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A blood-based assay for diagnosis of early-stage pancreatic cancer.

234 Background: Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. Biomarker are needed to facilitate early and preferably noninvasive detection of PDAC, which directly may influence patients’ prognosis. Here we aimed to test a new biomarker combination for early PDAC, consisting of thrombospondin-2 (THBS2), CA19-9 and circulating tumor DNA (ctDNA) analysis. Methods: Thirty-nine patients with histologically proven and clearly resectable PDAC (recruited from the NEONAX trial, NCT02047513) were enrolled. Fifteen patients with benign pancreatic disease (intraductal papillary-mucinous neoplasms, IPMN) served as controls. Blood samples were collected prior treatment. KRAS genotyping was performed after isolation of ctDNA from plasma (QIAamp MinElute ccfDNA Kit, Qiagen) by digital droplet PCR ( KRAS Screening Multiplex Kit; QX200 system, both: Bio-Rad). Clinical data and CA 19-9 levels were assessed by ELISA (Roche); THBS2 values were determined by Quantikine ELISA Human Thrombospondin-2 (R&D Systems). Statistical analyses were done by using GraphPad Prism Version 7.00, GraphPad Software, Inc. Results: THBS2 had a c-statistic of 0.73 for all PDAC stages which was comparable to that of CA 19-9 (0.78). The c-statistic was improved to 0.94 by combining CA 19-9, THBS2 and total cfDNA amount. This marker combination performed best for all stages. C-statistics of defined PDAC stages was 0.93, 1.00 and 0.92 for stage I, stage II and stage III, respectively. Of note, the biggest improvement in sensitivity and specificity was seen for stage I PDAC. Here, c-statistic improved from 0.69 or 0.85 for CA 19-9 alone or the combination of CA 19-9 and THBS2, respectively, to 0.93 for the three-marker combination. Conclusions: These data underscore that CA 19-9, THBS2 and cfDNA marker combination constitutes a composite liquid biomarker for non-invasive diagnosis of early-stage PDAC with a remarkable specificity. Larger studies are needed to examine the power of this approach.