A Korean Cohort Study of TDF Rescue Therapy for Difficult-to-treat CHB Patients: a Comparison Between TDF Monotherapy and TDF-based Combination Therapy

Study Overview
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Brief Summary
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Antiviral resistance remains an important issue for long-term NA therapy. For lamivudine (LAM), the rtM204V/I and rtL180M mutations occur in more than 70% after 5 years of therapy. In Korea, primarily owing to limited subsidization policy in the health insurance system, many patients with LMV-resistance had been treated with either rescue ADV or ETV 1.0 mg monotherapy, ultimately leading to the higher prevalence of MDR strain. For those patients, rescue therapies of combining ADV with either ETV or LAM had been tried, but frequently with suboptimal responses. Rescue TDF monotherapy or TDF-based combination therapy are available in Korea for patients who had difficult-to-treat antiviral resistance owing to prior treatment failures. However, which is the better has not been evaluated yet. A long-term efficacy and safety of TDF-based rescue therapies in real practice for those patients should be necessary to revise the Korean guideline for the treatment of chronic hepatitis B in near future.

Conditions
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The Difficult-to-treat Chronic Hepatitis B

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: more than 20 years old adults chronic hepatitis B the patients treated by tenofovir alone or tenofovir based combination therapy because of the previous treatment failure the patients who agree and singed on the consent form Exclusion Criteria: co-infected patients with HCV, HDV or HIV pregnancy or breast feeding woman or female patients who are planning to be pregnant past history with hepatocellular carcinoma combined with other liver disease including wilson, alcoholic, NASH, alpha-1 antitrypsin deficiency liver disease. patients with hypersensitivity for drugs patients who were enrolled in other clinical study within 60 days patients who were eligible for the clinical study according to the investor

Ages Eligible for Study
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Minimum Age: 20 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| TDF monotherapy<br>TDF monotherapy - treated by tenofovir alone patients with CHB receiving rescue TDF (300mg once daily) monotherapy | |
| TDF-based combination therapy<br>TDF-based combination therapy - treated by tenofovir based combination therapy. patients with CHB receiving rescue TDF-based combination therapy (TDF 300mg once daily with any other nucleoside analogue such as lamivudine 100mg, telbivudine 600mg, or entecavir 1.0 mg once daily). | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The proportion of subjects who achieve a sustained HBV DNA < 60 IU/mL (Undetectable serum HBV DNA by PCR method) at each year during the on treatment follow-up period. | The viral response which is defined as serum HBV DNA < 60 IU/mL | 1, 2, and 3 years after the treatment initiation. |