Exploratory analysis of lamivudine legacy and clonal selection of HBs truncation mutants in HBV-related hepatocellular carcinoma

Hepatitis B virus (HBV) integration and persistent covalently closed circular DNA (cccDNA) are key drivers of hepatocarcinogenesis and remain uncured by current nucleos(t)ide analog (NA) therapy. While high-barrier NAs like entecavir effectively suppress viral replication, they do not eliminate transcriptionally active HBV integrants. In this exploratory study, we analyzed HBV surface (HBs) gene truncation mutations in four patients with HBV-related hepatocellular carcinoma (HCC), including two with prior lamivudine exposure. Next-generation sequencing of DNA and RNA from serum, tumor, and para-neoplastic liver tissues revealed truncation variants, such as sW172* and sW182* were, exclusively in the two lamivudine-experienced patients. These variants were predominantly enriched in tumor RNA, raising the possibility of clonal selection during hepatocarcinogenesis. No truncation mutations were observed in the two patients treated solely with entecavir, despite detectable intrahepatic cccDNA. These findings support the hypothesis that transcriptionally active HBV integrants, possibly shaped by prior lamivudine treatment, may contribute to HCC via truncated HBs protein expression. The selective presence of certain mutants in tumor tissue suggests a potential biological role, though further validation is needed. Given the small sample size and limited number of lamivudine-experienced cases, our observations should be interpreted with caution. Nevertheless, the results highlight the relevance of antiviral treatment history in shaping HBV mutational profiles and raise the possibility that integrant-derived HBs truncation variants could serve as biomarkers for HCC risk stratification. Early detection of such variants may help refine surveillance strategies in virally suppressed patients and inform future therapeutic approaches.