trials investigating the prevalence of PS in patients with PDAC. Eligible studies reporting on PS, assessed via imaging or histology, were included. Our primary objective was to determine the association between PDAC and PS by comparing the prevalence of PS in individuals with- and without PDAC. Subsequently, an evaluation was conducted to determine whether the method of assessment (CT, MRI, EUS or histology) and study country was correlated with the association between PS and PDAC. Measures of effect size were determined using odds ratios (ORs) and corresponding 95% confidence intervals (95% CI).

Results

The systematic review identified a total of 23 studies, of which seventeen studies examined PS prevalence among PDAC patients. Overall, the pooled prevalence of PS in patients with PDAC. was 53.6% (95% CI 40.9-66.2). No significant difference in PS prevalence was observed across various diagnostic methods or geographical regions (p= 0.71 and p= 0.50, respectively). Overall, the pooled OR for PS in in patients with PDAC compared to controls was 3.23 (95% CI 1.86-5.60, Figure 1). Subgroup analysis did not reveal any difference according to country (p= 0.52), but higher OR was observed in studies using EUS for the assessment of PS (pooled OR=6.26, 95% CI 1.23-31.8) compared to studies using CT (pooled OR=3.31, 95% CI 1.93-5.68), histology (pooled OR=1.76, 95% CI 1.22-2.54) or MRI (pooled OR=1.19, 95% CI 1.06-1.33).

Conclusion

Patients with PDAC have notable prevalence of pancreatic steatosis (53.6%). Furthermore, PDAC patients are significantly more likely to have PS (OR 3.23). These findings underscore the importance of prioritizing a standardized approach to the diagnosis, follow-up, and treatment of PS. Future studies should prioritize the identification of patients with PS who will benefit from PDAC surveillance programs.