Entecavir shows limited efficacy in HBeAg-positive hepatitis B patients with a partial virologic response to adefovir therapy

New therapeutic options for persistent low-level viremia in patients with chronic hepatitis B virus infection: Increase of entecavir dosage

Chronic hepatitis B virus (HBV) infection (CHB) is a public health concern worldwide. Current therapies utilizing nucleos(t)ide analogs (NA) have not resulted in a complete cure for CHB. Furthermore, patients on long-term NA treatment often develop low-level viremia (LLV). Persistent LLV, in addition to causing the progression of liver disease or hepatocellular carcinoma, may shed light on the current plight of NA therapy. Here, we review the literature on LLV, NA treatment, and various doses of entecavir to find a strategy for improving the efficacy of this antiviral agent. For LLV patients, three therapeutic options are available, switching to another antiviral monotherapy, interferon-α switching therapy, and continuing monotherapy. In real-world clinical practice, entecavir overdose has been used in antiviral therapy for CHB patients with NA refractory and persistent LLV, which encouraged us to conduct further in-depth literature survey on dosage and duration related entecavir studies. The studies of pharmacodynamics and pharmacokinetics show that entecavir has the maximal selected index for safety, and has great potential in inhibiting HBV replication, in all of the NAs. In the particular section of the drug approval package published by the United States Food and Drug Administration, entecavir doses 2.5-20 mg/d do not increase adverse events, and entecavir doses higher than 1.0 mg/d might improve the antiviral efficacy. The literature survey led us to two suggestions: (1) Increasing entecavir dose to 1.0 mg/d for the treatment of NA naïve patients with HBV DNA >2 × 10⁶ IU/mL is feasible and would provide better prognosis; and (2) Further research is needed to assess the long-term toxic effects of higher entecavir doses (2.5 and 5.0 mg/d), which may prove beneficial in treating patients with prior NA treatment, partial virological response, or LLV state.

Antiviral effects of a niobium-substituted heteropolytungstate on hepatitis B virus-transgenic mice

To study the efficacy of a polyoxometalate, Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O, as an antiviral treatment in HBV transgenic mice. HBV transgenic mice were treated with Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O by intragastric administration. Adefovir and distilled water were administered as controls. Serum HBV DNA, liver HBV RNA levels were measured by quantitative RT-PCR. Serum HBsAg levels were measured by ELISA. The hepatitis B virus surface antigen (HBsAg) in liver cells was detected by immunohistochemistry (IHC). Pathological changes in the liver tissues were also observed by light and electron microscopy. Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O significantly decreased serum HBsAg and HBV DNA levels. Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O resulted in a 98% decrease in serum HBV DNA at 28 days, from 4.3 log₁₀ copies/ml at baseline to 2.5 log₁₀ copies/ml after treatment, and the inhibition rate of HBV DNA was higher than ADV at the same dose. The HBV replication levels in each group slightly increased at 7 days after withdrawal, but rebounded slightly more in the Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O treatment group compared to the H₂ O control group (p < .05). There were no differences in HBV RNA levels. No significant differences were observed in the pathology, but there were decreased HBsAg levels in the Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O-treated group compared to the control group. The results demonstrated that Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O displayed potent anti-HBV activity in HBV transgenic mice and supported for future clinic study.

HBV epidemiology and genetic diversity in an area of high prevalence of hepatitis B in southern Brazil

Background

Hepatitis B virus (HBV) infection is a major public health problem in Brazil. HBV endemicity is usually moderate to low according to geographic regions, and high prevalence of this virus has been reported in people of some specific Brazilian counties, including those with a strong influence of Italian colonization in southern Brazil. Analysis of HBV diversity and identification of the main risk factors to HBV infection are necessary to understand hepatitis B epidemiology in these high prevalence regions in southern Brazil.

Objective

To investigate epidemiological characteristics and HBV genotypes and subgenotypes circulating in a specific city with high HBV prevalence.

Methods

A cross-sectional study was performed with 102 HBV chronically infected individuals, recruited in reference outpatient clinics for viral hepatitis in a city of high HBV prevalence (Bento Gonçalves) in Rio Grande do Sul state, Brazil between July and December 2010. Socio-demographic, clinical and behavior-related variables were collected in a structured questionnaire. HBV serological markers (HBsAg, anti-HBc), viral load, genotypes/subgenotypes and drug resistance were evaluated and comparatively analyzed among all patients.

Results

The HBV infected subjects had a mean age of 44.9 (±12.2) years, with 86 patients (84.3%) reporting to have a family history of HBV infection, 51 (50.0%) to share personal objects, and were predominantly of Italian descendants (61; 64.9%). There was a predominance of genotype D (49/54; 90.7%), but genotype A was also detected (5/54; 9.3%). Subgenotypes D1 (1; 4.7%), D2 (3; 14.3%), and D3 (17; 81.0%) were identified. LAM-resistant mutation (rtM204I) and ADV-resistant mutations (rtA181V) were detected in only one patient each.

Conclusions

These results demonstrate a pivotal role of intrafamilial transmission for HBV spreading in this population. Furthermore, there is a high prevalence of HBV genotype D in this region.

A five years study of antiviral effect of entecavir in Chinese chronic hepatitis B patients

Entecavir (ETV) is a potent viral replication inhibitor for chronic hepatitis B (CHB) patients. To investigate the efficacy of ETV in Chinese nucleos(t)ide(NA)-experienced CHB patients. Among 89 CHB patients with ETV monotherapy for ≥6 months, 33/89 (37%) or 56/89 (73%) were NA-naïve or NA-experienced. During a median follow-up of 5.75 years, all NA-naïve CHB patients achieved VR without genotypic ETV-resistance. However, VR was observed in 50/56 (~90%) of NA-experienced CHB patients during a median follow-up of 4.75 years. Antiviral efficacy was not reduced in patients with previous lamivudine (LAM) with/without LAM-resistance (HR 0.465; 95% CI 0.196–1.100; p > 0.05) (HR 0.472; 95% CI 0.205–1.091; p > 0.05). Patients with a primary treatment failure to adefovir (ADV) had a reduced probability of achieving VR compared to NA-naïve (HR 0.496; 95% CI 0.287–0.857; p < 0.01). Previous ADV-experienced patients with a partial VR (HR 1.253; 95% CI 0.429–3.665; p > 0.05) did not influence antiviral response to ETV. The antiviral efficacy of ETV is not influenced by previous treatment LAM with/without LAM-resistance. ETV may still be an option in ADV-experienced patients with a partial VR, but not advised in patients with a primary treatment failure to ADV.

