Clevudine for the treatment of chronic hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a major health problem that is responsible for < or = 1 million deaths and 500,000 cases of hepatocellular carcinoma worldwide each year. Drugs that are currently approved by the FDA for the treatment of chronic HBV consist of two groups: the immunomodulators, such as conventional IFN-alpha and pegylated IFN-alpha2a; and nucleoside/nucleotide analogues, such as lamivudine, adefovir dipivoxil and entecavir. However, due to the limitations of these agents, newer agents with improved efficacy are currently being developed. One nucleoside/nucleotide analogue that is drawing a wide range of interest is clevudine, which is an analogue of the unnatural beta-L configuration. In the woodchuck hepatitis virus (WHV), clevudine 10 mg/kg has proven to be effective in suppressing viral replication with < or = 9 log10 decreases in WHV. At this dose, a significant reduction of intrahepatic WHV RNA and covalently closed circular WHV DNA levels can also be observed. Treatment with clevudine 10 mg/kg can confer additional antiviral benefit in the form of a more sustained reduction in WHV replication, serum woodchuck hepatitis surface antigen and intrahepatic woodchuck hepatitis core antigen expression following the withdrawal of clevudine. In humans, clevudine 10, 50, 100 or 200 mg/day for 28 days can reduce the median HBV DNA by -2.5, -2.7, -3 and -2.6 log10, respectively. More importantly, this suppression of antiviral activity is maintained at 12 and 24 weeks post treatment. Based on the early results of clevudine, more large-scale human studies with clevudine monotherapy or combination therapy is eagerly awaited.