Huang Q, Zhou B, Cai D, et al. - This study was undertaken to evaluate whether the understanding of the turnover time of preexisting covalently closed circular DNA (cccDNA) pools could help in designing strategies to clear hepatitis B virus (HBV) by fully blocking the de novo generation of cccDNA. Researchers retrospectively assessed the emergence and reversion of the rtM204I/V mutant, a signature lamivudine resistance mutation serving as a biomarker of cccDNA turnover in liver biopsies and longitudinal serum samples from two clinical trials. The results of this study demonstrated that genetic composition dynamics of serum HBV RNA and biopsy cccDNA in treated HBV patients highlights that cccDNA turnover occurs relatively rapidly (several months), offering a possibility of HBV cure with finite therapy through completely blocking cccDNA replenishment.