Antiviral Efficacy of Switching to ETV Plus TDF

Chronic Hepatitis B

Chronic hepatitis B, Partial virologic response, YMDD mutation

Switching to Entecavir(ETV) plus Tenofovir Disoproxil Fumarate(TDF) combination will result in faster and greater antiviral activity and lower rates of resistance emergence over maintaining Lamivudine(LAM)/Telbivudine(LdT)+Adefovir(ADV) combination in partial responders to LAM/LdT+ADV rescue therapy. Earlier switching to combination with the most potent regimen will be more effective to achieve virologic response(VR) and prevent further resistance emergence. All subjects will orally take assigned drugs once daily for 48 weeks. All subjects will be assessed at baseline and every three months thereafter. Evaluations at each visit will include vital signs, physical examinations, laboratory tests, HBV DNA levels and adverse events. At baseline and every six months thereafter, serum will be assayed for HBV serology. Genotypic analysis will be performed at baseline and 48 weeks.

1. As TDF has not been approved yet in Korea, current KASL practice guideline generally recommends to add ADV in LAM-resistant or LdT-resistant patients. 2. However, several local literatures reported a substantial proportion of patients treated with LAM plus ADV combination therapy showed a persistently inadequate or partial virologic response('VR') and YMDDm still maintained in spite of under rescue combination therapy. 3. Due to the unavailability of TDF in Korea, ETV plus ADV combination has being considered a better salvage therapy with non-overlapping cross-resistance profiles in pts who fail to LAM plus ADV rescue therapy and local report demonstrated that the rate of VR was significantly higher with ETV+ADV switching group than LAM+ADV continuation group in partial responder to LAM plus ADV combination rescue therapy for LAM resistance. 4. Hence, more earlier combination therapy with the most potent Nucleoside and Nucleotide analogue would be a promising salvage treatment for previous NA treatment failures but comparative prospective trials are limited. 5. Therefore, this study will investigate the greater effectiveness and safety of switching to the most potent combination versus maintaining LAM(or LdT) plus ADV and also compare the rate of VR based on the HBV DNA cut-off level at switching - more than and less than 20,000 IU/mL. All subjects will orally take assigned drugs once daily for 48 weeks. All subjects will be assessed at baseline and every three months thereafter. Evaluations at each visit will include vital signs, physical examinations, laboratory tests, HBV DNA levels and adverse events. At baseline and every six months thereafter, serum will be assayed for HBV serology. Genotypic analysis will be performed at baseline and 48 weeks.