Abstract 581: Feasibility test of KRAS mutation in urine circulating tumor DNA in metastatic pancreatic ductal adenocarcinoma

Abstract

Abstract Circulating tumor DNA (ctDNA) has been known to be released from tumor cells and evaluated as potential biomarkers for therapeutic responses. In our previous study, we selected KRAS mutation and evaluated applicability as a prognostic marker through the quantitative analysis of plasma ctDNA. Then we proved that KRAS mutation of ctDNA from plasma is significant biomarker for prediction of clinical outcome in pancreatic ductal adenocarcinoma (PDA). Here we investigated whether KRAS mutation in urine ctDNA had the prognostic impact as shown of plasma ctDNA. Of the 106 patients enrolled, 67 were males and median age was 66 years. Total of 51 PDA has been enrolled in this study and the median age was 63 years old and 30 males (58.8%). Urine was separated by established centrifugation method and ctDNA were extracted using QIAamp Circulating Nucleic Acid Kit (Qiagen, Germany) from 4 mL of urine. Extracted ctDNA was quantified using the Qubit dsDNA HS Assay Kit (Thermo Fisher Scientific, USA). QX200 Droplet Digital PCR System (Biorad, USA) was applied to measure frequency of KRAS mutation by KRAS screening multiplex droplet digital PCR kit, which covers seven common mutation sites (Biorad, USA). Mutant concentration and fractional abundance were analyzed by QuantaSoft software (Biorad, USA). There was no significant difference between resectable (N=21), locally advanced (N=11) and metastatic (N=19) groups. When compared high versus low KRAS mutation concentration and KRAS fractional abundance group in each stage, high KRAS mutation groups showed short overall survival (p = 0.0321) in metastatic group. However, the correlation between plasma and urine was low (r=0.193) in metastatic group. This study represented the possibility of KRAS mutation concentration and fractional concentration of urine ctDNA as prognostic factors in metastatic PDA. Urine cfDNA role has not been well investigated in PDA. Urine is easy to obtain and is not well known for its mechanism. Therefore, we have conducted a pilot study and we will explore KRAS mutation status in urine ctDNA in further studies. (This study was supported by National Cancer Center, Korea, Grant no. 1510203.) Citation Format: Min Jeong Kwon, Min Kyeong Kim, Sang Myung Woo, Kyong-Ah Yoon, Yun Hee Kim, Boram Park, Jung Nam Joo, Sang Jae Park, Sun-Young Kong. Feasibility test of KRAS mutation in urine circulating tumor DNA in metastatic pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 581.