[Management of antiviral-resistant chronic hepatitis B virus infection]

Substantial progress has been made in the treatment of chronic hepatitis B during the past decade. Nucleos(t)ide analogues are now widely used due to their convenience, less side effects, and considerable response rates. However, development of antiviral resistance is a major problem being considered as the most important factor for the treatment failure. Viral breakthrough associated with selection of antiviral-resistant hepatitis B virus (HBV) is usually followed by biochemical breakthrough, clinical deterioration, and even progressive liver failure. Therefore, appropriate management of antiviral resistance is critical for improving treatment outcomes. Strategies for the management of antiviral-resistant chronic HBV infection are described herein considering recently published guidelines. Lamivudine/telbivudine resistance can be managed by adding adefovir. Switching to adefovir or entecavir is also a viable option. However, careful follow-up of viral load is mandatory to detect any primary or secondary treatment failure in case of sequential monotherapy. Interferon or peg-interferon therapy can also be considered in case of young patients with compensated liver disease. For adefovir resistance, lamivudine can be added, but adding or switching to entecavir is a more reasonable option. Likewise, adding or switching to adefovir can be considered for entecavir resistance. Adding or switching to tenofovir needs to be considered upon availability. Experiences for clevudine resistance are still lacking, and need to be studied further upon the isolation of clinically resistant strains. To avoid emergence of resistant mutations, antiviral therapy should be initiated after careful balance of risk and benefit, and the most potent antiviral agent with the lowest resistance rate should be selected.