Current antiviral therapies for chronic hepatitis B

A deep-sequencing method detects drug-resistant mutations in the hepatitis B virus in Indonesians

OBJECTIVE

The long-term administration of a nucleos(t)ide analogue (NA) for the treatment of chronic hepatitis B may encourage the emergence of viral mutations associated with drug resistance. Minor populations of viruses may exist before treatment, but are difficult to detect because of technological limitations. Identifying minor viral quasispecies should be useful in the clinical management of hepatitis B virus (HBV) infection.

METHODS

Six treatment-naïve Indonesian patients with chronic HBV infection participated in this study. The polymerase region of the HBV genome, including regions with known drug-resistant mutations, was subjected to capillary sequencing and MiSeq sequencing (Illumina). Mutations were analyzed with Genomics Workbench software version 6.0.1 (CLC bio).

RESULTS

The mean mapping reads for the six samples was 745,654, and the mean number of amplified fragments ranged from 17,926 to 25,336 DNA reads. Several known drug-resistant mutations in the reverse transcriptase region were identified in all patients, although the frequencies were low (0.12-1.06%). The proportions of the total number of reads containing mutations I169L/M, S202R, M204I/L or N236S were >1.0%.

CONCLUSION

Several known NA-resistant mutations were detected in treatment-naïve patients in Indonesia using deep sequencing. Careful management of such patients is essential to prevent drug-resistant mutations from spreading to other patients.

Sequential analysis of amino acid substitutions with hepatitis B virus in association with nucleoside/nucleotide analog treatment detected by deep sequencing

Taking nucleoside/nucleotide analogs is a major antiviral therapy for chronic hepatitis B infection. The problem with this treatment is the selection for drug-resistant mutants. Currently, identification of genotypic drug resistance is conducted by molecular cloning sequenced by the Sanger method. However, this methodology is complicated and time-consuming. These limitations can be overcome by deep sequencing technology. Therefore, we performed sequential analysis of the frequency of drug resistance in one individual, who was treated with lamivudine on-and-off therapy for 2 years, by deep sequencing. The lamivudine-resistant mutations at rtL180M and rtM204V and the entecavir-resistant mutation at rtT184L were detected in the first subject. The lamivudine- and entecavir-resistant strain was still detected in the last subject. However, in the deep sequencing analysis, rt180 of the first subject showed a mixture in 76.9% of the methionine and in 23.1% of the leucine, and rt204 also showed a mixture in 69.0% of the valine and 29.8% of the isoleucine. During the treatment, the ratio of resistant mutations increased. At rt184, the resistant variants were detectable in 58.7% of the sequence, with the replacement of leucine by the wild-type threonine in the first subject. Gradually, entecavir-resistant variants increased in 82.3% of the leucine in the last subject. In conclusion, we demonstrated the amino acid substitutions of the serial nucleoside/nucleotide analog resistants. We revealed that drug-resistant mutants appear unchanged at first glance, but actually there are low-abundant mutations that may develop drug resistance against nucleoside/nucleotide analogs through the selection of dominant mutations.

Application of deep sequence technology in hepatology

Deep sequencing technologies are currently cutting edge, and are opening fascinating opportunities in biomedicine, producing over 100-times more data compared to the conventional capillary sequencers based on the Sanger method. Next-generation sequencing (NGS) is now generally defined as the sequencing technology that, by employing parallel sequencing processes, producing thousands or millions of sequence reads simultaneously. Since the GS20 was released as the first NGS sequencer on the market by 454 Life Sciences, the competition in the development of the new sequencers has become intense. In this review, we describe the current deep sequencing systems and discuss the application of advanced technologies in the field of hepatology.

Clevudine for chronic hepatitis B: antiviral response, predictors of response, and development of myopathy

Clevudine has been approved for the treatment of chronic hepatitis B (CHB) in South Korea. However, its long-term antiviral effect and safety awaits more study. The aim of this study was to evaluate antiviral efficacy, predictors of virologic response, and development of myopathy after clevudine therapy for CHB. The study included 102 nucleoside naïve CHB patients who had received clevudine for more than 6 months with good compliance. The median duration of clevudine treatment was 53 weeks (range, 25-90 weeks). A retrospective analysis of data retrieved from medical records was performed. The cumulative rate of virologic response [hepatitis B virus (HBV) DNA level <2000 copies/mL] at 48 weeks of clevudine therapy was 81%, and cumulative rate of clevudine resistance was 11% at 60 weeks of treatment. Independent predictors of virologic response to clevudine therapy were hepatitis B e antigen (HBeAg) negativity and rapid decrease of viral load during the early phase of treatment. The clevudine-related myopathy developed in 3.9% of patients, and was reversible after discontinuation of clevudine. Clevudine showed a potent antiviral response, and its effect was higher in HBeAg-negative patients, with rapid viral load reduction after therapy. However, long-term therapy for more than 1 year resulted in the development of considerable resistance and myopathy. Therefore, we should consider alternative antiviral agents if clevudine resistance or clevudine-induced myopathy is developed in patients on clevudine for the treatment of CHB.

Efficacy of consensus interferon in treatment of HbeAg-positive chronic hepatitis B: a multicentre, randomized controlled trial

Background

Consensus interferon (CIFN) is a newly developed type I interferon.

Aims

This multicentre, controlled trial was conducted to determine the efficacy of CIFN and to compare it with alpha-1b-interferon (IFN-α1b) in the treatment of patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B.

Methods

144 Patients were randomly assigned to receive 9 μg CIFN (CIFN group) or 50 μg INF-α1b (IFN-alpha group) subcutaneously 3 times weekly for 24 weeks, followed by 24 weeks of observation. Efficacy was assessed by normalization of serum alanine transaminase (ALT) levels and the non-detectability of serum hepatitis B virus DNA or HBeAg at the end of treatment and 24 weeks after stopping treatment.

Results

There was no statistically significant difference in the serological, virological and biochemical parameters between CIFN and IFN-α1b groups at the end of the therapy and follow-up period (p > 0.05). Overall, at the end of treatment, 7.0% (5/71) and 35.2% (25/71) of patients in the CIFN group showed a complete or partial response compared with 7.4% (5/68) and 33.8% (23/68) of the IFN-alpha group (p = 0.10). At 24 weeks after stopping treatment, 6.9% (5/72) and 37.5% (27/72) of patients in the CIFN group showed complete response or partial response compared with 7.1% (5/70) and 34.3% (24/70) of the IFN-alpha group (p = 0.10).

Conclusion

These findings suggest that 9 μg CIFN is effective in the treatment of patients with HBeAg-positive chronic hepatitis B. It can gradually induce ALT normalization and HBV DNA clearance and HBeAg loss or HBeAg/HBeAb seroconversion.

New antiviral choice for chronic hepatitis B: tenofovir disoproxil fumarate

Tenofovir disoproxil fumarate (TDF) is an oral prodrug of tenofovir, a novel, acyclic nucleotide analogue with in vitro activity against HIV-1 and HIV-2. TDF is licensed by American Food and Drug Administration (FDA) in 2001 for the treatment of HIV infection. TDF is currently one of the most widely used nucleotide reverse transcriptase inhibitors (NRTIs) for the treatment of HIV infection. Its efficacy, favorable toxicity profile, and convenient dosing have made this drug one of the most popular first-line treatment. Numerous studies have demonstrated the use of TDF in the treatment of HIV infection. It also has been shown to be effective in HIV/HBV coinfected patients and in patients with wild-type and lamivudine-resistant strains. Accumulating evidence suggests that TDF is more potent in suppressing HBV replication. In this review, we summarize the study progress of TDF in treating HBV infection.