Antiviral efficacies of currently available rescue therapies for multidrug-resistant chronic hepatitis B

ALT Is Not Associated With Achieving Subcirrhotic Liver Stiffness and HCC During Entecavir Therapy in HBV-Related Cirrhosis

BACKGROUND & AIMS

We investigated whether baseline and on-treatment alanine aminotransferase (ALT) levels during entecavir (ETV) therapy are associated with achieving subcirrhotic liver stiffness (LS) and hepatocellular carcinoma (HCC) development in patients with hepatitis B virus (HBV)-related cirrhosis.

METHODS

We analyzed data from 347 treatment-naïve patients with HBV-related cirrhosis, who started ETV between 2006 and 2011 and were followed up for >5 years without developing HCC. The study outcomes were achieving subcirrhotic LS at 5 years of ETV, and risk of HCC development beyond 5 years of ETV. Subcirrhotic LS was defined as <12 kPa by transient elastography.

RESULTS

After 5 years of ETV, 227 (65.4%) patients achieved subcirrhotic LS. During a median follow-up of 9.2 years, 49 (14.1%) patients developed HCC beyond 5 years of ETV. ALT levels at baseline, at 1 year of ETV therapy, and 5 years of ETV therapy were not associated with the probability of achieving subcirrhotic LS at 5 years of ETV therapy or risk of HCC development beyond 5 years of ETV therapy (all P > .05). Patients achieving subcirrhotic LS at 5 years of ETV therapy had significantly lower risk of HCC development than those who did not (adjusted hazard ratio, 0.33; 95% confidence interval, 0.17-0.64; P = .001).

CONCLUSIONS

Baseline and on-treatment ALT levels were not associated with achieving subcirrhotic LS at 5 years of ETV therapy or with risk of HCC development beyond 5 years of ETV therapy in patients with HBV-related cirrhosis. Achieving subcirrhotic LS at 5 years of ETV therapy was independently associated with lower risk of HCC development beyond 5 years of ETV therapy.

Revised Korean Antiviral Guideline Reduces the Hepatitis B-related Hepatocellular Carcinoma Risk in Cirrhotic Patients

BACKGROUND

Since September 2015, the initiation of antiviral therapy (AVT) for patients with chronic hepatitis B (CHB)-related cirrhosis has been reimbursed according to the revised Korean Association for the Study of Liver (KASL) guideline, if the patient had hepatitis B virus DNA level ≥ 2,000 IU/L, regardless of aminotransferase or alanine aminotransferase levels. This study investigated whether the KASL guideline implementation reduced the risk of CHB-related hepatocellular carcinoma (HCC) in patients with cirrhosis in South Korea.

METHODS

A total of 429 patients with CHB-related cirrhosis who initiated AVT between 2014 and 2016 were recruited. The risk of HCC development was compared between patients who initiated AVT before and after September 2015 (pre-guideline [n = 196, 45.7%] vs. post-guideline implementation [n = 233, 54.3%]).

RESULTS

Univariate analysis showed that AVT initiation before guideline implementation, older age, male gender, and diabetes significantly predicted increased risk of HCC development (all P < 0.05). Subsequent multivariate analysis showed that AVT initiation before guideline implementation (HR = 1.941), older age (HR = 5.762), male gender (HR = 2.555), and diabetes (HR = 1.568) independently predicted increased risk of HCC development (all P < 0.05). Additionally, multivariate analysis showed that AVT initiation before guideline implementation (HR = 2.309), male gender (HR = 3.058), and lower platelet count (HR = 0.989) independently predicted mortality (P < 0.05). The cumulative incidences of HCC and mortality were significantly higher in patients who initiated AVT before guideline implementation than in those who initiated AVT after guideline implementation (all P < 0.05, log-rank test).

CONCLUSION

The prognosis of patients with CHB-related cirrhosis who initiated AVT improved after guideline implementation according to the revised KASL guideline.

Entecavir-based combination therapies for chronic hepatitis B: A meta-analysis

BACKGROUND

Currently, there is no consensus on the efficacy and safety of the entecavir (ETV) monotherapy versus the ETV-based combination therapy for chronic hepatitis B.

METHODS

A comprehensive literature search was performed on the comparison of ETV-based combination therapy and monotherapy for chronical hepatitis B (CHB) patients in the PubMed, Embase, Web of Science, the Cochrane Libraries, and the Chinese BioMedical Literature Database. Both dichotomous and continuous variables were extracted, and pooled outcomes were expressed as odds ratio (OR) or mean difference (MD).

