Low efficacy of entecavir therapy in adefovir-refractory hepatitis B patients with prior lamivudine resistance

Comparing the efficacy and safety of tenofovir and adefovir or combined drug treatment for the treatment of chronic hepatitis B infection: a systematic review and meta-analysis

BACKGROUND

Chronic hepatitis B (CHB) affects a vast population globally. A variety of drugs are available for the treatment of CHB, including tenofovir (TDF) and adefovir (ADV). However, the efficacy of monotherapy drug treatment is inconclusive, the safety and efficacy of TDF remain unclear, more data are needed to be included and combined drug treatment is considered to exhibit higher efficacy. To explore this issue, we performed a current literature review and meta-analysis to compare the efficacy and safety of ADV vs. TDF, TDF vs. ADV + lamivudine (LAM); TDF vs. ADV + entecavir (ETV).

METHODS

We systematically searched China National Knowledge Infrastructure, the Cochrane Library, Embase, PubMed, Chinese VIP, and Wanfang Data, for relevant clinical trials since July 2015, all included studies were based on PICOS principles and evaluated independently by the reviewers in accordance with the Cochrane Handbook (Rob2.0). A meta-analysis was performed by using Review Manager 5.4.

RESULTS

We included a total of 32 studies, including 31 randomized controlled trials and one retrospective study involving 2,473 patients. The results revealed a low risk of bias in included studies, that the virologic response of TDF was superior to ADV (P<0.05). And TDF was also superior to ADV in Serum creatinine levels, Immunologic function, and safety profile. However, when ADV was combined with other medications, it was superior to TDF in alanine aminotransferase (ALT) level and Tbil level and adverse reactions, but on other indicators, TDF was superior to drug combination therapy.

CONCLUSIONS

Results showed that TDF was superior to ADV in the parameters of ALT, hepatitis B virus (HBV)-DNA reduction, HBeAg-negative conversion rate, safety, and total bilirubin levels in patients with CHB. However, when ADV was combined with LAM or ETV, they often showed the same therapeutic effect as TDF in parameters such as ALT level and Tbil level and combined therapy can effectively reduce the occurrence of adverse reactions. In this study, because the sample source countries were limited, a greater number of global studies are needed in the future to verify the current findings.

Coevolution analysis of amino-acids reveals diversified drug-resistance solutions in viral sequences: a case study of hepatitis B virus

The study of mutational landscapes of viral proteins is fundamental for the understanding of the mechanisms of cross-resistance to drugs and the design of effective therapeutic strategies based on several drugs. Antiviral therapy with nucleos(t)ide analogues targeting the hepatitis B virus (HBV) polymerase protein (Pol) can inhibit disease progression by suppression of HBV replication and makes it an important case study. In HBV, treatment may fail due to the emergence of drug-resistant mutants. Primary and compensatory mutations have been associated with lamivudine resistance, whereas more complex mutational patterns are responsible for resistance to other HBV antiviral drugs. So far, all known drug-resistance mutations are located in one of the four Pol domains, called reverse transcriptase. We demonstrate that sequence covariation identifies drug-resistance mutations in viral sequences. A new algorithmic strategy, BIS2TreeAnalyzer, is designed to apply the coevolution analysis method BIS2, successfully used in the past on small sets of conserved sequences, to large sets of evolutionary related sequences. When applied to HBV, BIS2TreeAnalyzer highlights diversified viral solutions by discovering thirty-seven positions coevolving with residues known to be associated with drug resistance and located on the four Pol domains. These results suggest a sequential mechanism of emergence for some mutational patterns. They reveal complex combinations of positions involved in HBV drug resistance and contribute with new information to the landscape of HBV evolutionary solutions. The computational approach is general and can be applied to other viral sequences when compensatory mutations are presumed.

[Efficacy of tenofovir-based rescue therapy for patients with drug-resistant chronic hepatitis B]

BACKGROUND/AIMS

Tenofovir disoproxil fumarate (TDF) plays a pivotal role in the management of drug-resistant chronic hepatitis B. However, it remains unclear whether TDF-nucleoside analogue combination therapy provides better outcomes than TDF monotherapy. This study aimed to compare the efficacy of TDF monotherapy with that of TDF-nucleoside analogue combination therapy in patients with drug-resistant chronic hepatitis B.

