Genentech Whole-Genome Sequencing of Four Hepatocellular Carcinoma Patients

Hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC). In this study we sequenced the whole genome (~80X) and transcriptome of tumor and non-tumor samples from four HCC patients and identified over two hundred HBV integration sites. We found significant clonal expansion of HBV-integrated hepatocytes specifically in the tumor samples. We observed a diverse collection of genomic perturbations near viral integration sites, including gene disruption, viral promoter-driven human transcription, viral-human transcript fusion and DNA copy number alteration. We also sequenced one patient at ultra-high coverage (~240X) to build the most comprehensive HBV-integration landscape yet attempted. Our data suggest that the viral integration significantly expands carcinogenic opportunities in HBV-infected individuals.