Mutational analysis of reverse transcriptase and surface proteins of patients with partial virological response during mono and combination antiviral therapies in genotype D chronic hepatitis B

Introduction

The mutational pattern of chronic Hepatitis B virus (HBV) is unclear in patients who show incomplete response to antiviral therapy. The aims of this study were 1) to determine the benefit of combination therapy with adefovir dipivoxil (ADV) and Lamivudine (LAM) versus ADV or LAM alone in maintaining virological, biochemical and histological responses and 2) to investigate the patterns of mutations in the reverse transcriptase and surface proteins of HBV with LAM and/or ADF-resistant in partially-responded chronic hepatitis B (CHB) patients.

Methods

The study group consisted of 186 chronic HBV carriers who were admitted to the Tehran Hepatitis Network from 2010 to 2013. We retrospectively selected 86 patients who partially responded to different nucleoside analogue regimens. After 48 weeks of therapy, five groups of patients were defined including eight Lamivudine (LAM) Group (I), 30 Adefovir (ADV) Group (II), 16 ADV add on LAM Group (III), 32 ADV+LAM Group (IV), and 100 controls (no therapy). Reverse transcriptase (RT) and surface genes were amplified and sequenced for mutational analysis.

Results

All groups showed differences between mean values for age, gender, alanine transaminase (ALT), aspartate transaminase (AST), and HBV DNA levels groups showed significant differences than other groups (p < 0.05). The mutation frequencies for groups were I (1.7%), II (1.39%), III (2.28%), IV (2.0%), and V (0.38%). T54N, L80I/V, I91L/V, L180M, M204I/V, Q215P/S, and F221Y/S showed the highest number of mutations in all groups with different frequencies. Four new, unreported mutations were found.

Conclusion

Those patients who failed to respond in the first 48 weeks, whether they were receiving mono or combination therapy, should be tested genotypically, for the early modification of treatment.

Treatment Outcomes With First-line Therapies With Entecavir and Tenofovir in Treatment-Naive Chronic Hepatitis B Patients in a Routine Clinical Practice

BACKGROUND

Given their high efficacy, entecavir (ETV) and tenofovir (TDF), are the recommended first-line therapies for chronic hepatitis B, but it is not clear whether the efficacy reported from pivotal trials is similar to the outcomes seen in routine practice.

GOALS

Our goal was to examine the treatment outcomes of antiviral therapy in such setting.

PATIENTS AND METHODS

We conducted a retrospective study of 557 consecutive treatment-naive patients who started either ETV (n=443) or TDF (n=114) at 3 US liver clinics between January 2005 and 2012. Primary study endpoint was complete viral suppression (CVS) rate (hepatitis B virus DNA<40 IU/mL).

RESULTS

The majority of patients in both ETV and TDF groups were Asians, hepatitis B e antigen (HBeAg) negative, male, and with similar pretreatment alanine aminotransferase and hepatitis B virus DNA levels. Similar proportions of patients in the ETV and TDF groups achieved CVS at 24 months: 87.7% versus 87.0%, respectively. Cumulative rates of virological breakthrough in the ETV and TDF groups were 1.0% versus 4.8% (P=0.26) and 3.7% versus 9.8% (P=0.04) at month 12 and 24, respectively; and all were associated with medication nonadherence. Cumulative rate of medication nonadherence was lower in the ETV than TDF group: 4.6% versus 7.8% at month 12 and 8.9% versus 16.9% at month 24, respectively.

CONCLUSIONS

Patients treated with either ETV or TDF achieve a similar rate of CVS at 24 months. The primary contributor to suboptimal response was medication nonadherence. Attention to medication adherence is needed in a routine clinical setting.

The Efficacy of Add-on Telbivudine Versus Switching to Pegylated Interferon Alfa-2a in Chronic Hepatitis B Patients With Poor Responses to Adefovir

BACKGROUND

There are limited options for chronic hepatitis B (CHB) patients who have poor responses to adefovir (ADV).

OBJECTIVES

The aim of this study is to evaluate the effects of adding on telbivudine (LdT) or switching to pegylated interferon alfa-2a (PEG-IFN-α2a) as alternative rescue therapies for patients with poor responses to the initial ADV treatments.

PATIENTS AND METHODS

Ninety-seven CHB patients with HBV DNA > 2 log10 copies/mL 48 weeks after ADV monotherapy were included in this study. Fifty-nine of these patients were treated with a combination of LdT plus ADV (LdT + ADV) daily, while thirty-eight patients were switched to PEG-IFN-α2a subcutaneous injections weekly for 48 weeks.

RESULTS

Both rescue strategies were proven to be safe and the majority of patients tolerated the therapies well. LdT + ADV led to more rapid reductions in viral loads than PEG-IFN-α2a monotherapy, with 2.14 (LdT + ADV) and 0.98 (PEG-IFN-α2a) log10 copies/mL decreases 48 weeks after rescue treatments, respectively (P < 0.00001). The rates corresponding to virological and biochemical responses were also elevated in patients who received the LdT + ADV combination therapy at the end of the observation period (88.1 vs. 68.4% for virological response, P = 0.017; 83.3 vs. 47.2%, P = 0.00045). However, the decline in the hepatitis B surface antigen (HBsAg) was more pronounced in PEG-IFN-α2a treated patients. Moreover, the cumulative rates of serological responses were higher in patients who switched to the PEG-IFN-α2a therapy.

CONCLUSIONS

Both add-on LdT and switching to PEG-IFN-α2a were satisfactory and optimal treatments for CHB patients with poor responses to ADV. Both rescue strategies resulted in significant reductions in serum viral load and ALT levels, and were associated with high rate of serological outcomes in our hospital.

Response to potent anti-HBV agents in chronic hepatitis B and combined effect of HBV reverse transcriptase mutations

BACKGROUND AND AIM

Response to nucleos(t)ide analogue therapy against HBV infection depends on a number of factors. One of them is appearance of drug resistance mutations. The present study aimed to investigate the efficacy of ETV and TDF as anti-HBV agents and to analyze the role of HBV-RT mutations in reducing the efficacy of mentioned drugs.

MATERIAL AND METHODS

Sixty nine treatment naïve CHB patients (mean age 33.8 ± 11.9 years) were enrolled and treated with ETV or TDF for one year. Complete virological response (CVR) was defined as undetectable serum HBV DNA after 12 months of therapy. Amino acid and nucleotide sequence analyses of HBV-RT region were performed using Geno2pheno HBV drug resistance tool. The 3D model of HBV-RT protein was built by I-TASSER server and RMSD was calculated between wild type and mutated HBV-RT protein.