RESULTS

We included randomized clinical trials (RCTs) and cohorts involving Group A: nucleos(t)ide-naive patients (four RCTs, n = 719 patients), Group B: nucleos(t)ide-resistant patients (four cohorts, n = 196 patients), and Group C: entecavir-treated patients with undetectable hepatitis B virus DNA (two RCTs and two cohorts, n = 297). Group A. ETV monotherapy was better for rates of undetectable HBV DNA, while the rates of the HBV DNA levels at the end of treatment, HBeAg Loss, ALT normalization were similar between the two groups [MD, -0.85 (95% CI, -0.173-0.03); OR, 0.92 (95% CI, 0.24-3.56); OR, 1.31 (95% CI, 0.17-9.82)]; Group B. ETV monotherapy was better for rates of undetectable HBV DNA, while the rates of the HBV DNA levels at the end of treatment, HBeAg Loss, ALT normalization were similar; Group C. The ETV-based combination therapy was better for the rate of HBV DNA relapse.

CONCLUSION

Based on the current data, ETV-based combination therapy seemed to be no better than ETV monotherapy. Further studies are needed to verify this conclusion.

Cost-Effectiveness Comparison Between the Response-Guided Therapies and Monotherapies of Nucleos(t)ide Analogues for Chronic Hepatitis B Patients in China

BACKGROUND AND OBJECTIVE

Nucleos(t)ide analogue (NA) monotherapies are typically used as the primary treatment for chronic hepatitis B (CHB) patients, including lamivudine (LAM), telbivudine (TBV), adefovir (ADV), entecavir (ETV) and tenofovir (TDF). For high-resistance NAs (LAM, TBV, ADV), they can generate excellent clinical outcomes by using response-guided therapy; however, their pharmacoeconomic profiles remain unclear in China. We aimed to evaluate the cost effectiveness between response-guided therapies and monotherapies of NAs for Chinese hepatitis B e-antigen (HBeAg)-positive and -negative CHB patients.

METHODS

We constructed a Markov model to simulate CHB progression associated with 12 treatment strategies using effectiveness and cost data from the published literature. We measured the lifetime costs, quality adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs). One-way sensitivity (especially to extend the range of the TDF price) and probabilistic sensitivity analyses were used to explore the uncertainties of the model.

RESULTS

For both HBeAg-positive and -negative patients, no treatment strategy generated the lowest lifetime costs (US$31,185-US$31,338) and QALYs (7.54-7.58). ETV and TDF monotherapies were not dominated by other treatments, whereas, the ICER of ETV monotherapy was the lowest (US$6112/QALY-US$8533/QALY). For each high-resistance NA, compared with its monotherapy, the ICERs of its response-guided therapies were below the willingness-to-pay threshold of US$22,833/QALY. Additionally, TDF monotherapy was the preferred treatment when its price dropped to US$1820/year or lower.

CONCLUSION

Among 12 treatment strategies evaluated, ETV monotherapy is the most cost-effective treatment for treatment-naive CHB patients in China. The response-guided therapies of high-resistance NAs are more cost-effective than their monotherapies.

The efficacy of tenofovir-based therapy in patients showing suboptimal response to entecavir-adefovir combination therapy

Background/Aims:

Before tenofovir (TDF) become available in South Korea, combination therapy with entecavir (ETV) and adefovir (ADV) was the most potent regimen for chronic hepatitis B (CHB) patients who fail to respond to rescue therapy for drug resistance. We analyzed the efficacy of ETV-ADV combination therapy and investigated the clinical and clonal results of TDF-based rescue therapy in CHB patients refractory to this combination.

Methods:

We retrospectively reviewed the medical records of CHB patients treated for up to 3 years with ETV-ADV combination therapy as a rescue therapy for drug resistance. In cases refractory to this combination, clinical and clonal analyses were performed for TDF-based rescue therapy.

Results:

The analysis was performed on 48 patients. Twelve patients achieved a virological response (VR) within 3 years. A VR was subsequently achieved in nine of the ten patients without a VR who switched to TDF monotherapy. A VR was also achieved in six of the seven patients who switched to lamivudine-TDF combination therapy, and in two of the two patients who switched to ETV-TDF combination therapy. In an in vitro susceptibility test, viral replication was detected with TDF monotherapy but not with ETV-TDF combination therapy.

Conclusions:

The efficacy of ETV-ADV combination therapy was insufficient in CHB patients who were refractory to rescue therapy. A more potent regimen such as ETV-TDF combination therapy may be considered in such refractory cases.

De novo entecavir+adefovir dipivoxil+lamivudine triple-resistance mutations resulting from sequential therapy with adefovir dipivoxil, and lamivudine

Background

Entecavir-resistance mutations are commonly induced by entecavir treatment in chronic hepatitis B patients. However, entecavir+adefovir dipivoxil+lamivudine triple-resistance mutations induced by sequential or combination treatment with lamivudine and adefovir dipivoxil have never been reported.

