High-Dimensional Immunophenotyping of Plasma-Derived Small Extracellular Vesicles in Pancreatic Cancer: An Exploratory Proof-of-Principle Study.

Pancreatic ductal adenocarcinoma (PDAC) is increasingly recognized as a systemic malignancy, characterized by profound alterations in tumor-host interactions. Small extracellular vesicles (sEVs) in peripheral blood may reflect these alterations and represent a promising minimally invasive source of biomarker information. In this proof-of-principle study, plasma-derived sEVs from patients with PDAC, healthy controls, and a comparative cohort with neuroendocrine lung cancer (NLC) were isolated by differential ultracentrifugation and characterized by western blotting and nanoparticle tracking analysis. Surface marker profiling was performed using the MACSPlex EV Kit IO, followed by univariate, multivariate, and machine-learning-based analyses. PDAC samples exhibited a distinct sEV immunophenotype with coordinated enrichment of angiogenesis-related markers (including CD105 and CD146), immune-regulatory markers (including CD25 and CD40), the coagulation-related marker CD142 and the invasion-associated marker MCSP. Principal component analysis, hierarchical clustering, and Random Forest classification showed exploratory separation of PDAC patients from healthy controls and NLC, supporting the presence of disease-specific vesicle surface marker patterns. In a very small subset of paired samples, descriptive longitudinal analyses illustrated measurable intra-individual changes during chemotherapy. Plasma sEV immunophenotyping is a technically feasible approach for capturing systemic disease-associated alterations in PDAC and provides a foundation for future biomarker-oriented validation studies.