Entecavir for treatment of lamivudine-refractory, HBeAg-positive chronic hepatitis B.

Abstract

Lamivudine treatment is associated with frequent development of resistant hepatitis B virus (HBV) and loss of treatment benefit. In preclinical and phase II studies, entecavir demonstrated potent antiviral activity against lamivudine-resistant HBV. In this phase III, double-blind trial, hepatitis B e antigen-positive patients who were refractory to lamivudine therapy (persistent viremia or documented YMDD mutations while receiving lamivudine) were randomized to switch to entecavir 1 mg daily (n = 141) or continue lamivudine 100 mg daily (n = 145) for a minimum of 52 weeks. Two coprimary end points were assessed at 48 weeks: histologic improvement and a composite end point (HBV branched DNA <0.7 MEq/mL and alanine aminotransferase [ALT] <1.25 times the upper limit of normal). Histologic improvement occurred in 55% (68/124) of entecavir-treated vs 28% (32/116) of lamivudine-treated patients (P < .0001). More patients on entecavir than lamivudine achieved the composite end point: 55% (77/141) vs 4% (6/145), respectively (P < .0001). Mean change from baseline in HBV DNA was -5.11 log(10) copies/mL for entecavir-treated patients and -0.48 log(10) copies/mL for lamivudine-treated patients (P < .0001). Virologic rebound because of entecavir resistance substitutions occurred in 2 of 141 of entecavir-treated patients, and genotypic evidence of resistance was detected in 10 patients. The safety profile of entecavir was comparable to lamivudine with fewer ALT flares on treatment. In patients with lamivudine-refractory chronic hepatitis B, switching to entecavir provides superior histologic improvement, viral load reduction, and ALT normalization compared with continuing lamivudine, with a comparable adverse event profile.