Abstract 733: Detection of HCC-derived major HBV integration junctions in urine and their implications for driver identification

Chronic Hepatitis B Virus (HBV) infection is a major etiology of hepatocellular carcinoma (HCC), a leading cause of cancer mortality worldwide. Integration of HBV DNA into the host genome occurs during the course of chronic infection. Integrated HBV DNA is observed in most of HBV-associated HCC. The integration junctions derived from the original tumor cell become abundant (referred to as major integration junctions) in the infected liver because of clonal expansion during tumor development. Detection of circulating DNA containing these tumor-derived integration junctions may therefore be useful for cancer detection. We have adapted a method known as Primer Extension Capture (PEC) to enrich integrated HBV DNA for next-generation sequencing (NGS). Our initial studies using this approach to enrich the HBV DR1-2 region (a common site for HBV integrated breakpoints) identified major integration junctions from HBV-HCC tissue samples and matched urine. Further analysis revealed that most recurrently targeted integrations from these HCC tumors have previously reported involvement in cancer. This suggested that identification of recurrently targeted genes is applicable for driver identification. Interestingly, we show how HBV targets the TERT promoter in a localized region even though no two TERT junctions examined are identical. We have further developed this PEC to enrich for the entire HBV genome and applied it to (i) liver tissue DNA from 20 matched HCC and adjacent non-HCC samples, and (ii) DNA from urine of 20 hepatitis, 20 cirrhosis and 20 HCC patients. The HBV enriched libraries were sequenced by NGS and the integration events were analyzed using the in-house developed software. The complexity of HBV junction sites in HCC and non-HCC tissue and urine derived circulating DNA is reported. Our approach has potential to be used for liquid biopsies to study the complexities of HBV integrations in chronic HBV infection and carcinogenesis, and to identify HCC-related DNA modifications for early detection and disease management. Citation Format: Selena Y. Lin, Jamin D. Steffen, Yih-Ping Su, Surbhi Jain, Ting-Tsung Chang, Wei Song, Ying-Hsiu Su. Detection of HCC-derived major HBV integration junctions in urine and their implications for driver identification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 733. doi:10.1158/1538-7445.AM2017-733