Tenofovir monotherapy and tenofovir plus entecavir combination as rescue therapy for entecavir partial responders.

BACKGROUND AND AIMS: Despite high potency, a significant proportion of patients treated with entecavir achieve only partial viral suppression. Our goal was to examine the complete viral suppression rate (undetectable HBV DNA PCR levels) with alternative therapies in such patients. METHODS: We retrospectively studied 42 consecutive patients with partial response to entecavir (detectable HBV DNA at ≥12 months of therapy) who were treated at three clinics with rescue therapies: entecavir + adefovir (n = 5), tenofovir (n = 6), and entecavir + tenofovir (n = 31). Antiviral resistance was excluded by negative mutation analysis and/or absence of virologic breakthrough (increase >1 log(10)IU/mL from nadir). RESULTS: All patients were Asian and 57 % were male with a median age of 36 (22-64) years. Only a few patients had prior exposure to lamivudine (7 %) or adefovir (7 %). Almost all patients (95 %) had positive HBeAg. Overall, the complete viral suppression rate was 79 %, and the alanine aminotransferase normalization rate was 83 % in entecavir partial responders after 6 months on rescue therapies. Cumulative complete viral suppression rates were significantly different (P = 0.0164) among the entecavir + adefovir, tenofovir, and entecavir + tenofovir treatment groups at 6 months (20 vs. 83 vs. 83 %, respectively) and 12 months (20 vs. 100 vs. 97 %). All three patients without complete viral suppression on entecavir + adefovir became aviremic 6 months after switching to entecavir + tenofovir. CONCLUSIONS: Virologic response to entecavir + tenofovir combination therapy and tenofovir monotherapy appeared to be similar in most patients, but not with the entecavir + adefovir combination.