METHODS

This retrospective cohort study included 76 patients receiving TDF-based rescue therapy for more than 12 months. Suboptimal response was defined as serum HBV-DNA level of > 60 IU/mL during prior rescue therapy. Multi-drug resistance was defined as the presence of two or more drug resistance-related mutations confirmed by mutation detection assay. The relationship between baseline characteristics and virologic response (HBV DNA < 20 IU/mL) at 12 months were evaluated using logistic regression analysis.

RESULTS

Fifty-five patients (72.4%) were suboptimal responders to prior rescue therapy, and 26 (34.2%) had multi-drug resistance. Forty-two patients (55.3%) received combination therapy with nucleoside analogues. Virologic response at 12 months was not significantly different between the TDF monotherapy group and TDF-nucleoside analogue combination therapy group (p = 0.098). The serum HBV DNA level was reduced to -4.49 ± 1.67 log10 IU/mL in the TDF monotherapy group and to -3.97 ± 1.69 log10 IU/mL in the TDF-nucleoside analogue combination therapy group at 12 months (p = 0.18). In multivariate analysis, female sex (p = 0.032), low baseline HBV-DNA level (p = 0.013), and TDF monotherapy (p = 0.046) were predictive factors for virologic response at 12 months.

CONCLUSIONS

TDF monotherapy showed similar efficacy to that of TDF-nucleoside analogue combination therapy in patients with drug-resistant chronic hepatitis B.

Antiviral Therapy in Lamivudine-Resistant Chronic Hepatitis B Patients: A Systematic Review and Network Meta-Analysis

The relative efficacy of different strategies for chronic hepatitis B (CHB) patients with lamivudine resistance (LAM-R) has not yet been systematically studied. Clinical trials were searched in PUBMED, MEDLINE, EMBASE, and CNKI databases up to February 15, 2016. Nine trials including 764 patients met the entry criteria. In direct meta-analysis, TDF showed a stronger antiviral effect than any one of ETV, LAM/ADV, and ADV against LAM-R hepatitis B virus. LAM/ADV therapy was superior to ADV in suppressing viral replication. ETV achieved similar rate of HBV DNA undetectable compared to ADV or LAM/ADV. In network meta-analysis, TDF had higher rates of HBV DNA undetectable compared to ETV (OR, 24.69; 95% CrI: 5.36–113.66), ADV (OR, 37.28; 95% CrI: 9.73–142.92), or LAM/ADV (OR, 21.05; 95% CrI: 5.70–77.80). However, among ETV, ADV, and LAM/ADV, no drug was clearly superior to others in HBV DNA undetectable rate. Moreover, no significant difference in the rate of ALT normalization or HBeAg loss was observed compared the four rescue strategies with each other. TDF appears to be a more effective rescue therapy than LAM/ADV, ETV, or ADV. LAM plus ADV therapy was a better treatment option than ETV or ADV alone for patients with LAM-R.

Clinical course of partial virological responders under prolonged entecavir monotherapy in patients with chronic hepatitis B

Studies about long-term entecavir (ETV) therapy for partial virological response (PVR) are lacking. This study aimed to assess the clinical course of PVR patients receiving ETV therapy and analyze the efficacy of tenofovir (TDF). We retrospectively evaluated 130 patients who showed a PVR to ETV. Among these patients, 102 were nucleot(s)ide analogue (NUC)-naïve and 28 were lamivudine (LAM)-experienced. The cumulative rates of VR were 54.1%, 70.8%, and 83.7% for the NUC-naïve group and 37.0%, 42.8%, and 42.8% for the LAM-experienced group after 24, 36, and 48 months of ETV therapy, respectively (P  = 0.008). Low HBV DNA level at 12 months (P < 0.001) and absence of a LAM treatment history (P  = 0.031) were significant associated factors for VR. In VR prediction at 36 months of ETV therapy in NUC-naïve patients, HBV DNA level <95 IU/ml at 12 months showed a 92.9% sensitivity and a 78.3% specificity (AUROC, 0.909; P < 0.001). ETV resistance did not develop in NUC-naïve patients with HBV DNA levels <95 IU/ml at 12 months. The cumulative probability of VR in patients who switched to or additionally received TDF was 91.3% at 15 months. Prolonged ETV therapy induced a VR without the risk of ETV resistance in NUC-naïve patients with HBV DNA levels <95 IU/ml at 12 months. All patients with LAM-experienced or NUC-naïve with HBV DNA levels ≥95 IU/ml at 12 months should be switched to TDF rescue therapy.

