BACKGROUND & AIMS: In long-term responder patients, it is unclear whether lamivudine (LAM) monotherapy should be continued or switched to a high-genetic-barrier analogue. This study aims at assessing LAM efficacy over a 5-year period and the residual risk of drug resistance. The rate of HBsAg clearance and LAM long-term safety profile were also evaluated. METHODS: One hundred and ninety-one patients with chronic HBeAg-negative hepatitis B successfully treated with LAM monotherapy for at least 5 years were included. Biochemical and virological tests were assessed every 3 months in all patients and HBsAg quantification was performed in 45/191. Reverse-transcriptase (RT) region was directly sequenced in virological breakthrough patients. RESULTS: One hundred and ninety-one patients (148 males, median age 53 years, 72 with compensated cirrhosis) responding to 60-month LAM monotherapy continued to receive LAM monotherapy beyond the initial 5 years and were followed for an additional 36-month median period (range 1-108). Virological response was maintained in 128/191 patients (67%) and HBsAg clearance was observed in 15/128 (11.7%) after a 32-month median period (range 1-65). The 63 remaining patients (33%) showed virological breakthrough after a 15-month median treatment (range 1-78). RT region analysis was performed in 38/63 breakthrough patients and LAM resistant mutations were found in 37/38. No significant side effects were observed. CONCLUSIONS: In long-term responder patients, continuation of LAM monotherapy resulted in persistent viral suppression in most cases with undetectable HBV DNA by real-time PCR; moreover, 11.7% of these patients cleared HBsAg. Selection of LAM resistance, however, can still occur even after successful long-term therapy, thus emphasising the importance of a careful virological monitoring.
BACKGROUND & AIMS: In long-term responder patients, it is unclear whether lamivudine (LAM) monotherapy should be continued or switched to a high-genetic-barrier analogue. This study aims at assessing LAM efficacy over a 5-year period and the residual risk of drug resistance. The rate of HBsAg clearance and LAM long-term safety profile were also evaluated. METHODS: One hundred and ninety-one patients with chronic HBeAg-negative hepatitis B successfully treated with LAM monotherapy for at least 5 years were included. Biochemical and virological tests were assessed every 3 months in all patients and HBsAg quantification was performed in 45/191. Reverse-transcriptase (RT) region was directly sequenced in virological breakthrough patients. RESULTS: One hundred and ninety-one patients (148 males, median age 53 years, 72 with compensated cirrhosis) responding to 60-month LAM monotherapy continued to receive LAM monotherapy beyond the initial 5 years and were followed for an additional 36-month median period (range 1-108). Virological response was maintained in 128/191 patients (67%) and HBsAg clearance was observed in 15/128 (11.7%) after a 32-month median period (range 1-65). The 63 remaining patients (33%) showed virological breakthrough after a 15-month median treatment (range 1-78). RT region analysis was performed in 38/63 breakthrough patients and LAM resistant mutations were found in 37/38. No significant side effects were observed. CONCLUSIONS: In long-term responder patients, continuation of LAM monotherapy resulted in persistent viral suppression in most cases with undetectable HBV DNA by real-time PCR; moreover, 11.7% of these patients cleared HBsAg. Selection of LAM resistance, however, can still occur even after successful long-term therapy, thus emphasising the importance of a careful virological monitoring.