Results

We retrospectively reviewed 1200 patients who had been tested for anti-HBV drug resistance at Beijing Ditan Hospital of Capital Medical University, and five patients showing multidrug resistance to lamivudine and adefovir dipivoxil were enrolled. Stored serum samples were used for genetic analysis, which yielded a total of 135 clones. Entecavir+adefovir dipivoxil+lamivudine triple-resistance mutations were identified in 60 % (3/5) entecavir-naïve patients who received sequential therapy with adefovir dipivoxil and lamivudine. Specifically, we found one rtM204I+rtL180 M+rtM250 V+rtA181 V clone among 23 clones from patient 1 (4.35 %), one rtM204 V+vrtL180 M +rtM250 V+rtA181 V clone among 24 clones from patient 2 (4.17 %), and 2 clones harboring rtM204 V+rtL180 M+rtM250 V+rtA181 V and rtM204 V+rtL180 M+rtI169 V+rtA181 V among 20 clones from patient 3 (10.0 %). The other 2 patients showed multidrug resistance after lamivudine/telbivudine and adefovir dipivoxil combination therapy, but no entecavir-resistance mutations were found in these two patients.

Conclusion

De novo entecavir+adefovir dipivoxil+lamivudine triple-resistance mutations can be induced by sequential therapy with adefovir dipivoxil and lamivudine in patients who never take entecavir. These results provide important information for sequential therapy with adefovir dipivoxil and lamivudine and the use of entecavir as a rescue therapy for these patients with multidrug resistance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12941-016-0138-0) contains supplementary material, which is available to authorized users.

Lamivudine-resistant rtL180M and rtM204I/V are persistently dominant during combination rescue therapy with entecavir and adefovir for hepatitis B

Adefovir (ADV) sequential monotherapy was included in the 2005 Asia-Pacific guidelines for the management of patients with lamivudine (LAM) resistance. However, following the development of ADV resistance, the proportion of resistant variants during combined rescue therapy with ADV and entecavir (ETV) were unknown. The present study characterized the dynamics of resistant variants in patients with chronic hepatitis B (CHB) and LAM-resistant variants during antiviral therapy consisting of ADV monotherapy followed by ADV-ETV combination therapy. A total of 3 patients were selected from a cohort of 55 patients with CHB due to developing ADV resistance. The patients had been previously treated with LAM (100 mg daily) for 21–24 months. At the initiation of sequential monotherapy with ADV, LAM-resistant variants (rtM204V/I and rtL180M) were detected in the three patients. These patients developed ADV resistance during 19–30 months of ADV sequential monotherapy, and then switched their antiviral regimen to ADV-ETV combination therapy. During ADV monotherapy and ADV-ETV combination therapy, the patients were monitored every 3 months for the first year of therapy, and then every 6 months thereafter. A total of 30 serum samples were collected from the patients throughout the monitoring period. In total, 10 mutants that were associated with commonly-used antiviral drugs were detected by pyrosequencing. During ADV sequential monotherapy, LAM-resistant variants were gradually decreased, whereas ADV-resistant rtA181V/T and rtN236T variants gradually increased in the viral population. During 30–41 months of ADV-ETV combination therapy, viral load reduction was 2.59–3.28 log₁₀ copies/ml; ADV-resistant variants rtA181T/V and rtN236T were undetectable following 11–24 months of combination therapy; and rtL180M and rtM204I/V remained dominant in the viral population. In conclusion, the results of the present study suggested that, in patients with LAM and ADV-resistant variants that developed during LAM-ADV sequential monotherapy, ETV-ADV combination therapy may partially inhibit the replication of HBV DNA; however, LAM-resistant rtL180M and rtM204I/V variants remained predominant following 30–41 months combination therapy.

Antiviral efficacy of entecavir versus entecavir plus adefovir for hepatitis B virus rtA181V/T mutants alone

BACKGROUND/AIMS

Hepatitis B virus (HBV) rtA181V/T mutants developed by long-term nucleos(t) ide analogue therapy are known to present cross-resistance for other nucleos (t) ide analogues, except entecavir (ETV). Some studies reported that HBV rtA181V/T mutants could induce cross-resistance to ETV and showed incomplete response as well as persistence of HBV DNA, despite rescue therapy by ETV. This study aimed to investigate the antiviral efficacy of ETV monotherapy and ETV plus adefovir (ADV) as rescue therapy for HBV rtA181V/T single mutation.

PATIENTS AND METHODS

A total of 30 patients who received ETV alone (1.0 mg/day, n = 16) or ETV plus ADV (10.0 mg/day, n = 14) over 48 weeks between April 2008 and October 2011 were enrolled. Virological, biochemical, and serological response at 48 weeks of rescue therapy were investigated retrospectively.

