Plenary Session l : A 96-week Randomized Trial of Switching to Entecavir in Chronic Hepatitis B Patients with a Complete Virologic Response to Lamivudine

Backgrounds: Entecavir has a higher potent antiviral efficacy and a lower drug resistance rate than Lamivudine in nucleoside- naive chronic hepatitis B (CHB) patients. The switch from Lamivudine to Entecavir in patients who have undetectable hepatitis B virus DNA (HBV DNA < 60 IU/mL) may lead to more prolonged viral suppression to undetectable level by PCR method, compared to patients with continuous Lamivudine treatment. This prospective, 96 week study investigated the antiviral efficacy, safety and tolerability of switching to Entecavir versus maintaining Lamivudine in CHB patients with virologic response to Lamivudine. Methods: A total of 73 HBeAg-positive patients, with serum HBV DNA < 60 IU/mL after at least 6 months Lamivudine monotherapy were randomized 1:1 into either switching to Entecavir 0.5 mg/day, or continuing with Lamivudine 100 mg/ day. Results: Mean duration of prior Lamivudine treatment (n=35) was 25.7 months in the Lamivudine-maintained, and 27.4 months in the Entecavir-switch patients. At 96 weeks of followup, 20/35 (57.1%) patients in the Lamivudine arm had persistently undetectable HBV DNA, compared with 37/38 (97.4%) patients in the Entecavir arm (P <0.001). Out of total 16 patients with HBV DNA rebound, 8/15 in the Lamivudine arm had HBV DNA of more than 1,000 IU/mL during rebound, while none in Entecavir arm. Genotypic resistance to assigned intervention emerged in 28.6% (10/35) of Lamivudine-maintained patients, and in 0% (0/38) of Entecavir-switched patients during 96 weeks (P <0.001). Seventeen Entecavir-switched (45.9%) and seven Lamivudine-maintained (21.2%) patients achieved HBeAg loss (P =0.043), and nine Entecavir (24.3%) and five Lamivudine (15.2%) patients achieved HBeAg seroconversion.