Efficacy of entecavir and adefovir combination therapy for patients with lamivudine- and entecavir-resistant chronic hepatitis B

Entecavir Combined With Adefovir Ameliorates Patients With Chronic Hepatitis B Who Fail to Respond to Nucleotide (Acid) Analog Monotherapy

The aim of this study was to evaluate the efficacy and safety of entecavir (ETV) combined treatment with adefovir (ADV) on chronic hepatitic B (CHB) patients who failed to respond to nucleotide (acid) analog (NA) treatment. On this basis, the possible factors in the combined treatment of these patients will be analyzed. The safety, biochemical index, and the possible factors that might affect the ETV and ADV combined treatment at different points in time were retrospectively analyzed. The biochemical index included the following: virological response, hepatitis B virus (HBV) DNA decline, primary nonresponse, biochemical response, and the hepatitis B virus E antigen/hepatitis B virus E antibody seroconversion rate. There were 94 CHB patients and compensated liver cirrhosis patients who received ETV plus ADV treatment for over 12 weeks after failure of treatment with NAs. The authors have also investigated 76 CHB patients (80.9%) and 18 hepatitis B cirrhosis patients (19.1%) in this study. The HBV DNA baseline was 4.4 ± 1.4 log10 IU/mL, and the positive rate of HBeAg before salvage treatment was 78.7% (74/94). The sample sizes were 94, 78, 42, 10, 6, and 1 for follow-up of 24, 48, 96, 144, 192, and 240 weeks, respectively. The virological responses (HBV DNA < 2 log10 IU/mL) and biochemical responses were 52.1%, 74.3%, and 90.4% and 63.1%, 61.6%, and 81.1%, respectively, at 24, 48, and 96 weeks, which showed significant differences (P < 0.001 and P < 0.005, respectively). The HBV DNA decline was presented as mean ± SEM, which were 1.53 ± 1.23, 1.75 ± 1.37, 2.07 ± 1.54, and 2.39 ± 1.77 log10 IU/mL at 12, 24, 48, and 96 weeks, respectively. They showed significant differences compared with the baseline (χ = 8.084, P < 0.05). The rate of primary nonresponse was 30.9% (29/94), and the primary treatment failure rates were 26.6% (25/94), 24.4% (19/78), and 4.8% (2/42) at 24, 48, and 96 weeks, respectively. They all have statistical difference (P = 0.011 < 0.05). There were 23 patients who experienced virological breakthrough after the HBV DNA levels were undetectable, whereas after follow-up for 12-24 weeks, the HBV DNA levels were back to undetectable again. ETV plus ADV treatment is an efficient and safe treatment for CHB and compensated liver cirrhosis patients who experienced NA treatment failure. The high quantity of baseline HBV DNA level is a risk factor for poor efficacy of salvage treatment.

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.

Management of entecavir-resistant chronic hepatitis B with adefovir-based combination therapies

AIM: To evaluate the long-term efficacy adefovir (ADV)-based combination therapies in entecavir (ETV)-resistant chronic hepatitis B (CHB) patients.

METHODS: Fifty CHB patients with genotypic resistance to ETV at 13 medical centers in South Korea were included for the analysis. All the patients received rescue therapy with the combination of ADV plus ETV (ADV/ETV, n = 23) or ADV plus lamivudine (LMV) (ADV/LMV, n = 27) for more than 12 mo. Patients were monitored at least every 3-4 mo during ADV-based combination therapy by clinical examination as well as biochemical and virological assessments. Hepatitis B virus (HBV) DNA levels were measured by real-time PCR and logarithmically transformed for analysis. Cumulative rates of virologic response (VR; HBV DNA < 20 IU/mL) were calculated using the Kaplan-Meier method, and the difference was determined by a log-rank test. Multivariate logistic regression and Cox proportional hazards models were used to identify independent risk factors significantly associated with short-term and long-term VR, respectively.

RESULTS: Baseline median HBV DNA levels were 5.53 (2.81-7.63) log₁₀ IU/mL. The most commonly observed ETV genotypic mutation sites were rt184 and rt202. Patients were treated for a median of 27 (12-45) mo. Overall, cumulative VR rates at 6, 12, 24, and 36 mo were 26%, 36%, 45%, and 68%, respectively. Patients treated with the ADV/ETV combination showed higher cumulative VR rates (35%, 43%, 65%, and 76%, respectively) than those with the ADV/LAM combination (18%, 30%, 30%, and 62%, respectively; P = 0.048). In the multivariate analysis, low baseline HBV DNA levels (< 5.2 log₁₀ IU/mL) and initial virologic response at 3 mo (IVR-3; HBV DNA < 3.3 log₁₀ IU/mL after 3 mo) were independent predictive factors for VR. Patients with favorable predictors achieved cumulative VR rates up to 90% at 36 mo. During the same period, the cumulative incidence of virologic breakthrough was as low as 6% in patients with the both favorable predictors.

