Rescue therapy for lamivudine-resistant chronic hepatitis B: Comparison between entecavir 1.0 mg monotherapy, adefovir monotherapy and adefovir add-on lamivudine combination therapy

Background and Aim: There have been no reports comparing the therapeutic results of adefovir (ADV) and entecavir (ETV) rescue therapy for patients with lamivudine (LAM)-resistant chronic hepatitis B (CHB). We aimed to compare the cumulative efficacy and resistance of ETV 1.0 mg monotherapy, ADV monotherapy and ADV add-on LAM combination therapy in LAM-refractory patients. Methods: One hundred and four patients were included in the following three treatment groups; group 1 (n = 24), LAM was switched to ETV (1.0 mg once a day); group 2 (n = 44), LAM was switched to ADV (10 mg once a day); and group 3 (n = 36), ADV was added to LAM (10 mg once a day). Results: After 6 months of rescue treatment, alanine aminotransferase normalization was observed in 75.0%, 65.9% and 74.3% of patients receiving ETV monotherapy, ADV monotherapy and ADV add-on therapy, respectively. A significantly higher log₁₀HBV-DNA drop at 6 months occurred in the ADV add-on group compared with the ETV group. The rate of HBV-DNA polymerase chain reaction undetectability (<300 copies/mL) 6 months after initiation of ETV monotherapy, ADV monotherapy and ADV add-on therapy was 33.3%, 27.3% and 68.6%, respectively (P = 0.003). The cumulative HBeAg seroconversion rate was significantly higher in ADV add-on/ADV monotherapy groups compared with the ETV monotherapy group (P = 0.022). Viral breakthrough and genotypic resistance were detected in six (25.0%) and six (13.6%) patients in the ETV and ADV monotherapy groups, whereas no cases of genotypic resistance were detected in ADV add-on group 24 months after initiation of antiviral treatment (P < 0.01). Conclusion: Adefovir add-on treatment in patients with LAM-resistant CHB suppresses HBV replication more effectively than ETV or ADV monotherapy. Additionally, no genotypic resistance was detected in the ADV add-on group.