Background:
Liquid biopsy in patients with pancreatic ductal adenocarcinoma (PDAC) has been challenged by the limited information obtained from systemic circulation (SC). Circulating Tumour Cells (CTCs) in portal circulation (PC) are deemed to be biologically relevant and potentially carrying prognostic significance, despite mostly been evaluated during surgery.

Methods:
This prospective, single-centre, interventional study enrolled PDAC patients to assess the feasibility and safety of EUS-guided transgastric and transhepatic Portal Vein sampling (EUS-PVS) for isolating, enumerating, and characterizing CTCs. PC and paired SC samples underwent microfluidic enrichment and dielectrophoretic (DEP) single-cell sorting based on immunostaining for epithelial and mesenchymal biomarkers. Targeted next-generation KRAS sequencing was performed on CTC subpopulations in a subset of patients.

Results:
Between May 2022 and October 2023, 20 PDAC patients (25% metastatic) underwent EUS-PVS with 100% feasibility and safety. CTCs were isolated in all patients from both districts, but the total CTC concentration was significantly higher in PC compared to SC (8.1 [5.8-21.3] vs. 4.1 [2.3-6] / 7.5 ml of blood, p= 0.01), particularly for mesenchymal CTCs. No associations with baseline clinical variables or disease stage were observed. A subset of CTCs exhibited KRAS codon 12 mutations, undetected in paired white blood cells.

Conclusion:
EUS-PVS is a feasible, safe, and effective method for portal blood sampling, supporting subsequent molecular investigations. Despite more sensitive enrichment modalities enhance the yield of peripheral CTCs evaluation, portal circulation remains more informative, especially for detecting epithelial-to-mesenchymal transition events. DEP single-cell sorting was feasible in all patients, providing libraries of viable cells with specific 100%-pure phenotypes, potentially suitable for downstream molecular applications.

Laura Apadula

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