Objective: We investigated the activation of pancreatic proenzymes and signs of peripancreatic inflammation in patients with clinically relevant postoperative pancreatic fistulas (POPFs). Summary Background Data: An increase of systemic amylase concentration was associated with POPFs. This suggested parallels in the pathomechanisms between the development of POPFs and pancreatitis. Methods: Trypsinogen, procathepsin B, and IL-6 concentrations as well as cathepsin B, myeloperoxidase and trypsin activities were determined throughout the first 7 postoperative days in drain fluids of 128 consecutive patients after pancreas resection. Histology and immunohistochemistry were performed in pancreatic specimens after total pancreatectomy due to complications and after placing experimental pancreatic sutures in the pancreatic tail of C57/Bl6 mice. Results: Trypsin activity, cathepsin B activity and myeloperoxidase activity on the first postoperative day were elevated and predictive for clinically relevant pancreatic fistulas. Drain fluid stabilized trypsin activity and prevented the activation of the cascade of digestive enzymes. Leukocytes were the source of cathepsin B in drain fluid. Findings differed between fistulas after distal pancreatectomy and pancreatoduodenectomy. Immunohistochemistry of the pancreatic remnant revealed an inflammatory infiltrate expressing cathepsin B, independent of the presence of pancreatic fistulas. The infiltrate could be reproduced experimentally by sutures placed in the pancreatic tail of C57/Bl6 mice. Conclusions: Trypsinogen activation, increased cathepsin B activity and inflammation around the pancreato-enteric anastomosis on post operative day 1 are associated with subsequent clinically relevant POPFs after pancreatoduodenectomy. The parenchymal damage seems to be induced by placing sutures in the pancreatic parenchyma during pancreatic surgery.

Pancreatic ductal adenocarcinoma (PDAC) is a disease with a very unfavorable prognosis. Surgical resection represents the only potentially curative treatment option, but recurrence after complete resection is almost certain. In an exploratory attempt we here aimed at identifying preoperative plasma protein biomarkers with the potential to predict early recurrence after resection of PDAC. Peripheral blood samples from 14 PDAC patients divided into three groups according to their time to tumor recurrence after curatively intended resection (early: < 6 months, medium: 6–12 months, late: > 12 months) underwent targeted proteome analysis. Proteins most strongly discriminating early and late recurrence were then examined in a number of established PDAC cell lines and their culture supernatants. Finally, PDAC organoid lines from primary tumors of patients with early and late recurrence were analyzed for confirmation and validation of results. In total, 23 proteins showed differential abundance in perioperative plasma from PDAC patients with early recurrence when compared to patients with late recurrence. Following confirmation of expression on a transcriptional and translational level in PDAC cell lines we further focused on three upregulated (MAEA, NT5E, AZU1) and two downregulated proteins (ATP6AP2, MICA). Increased expression of NT5E was confirmed in a subset of PDAC organoid cultures from tumors with early recurrence. MICA expression was heterogeneous and ATP6AP2 levels were very similar in both organoids from early and late recurrent tumors. Most strikingly, we observed high MAEA expression in all tested PDAC (n = 7) compared to a non-cancer ductal organoid line. MAEA also demonstrated potential to discriminate early recurrence from late recurrence PDAC organoids. Our study suggests that identification of plasma protein biomarkers released by tumor cells may be feasible and of value to predict the clinical course of patients. Prediction of recurrence dynamics would help to stratify up-front resectable PDAC patients for neoadjuvant chemotherapy approaches in an individualized fashion. Here, MAEA and NT5E were the most promising candidates for further evaluation.

This prospective observational biomarker trial evaluated the diagnostic and prognostic value of circulating KRAS mutations (cmKRAS) and their perioperative dynamics in patients with resectable pancreatic ductal adenocarcinoma (PDAC). Plasma cmKRAS samples (G12D, G12V, G12R, and G12C) were analysed by droplet digital PCR in 51 patients with resectable PDAC, 20 with advanced PDAC, and 34 with non-malignant pancreatic pathology. Preoperative detection of cmKRAS alone did not correlate with poorer overall and disease-free survival in this patient cohort. However, a perioperative change in cmKRAS, particularly accurate when an intraoperative sample was included, was identified as a new and useful marker for prediction of prolonged survival. Promising biomarker

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