Clinical trial results of new therapies for HBV: implications for treatment guidelines.

Currently approved treatments for chronic infection with hepatitis B virus (HBV) are limited by low rates of sustained response, side effects, and in some cases, the emergence of drug resistance. Thus, new treatments, characterized by more potent antiviral effects less toxicity, and minimal or no risk of resistance, are needed. During the last few years, several agents have been developed that have increased potency and reduced potential for resistance--among them, entecavir and pegylated interferons. In addition, several novel anti-HBV agents recently evaluated in phase II clinical trials, such as tenofovir, clevudine, telbivudine, pradefovir, and valtorcitabine, appear to be promising agents for the treatment of chronic hepatitis B. This article describes the clinical experience with new antiviral agents and the implications of the trial results for practice guidelines.