Tenofovir Plus Entecavir vs. Tenofovir in Adefovir-Resistant Chronic Hepatitis B

Inclusion Criteria: All of below * Compensated liver disease (Child-Pugh class A) * HBsAg positive at least 6 months or more * HBeAg positive or negative * Confirmation of ADV resistance mutation at any time before screening (rtA181V or rtA181T or rtN236T) * Serum HBV DNA ≥ 60 IU/mL despite continued preceding oral antiviral treatment (Serum HBV DNA should be determined by the PCR assay at the local laboratory at screening for this study) * Patient is ambulatory. * Patient is willing and able to comply with the study drug regimen and all other study requirements. * The patient is willing and able to provide written informed consent to participate in the study. Exclusion Criteria: Any of below * Patient previously received TDF for more than 1 week * Patient has a history of hepatocellular carcinoma (HCC) or findings suggestive of possible HCC, such as suspicious foci on imaging studies. In patients with such findings, HCC should be ruled-out prior to randomizing the patient for the present study. * Patient has received interferon or other immunomodulatory treatment for HBV infection in the 12 months before screening for this study. * Patient has concomitant other chronic viral infection (HCV or HIV) * Patient has evidence of renal insufficiency defined as serum creatinine \> 1.5 mg/dL * Patient has medical condition that requires concurrent use of systemic prednisolone or other immunosuppressive agent (including chemotherapeutic agent) * Patient is currently abusing alcohol (more than 40 g/day) or illicit drugs, or has a history of alcohol abuse or illicit substance abuse within the preceding two years. * Patient is pregnant or breastfeeding or willing to be pregnant * Patient has one or more additional known primary or secondary causes of liver disease, other than hepatitis B (e.g., alcoholism, autoimmune hepatitis, malignancy with hepatic involvement, hemochromatosis, alpha-1 antitrypsin deficiency, Wilson's Disease, other congenital or metabolic conditions affecting the liver, congestive heart failure or other severe cardiopulmonary disease, etc.). * A history of treated malignancy (other than hepatocellular carcinoma) is allowable if the patient's malignancy has been in complete remission, off chemotherapy and without additional surgical intervention, during the preceding three years. * Clinical signs of decompensated liver disease as indicated by any one of the following: 1. serum bilirubin \> 3 mg/dL 2. prothrombin time \> 6 seconds prolonged or INR \>1.5 3. serum albumin \< 2.8 g/dL 4. History of ascites, variceal hemorrhage, or hepatic encephalopathy 5. Child-Pugh score ≥7