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.

Entecavir plus adefovir combination therapy versus lamivudine add-on adefovir for lamivudine-resistant chronic hepatitis B: A meta-analysis

To determine whether adefovir (ADV) in combination with entecavir (ETV) is more effective than with lamivudine (LAM) in patients with lamivudine-resistant chronic HBV infection, electronic databases were searched through May 10th, 2013 to obtain relevant trials which met the inclusion criteria. Meta-analysis was performed on randomized controlled trials (RCTs) and non-randomized studies. Four trials containing a total of 323 patients were included. Serum HBV DNA reductions after 3 and 6 months of treatment in the ETV + ADV group were greater than that of LAM + ADV group (mean difference (MD) = 0.90, 95% confidence interval (CI): 0.74-1.07, P < 0.00001; MD = 0.81, 95% CI: 0.57-1.06, P < 0.00001). The rate of 6 months HBV DNA undetectability with ETV and ADV was higher than that of LAM and ADV (relative risk (RR) = 1.63, 95% CI: 1.14-2.34, P < 0.007). There were higher rates of serum ALT normalization than those in LAM + ADV group after 6 months of treatment (RR = 1.40, 95% CI: 1.11-1.77, P < 0.005). The ETV + ADV group had lower viral breakthrough and genotypic mutation rates than LAM + ADV group after 12 months of treatment (RR = 0.24, 95% CI: 0.10-0.58, P = 0.002). The combination of ETV plus ADV is a more effective rescue therapy than LAM add-on ADV in patients with LAM-resistant HBV.

Options for the management of antiviral resistance during hepatitis B therapy: reflections on battles over a decade

Although much advancement has been achieved in the treatment of chronic hepatitis B, antiviral resistance is still a challenging issue. Previous generation antiviral agents have already developed resistance in a number of patients, and it is still being used especially in resource limited countries. Once antiviral resistance occurs, it predisposes to subsequent resistance, resulting in multidrug resistance. Therefore, prevention of initial antiviral resistance is the most important strategy, and appropriate choice and modification of therapy would be the cornerstone in avoiding treatment failures. Until now, management of antiviral resistance has been evolving from sequential therapy to combination therapy. In the era of tenofovir, the paradigm shifts again, and we have to decide when to switch and when to combine on the basis of newly emerging clinical data. We expect future eradication of chronic hepatitis B virus infection by proper prevention and optimal management of antiviral resistance.

HBsAg, HBcAg, and combined HBsAg/HBcAg-based therapeutic vaccines in treating chronic hepatitis B virus infection

BACKGROUND

As the host immunity is diminished in patients with chronic hepatitis B (CHB), different approaches have been used to up-regulate their immune responses to produce therapeutic effects. But, cytokines, growth factors and polyclonal immune modulators could not exhibit sufficient therapeutic effects in these patients. Immune therapy with HBV-related antigens (vaccine therapy) has been used in CHB patients. But there is a paucity of information about the design of HBV antigen-based immune therapy in these patients.

DATA SOURCE

Preclinical and clinical studies on immune therapy with HBsAg-based vaccine, HBcAg and combination of HBsAg/HBcAg-based vaccines have been discussed.

RESULTS

HBsAg-based prophylactic vaccine was used as an immune therapeutic agent in CHB patients; however, monotherapy with HBsAg-based immune therapy could not lead to sustained control of HBV replication and/or liver damages. HBsAg-based vaccine was used as a combination therapy with cytokines, growth factors, and antiviral drugs. HBsAg-based vaccine was also used for cell-based therapy. However, satisfactory therapeutic effects of HBsAg-based vaccine could not be documented in CHB patients. In the mean time, evidences have supported that HBcAg-specific immunity is endowed with antiviral and liver protecting capacities in CHB patients. Recent data concentrate on the clinical use of combined HBsAg- and HBcAg-based vaccines in CHB patients.