RESULTS

No significant difference in baseline characteristics was observed between the ETV group and the ETV plus ADV group. Virological response showed complete response (62.5 vs. 42.9%), partial response (6.3 vs. 28.6%), non-response (25.0 vs. 28.6%), and virological breakthrough (6.3 vs. 0%) in the two groups, respectively. Virological response did not statistically differ between both groups (P = 0.278). No significant difference in the mean reduction of serum HBV DNA and biochemical response was observed between both groups (4.3 ± 2.9 vs. 4.1 ± 1.8 log 10 IU/ml; P = 0.294 and 88.9 vs. 100%; P = 1.000, respectively). In addition, no significant difference in HBeAg loss or seroconversion was observed between the two groups (26.7 vs. 28.6%; P = 1.000).

CONCLUSIONS

ETV monotherapy and ETV plus ADV therapy were clinically effective and comparable as rescue therapy for HBV rtA181V/T mutants alone.

Tenofovir disoproxil fumarate monotherapy for nucleos(t)ide-naïve chronic hepatitis B patients in Korea: data from the clinical practice setting in a single-center cohort

BACKGROUND/AIMS

This study assessed the antiviral efficacy and safety of tenofovir disoproxil fumarate (TDF) for up to 12 months in Korean treatment-naïve chronic hepatitis B (CHB) patients.

METHODS

A total of 411 treatment-naïve CHB patients who had been treated with TDF for at least 3 months (median 5.6) were consecutively enrolled. Clinical, biochemical, virological parameters and treatment adherence were routinely assessed every 3 months.

RESULTS

The median age was 51.3 years, 63.0% of the patients were male, 49.6% were HBeAg (+), and 210 patients had liver cirrhosis. The median baseline HBV DNA was 5.98 (SD 1.68) log10 IU/mL. Among the patients completing week 48, 83.3% had a complete virologic response (CVR, <12 IU/mL by HBV PCR assay), and 88.2% had normalized levels of alanine aminotransferase (ALT). The cumulative probabilities of CVR at 3, 6, 9 and 12 months were 22.8%, 53.1%, 69.3% and 85.0%. During the follow-up period, 9.8% patients achieved HBeAg loss and 7.8% patients achieved HBeAg seroconversion. There was no virological breakthrough after initiating TDF. The most common TDF-related adverse event was gastrointestinal upset, and three patients discontinued TDF therapy. However, no serious life-threatening side effect was noted.

CONCLUSIONS

In a clinical practice setting, TDF was safe and highly effective when administered for 12 months to Korean treatment-naïve CHB patients.

Relevance of hepatitis B surface antigen levels in patients with chronic hepatitis B during 5 year of tenofovir treatment

The role of quantitative hepatitis B surface antigen (HBsAg) levels in patients receiving highly potent oral antiviral therapy is controversial, and here, we determined the HBsAg response in 121 chronic hepatitis B patients treated with tenofovir 300 mg daily. During tenofovir treatment, HBsAg decline of ≥ 1.0 log from baseline was seen in 16.1%, 16.3%, 18.4%, 34.6%, 36.4% and 11.8%, 15.2%, 14.8%, 28.6%, 20% at years 1, 2, 3, 4, 5 for HBeAg-positive and HBeAg-negative patients, respectively. Early decline in HBsAg levels at week 4 was predictive of subsequent significant HBsAg level decline. HBeAg seroconversion occurred in 29.9% of HBeAg-positive patients. On multinomial logistic regression, HBsAg level decline from baseline at week 4 and week 12 or any time subsequently did not correlate with HBeAg seroconversion and HBV DNA level decline from baseline at week 4 and week 12 (OR = 3.704; 95% CI = 1.511-9.076; P = 0.006 and OR = 1.732; 95% CI = 1.032-2.867; P = 0.037, respectively) was significantly predictive of seroconversion. A small proportion of chronic HBV-infected patients treated with tenofovir exhibit a significant (≥ 1.0 log) decline in HBsAg levels. Early decline in HBsAg levels at week 4 was predictive of subsequent and significant HBsAg level decline. The HBsAg decline did not correlate with HBeAg seroconversion in HBeAg-positive patients. Reduction in HBV DNA levels at week 4 and 12 correlated with seroconversion.

Molecular diagnosis and treatment of drug-resistant hepatitis B virus

Oral antiviral agents have been developed in the last two decades for the treatment of chronic hepatitis B (CHB). However, antiviral resistance remains an important challenge for long-term CHB therapy. All of the clinically available oral antiviral agents are nucleoside or nucleotide analogues that target the activity of viral reverse transcriptase (RT), and all are reported to have resistant mutations. Since the hepatitis B virus (HBV) RT, like other viral polymerases, lacks proofreading activity, the emergence of drug-resistance occurs readily under selective pressure from the administration of antiviral agents. The molecular diagnosis of drug-resistant HBV is based on sequence variations, and current diagnostic methods include sequencing, restriction fragment polymorphism analysis, and hybridization. Here, we will discuss the currently available molecular diagnosis tools, in vitro phenotypic assays for validation of drug-resistant HBV, and treatment options for drug-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.