RESULTS

After 12 months of treatment, four CHB patients did not achieve CVR and all of them were with HBV genotype D. HBeAg seroconversion was achieved in 56% HBeAg positive patients after 12 months of antiviral therapy. The HBV-RT amino acid sequences from these four patients were used for in-silico analysis. It was found that the presence of many mutations in HBV-RT region of HBV isolated from these patients led to a high degree of variation in configuration of atoms of HBV-RT protein and also caused displacement of active site of this protein.

CONCLUSION

The efficacy of antiviral drugs in inhibiting HBV replication may be reduced by combined effect of many HBV-RT mutations; however, an in vitro study is needed to validate the findings.

Safety and efficacy of entecavir in adefovir-experienced patients

BACKGROUND AND AIM

Suboptimal viral suppression with adefovir (ADV) poses a challenge in managing chronic hepatitis B. Few studies have evaluated the efficacy of entecavir (ETV) in ADV-experienced patients. Our aim is to assess treatment effectiveness of ETV in ADV-experienced patients.

METHODS

ADV-experienced patients switched to ETV were enrolled from six US clinics. Patients completed a median of 24 months of ETV after switch. Patients were categorized into partial responders (detectable HBV-DNA at switch) or complete responders (undetectable HBV-DNA at switch) to ADV. Primary and secondary outcome measurements were complete viral suppression (CVS, HBV-DNA < 60 IU/mL) and biochemical response (BR, alanine aminotransferase [ALT] < 40 U/L), respectively.

RESULTS

A total of 120 patients were included in the analysis (80 ADV partial responders; 40 ADV complete responders). In partial responders, CVS rate was 84% after 24 months of ETV. BR rate was 58% at switch to ETV and increased to 90% after 24 months. All complete responders continued to experience CVS after switch. On multivariate analysis inclusive of age, male gender, ALT level at switch, and history of lamivudine (LAM) exposure, we identified positive, hepatitis B e antigen status before ADV and higher HBV-DNA level at time of switch as significant independent negative predictors of CVS. In eight patients with ADV resistance, seven achieved CVS after 24 months of ETV, and all achieved BR.

CONCLUSION

In ADV-experienced patients, high rates of CVS and BR can be achieved/sustained after switching to ETV, including those with ADV resistance or with prior exposure to LAM.

Antiviral effect of entecavir in nucleos(t)ide analogue-naïve and nucleos(t)ide analogue-experienced chronic hepatitis B patients without virological response at week 24 or 48 of therapy

We investigated the antiviral effect of entecavir in nucleos(t)ide analogue (NA)-naïve and NA-experienced chronic hepatitis B patients without virological response (VR, HBV DNA < 300 copies/mL) at week 24 or 48. A total of 369 NA-naïve and 181 NA-experienced patients treated with entecavir monotherapy were analysed. Of the 369 NA-naïve patients, 34 did not achieve VR at week 48. Of them, patients with HBV DNA ≤ 2000 copies/mL at week 48 achieved a higher VR rate than those with HBV DNA >2000 copies/mL (18/23 vs 3/11, P = 0.004). Two naïve patients with HBV DNA >2000 copies/mL developed entecavir- or lamivudine-resistant mutants. In 98 lamivudine-experienced patients without ever having lamivudine resistance, most patients with VR (72/72) and partial VR (300-10(4) copies/mL; 20/23) at week 24 or VR at week 48 (89/91) could maintain or achieve VR after prolonged therapy. In 75 patients with prior resistance to lamivudine, prolonged entecavir therapy led to low VR rate in those without VR at week 24 (13/45) or 48 (4/34) and high entecavir-resistance rate in those with or without VR at week 24 (6/30 with and 23/45 without) and 48 (8/41 with and 21/34 without). VR at week 48 was an independent predictor (HR 0.14, 95% CI 0.06-0.33) for entecavir-resistant mutant development among the 75 patients with prior lamivudine-resistant mutants. In conclusion, prolonged entecavir treatment resulted in a poor response in naïve patients with HBV DNA >2000 copies/mL at week 48 and patients with prior lamivudine-resistant mutants without VR at week 24 or 48.

The 104-week efficacy and safety of telbivudine-based optimization strategy in chronic hepatitis B patients: a randomized, controlled study

An optimization strategy based on the Roadmap concept is supposed to improve the clinical outcomes of patients with suboptimal antiviral response. The aim of this study was to prove the concept with a multicenter, open-label, randomized, controlled study. In all, 606 hepatitis B e antigen (HBeAg)-positive, nucleos(t)ide-naive chronic hepatitis B patients were randomized to the Optimize or Mono group. Patients in the Optimize group were treated with telbivudine for 24 weeks, after which those suboptimal responders with HBV DNA ≥300 copies/mL at week 24 received telbivudine plus adefovir until week 104, while the early virological responders continued telbivudine monotherapy. Patients in the Mono group received telbivudine monotherapy. All patients with telbivudine monotherapy had adefovir added if viral breakthrough developed. Sixty-eight percent (204/300) of patients in the Optimize group had adefovir added due to suboptimal response. At week 104, compared to the Mono group, more patients in the Optimize group achieved HBV DNA <300 copies/ml (76.7% versus 61.2%, P < 0.001) with less genotypic resistance (2.7% versus 25.8%, P < 0.001). The rates of HBeAg seroconversion and alanine aminotransferase (ALT) normalization were comparable between the two groups (23.7% versus 22.1%; 80.7% versus 79.2%). For week 24 suboptimal responders, telbivudine plus adefovir showed an additive antiviral potency, with 71.1% achieving virological response at week 104 and only 0.5% developing genotypic resistance, compared with 46.6% who achieved virological response and 37.8% who developed genotypic resistance with telbivudine monotherapy. Both treatment regimens were well tolerated, with an observed persistent increase of the glomerular filtration rate.

CONCLUSION

For suboptimal virological responders to telbivudine at week 24, adjusting the treatment strategy is recommended. Adding adefovir can benefit these patients with additive antiviral potency and low resistance without increased side effects.

Efficacy of switching to telbivudine plus adefovir in suboptimal responders to lamivudine plus adefovir

AIM: To examine the efficacy of telbivudine (LdT) + adefovir (ADV) vs continuation of lamivudine (LAM) + ADV in patients with LAM-resistant chronic hepatitis B (CHB) who show a suboptimal response to LAM + ADV.