CONCLUSION

Antigen-based immune therapy with HBV-related antigens may be an alternative method for the treatment of CHB patients but proper designs of antigens, types of adjuvants, dose of vaccinations, and routes of administration need further analyses for the development of an effective regimen of immune therapy against HBV.

Restriction fragment mass polymorphism (RFMP) analysis based on MALDI-TOF mass spectrometry for detecting antiretroviral resistance in HIV-1 infected patients

Viral genotype assessment is important for effective clinical management of HIV-1 infected patients, especially when access and/or adherence to antiretroviral treatment is reduced. In this study, we describe development of a matrix-assisted laser desorption/ionization-time of flight mass spectrometry-based viral genotyping assay, termed restriction fragment mass polymorphism (RFMP). This assay is suitable for sensitive, specific and high-throughput detection of multiple drug-resistant HIV-1 variants. One hundred serum samples from 60 HIV-1-infected patients previously exposed to nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs) were analysed for the presence of drug-resistant viruses using the RFMP and direct sequencing assays. Probit analysis predicted a detection limit of 223.02 copies/mL for the RFMP assay and 1268.11 copies/mL for the direct sequencing assays using HIV-1 RNA Positive Quality Control Series. The concordance rates between the RFMP and direct sequencing assays for the examined codons were 97% (K65R), 97% (T69Ins/D), 97% (L74VI), 97% (K103N), 96% (V106AM), 97% (Q151M), 97% (Y181C), 97% (M184VI) and 94% (T215YF) in the reverse transcriptase coding region, and 100% (D30N), 100% (M46I), 100% (G48V), 100% (I50V), 100% (I54LS), 99% (V82A), 99% (I84V) and 100% (L90M) in the protease coding region. Defined mixtures were consistently and accurately identified by RFMP at 5% relative concentration of mutant to wild-type virus while at 20% or greater by direct sequencing. The RFMP assay based on mass spectrometry proved to be sensitive, accurate and reliable for monitoring the emergence and early detection of HIV-1 genotypic variants that lead to drug resistance.

Multidrug-resistant hepatitis B virus resulting from sequential monotherapy with lamivudine, adefovir, and entecavir: clonal evolution during lamivudine plus adefovir therapy

Whether multidrug-resistant (MDR) hepatitis B virus (HBV) harbors mutations co-located in the same HBV clones that confer reduced sensitivity to antiviral therapy remains uncertain. This study investigated the evolution of MDR HBV strains developed from sequential monotherapy with lamivudine (LAM), adefovir (ADV), and entecavir (ETV) during LAM plus ADV salvage therapy. Sera were obtained from six patients who had developed sequential resistance to LAM, ADV, and ETV before and during LAM plus ADV therapy. The HBV genomes from each patient were amplified, cloned, and sequenced. Among 6 sets of 20 clones obtained before salvage therapy, all clones harbored the rtM204V mutation, and ETV-resistant mutations were detected with the rtM204V in 108 clones. The rtA181 mutation was not detected at baseline, but emerged in five patients during therapy. Among 9 sets of 20 clones obtained during salvage therapy, 39 clones harbored rtA181T/V ± rtN236T mutations, which were detected in the absence of rtM204 and ETV-resistant mutations in 37 clones (94.9%). Only two clones (5.1%) harbored both rtA181T/V and ETV-resistant mutations. The rtA181T/V mutation emerged after reversion from ETV-resistant mutants to wild-type HBV. Five patients achieved a partial virologic response to LAM plus ADV therapy. In conclusion, the majority of MDR mutations existed in different genomes. Suboptimal response to LAM plus ADV therapy may not result from the co-localization of MDR HBV mutations in the same genome, but instead the low antiviral potency of these drugs. Thus, more potent antiviral drug combinations may be an effective salvage therapy for patients infected with MDR HBV.

Do different lamivudine-resistant hepatitis B genotypes carry the same risk of entecavir resistance?

