We aimed to determine the antiviral activity and safety of a new nucleotide analogue, LB80380, in chronic hepatitis B (CHB) patients with lamivudine-resistant virus. Sixty-five patients with lamivudine-resistant virus were randomized to receive five ascending daily doses (30, 60, 90, 150, 240 mg) of LB80380. LB80380 was given together with lamivudine for the first 4 weeks, followed by 8 weeks of LB80380 monotherapy. This was then followed by 24 weeks of adefovir. Hepatitis B virus (HBV) DNA levels, serology, liver biochemistry, and safety were monitored. The extent of the HBV DNA reduction at week 12 was dose-dependent. The mean reduction from baseline was 2.81, 3.21, 3.92, 4.16, and 4.00 log10 copies/mL for the five ascending dose groups. The dose-proportionate effect was statistically significant (P<0.001) with a decrease of HBV DNA levels by an average of 1.54 log10 copies/mL for every 1-unit increase in log10 dose of LB80380. In 93.4% of patients, HBV DNA decreased by >2 log10 copies/mL, and 11.5% of patients had undetectable HBV DNA levels (<300 copies/mL) by week 12. HBV DNA suppression was maintained during the 24 weeks of adefovir treatment. Hepatitis B e antigen seroconversion and normalization of alanine aminotransferase were seen in 14.6% and 24.6% of patients, respectively, at week 12; 44.6% of patients experienced mild and self-limiting adverse events, none of which were attributed to the study drug. Conclusion: LB80380 at doses of up to 240 mg is safe, well tolerated, and effective at reducing viral load in CHB patients with lamivudine-resistant virus for a period of 12 weeks.
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