METHODS: This was a randomized, active-control, open-label, single-center, parallel trial. All eligible patients were enrolled in this study in Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea, between March 2010 and March 2011. Hepatitis Be antigen (HBeAg)-positive CHB patients whose serum hepatitis B virus (HBV) DNA remained detectable despite at least 6 mo of LAM + ADV therapy were included. Enrolled patients were randomized to either switching to LdT (600 mg/d orally) plus ADV (10 mg/d orally) (LdT + ADV group) or to continuation with LAM (100 mg/d orally) plus ADV (10 mg/d orally) (LAM + ADV group), and were followed for 48 wk. One hundred and six patients completed the 48-wk treatment period. Serum HBV DNA, HBeAg status, liver biochemistry and safety were monitored at baseline and week 12, 24, 36 and 48.

RESULTS: The duration of prior LAM + ADV treatment was 18.3 (LdT + ADV) and 14.9 mo (LAM + ADV), respectively (P = 0.131). No difference was seen in baseline serum HBV DNA between the two groups [3.66 (LdT + ADV) vs 3.76 (LAM + ADV) log₁₀ IU/mL, P = 0.729]. At week 48, although there was no significant difference in the mean reduction of serum HBV DNA from baseline between LdT + ADV group and LAM + ADV group (-0.81 vs -0.47 log₁₀ IU/mL, P = 0.167), more patients in the LdT + ADV group had undetectable HBV DNA levels compared to those in the LAM + ADV group (30.2% vs 11.5%, P = 0.019). Three patients with LdT + ADV treatment and 2 patients with LAM + ADV treatment achieved HBeAg loss. The patients in both groups tolerated the treatment well without serious adverse events. The proportion of patients with estimated glomerular filtration rate ≥ 90 mL/min per 1.73 m² in the LdT + ADV group increased from 49.1% (26/53) at baseline to 58.5% (31/53) at week 48, while that in the LAM + ADV group decreased from 37.7% (20/53) at baseline to 30.2% (16/53) at week 48.

CONCLUSION: The switch to LdT + ADV in suboptimal responders to LAM + ADV showed a significantly higher rate of virologic response at week 48. These results suggest that LdT + ADV could be a therapeutic option for patients who are unable to use enofovir disoproxil fumarate for any reason.

Long-term efficacy of entecavir plus adefovir combination therapy versus entecavir monotherapy in adefovir refractory chronic hepatitis B patients with prior lamivudine resistance

OBJECTIVES

We investigated the long-term efficacy of entecavir (ETV) + adefovir (ADV) combination therapy versus ETV monotherapy in lamivudine (LAM)-resistant chronic hepatitis B (CHB) patients who failed to respond to ADV rescue therapy.

METHODS

A total of 91 ADV refractory patients with prior LAM resistance received ETV (1.0 mg/day) + ADV (10 mg/day) combination therapy (group A, n = 45) or ETV (1.0 mg/day) monotherapy (group B, n = 46) for more than 48 weeks.

RESULTS

The rates of undetectable serum hepatitis B virus DNA levels (≤20 IU/ml) at weeks 48 and 96 were not significantly different between group A and group B (31.1 vs. 23.9% at week 48, p = 0.442, and 44.7 vs. 34.5% at week 96, p = 0.457). However, the incidence of virological breakthrough in group A was significantly lower than that in group B (0 vs. 17.4% at week 48, p = 0.006, and 2.6 vs. 44.8% at week 96, p < 0.001). ETV monotherapy was the only independent factor significantly associated with virologic breakthrough (p = 0.015).

CONCLUSIONS

ETV + ADV combination therapy is a better therapeutic option than ETV monotherapy for ADV refractory CHB patients with prior LAM resistance.

Efficacy of telbivudine treatment for hepatitis B e antigen-positive chronic hepatitis B patients with poor response to adefovir dipivoxil

Telbivudine (LdT) has demonstrated potent antiviral activity in nucleos(t)ide analogue (NA)-naïve chronic hepatitis B patients (CHB), but data on its efficacy in NA-experienced patients are limited. The aim of this study was to investigate the effect of LdT in hepatitis B e antigen-positive CHB patients with poor response to initial adefovir dipivoxil (ADV). Forty-two CHB patients with HBV DNA > 4 log10  copies/mL after 12 months of ADV monotherapy were enroled in the study and thereafter treated with LdT 600 mg daily for 18 months. Telbivudine led to a rapid decrease in viral load, and viral replication was persistently suppressed with a reduction of 2.26 log10  copies/mL 18 months after LdT treatment. The rates corresponding to virological and biochemical response at the end of observation were 97.6% (41/42) and 65.8% (25/38), respectively. HBeAg loss was found in 30.8% (12/39) of patients, while HBeAg/anti-HBe seroconversion was found in 17.9% (7/39). Only one patient was detected to have LdT-associated mutation, and no severe adverse events were reported. Optimization therapy with LdT monotherapy may be a good choice for CHB patients with poor response to ADV, and switching to LdT may be the most cost-effective rescue therapeutic strategy for patients with poor response to initial ADV monotherapy.

Entecavir plus adefovir combination treatment for chronic hepatitis B patients after failure of nucleoside/nucleotide analogues

BACKGROUND

The combination of entecavir, a nucleoside analogue, and adefovir, a nucleotide analogue, would be a promising salvage treatment for chronic hepatitis B (CHB) patients who fail nucleoside/nucleotide analogue (NA) regimens.

METHODS

A total of 89 CHB patients who had failed NA regimens and were treated with entecavir plus adefovir combination for at least 12 months were included.

RESULTS

Mean baseline HBV DNA of patients was 6.16 ±1.44 log(10) IU/ml. Patients were classed by the number of previously failed NAs; 1 NA (lamivudine; n=15; Group 1), 2 NAs (lamivudine and either adefovir or entecavir; n=39; Group 2) and 3 NAs (lamivudine, adefovir and entecavir; n=35; Group 3). After 12 months of treatment, the mean reduction in HBV DNA was greater in Group 1 than in Group 2 or 3 (-5.81 ±1.71, -3.20 ±1.36 and -2.93 ±1.56 log(10) IU/ml, respectively; P<0.01). The rates of virological response (HBV DNA<2,000 IU/ml) were 100%, 79.5% and 34.3% (P<0.01), and the rates of complete virological response (HBV DNA<60 IU/ml) were 53.3%, 25.6% and 14.3% in Group 1, 2 and 3, respectively (P<0.01) at 12 months. Higher baseline HBV DNA (odds ratio =0.59; P=0.02) and increasing number of previously failed NAs (P<0.01) were independently associated with a lower rate of complete virological response at 12 months.

