Early detection of pancreatic ductal adenocarcinoma using abnormal urinary fragmentation ratio of a liver-originated protein.

Abstract

214 Background: Non PDAC tissue-originated proteins are cleaved by proteases derived from PDAC, which can result in abnormal cleavage patterns in the urine of PDAC patients. Urinary proteomic analysis for quantifying the ratios of the abnormal protein fragments to the non-fragmented protein levels in the urine may be useful to distinguish early PDAC from healthy controls. This proof-of-concept study was planned to determine the usefulness of measuring the protein fragments from non PDAC tissue-originated proteins in the urine using the multiple-reaction-monitoring technique (MRM) for discriminating resectable PDAC from healthy controls. Methods: Urinary proteins were digested with trypsin, and resultant peptides were measured by MRM analysis and the ratio of the level of each fragment to the non-fragmented protein level (fragmentation ratio) was calculated. Fragments for which the fragmentation ratios were higher in the PDAC group than those in the healthy group were defined as abnormal protein fragments. The diagnostic capability of each abnormal protein fragment for discriminating cases of PDAC from healthy controls was evaluated by receiver operating characteristic (ROC) curve analysis. Results: A total of 21 patients with resectable PDAC and 30 healthy control subjects were enrolled in this study. All the PDAC patients were treated by pancreatic resection. Urine samples for this study were collected prior to the surgery from the PDAC patients. The non PDAC tissue-originated protein was determined as a liver-originated protein. The fragmentation ratios for six fragments were found to be higher in the PDAC group as compared to those in the healthy control group, and these fragments were determined as abnormal protein fragments. ROC curve analysis was performed for each of the abnormal fragments to determine the areas under the curve (AUCs) for discriminating cases of PDAC from healthy controls. The best AUC was 0.81 (95% CI, 0.68-0.91). Conclusions: The urinary fragmentation ratios showed the ability to discriminate cases of resectable PDAC from a healthy control group; abnormal fragmentation ratios may be promising, noninvasively measurable biomarkers of early PDAC.