Covalently closed-circular hepatitis B virus DNA reduction with entecavir or lamivudine

AIM: To investigate the reduction in hepatitis B virus(HBV) covalently closed-circular DNA(ccc DNA) with entecavir(ETV) or lamivudine(LAM). METHODS: This analysis included patients who had participated in the randomized Phase Ⅲ study ETV-022 comparing ETV vs LAM in nucleos(t)ide-naive, HBe Agpositive patients. Patients received ETV(0.5 mg daily) or LAM(100 mg daily) for a minimum of 52 wk. Patients were eligible to participate in this sub-study if they had paired biopsies at baseline and week 48 with evaluable measurements for hepatic HBV ccc DNA and total hepatic HBV DNA. The main objective was to compare changes in hepatic HBV ccc DNA and total hepatic HBV DNA at week 48 of ETV or LAM treatment, which was a secondary endpoint of study ETV-022. Additional post hoc analyses included linear regression analyses to assess associations of baseline levels and on-treatment changes of ccc DNA with other baseline factors [sex,age, serum HBV DNA, alanine aminotransferase(ALT), Knodell necroinflammatory score, Ishak fibrosis score, total hepatic HBV DNA, and HBV genotype], or ontreatment factors(changes from baseline at week 48 in serum HBV DNA, ALT, Knodell necroinflammatory score, Ishak fibrosis score, total hepatic HBV DNA, and HBe Ag loss at week 48).RESULTS: Overall, 305 patients(ETV = 159; LAM = 146) of ETV-022 had paired baseline and week 48 liver biopsies with evaluable measurements for hepatic HBV ccc DNA and total hepatic HBV DNA, and were included in this analysis. Baseline demographics and disease characteristics were comparable between the two arms. After 48 wk, ETV resulted in significantly greater reductions in hepatic HBV ccc DNA [-0.9 log10 copies/human genome equivalent(HGEq) vs-0.7 log10 copies/HGEq; P = 0.0033] and total hepatic DNA levels(-2.1 log10 copies/HGEq vs-1.6 log10 copies/HGEq; P < 0.0001) than LAM. Virologic, biochemical, and histologic response rates at week 48 were also greater with ETV than with LAM. Baseline HBV ccc DNA levels were positively associated with baseline levels of serum HBV DNA and total hepatic HBV DNA, and negatively associated with HBV genotype F. On-treatment changes in HBV ccc DNA levels were negatively associated with baseline levels of serum HBV DNA and baseline ALT, and were positively associated with on-treatment changes in the levels of serum HBV DNA, total hepatic HBV DNA levels, and ALT, change in Knodell necroinflammatory score, and HBe Ag loss.CONCLUSION: Forty-eight weeks of ETV resulted in greater reductions in ccc DNA and total hepatic HBV DNA than LAM, but long-term therapy may be needed for ccc DNA elimination.

The Discovery and Development of a Potent Antiviral Drug, Entecavir, for the Treatment of Chronic Hepatitis B

Since the first approval of interferon for the treatment of chronic hepatitis B virus (HBV) infection in 1992, six additional antivirals have been developed: pegylated interferon-alfa2a, and the oral antivirals lamivudine, adefovir, telbivudine, entecavir and tenofovir. The availability of animal models for HBV infection and hepatocyte cell culture led to the discovery and development of oral antivirals targeted at HBV polymerase and reverse transcriptase, which inhibit viral replication. The discovery and development of entecavir, the first oral anti-HBV drug with both potent antiviral activity and a high genetic barrier to resistance, took more than 10 years before it was first approved in the USA. Since then, multiple real-life studies have provided data consistent with the findings of the registration trials and the long-term rollover study in terms of efficacy, resistance, and safety. Data from the long-term follow-up of patients enrolled in the registra-tion studies showed that treatment with entecavir can lead to significant improvements in liver histopathology, and recent cohort studies have demonstrated that treatment with entecavir may reduce disease progression and the develop-ment of hepatocellular carcinoma (HCC) in patients with chronic hepatitis B. In addition, real-life studies suggest that entecavir may reduce HCC recurrence and increase survival rates in patients with HBV-related HCC post-surgical resection.