CONCLUSIONS

Entecavir plus adefovir combination treatment was effective in achieving virological response in CHB patients after failure of NAs. However, its effect progressively decreased as the number of previously failed NAs increased.

Evolution of adefovir-resistant HBV polymerase gene variants after switching to tenofovir disoproxil fumarate monotherapy

BACKGROUND

Tenofovir disoproxil fumarate (TDF), an acyclic nucleotide analogue was shown to be effective in many HBV-infected patients with resistance to adefovir dipivoxil (ADV). This observation is intriguing because in vitro studies show that HBV mutations selected by ADV confer cross-resistance to TDF. To assess the clinical relevance of this cross-resistance, we studied the evolution of HBV polymerase gene variants in patients with genotypic resistance against ADV (rtN236T and/or rtA181V/T) during TDF treatment.

METHODS

In 10 HBV-monoinfected patients (9 male, mean age 47 ±11 [range 27-67] years, 6 hepatitis B e antigen-positive) with virological breakthrough during ADV treatment associated with the mutations rtN236T and/or rtA181T/V, HBV polymerase gene variants were studied during up to 24 months of consecutive monotherapy with TDF by population sequencing, line probe assay and clonal analysis.

RESULTS

In all patients, switching to TDF resulted in a continuous reduction of HBV DNA from a median of 7.6 (4.6-9.4) log(10) copies/ml to 3.3 (2-5) log(10) copies/ml, remaining in 7 patients >400 copies/ml at 12 months. ADV-resistance mutations remained detectable throughout the whole observation period in most patients. Apart from an M204Q mutation in one sample, no new HBV polymerase gene mutations were found. In two patients with low level viraemia after 72 weeks of TDF, adding lamivudine led to a complete response within a few weeks.

CONCLUSIONS

ADV-resistant HBV variants may further become selected during TDF treatment, however they cause only a mild decrease in TDF susceptibility.

Lamivudine plus adefovir vs. entecavir in HBeAg-positive hepatitis B with sequential treatment failure of lamivudine and adefovir

BACKGROUND AND AIMS

Few studies have adequately examined the efficacy of lamivudine plus adefovir (LAM+ADV) combination therapy vs. entecavir (ETV) monotherapy in HBeAg-positive hepatitis B patients who fail to respond to sequential treatment with LAM and ADV. We compared directly the efficacy of LAM+ADV vs. ETV in such patients and assessed prognostic factors associated with a virologic response at month 12.

METHODS

In total, 72 HBeAg-positive patients who showed resistance (n = 33) or a suboptimal virologic response (n = 39) to ADV monotherapy with resistance to LAM therapy underwent rescue therapy (31 LAM+ADV and 41 ETV). All patients were followed for at least 12 months.

RESULTS

Following 12 months of treatment, in the LAM+ADV and ETV groups, a virologic response was observed in 7/31 (22.6%) and 8/41 (19.5%; P = 0.777) patients; ALT normalization occurred in 11/13 (84.6%) and 16/18 (88.9%; P = 0.566); HBeAg seroconversion in 1/31 (2.3%) and 4/41 (9.8%; P = 0.341) and a virologic breakthrough in 3/31 (9.0%) and 5/41 (12.1%; P = 0.452) respectively. Independent prognostic factors associated with a virologic response were the baseline HBV-DNA level (OR = 0.37; 95% CI 0.17-0.80; P = 0.011) and the duration of prior ADV monotherapy (OR = 0.89; 95% CI 0.83-0.95; P = 0.044).

CONCLUSIONS

Neither LAM+ADV nor ETV was adequately effective in patients with sequential LAM and ADV treatment failure. Thus, when chronic hepatitis B patients show resistance or suboptimal response to ADV monotherapy, early modification of treatment should be considered.

Lamivudine plus adefovir or telbivudine plus adefovir for chronic hepatitis B patients with suboptimal response to adefovir

BACKGROUND

There is no standard management of chronic hepatitis B (CHB) patients with suboptimal response to nucleoside/nucleotide analogues (NAs). This study aimed to evaluate two different NA combination therapies in patients with suboptimal response to adefovir (ADV).

METHODS

In this study, 72 CHB patients with suboptimal response to ADV were assessed, with 37 patients receiving lamivudine plus ADV (group A) and 35 patients receiving telbivudine plus ADV (group B).

RESULTS

Baseline characteristics between two groups were similar. At month 12, rates of biochemical response (BR) and virological response (VR) were similar between groups A and B (17/19 versus 18/20 for BR, [P=0.269] and 30/37 versus 31/35 for VR [P=0.377]), and cumulative rates of serological response were greater in group B than in group A (10/26 versus 2/28 in hepatitis B e antigen [HBeAg] loss [P=0.006] and 7/26 versus 1/28 in HBeAg/hepatitis B e antibody seroconversion [P=0.022]). After 12-month treatment, 8.1% (3/37) of patients in group A and 5.7% (2/35) of patients in group B had VR; among patients in group A, two had rtM204V/I and rtL180M and one had rtN236T, whereas the two patients in group B had rtM204I+rtL180M.

CONCLUSIONS

Both combination therapies led to a significant decrease in HBV DNA. HBeAg serological outcomes were higher with telbivudine plus ADV combination therapy.

Antiviral efficacy of combination therapy with entecavir and adefovir for entecavir/lamivudine-resistant hepatitis B virus with or without adefovir resistance

There is little clinical information on the management of hepatitis B virus (HBV) that is resistant to multiple drugs including entecavir (ETV). The present retrospective cohort study assessed the antiviral efficacy of ETV/adefovir dipivoxil (ADV) combination therapy for ETV-resistant HBV with prior lamivudine (LAM) resistance, and either with or without previous ADV resistance. The cumulative probability of achieving a virological response (undetectable serum HBV DNA) was compared by Kaplan-Meier analysis and the Breslow method. Seventeen patients with ETV-resistant HBV who were treated with ETV/ADV combination therapy for at least 6 months at a tertiary care center, were included; seven had dual resistance to ETV and LAM [ADV-r(-) group] and 10 had triple resistance to ETV, LAM, and ADV [ADV-r(+) group]. The median follow-up period was 9 months (range, 6-23). A virological response was noted in seven patients after a median of 3 months (range, 3-12) of treatment; five in the ADV-r(-) group and two in the ADV-r(+) group. The cumulative probability of a virological response was significantly higher in the ADV-r(-) group than in the ADV-r(+) group (6 months cumulative probability, 57.1% vs. 11.1%). In conclusion, ETV/ADV combination therapy led to virological responses in five of seven patients with resistance to ETV and LAM, but a significantly poorer response in patients with prior ADV resistance than in those without prior ADV resistance. Therefore, ETV/ADV combination therapy could be a useful therapeutic option for ETV- and LAM-resistant HBV without prior ADV resistance.