Entecavir switch is one of the treatment options for lamivudine-resistant hepatitis B (HBV) patients in Asia. This study examined the outcome of patients with different baseline resistance genotypes in a cohort study. In this study, 14 patients with chronic HBV were treated with entecavir 1 mg/day for 5 years. Enrolment criteria include: documented lamivudine resistant mutations, treatment with adefovir 10 mg/day for at least 24 weeks, and Child-Pugh score <7. Most had previous failed adefovir therapy and compensated cirrhosis of the liver. Clinical outcomes, liver biochemistries, and HBV DNA were monitored regularly. Patients with virologic breakthrough were rescued with add-on adefovir. At the end of the treatment period, the mean HBV DNA fell from 5.92 × 10(6) (baseline) to 3.67 × 10(1)  IU/ml. The presence of a HBV polymerase rtM204V mutation at the baseline was found to be the major risk factor for adverse outcomes. Compared to the patients with the rtM204I mutant, patients with the rtM204V mutant had increased risk of virologic breakthrough (80% vs. 0%, P = 0.010) requiring add-on adefovir, slower virologic responses (log rank test, P = 0.0011), failure to reach undetectable HBV DNA levels (60% vs. 0%, P = 0.045), and higher risk of entecavir-resistance (60% vs. 0%, P = 0.045). All the patients with rtM204I and rtA181 mutants had undetectable HBV DNA from 18th month. In summary, lamivudine-resistant HBV patients with the rtM204V mutation have the highest risk of developing entecavir resistance, and entecavir monotherapy should be avoided. Those with the rtM204I and rtA181V mutations may have lower risks, but regular surveillance for viral breakthrough is required.

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.

Treatment response and evolution of HBV resistance during lamivudine plus adefovir or entecavir therapy in patients with adefovir-resistant mutants

BACKGROUND

Here, we investigated the treatment response and evolution of HBV resistance during lamivudine (LAM) plus adefovir (ADV) and entecavir (ETV) monotherapy in patients with ADV-resistant mutants.

METHODS

Of the 53 patients with ADV-resistant mutants, 25 received combined LAM plus ADV therapy (LAM+ADV group) and 28 received ETV monotherapy (ETV group) for at least 12 months (median 24 months and range 12-67 months).

RESULTS

During 24 months therapy, no significant difference was noted in HBV DNA reduction from baseline, HBV DNA<200 copies/ml, hepatitis B e antigen loss and ALT normalization between the two groups. In the LAM+ADV group, patients with single rtN236T resistant mutation had higher rates of undetectable HBV DNA than those with the double mutant rtA181T/V+rtN236T at months 3-18 of therapy. No virological breakthrough occurred except for one patient with rtN236T resistant mutation who experienced virological and biochemical breakthrough after the emergence of an additional rtA181T mutant under LAM+ADV therapy. Of the 28 patients receiving ETV monotherapy, ETV-resistant mutants developed in 8. The cumulative rates of ETV-resistant mutations and virological breakthrough at months 12, 24 and 36 were 3.6%, 25.7% and 46.8%, respectively. ADV-resistant mutations were rapidly replaced by LAM-resistant mutations (median 12 months) followed by ETV-resistant mutations.

CONCLUSIONS

There was no significant difference in virological response between the LAM+ADV and ETV groups in patients with ADV-resistant mutants. LAM+ADV were less effective in patients with the double mutant rtA181T/V+rtN236T than the single rtN236T mutation. The incidence of ETV-resistant mutation was high in patients with LAM/ADV-resistant mutants treated with ETV monotherapy.

Long-term efficacy of entecavir in adefovir-refractory chronic hepatitis B patients with prior lamivudine resistance

