BACKGROUND: Lamivudine was approved for the treatment of chronic hepatitis B in China in 1999; however the long-term result has not yet been reported in detail. This clinical trial was to evaluate the long-term efficacy and safety of 3-year lamivudine treatment for chronic hepatitis B and the impact of emergence of YMDD mutation of hepatitis B virus (HBV).
METHODS: This multi-center, randomized, double-blind, placebo controlled trial began from 1996 to 1999. A total of 429 patients with serum HBsAg, HBeAg and HBV DNA positive were randomized to receive either lamivudine 100 mg daily (322 patients) or placebo (107) for the first 12 weeks. All patients were given subsequently open labelled lamivudine 100 mg/d for a total of 156 weeks.
RESULTS: After 12-week lamivudine therapy, the levels of serum HBV DNA decreased rapidly. The negativity of HBV DNA (<1.6 pg/ml) at week 12 was 92.2% in the lamivudine group, whereas it was only 14.1% in the placebo group (P<0.01). After 1-year lamivudine treatment, 72.7% of the patients showed undetectable serum HBV DNA (<1.6 pg/ml). At the end of 3 years, serum HBV DNA continued to be substantially suppressed with a median level below a detectable level in patients with non-YMDD variant HBV, which was increased to 86 mEq/ml (bDNA method, equivalent hybridization method 10 pg/ml) in patients with YMDD mutation. At the end of 1, 2 and 3 years, the rates of HBeAg loss were 9.5%, 16.8% and 20.0% respectively and the rates of HBeAg/anti-HBe seroconversion were 8.3%, 11.5% and 17.3%. The rates of HBeAg loss and seroconversion were correlated with the baseline level of ALT. In patients with a baseline level of alanine transaminase (ALT)>2×upper limit of normal (ULN) and ALT >5×ULN, the rates of HBeAg loss were 42.2% and 66.7%, and the rates of seroconversion were 34.4% and 61.1% respectively (P<0.01) at the end of year 3. The levels of ALT at year 3 remained normal in 58.8% of patients whose baseline level of ALT was elevated, and in 79.1% of patients whose level of ALT was normal before treatment. YMDD mutations occurred in 12.1%, 49.7% and 70.5% of patients respectively at year 1, 2 and 3. In patients with YMDD mutation, the levels of HBV DNA were increased slightly with mild to moderate elevation of ALT level. HBeAg loss and seroconversion were 20.0% and 15.1% in patients with YMDD mutation at the end of year 3, which were lower than those in non-variant patients (P<0.01). Adverse drug reactions or events varied generally from mild to moderate. In 2 patients serious adverse events (fatigue and abdominal distension) were related to medication. ALT flares (ALT>5×ULN) occurred in 17 patients: 10 were YMDD mutants and 7 were non-mutants; all of them were relieved. No death occurred in the period of 3 years.
CONCLUSION:  Sustained inhibition of HBV replication and clinical improvement could be obtained after 3-year lamivudine therapy of good tolerance and safety.