Randomized trial of entecavir plus adefovir in patients with lamivudine-resistant chronic hepatitis B who show suboptimal response to lamivudine plus adefovir

A substantial proportion of patients with lamivudine-resistant hepatitis B virus (HBV) show suboptimal virologic response during rescue combination treatment with lamivudine plus adefovir. In this randomized active-control trial, 90 patients with serum HBV DNA levels of >2,000 IU/ml after at least 24 weeks of treatment with lamivudine-plus-adefovir therapy for lamivudine-resistant HBV were randomized to combination treatment with entecavir plus adefovir (ETV+ADV, n = 45) or continuation of lamivudine plus adefovir (LAM+ADV, n = 45) for 52 weeks. At baseline, patients' mean serum HBV DNA level was 4.60 log(10) IU/ml (standard deviation [SD], 1.03). All 90 patients completed 52 weeks of treatment. At week 52, the proportion of patients with serum HBV DNA levels of <60 IU/ml, the primary endpoint, was significantly higher in the ETV+ADV group than in the LAM+ADV group (n = 13, 29%, versus n = 2, 4%, respectively; P = 0.004). The mean reduction in serum HBV DNA levels from baseline was significantly greater in the ETV+ADV group than in the LAM+ADV group (-2.2 log(10) IU/ml versus -0.6 log(10) IU/ml, respectively; P < 0.001). At week 52, additional mutations causing resistance to adefovir or entecavir were analyzed in all patients with detectable HBV DNA by restriction fragment mass polymorphism assays and detected in none of the ETV+ADV group but in 15% of patients in the LAM+ADV group (P = 0.018). Safety and adverse event profiles were similar in the two groups. In conclusion, entecavir-plus-adefovir combination therapy provides superior virologic response and favorable resistance profiles, compared with the continuing lamivudine-plus-adefovir combination, in patients with lamivudine-resistant HBV who fail to respond to lamivudine-plus-adefovir combination therapy.

Rescue therapy for lamivudine-resistant chronic hepatitis B: adefovir monotherapy, adefovir plus lamivudine or entecavir combination therapy

OBJECTIVE

We aimed to compare the cumulative efficacy and resistance of ADV monotherapy, ADV add-on LAM (ADV + LAM), ADV and ETV (ADV + ETV) combination therapy in LAM-resistant patients.

METHODS

Ninety-one adult CHB patients with LAM-resistance mutations (YMDD) were identified. Of these 91, 29 patients were treated with ADV monotherapy, 30 were treated with ADV + LAM and 32 were treated with ADV + ETV combination therapy, for at least 24 months.

RESULTS

The mean serum HBV-DNA decreases from baseline at 3, 6, 12, and 24 months were -3.23, -4.41, -5.32, and -5.58 log(10) IU/mL in the ADV + ETV combination therapy groups, respectively; the most significant among the three treatment groups (p<0.01). The rate of HBV-DNA PCR undetectability (<60 IU/mL) at 6 months in ADV + ETV combination therapy was 78.1%; also the most significant among the three treatment groups (p=0.024). Viral breakthrough and genotypic mutations were detected in 8 (27.6%) and 4 (13.3%) patients in the ADV monotherapy and ADV+LAM therapy groups, respectively; whereas no case of viral breakthrough and genotypic resistance was detected in the ADV+ETV combination therapy group after 24 months (p<0.05).

CONCLUSION

ADV + ETV combination therapy demonstrated faster and significantly greater suppression of HBV DNA compared with ADV add-on LAM combination therapy for patients with LAM-resistance mutations. ADV + ETV was superior to ADV + LAM in achieving initial virological response and long-term suppression activity against HBV. ADV + ETV combination therapy was the most effective to refrain from selecting HBV strains with cross-resistance to three NAs (LAM, ADV and ETV) for LAM-resistance patients.

The efficacy of entecavir therapy in chronic hepatitis B patients with suboptimal response to adevofir

BACKGROUND

An increasing number of patients with chronic hepatitis B (CHB) have experienced treatment failure to adefovir (ADV) and their management poses a growing challenge. Very limited data are available on the efficacy of entecavir (ETV) in patients previously treated with ADV.

AIM

To examine the effect of ETV monotherapy on HBV DNA and ALT levels in CHB patients previously treated with ADV, but switched to ETV due to suboptimal response.

METHODS

Study candidates were enrolled from five community gastroenterology clinics in the U.S. Each completed at least 12 months of ETV treatment after being previously treated with ADV and experiencing suboptimal response. Primary and secondary outcome measurements were complete viral suppression (CVS, HBV DNA <100 IU/mL) and biochemical response (BR, ALT < 40 U/L), respectively.

RESULTS

A total of 60 patients were included in this analysis. Twelve were lamivudine (LAM)-experienced and none were LAM-resistant. At time of switch to ETV, no patients had experienced CVS. The CVS rate was 68% after 12 months of ETV therapy. The BR rate was 67% at switch to ETV and 80% after 12 months. There was no significant difference in response rates between LAM-experienced and naïve patients. Among the eight patients with ADV resistance, each achieved CVS after 12 months of ETV therapy and seven achieved BR.

CONCLUSIONS

In patients with suboptimal response to adefovir, complete viral suppression and biochemical response can be achieved in the majority by 12 months after switching to entecavir, including patients with prior exposure to lamivudine and those with adefovir resistance.