CONCLUSION: If tenofovir is not available, ADV/ETV combination could be considered in ETV-resistant patients with low HBV DNA titers, and may be continued if IVR-3 is achieved.

Label-free silver nanoparticles for the naked eye detection of entecavir

A simple, rapid, field-portable colorimetric method for the detection of entecavir was proposed based on the color change caused by the aggregation of silver nanoparticles. Neutralization of the electrostatic repulsion from each silver nanoparticle resulted in the aggregation of AgNPs and a consequent color change of AgNPs from yellow to wine-red, which provided a platform for rapid and field-portable colorimetric detection of entecavir. The concentration of entecavir could be determined with naked eye or UV-vis spectrometer. The proposed method can be used to detect entecavir in human urine with a detection limit of 1.51μg mL(-1), within 25min by naked eye observation without the aid of any advanced instrument or complex pretreatment. Results from UV-vis spectra showed that the absorption ratio was linear with the concentration of entecavir in the range of 5.04-25.2μg mL(-1) and 1.01-5.04μg mL(-1) with linear coefficients of 0.9907 and 0.9955, respectively. The selectivity of AgNPs detection system for entecavir is excellent comparing with other ions and analytes. Due to its rapid, visible color changes, and excellent selectivity, the AgNPs synthesized in this study are suitable to be applied to on-site screening of entecavir in human urine.

Adefovir and Lamivudine Combination Therapy in Patients with Entecavir-Resistant Chronic Hepatitis B: Antiviral Responses and Evolution of Mutations

<b><i>Objective:</i></b> This study was designed to prospectively evaluate the antiviral responses and evolution of resistance mutations during adefovir (ADV) plus lamivudine (LMV) therapy in patients with entecavir (ETV)-resistant hepatitis B virus (HBV) infection. <b><i>Methods:</i></b> Twenty chronic hepatitis B (CHB) patients who had been receiving ETV for more than 6 months and developed virologic breakthrough due to ETV resistance were consecutively enrolled. <b><i>Results:</i></b> Patients received ADV plus LMV therapy for 12 months. The baseline mean serum HBV DNA level was 5.59 ± 1.28 log₁₀ IU/ml. The rtT184L/I/A/F (50%), rtS202G (25%) and mixed ETV-resistant mutations (25%) were detected at enrollment. The mean reduction in serum HBV DNA levels from baseline to 12 months was -2.3 ± 1.06 log₁₀ IU/ml (p<i> <</i> 0.001). Seventeen patients were followed up for the full 12 months, and complete virologic response (HBV DNA <20 IU/ml) was observed in 4 patients (23.5%). Among the remaining 13 patients who still had detectable HBV DNA, 7 patients showed disappearance of ETV-resistant mutations or reduction of the proportion of ETV-resistant mutants. An ADV- and LMV-resistant mutant (rtA181T) emerged in 2 patients (11.7%). <b><i>Conclusions:</i></b> ADV plus LMV combination therapy suppresses ETV-resistant mutants in the viral population and significantly reduces serum HBV DNA levels in ETV-resistant CHB patients.

Efficacy of adefovir-based combination therapy for patients with Lamivudine- and entecavir-resistant chronic hepatitis B virus infection

Treatment strategies for entecavir (ETV)-resistant chronic hepatitis B (CHB) patients are not yet well established. The aim of this study was to evaluate overall antiviral efficacy and to compare the efficacy of combination therapy with adefovir (ADV) plus nucleoside analogues (lamivudine [LAM], telbivudine [LdT], or ETV) in patients infected with LAM- and ETV-resistant hepatitis B virus (HBV) variants. Virologic, biochemical, and serologic responses during combination therapy with ADV plus nucleoside analogues were assessed. Propensity score analysis was used to select a matched group of patients for the comparison of rescue therapy regimens. A total of 67 consecutive patients were analyzed. Complete virologic suppression was achieved in 27 patients. The overall cumulative incidence of complete virologic suppression at month 24 was 47.4%: 44.3% in the LAM or LdT plus ADV group and 51.4% in the group given ETV and ADV. There was no significant difference between these two groups (P = 0.234). The cumulative incidences of complete virologic suppression were still comparable between the two groups selected and matched using the propensity score model (P = 0.419). Virologic breakthrough was observed in 9 patients, and rtA181V substitution was newly detected in one patient. Hepatitis B e antigen (HBeAg) negativity and lower baseline HBV DNA level were associated with complete virologic suppression in univariate analysis. In multivariate analysis, lower baseline HBV DNA level remained an independent predictor. In conclusion, combination therapy with ADV plus nucleoside analogues fails to show sufficient antiviral efficacy in CHB patients with resistance to both LAM and ETV. Further study is warranted to evaluate the efficacy of a more potent tenofovir-based regimen in such patients.

