Plasma Exosomal circRNA Signature for Early Detection of Pancreatic Ductal Adenocarcinoma: A Multicenter Diagnostic Study

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is typically diagnosed at advanced stages due to the lack of reliable early biomarkers. Circulating exosomal circular RNAs (circRNAs) have emerged as promising non-invasive diagnostic candidates due to their stability and tissue-specific expression patterns. This study aims to identify and validate a plasma exosomal circRNA signature for early-stage PDAC detection—a strategy never reported before.

Methods: A discovery cohort (n=30 PDAC, n=30 healthy controls) underwent small RNA sequencing of plasma-derived exosomes to identify differentially expressed circRNAs. Candidate circRNAs were validated in a multicenter cohort comprising 240 participants: early-stage PDAC (stage I–II, n=80), chronic pancreatitis (n=40), healthy controls (n=80), and other gastrointestinal cancers (n=40). Exosomal circRNAs were quantified by droplet digital PCR (ddPCR). A diagnostic model was constructed using logistic regression and evaluated by receiver operating characteristic (ROC) analysis.

Results: Three circRNAs—hsa_circ_0001946, hsa_circ_0009024, and hsa_circ_0001492—were significantly upregulated in PDAC plasma exosomes (all fold-change >4.5, p<0.001). The three-circRNA signature distinguished early-stage PDAC from healthy controls with an area under the curve (AUC) of 0.94 (95% CI: 0.90–0.98), sensitivity of 87.5%, and specificity of 91.3%. Notably, the panel discriminated PDAC from chronic pancreatitis (AUC=0.89) and from other gastrointestinal cancers (AUC=0.86), demonstrating high specificity. In stage I PDAC (n=32), the signature achieved a detection rate of 81.3%, significantly outperforming CA19-9 (AUC: 0.94 vs. 0.78, p<0.001). Pathway analysis revealed that target genes of these circRNAs were enriched in KRAS and TGF-β signaling pathways.

Conclusions: This study identifies a novel plasma exosomal circRNA signature (hsa_circ_0001946, hsa_circ_0009024, hsa_circ_0001492) that enables accurate early detection of PDAC with high sensitivity and specificity. This non-invasive liquid biopsy approach holds promise for improving early diagnosis and clinical management of PDAC.