Better preoperative characterization of patients with pancreatic ductal adenocarcinoma (PDAC) would aid in treatment optimization. Extracellular vesicles (EV) are promising, largely unexplored biomarkers in PDAC. This study aimed to evaluate if plasma EV characteristics are associated with PDAC clinical characteristics and overall survival (OS). The prospective cohort included 34 PDAC patients undergoing surgery with curative intent. Patient data and plasma samples were collected preoperatively, intraoperatively and one month postoperatively. Small plasma EV (sEV) concentration and size were determined by nanoparticle-tracking analysis. A Mann-Whitney test, Spearman's rho and Cox regression were used in statistical analysis. Preoperatively, patients with poorly differentiated tumors had significantly larger plasma sEVs when compared to patients with well/moderately differentiated tumors (mean diameter 176.9 vs. 149.2 nm, p = 0.021), the sEV size even enabling discrimination of the two groups (AUC = 0.742, 95% CI = 0.560-0.923). Plasma sEV characteristics were also a predictor of OS in multivariable analysis. Patients with a more than 33.8% increase in sEV concentration after one month had 7.2 months shorter median OS (p = 0.002), while patients with a more than 28.0% decrease in sEV size had 9.2 months shorter median OS (p = 0.045). Plasma sEV concentration and size correlate with tumor differentiation and may predict OS in PDAC patients. In the future, plasma sEV characteristics could contribute to improved patient stratification for optimized treatment.
Keywords: extracellular vesicles; liquid biopsy; nanoparticle-tracking analysis; overall survival; pancreatic cancer; plasma biomarkers; tumor differentiation.