This study aimed to evaluate the long-term efficacy of entecavir (ETV) in adefovir (ADV)-refractory chronic hepatitis B (CHB) patients with prior lamivudine (LMV) resistance. A total of 55 ADV-refractory CHB patients with prior LMV resistance, who received rescue therapy with ETV 1 mg daily for at least 12 months, were consecutively enrolled and analysed. Forty-four patients were men, and their median age was 47 (25-69). Ten patients had liver cirrhosis and 46 patients were positive for hepatitis B e antigen (HBeAg). Median hepatitis B virus DNA levels were 6.6 (4.3-8.0) log(10) copies/mL, and the median duration of ETV therapy was 24 (12-47) months. Cumulative virologic response rates at 6, 12, 24 and 36 months were 18%, 29%, 58% and 75%, respectively. HBeAg loss occurred in 10 (21.7%) of 46 HBeAg-positive patients. In multivariate analysis, only initial virologic response at 3 months remained as an independent predictor for virologic response (RR 3.143; 95% CI 1.387-7.120; P = 0.006). The patients with a virological response at 3 months had not only a significantly higher probability of achieving a virologic response (P < 0.001) but also lower probability of experiencing a virologic breakthrough (P = 0.043) than the patients without an early response. Viral breakthrough was observed in 29 patients during the follow-up period. Cumulative breakthrough rates at 6, 12, 24 and 36 months were 0%, 15%, 45% and 73%, respectively. ETV monotherapy may be considerably efficacious in cases with an initial virological response but its efficacy is attenuated by frequent emergence of ETV resistance in ADV-refractory CHB patients with prior LMV resistance.

Current Nucleos(t)ide Analogue Therapy for Chronic Hepatitis B

Although the prevalence of chronic hepatitis B has decreased considerably in recent years due to widespread use of the hepatitis B virus (HBV) vaccine, its prevalence still remains high in adults, and this can place a significant burden on health care in areas with endemic HBV. Since the introduction of nucleos(t)ide analogues (NUCs), there has been marked improvement in the care of patients with chronic hepatitis B, resulting in increased survival. However, the emergence of drug resistance in patients treated with NUCs is a major concern. The number of multi-drug resistant patients is increasing, and many patients may not respond to the currently available drugs. In this review, we describe the current status of NUC therapy for antiviral-naïve and -resistant patients.

Treatment of chronic hepatitis B: update of the recommendations from the 2007 Italian Workshop

The Italian recommendations for the therapy of hepatitis B virus (HBV)-related disease were issued in 2008. Subsequently in 2008 the nucleotide analogue (NA) Tenofovir was approved for antiviral treatment. The introduction of this important new drug has called for the current guidelines update, which includes some additional revisions: (a) the indication for therapy is extended to mild liver fibrosis and the indication for treatment is graded as "possible", "optional" or "mandatory" according to the fibrosis stage; (b) two different treatment strategies are described: first line definite duration treatment with interferon, long-term treatment of indefinite duration with NA; (c) the indication to follow either strategy is also based on the stage of liver fibrosis; (d) virological monitoring is modified to include the definitions of failure and of sustained virological response to interferon therapy; (e) the recommendation to use HBV DNA assays with high sensitivity and wide linear ranges is underlined (f) guidelines on post-treatment follow-up after finite treatment with NA, potential side effects of therapy and non-virological monitoring are defined; (g) definitions and treatment of patients without optimal response to NA are reported; (f) treatment and monitoring of compensated or decompensated cirrhosis and hepatocellular carcinoma are updated.

Antiviral drugs for HBV liver disease

INTRODUCTION

Chronic hepatitis B (CHB) virus infection affects about 400 million people around the globe and is among the world's leading causes of death. The management of CHB has evolved rapidly, several therapeutic options are now available to prevent both progression of liver disease and anticipated liver morbidity and mortality.

AREAS COVERED

Current treatment modalities for CHB patients, together with suggestions from our own experience are summarized. The most relevant works published in recent years on pegylated interferon, nucleos(t)ides analogues (NUC) and the 2009 update of the American Association for the Study of Liver Diseases Practice Guidelines and the 2009 European Association for the Study of the Liver (EASL) Clinical Practice Guidelines on the management of chronic hepatitis B are discussed.

EXPERT OPINION

Pegylated interferon and NUC have advantages and limitations, as short-term interferon treatment induces a sustained virological response in a third of patients, whereas long-term suppressive therapy by NUC rapidly inhibits HBV replication in most patients but drug resistance and safety in the long-term will remain the most important unresolved questions. Careful evaluation of patient history, staging of liver disease and virological factors should guide the start of treatment and the choice to the most appropriate individualized treatment strategy in all CHB patients.

[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.