CD63-positive extracellular vesicles are potential diagnostic biomarkers of pancreatic ductal adenocarcinoma.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest gastrointestinal cancers with a 5-year survival rate of less than 10%. Biomarkers for early PDAC detection are useful in treating patients with PDAC. Extracellular vesicles (EVs) are lipid-bound vesicles that are potential biomarkers of various diseases such as PDAC. In this study, we quantitatively measured the serum levels of EVs (CD63+-EVs) or platelet-derived EVs (CD41+- and CD61+-EVs) and evaluated their potential use as biomarkers of PDAC. METHODS: We measured the serum levels of CD63+-, CD41+-, CD61+-EVs using sandwich enzyme-linked immunosorbent assay based on Tim4 with specificity for phosphatidylserine on EVs in age- and sex-matched healthy controls (HCs, n = 39) and patients with PDAC (n = 39). We also examined the effect of tumor burden on the serum EV levels after surgical resection (n = 28). CA19-9, a clinical PDAC biomarker, was also measured for comparison. RESULTS: Serum levels of CD63+-EVs, CD41+-EVs, and CD61+-EVs were significantly increased in patients with PDAC compared to HCs. Receiver operating characteristic analysis revealed that CD63+-EVs exhibited the highest diagnostic performance to discriminate patients with PDAC from HCs (area under the curve (AUC): 0.846), which was comparable to CA19-9 (AUC: 0.842). CA19-9 showed lower AUC values in early stages (I-II, AUC: 0.814) than in late stages (III-IV, AUC: 0.883) PDAC. Conversely, CD63+-EVs, CD41+-EVs, and CD61+-EVs showed comparable AUCs between early- and late-stage PDAC. The combined use of CA19-9 and CD63+-EVs showed a higher diagnostic performance for early-stage PDAC (AUC: 0.903) than CA19-9. The serum levels of CD63+-EVs, CD41+-EVs, CD61+-EVs, and CA19-9 decreased significantly after surgical resection, demonstrating that EVs are increased in sera of patients depending on the tumor burden. CONCLUSIONS: The serum levels of CD63+-EVs and platelet-derived EVs (CD41+-EVs, CD61+-EVs) are increased in patients with PDAC than HCs. Since CD63+-EVs showed a high AUC to discriminate patients with PDAC from HCs; they might be useful as potential biomarkers for PDAC.