In Korea, the number of suboptimal responders to rescue combination therapy is also increasing. As a matter of fact, according to the investigations in Korea, HBV DNA undetectability at 48 weeks of adefovir and lamivudine combination rescue therapy for patients with lamivudine resistance was reported to be only 32.4%, which suggested that the appropriate another rescue therapy might be urgently required. However, there is no promising oral antiviral agents to control these patients in Asia-Pacific region, where tenofovir is not widely available. Tenofovir has a higher potent antiviral efficacy and a negligible drug resistance rate. The switch from adefovir to tenofovir in patients who have insufficient hepatitis B virus (HBV) suppression (HBV DNA ≥ 60 IU/mL by PCR) may lead to increased viral suppression or more HBeAg loss/seroconversion.

Here, the investigators aimed to conduct a randomized study on evaluating the antiviral efficacy, safety, and tolerability of switching from adefovir to tenofovir in chronic hepatitis B patients who have suboptimal response to adefovir-based combination rescue therapy due to nucleoside analogues Resistance (SATIS study).

The major goal of antiviral therapy against chronic hepatitis B is to suppress viral replications successfully, ultimately preventing the chronic liver damage, development of liver cirrhosis and hepatocellular carcinoma. In Korea, the number of multi-drug resistant CHB has been rapidly increased last few years. It is because that the national health insurance coverage is very limited for the patients who experienced primary treatment failure. The only switch to adefovir has been allowed in lamivudine resistant patients and thus this sequential rescue therapy generated multi-drug resistance to both adefovir and another drugs. Thus, nowadays, add-on therapy rather than switch therapy might be preferred from major guidelines in this point.

However, the number of suboptimal responders to rescue combination therapy is also increasing. As a matter of fact, according to the investigations in Korea, HBV DNA undetectability at 48 weeks of adefovir and lamivudine combination rescue therapy for patients with lamivudine resistance was reported to be only 32.4%, which suggested that the appropriate another rescue therapy might be urgently required. However, there is no promising oral antiviral agents to control these patients in Asia-Pacific region, where tenofovir is not widely available. Tenofovir has a higher potent antiviral efficacy and a negligible drug resistance rate. It belongs to the different class compared to other oral nucleoside analogues (NAs) such as lamivudine, telbivudine, clevudine and entecavir. The switch from adefovir to tenofovir in patients who have insufficient hepatitis B virus (HBV) suppression (HBV DNA ≥ 60 IU/mL by PCR) may lead to increased viral suppression or more HBeAg loss/seroconversion. The results of this study will provide a rationale for switch from adefovir to tenofovir in combination to another drug continued (lamivudine, telbivudine, clevudine and entecavir).

Here, the investigators aimed to conduct a randomized study on evaluating the antiviral efficacy, safety, and tolerability of switching from adefovir to tenofovir in chronic hepatitis B patients who have suboptimal response to adefovir-based combination rescue therapy due to nucleoside analogues Resistance (SATIS study).

Inclusion Criteria:

• subjects with age >= 20 years
• subjects with chronic hepatitis B
• subjects treated with nucleoside analogues plus adefovir for at least 6 months due to resistance to nucleoside analogues (Lamivudine, Telbivudine, Entecavir, or Clevudine)
• subjects with partial virologic response to nucleoside analogues plus adefovir HBV DNA ≥ 60 IU/mL)
• subjects with ALT less than 5 times of upper limit of normal
• subjects who agreed to participate in the clinical trials and signed the informed consents

Exclusion Criteria:

• subjects with decompensate liver cirrhosis Child-Pugh B, C)
• subjects with Adefovir mutation
• subjects with HCV, HDV, or HIV infection
• pregnant or lactating women
• women of childbearing age who do not use the appropriate contraception method
• subjects who have the abnormal lesion suspected of hepatocellular carcinoma on imaging modalities
• subjects with other liver diseases such as hemochromatosis, Wilson's disease, alcoholic liver disease, nonalcoholic liver disease, alpha-1 antitrypsin deficiency
• subjects with hypersensitivity for study drugs
• subjects who participated in other clinical trials 60 days before the current recruitment
• subjects who are judged as inappropriate by investigators