Management of Clevudine-Resistant Chronic Hepatitis B: A Multicenter Cohort Study

Maintaining Antiviral Efficacy after Switching to Generic Entecavir 1 mg for Antiviral-resistant Chronic Hepatitis B

Background/Aims

Clinical equivalence of generic antiviral agents for chronic hepatitis B (CHB) has not been demonstrated, particularly in cases with previous antiviral resistance. Entecavir 1 mg is prescribed frequently as a mono- or combination therapy in antiviral-resistant CHB patients. This study evaluated the efficacy and safety of switching to generic entecavir 1 mg (Baracle^®) in CHB patients taking brand-name entecavir 1 mg (Baraclude^®) alone or in combination with other nucleotide analogs after the development of antiviral resistance.

Methods

This study was a single-arm prospective study. The primary endpoint was undetectable HBV DNA (<20 IU/mL) at 12 months after switching treatment. The biochemical and serologic responses, virologic breakthrough, and antiviral resistance rates were also evaluated.

Results

Forty CHB patients with undetectable HBV DNA through the brand-name entecavir 1 mg treatment as a mono- or combination therapy after developing antiviral resistance to nucleos(t)ide analogs were enrolled in this study. No significant difference in the HBV DNA non-detection rate was observed between the baseline and 12 months after switching therapy (p=0.324). Furthermore, non-inferiority of the generic entecavir 1 mg to the brand-name entecavir 1 mg with 10% margin in maintaining undetectable HBV DNA was demonstrated (95% CI -2.80 to 8.20%). Similarly, no difference in the biochemical response rate was observed after switching therapy. Serum hepatitis B e antigen loss was observed in 12.5%. No virologic breakthrough was reported.

Conclusions

Generic entecavir 1 mg is a reasonable alternative to the brand-name entecavir 1 mg in antiviral-resistant CHB patients with viral suppression.

New treatments to reach functional cure: Virological approaches

Current therapies of chronic hepatitis B (CHB) remain limited to pegylated-interferon-alpha (pegIFN-α) or any of the five approved nucleos(t)ide analogues (NA). If viral suppression can be achieved in the majority of patients with the high-barrier-to-resistance new-generation of NA, i.e. entecavir and tenofovir, HBsAg loss is achieved by PEG-IFN-α and/or NA in only 10% of patients, after a 5-year follow-up. Attempts to improve the response by administering two different NA or a combination of NA and PEG-IFN-α have not provided a dramatic increase in the rate of "functional cure". Because of this and the need of long-term NA administration, there is a renewed interest regarding the understanding of various steps of the HBV replication cycle, as well as specific virus-host cell interactions, in order to define new targets and develop novel drugs. This includes the direct inhibition of several HBV life cycle steps by either entry inhibitors, drugs targeting cccDNA, siRNA targeting viral transcripts, capsid assembly modulators, and approaches targeting the secretion of viral envelope proteins. The addition of one or several new drugs to current therapies should offer the prospect of a markedly improved response to treatments and an increased rate of functional cure. This should lead to a reduced risk of antiviral drug resistance, and to a decreased incidence of cirrhosis and hepatocellular carcinoma (HCC). In this chapter, we review investigational and early clinical efforts regarding the identification and characterization of antiviral targets that are being evaluated for the development of innovative DAA concepts for chronic HBV infections.