Efficacy of adefovir-based combination therapy for patients with Lamivudine- and entecavir-resistant chronic hepatitis B virus infection

Treatment strategies for entecavir (ETV)-resistant chronic hepatitis B (CHB) patients are not yet well established. The aim of this study was to evaluate overall antiviral efficacy and to compare the efficacy of combination therapy with adefovir (ADV) plus nucleoside analogues (lamivudine [LAM], telbivudine [LdT], or ETV) in patients infected with LAM- and ETV-resistant hepatitis B virus (HBV) variants. Virologic, biochemical, and serologic responses during combination therapy with ADV plus nucleoside analogues were assessed. Propensity score analysis was used to select a matched group of patients for the comparison of rescue therapy regimens. A total of 67 consecutive patients were analyzed. Complete virologic suppression was achieved in 27 patients. The overall cumulative incidence of complete virologic suppression at month 24 was 47.4%: 44.3% in the LAM or LdT plus ADV group and 51.4% in the group given ETV and ADV. There was no significant difference between these two groups (P = 0.234). The cumulative incidences of complete virologic suppression were still comparable between the two groups selected and matched using the propensity score model (P = 0.419). Virologic breakthrough was observed in 9 patients, and rtA181V substitution was newly detected in one patient. Hepatitis B e antigen (HBeAg) negativity and lower baseline HBV DNA level were associated with complete virologic suppression in univariate analysis. In multivariate analysis, lower baseline HBV DNA level remained an independent predictor. In conclusion, combination therapy with ADV plus nucleoside analogues fails to show sufficient antiviral efficacy in CHB patients with resistance to both LAM and ETV. Further study is warranted to evaluate the efficacy of a more potent tenofovir-based regimen in such patients.

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.

Use of ALLGIO probe assays for detection of HBV resistance to adefovir in patients with chronic hepatitis B, Kerman, Iran

Hepatitis B virus (HBV) infection is contagious with transmissiobn vertically or horizontally by blood products and body secretions. Over 50% of Iranian carriers contracted the infection prenatally, making this the most likely route of transmission of HBV in Iran. To evaluate the resistance to adefovir (ADV) therapy in patients with chronic hepatitis B infection, a study was conducted on 70 patients (63 males and 7 females), who had received in first line lamivudine and second line adefovir. All were tested for the presence of hepatitis B surface antigen (HBsAg), hepatitis B envelope antigen (HBeAg), serum alanine amino transferase (ALT) level and HBV DNA load before and after treatment with ADV. In all samples, resistance to lamivudine and ADV was tested with real time PCR. Among seventy patients with chronic hepatitis B infection, 18 (25.7%) were resistant to LAM and 8 (11.4%) were resistant to ADV. Only one patient was negative for the presence of HBS-Ag (5.6%) and two were negative for HBe-Ag (11.1%). In this study we used a new method (ALLGIO probe assay) that has high sensitivity in detection of adefovir resistance mutants, which we recommend to other researchers. Mutant strains of the YMDD motif of HBV polymerase can be found in some patients under treatment with lamivudine and ADV. ADV has been demonstrated to be efficient in patients with lamivudine resistant HBV.

A novel method for the analysis of drug-resistant phenotypes of hepatitis B virus

Chronic hepatitis B virus (CHB) infection is a major cause of cirrhosis and hepatocellular carcinoma. Nucleoside analogs (NAs) are popularly used to treat chronic hepatitis B virus (HBV) infections; however, the anti-HBV effect is attenuated by drug-resistant viral mutations selected during long-term antiviral therapy. The timely analysis of drug-resistance mutations is essential in order to adjust treatment regimes. In this study, a T1699C substitution was introduced into the x gene of pHBV1.3 to generate an additional XhoI site, termed pHBV1.3‑XhoI, which is a nonsense mutation and does not influence protein expression, HBV replication ability, or NA susceptibility. Based on co-transfection with weak or non-replicative HBV plasmids and pHBV1.3-XhoI or pHBV1.3 and -XhoI-P-null plasmids into hepatocellular carcinoma cells, PCR was used to amplify 1176‑bp segments of T/C1699 using the isolated HBV encapsulated DNA as a template, modified by XhoI digestion and subjected to agarose gel electrophoresis. Different bands composed of different virions were used to distinguish the replication capacities of the plasmids. Our results demonstrated no significant effects when different virions co-existed. A novel resistance test method was developed by co-transfection with pHBV1.3-XhoI and -rtL180M/M204V and treatment with various NA concentrations. Different bands composed of pHBV1.3-XhoI or -rtL180M/M204V were used to distinguish NA susceptibility. The bands composed of pHBV1.3 were more sharply reduced by lamivudine (LMV) than -rtL180M/M204V. The data demonstrate that the method established in our study may be used for the analysis of drug-resistant phenotypes at the cellular level.