Entecavir treatment for chronic hepatitis B: adaptation is not needed for the majority of naïve patients with a partial virological response

Entecavir (ETV) is a potent inhibitor of viral replication in nucleos(t)ide analogue (NA)-naïve chronic hepatitis B (CHB) patients. The aim of this study was to investigate the long term efficacy and safety of ETV in NA-naïve CHB patients, particularly in those with detectable hepatitis B virus (HBV) DNA after 48 weeks, in whom treatment adaptation is suggested by current guidelines. In a multicenter cohort study, we investigated 333 CHB patients treated with entecavir monotherapy. The NA-naïve population consisted of 243 patients, whereas 90 were NA-experienced. Virological response (VR) (HBV DNA<80 IU/mL) was achieved in 48%, 76%, and 90% of hepatitis B e antigen (HBeAg)-positive and in 89%, 98%, and 99% of HBeAg-negative NA-naïve patients at weeks 48, 96, and 144, respectively. Thirty-six of 175 (21%) NA-naïve patients with at least 48 weeks of follow-up had a detectable load at week 48 (partial virological response [PVR]). Twenty-nine (81%) patients with PVR reached VR during prolonged ETV monotherapy, and none of them developed ETV-resistance. Among 22 patients with HBV DNA<1,000 IU/mL at week 48, VR was achieved in 21 (95%) patients, compared with eight of 14 (57%) patients with HBV DNA≥1,000 IU/mL. Continuous HBV DNA decline was observed in most patients without VR during follow-up, and in three patients adherence was suboptimal according to the treating physician. ETV was safe and did not affect renal function or cause lactic acidosis.

CONCLUSION

ETV monotherapy can be continued in NA-naïve patients with detectable HBV DNA at week 48, particularly in those with a low viral load because long-term ETV leads to a virological response in the vast majority of patients.

[Analogs combination therapy in chronic hepatitis B: when and how?]

Hepatitis B virus (HBV) genomic variability is responsible for the complexity of the viral quasi-species and its evolution during the course of infection. The persistence of infected cells promotes the selection of drug-resistant strains. The development of nucleoside analogs without cross-resistance has provided a rationale for combination therapy. De novo combination, with low genetic barrier drugs, prevents the emergence of resistance in the short-term for drugs with a low genetic barrier and improves the control of infection. Long-term studies are needed to determine whether de novo combination is beneficial for analogs with a high genetic barrier as well. The add-on strategy is a standard in case of emergence of resistant mutants. This strategy needs to be implemented as early as possible before the virological breakthrough, especially if the viral suppression is sub-optimal. Clinical trials are mandatory in order to assess whether a) de novo combination is better than an early add-on strategy; and b) whether in case of sub-optimal viral suppression, an early add-on strategy is better in the long-term than a switch to a more potent drug with a high genetic barrier.

A low viral load predicts a higher initial virologic response to adefovir in patients with Lamivudine-resistant chronic hepatitis B

BACKGROUND/AIMS

Adefovir (ADV) is the preferred drug for treating lamivudine (LAM)-resistant hepatitis B. However, not all patients who face virologic breakthrough during LAM treatment respond to ADV. The aim of this study was to determine the factors associated with efficacy of ADV in LAM-resistant hepatitis B patients.

METHODS

The medical records of 231 patients who received ADV due to LAM-resistance were reviewed. Efficacy was assessed by the initial virologic response (IVR), defined as hepatitis B virus (HBV) DNA not being undetectable by real-time PCR at 6 months of ADV treatment.

RESULTS

Seventy patients (30%) achieved IVR. While 'add-on' modality, hepatitis B e antigen (HBeAg) negativity, and low baseline HBV DNA levels were associated with IVR in univariate analysis, multivariate analysis revealed HBeAg status and the DNA level to be the significant factors. The probability of IVR achievement increased sharply per each log(10) copies/mL decrement in the baseline viral load, which was 133 times in patients who had HBV DNA <10(5) copies/mL compared with those who had ≥10(8) copies/mL.

CONCLUSIONS

Factors associated with the IVR were HBeAg negativity and a low baseline viral load. Therefore, when virologic breakthrough with genotypic resistance emerges during LAM therapy, ADV treatment should be considered immediately before further increases in viral load. Additional long-term follow-up data are warranted.

Lamivudine plus adefovir or entecavir for patients with chronic hepatitis B resistant to lamivudine and adefovir

BACKGROUND & AIMS

Little is known about the optimal management of patients with chronic hepatitis B (CHB) who developed multiple-drug resistance.

METHODS

We assessed 91 patients with compensated CHB who developed adefovir-resistant mutations during adefovir monotherapy for lamivudine-resistant CHB. Of these, 41 were treated with a combination of lamivudine plus adefovir (LAM+ADV group) and 50 were treated with entecavir monotherapy (ETV group).

RESULTS

There were no significant differences between the two groups in baseline characteristics, including serum HBV DNA levels (p>0.05). The rate of virologic non-response (HBV DNA reduction <1 log(10) IU/ml at 6 months) was significantly greater in the LAM+ADV than in the ETV group (51.2% vs. 16.0%, p<0.01). At 12 months, HBV DNA declined less in the LAM+ADV than in the ETV group (-1.49+/-1.78 vs. -3.47+/-2.13 log(10) IU/ml, p<0.01). Only 12.2% and 22.0% of patients in the LAM+ADV and ETV groups, respectively, achieved complete virologic response (HBV DNA <60 IU/ml) at 12 months. Multivariable analysis showed that LAM+ADV group (OR=0.08, CI=0.02-0.28) and the presence of the rtA181V/T mutation (OR=0.21, CI=0.05-0.91) were independently associated with a decreased rate of virologic response (HBV DNA <2000 IU/ml) at 12 months.

CONCLUSIONS

In patients with CHB resistant to lamivudine and adefovir, combination therapy with these two drugs was not effective and was inferior to entecavir monotherapy in suppressing HBV DNA. However, the response to entecavir monotherapy was also not optimal. These results emphasize the importance of preventing the development of multidrug-resistant HBV and of exploration for adequate combination therapy in treatment of multidrug-resistant CHB.

Antiviral treatment of chronic hepatitis B virus (HBV) infections

While 25 compounds have been formally licensed for the treatment of HIV infection (AIDS), only seven licensed products are currently available for the treatment of chronic hepatitis B virus (HBV) infection: interferon-α, pegylated interferon-α, lamivudine, adefovir (dipivoxil), entecavir, telbivudine and tenofovir (disoproxil fumarate). In contrast to the treatment of HIV infections where the individual drugs are routinely used in combination, for the treatment of chronic HBV infection the individual drugs are generally used in monotherapy. In principle, combination drug therapy should allow reducing the likelihood of drug-resistant development.

Antiviral effect of entecavir in chronic hepatitis B: influence of prior exposure to nucleos(t)ide analogues

BACKGROUND & AIMS

Entecavir is a potent inhibitor of viral replication in nucleos(t)ide analogue (NA)-naïve chronic hepatitis B patients, but data on the efficacy in NA-experienced subjects are limited.

METHODS

In a multi-center cohort study we investigated 161 chronic hepatitis B patients (34% NA-experienced) treated with entecavir monotherapy.

