Backgrounds/aims: Clevudine is an effective antiviral nucleoside analogue, but there are few data regarding its long-term effects, resistance, and safety. The aim of this study was to evaluate the long-term clinical efficacy of clevudine over a 1-year treatment period in nucleos(t)ide-naive and lamivudine-experienced chronic hepatitis B patients.
Methods: Nucleos(t)ide-naive (group A, n=196) and lamivudine-experienced (serum hepatitis B virus, HBV DNA >2,000 copies/mL without resistant mutants at the start of clevudine therapy, group B, n=75) patients were included in this study. Basic clinical characteristics including age, sex, the presence of cirrhosis, laboratory data, and hepatitis B surface antigen (HBeAg) positivity were similar between the two groups. Pretreatment serum levels of HBV DNA were 7.4 and 6.6 log(10) copies/mL (P<0.001). The mean treatment duration was 8 months for both groups (range for group A: 3-21 months; range for group B: 3-20 months). Genotypic analysis for resistant mutations in the reverse transcriptase of HBV was performed after viral breakthrough.
Results: After 1 year of therapy, 75.0% and 51.9% of groups A and B, respectively, had HBV DNA levels of <2,000 copies/mL (P=0.032), and HBeAg seroconversion rates were 16.9% and 16.7%, respectively. The rates of viral breakthrough at 1 year were 10.0% (8/80) and 44.4% (12/27), respectively (P<0.001). Proven sites of mutation of HBV DNA polymerase in naive patients were, for example, L80I, L180M, A181V/T, M204I and V207I. Ten patients complained of prominent fatigue and revealed elevated serum levels of aspartate aminotransferase (AST) and creatine phosphokinase (CPK). Two of these patients presented with severe myopathy from which they recovered completely after quitting clevudine.
Conclusions: Clevudine is one of the recommended first-line medicines for the treatment of chronic hepatitis B, but it is not free from resistance, particularly in patients with a history of previous lamivudine treatment, but also in naive patients. Clevudine should be avoided in previously lamivudine-exposed patients. In addition, reelevation of serum AST and CPK levels is not a rare occurrence, and close observation and follow-up tests are essential.