Tenofovir Disoproxil Fumarate vs. Entecavir in Chronic Hepatitis B Patients With Partial Virologic Response to Entecavir

Overview

Entecavir, a potent antiviral agent, has been widely used for treatment-naïve chronic hepatitis B patients. However, about 20% of patients showed partial virologic response after 2 year of entecavir therapy (33% in HBeAg positive, 10% in HBeAg negative patients). Tenofovir is a nucleotide analogue with more potent antiviral activity. In addition, there is no cross resistance between the two drugs. Therefore it is assumed that tenofovir would be effective in the treatment of chronic hepatitis B patients who shows partial virologic response (detectable HBV DNA by real time PCR after 12 months of treatment) despite treatment with entecavir. In this study, we will compare the efficacy of switching to tenofovir with continuing entecavir in patients who shows partial virologic response to entecavir.

The number of patients needed was calculated using PASS 2008. We hypothesized that two-thirds (65%) of the patients receiving TDF, and one-fifth (20%) of the patients receiving ETV, would achieve virologic response. We also assumed a 15% drop-out rate; thus, 22 patients were needed in each group to achieve 80% power to demonstrate a difference between the groups with a 5% level of significance. The primary efficacy end point will be analyzed on a per-protocol basis, including only those patients who had completed the treatment schedule of study. In contrast, the intention-to-treat analysis will include all randomized subjects, even those dropped-out from the study before 12 months, as cases of treatment failure.

Conditions