Diagnostic and therapeutic progress of multi-drug resistance with anti-HBV nucleos(t)ide analogues

Nucleos(t)ide analogues (NA) are a breakthrough in the treatment and management of chronic hepatitis B. NA could suppress the replication of hepatitis B virus (HBV) and control the progression of the disease. However, drug resistance caused by their long-term use becomes a practical problem, which influences the long-term outcomes in patients. Liver transplantation is the only choice for patients with HBV-related end-stage liver disease. But, the recurrence of HBV after transplantation often caused by the development of drug resistance leads to unfavorable outcomes for the recipients. Recently, the multi-drug resistance (MDR) has become a common issue raised due to the development and clinical application of a variety of NA. This may complicate the antiviral therapy and bring poorly prognostic outcomes. Although clinical evidence has suggested that combination therapy with different NA could effectively reduce the viral load in patients with MDR, the advent of new antiviral agents with high potency and high genetic barrier to resistance brings hope to antiviral therapy. The future of HBV researches relies on how to prevent the MDR occurrence and develop reasonable and effective treatment strategies. This review focuses on the diagnostic and therapeutic progress in MDR caused by the anti-HBV NA and describes some new research progress in this field.

Efficacy of 3 years of adefovir monotherapy in chronic hepatitis B patients with lamivudine resistance

AIM

To study the effect of rescue monotherapy with adefovir (ADV) in patients with chronic hepatitis B (CHB) who developed drug resistance to lamivudine (LAM).

METHODS

A total of 76 treated CHB patients with resistance to LAM were enrolled in the present study. The patients' baseline characteristics, such as age, gender, blood tests and hepatitis B virus (HBV) DNA were collected; therapy duration and the response of each patient were also recorded. ADV monotherapy was set as the observation group A. Twenty-four patients with LAM resistance, who were set as group B, accepted combined therapy with LAM + ADV. Patients were followed up at 0, 12, 24, 52, 104 and 156 wk. Hepatitis B surface antigen status, hepatitis B e antigen (HBeAg)/anti-HBe status, HBV DNA level and biochemical indexes were monitored. Sequencer of HBV polymerase gene was performed on the ABI 3730 automated sequencer. If no desired effects had been achieved during the course of treatment, patients' choices were also taken into account. The control group was tested at the same time.

RESULTS

In the two groups, 27 cases developed viral breakthrough after LAM treatment response. The remaining 49 cases underwent biochemical rebound accompanied by rtM204I/V or rtL180M mutation. In group A, 52 cases finished 156 wk of ADV monotherapy; of whom, 36 cases were HBeAg positive and 16 HBeAg negative. In patients whose baseline HBV DNAs were 10(3)-10(5) copies/mL, 88.8% of patients' HBV DNAs were lower than the lower test limit (10(3) copies/mL) after 12 to 156 wk of ADV treatment. In patients whose baseline HBV DNAs were ≥ 10(6) copies/mL, 41.1%-47.0% of patients' HBV DNAs were lower than the lower test limit after the same course of ADV therapy (χ(2) were 4.35-5.4, 41.1%-47.0% vs 88.8% group 10(3)-10(5) copies/mL, P < 0.01). In group A, seroconversion of HBeAg developed in 8 of 36 cases (22.2%). In group B, 24 cases finished 156 wk of LAM + ADV; of whom, 17 cases were HBeAg positive and 7 HBeAg negative. In patients whose baseline HBV DNAs were 10(3)-10(5) copies /mL, 81.8% of patients' HBV DNAs were lower than the lower test limit (10(3) copies/mL) after 12 to 156 wk of treatment. In the patients whose baseline HBV DNAs were ≥ 10(6) copies/mL, 46.1%-53.8% of patients' HBV DNAs were lower than the lower test limit after the same course of LAM + ADV therapy (χ(2) were 4.1-5.0, 46.1%-53.8% vs 81.8% group 10(3)-10(5) copies/mL, P < 0.05-0.01). In group B, 4 of 17 cases (23.5%) developed seroconversion of HBeAg. Treatment outcomes in groups A and B were comparable.

CONCLUSION

In both group A and B, the ratios of virological response have similar efficacy in patients with lower baseline HBV DNAs.