RESULTS

During a median follow-up of 11 (3-23)months, 82 (79%) of 104 NA-naïve patients achieved virologic response (VR), defined as HBV DNA <80IU/ml, and none of the patients (0%) developed genotypic entecavir-resistance. VR was demonstrated in 31 (54%) of 57 NA-experienced patients during a median follow-up of 12 (3-31)months. Patients with lamivudine-resistant mutations at the start of entecavir monotherapy had a reduced probability of achieving VR compared to lamivudine-naïve patients (HR 0.14; 95% CI 0.04-0.58; p=0.007). Antiviral efficacy was not decreased by prior treatment with lamivudine when lamivudine-resistance had never developed (HR 0.81; 95% CI 0.43-1.52; p=0.52). Prior adefovir therapy without development of adefovir-resistance (HR 0.84; 95% CI 0.43-1.64; p=0.61) and presence of adefovir-resistance (HR 0.86; 95% CI 0.27-2.71; p=0.80) did not influence antiviral response to entecavir. Switching to a tenofovir-containing treatment regimen resulted in viral load decline in patients with entecavir-resistance associated mutations.

CONCLUSIONS

Entecavir proved to be efficacious in NA-naïve patients. The antiviral efficacy of entecavir was not influenced by prior treatment with adefovir or presence of adefovir-resistance. Entecavir should not be used in patients with previous lamivudine-resistance, yet it may still be an option in lamivudine-experienced patients in case lamivudine-resistance never developed.

Monotherapy versus combination therapy for the treatment of chronic hepatitis B

BACKGROUND

Nucleos(t)ide analogues, active against hepatitis B polymerase, suppress viral replication and improve clinical outcome. However, the emergence of drug-resistant mutants can result in treatment failure.

OBJECTIVES

We describe how the choice of first-line therapy is critical to long-term treatment success.

METHODS

A review of current drug therapies is provided.

RESULTS/CONCLUSIONS

Monotherapy with early-generation drugs (lamivudine or adefovir) was associated with a high rate of viral drug resistance and combination therapy with these agents was shown to reduce the incidence of resistance. The latest-generation drugs (entecavir and tenofovir) are potent inhibitors of viral replication and, in treatment-naive subjects, viral resistance to entecavir is uncommon and is not yet reported to tenofovir. Therefore, monotherapy with either entecavir or tenofovir is the current preferred option in treatment-naive patients. Combination therapy is appropriate in those with drug-resistant HBV infection, where drug choice is guided by the viral drug-resistance genotype/phenotype. Although combination therapy has been advocated in other patient groups (e.g., those with decompensated cirrhosis and following liver transplantation), there are, as yet, no data to mandate the use of combination therapy in such patients and any perceived benefit must be weighed against increased cost and risk for toxicity.

Evolution of hepatitis B virus mutation during entecavir rescue therapy in patients with antiviral resistance to lamivudine and adefovir

BACKGROUND

The efficacy of entecavir (ETV) monotherapy in treatment-experienced patients with chronic hepatitis B (CHB) is debatable.

METHODS

A total of 22 hepatitis B e antigen (HBeAg)-positive CHB patients who had shown viral breakthrough or suboptimal response with lamivudine (3TC) and adefovir disoproxil (ADV) therapy were treated with 1.0 mg of ETV. Clinical and virological parameters were monitored every 3 months. Restriction fragment mass polymorphism assays were used to detect antiviral resistance.

RESULTS

During 3TC and ADV therapy, 11 patients had rtM204V/I mutations, 2 had rtA181V/T or rtN236T, 7 had both and 2 had no 3TC- or ADV-related mutations. After switching to ETV monotherapy, the median change in serum hepatitis B virus (HBV) DNA level was -2.1 log(10) copies/ml. Virological response (HBV DNA<300 copies/ml) was achieved in 1 of 18 patients with pre-existing rt204 mutations, whereas it was achieved in all 4 patients without pre-existing rt204 mutations regardless of the presence of rt181 or rt236 mutations. Changes in mutational patterns during ETV therapy showed that rt204 mutations persisted or re-emerged. Relative abundances of rtM204V/I mutations in total viral populations gradually increased under ETV rescue, whereas those with rtA181V/T and rtN236T mutations decreased. ETV resistance mutations (rtL180M+rtT184I/L[rtS202G]+rtM204V) were detected in five patients with pre-existing rt204 mutations.

CONCLUSIONS

ETV monotherapy resulted in a limited virological response in patients who had previously failed 3TC and ADV rescue therapy. The limited efficacy might be associated with residual or reselected rtM204V/I mutations leading to ETV resistance. Combination treatment including potent antiviral agents should be recommended for patients with pre-existing rtM204V/I mutations.

[Development of clevudine resistance after switching from lamivudine in a patient with chronic hepatitis B]

Background/Aims

Newly developed and potent antiviral agents suffer from the problem of drug resistance. Multidrug resistance is a major impediment in the treatment of patients with chronic hepatitis B (CHB). In line with American Association for the Study of Liver Diseases guidelines, adefovir dipivoxil (ADV) add-on therapy is recommended in the case of lamivudine resistance, while tenofovir disoproxil fumarate (TDF) is recommended for ADV or entecavir (ETV) resistance. TDF is currently not available in Korea. ADV+ETV combination therapy may be a viable alternative to TDF in patients with either ADV or ETV resistance. However, the efficacy of ADV+ETV combination therapy in patients with CHB and multidrug resistance is unclear. This study investigated the efficacy of ADV+ETV combination therapy in patients with multidrug resistance.

Methods

Twenty-five patients were enrolled and were administered ADV+ETV combination therapy for at least 6 months. Blood was drawn at baseline and at 3, 6, 9, and 12 months after commencing treatment, and the following blood parameters were analyzed: alanine transaminase, hepatitis B e-antigen (HBeAg), anti-hepatitis B e-antigen, and hepatitis B virus (HBV) DNA levels. The initial virological response (IVR) was defined as an HBV DNA level of <4 log₁₀ copies/mL after 6 months of combination therapy.

Results

The IVR rate was 76%. The proportion of patients with a high viral load (≥5.0 log) dropped from 76% at baseline to only 5% after 6 months of treatment. The biochemical response rate during the first 6 months was 71%. HBeAg was lost in 2 patients (10%).

Conclusions

ADV+ETV combination therapy induced a good IVR in CHB patients who were refractory to more than 2 antiviral agents. This regimen may be a good alternative to TDF in Korea, where that drug is not available.