Mg Of Entecavir Research Articles

The Relation between Entecavir Dose and Therapeutic Effect in the Treatment of Hepatitis B Virus

This study investigated the relation between entecavir dose and therapeutic effect in the treatment of chronic hepatitis B. About 180 chronic hepatitis B patients were enrolled as research subjects. They were randomly divided into the control group accepting 0.5 mg of entecavir and the research group accepting 1.0 mg of entecavir, each containing 90 patients. Indices monitored included hepatitis B virus-DNA, liver function (alanine aminotransferase, total bilirubin), alanine aminotransferase recurrence, hepatitis B virus-DNA negative conversion, HBeAg/HBeAb negative conversion were analyzed comparatively. After accepting different treatments, the hepatitis B virus-DNA level was lower significantly in the research group than that in the control group, p<0.05. The research group gained more significant improvement of liver function, alanine aminotransferase recurrence, hepatitis B virus-DNA negative conversion rate and HBeAg/HBeAb negative conversion rate, p<0.05. It can be concluded that entecavir is an ideal antihepatitis B viral drug, which can help patients improve their treatment efficiency and has high reliability.

Hepatitis B Core Antigen Expression in Hepatocytes Reflects Viral Response to Entecavir in Chronic Hepatitis B Patients

Background/AimsHepatitis B core antigen is known to be a major target for virus-specific T cells and also reflects the progression of liver dissease and viral replication. Hepatitis B core antigen expression in hepatocytes leads to altered histological activity, viral replication, and immune response. The purpose of this study is to evaluate whether the topographical distribution of hepatitis B core antigen expression can predict the viral response to entecavir in patients with chronic hepatitis B.MethodsWe enrolled 91 patients with treatment-naïve chronic hepatitis B. All the patients underwent liver biopsy, and the existence and pattern of hepatitis B core antigen evaluated by immunohistochemistry. All patients received 0.5 mg of entecavir daily following a liver biopsy. We checked the viral response at 3, 6, and 12 months during antiviral therapy.ResultsOf the 91 patients, 64 (70.3%) had hepatitis B core antigen expression. Of the subcellular patterns, the mixed type was dominant (n=48, 75%). The viral response was significantly higher in the hepatitis B core antigen-negative group than in the hepatitis B core antigen-positive group (88.9% and 54.7%, respectively; p=0.001) after 12 months of entecavir therapy.ConclusionsChronic hepatitis B patients who are hepatitis B core antigen-negative have a better response to entecavir therapy than do hepatitis B core antigen-positive patients.

Short-term entecavir versus lamivudine therapy for HBeAg-negative patients with acute-on-chronic hepatitis B liver failure

Selection of drugs for antiviral therapy of patients with hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF) remains difficult. This study was undertaken to evaluate the short-term efficacy of entecavir versus lamivudine on hepatitis B e antigen (HBeAg)-negative patients with ACLF. The data of 182 HBeAg-negative patients with ACLF were retrospectively collected from patient profiles of the hospital. In these patients, 93 HBeAg-negative patients with ACLF were treated orally with 0.5 mg of entecavir and 89 were treated orally with 100 mg of lamivudine every day. The gender and age were matched between the two groups. Biochemical items, the model for end-stage liver disease (MELD) score, and HBV DNA level were matched at baseline between the two groups and monitored during treatment. The 3-month mortalities of the two groups were compared. No significant differences were found in biochemical items, MELD score, and HBV DNA level at baseline (P>0.05). HBV DNA level decreased within 3 months in both groups (P<0.05), regardless of the pretreatment MELD score. In patients with the same range of pretreatment MELD scores, treatment duration, posttreatment HBV DNA levels, percentage of HBV DNA level <2.7 lg copies/mL, biochemical items, MELD scores and 3-month mortality were similar in the two groups (all P>0.05). Pretreatment MELD score was not related to posttreatment HBV DNA levels (P>0.05), but related to a 3-month mortality in both groups (both P<0.001). In HBeAg-negative patients with ACLF, the short-term efficacy of entecavir versus lamivudine was similar. The degree of pretreatment liver failure significantly affected the outcome of treatment.

Emergence of entecavir-resistant mutations in nucleos(t)ide-naive Japanese patients infected with hepatitis B virus: Virological breakthrough is also dependent on adherence to medication

Objective. Currently, five nucleos(t)ide analogues (NUCs) are available for the treatment of chronic hepatitis B in the world. We examined the prevalence of hepatitis B virus (HBV) DNA and alanine aminotransferase normalization in patients receiving entecavir (ETV) and the frequency of ETV-resistant mutations during an approximately 27-month use of ETV in chronic hepatitis B patients in an urban hospital in Japan. Materials and methods. A retrospective analysis of 81 NUC-naive chronic hepatitis B patients who received 0.5 mg of ETV daily was performed. HBV DNA was measured and sequence analysis of HBV DNA was performed in virological breakthrough patients. Results. Hepatitis B e antigen (HBeAg)-positive patients with HBV DNA 5.0–7.0 log IU/mL group and all HBeAg-negative patients achieved serum HBV DNA negativity by 12 months. Four patients experienced virological breakthrough during ETV therapy. Two patients had no genotypic mutations, and medical interviews revealed that they had poor adherence to ETV. Conclusions. We found that some of the HBV virological breakthroughs during ETV treatment were related to poor adherence to medication, highlighting that clinicians should pay attention to the emergence of resistant mutants as well as adherence to ETV.

A comparison of 48-week treatment efficacy between clevudine and entecavir in treatment-naïve patients with chronic hepatitis B

Clevudine and entecavir are currently available in Korea as antiviral drugs against chronic hepatitis B (CHB). We aimed to compare the efficacy of clevudine and entecavir therapy. Treatment-naïve CHB patients who received 30mg of clevudine or 0.5mg of entecavir a day were analyzed. Mean reduction of hepatitis B virus (HBV) DNA levels, complete virological response (cVR, undetectable HBV DNA by real-time PCR), biochemical response (recovery to normal ALT level), and hepatitis B e antigen (HBeAg) seroconversion rate at the 48th week of treatment were assessed. A number of 59 patients in clevudine group and 61 patients in entecavir group were included. Mean HBV DNA reductions from baseline were similar in the clevudine and entecavir groups, -6.4 versus -6.8 log(10) copies/mL in HBeAg-positive (p=0.417) and -6.9 versus -7.0 log(10) copies/mL in HBeAg-negative patients (p=0.640). The proportion of patients who achieved cVR was not different between the two groups, 53 versus 55% in HBeAg-positive (p=1.000) and 100 versus 95% in HBeAg-negative patients (p=0.452). Biochemical response rates and HBeAg seroconversion rates were also similar in both the groups. Two (3.4%) patients in clevudine group showed virologic breakthrough with rtM204I mutation using direct sequencing analysis. Clinical myopathy occurred in two (3.4%) patients in clevudine group. Mean reduction of viral loads was similar between clevudine and entecavir groups during 48weeks. However, virologic breakthrough and significant myopathy were noted only in clevudine-treated patients. Therefore, more attention should be paid to patients receiving clevudine.

Comparison of the efficacy of 48 week-Entecavir therapy with that of Adefovir therapy for chronic hepatitis B patients

To compare the efficacy of 48 week-Entecavir therapy with that of Adefovir therapy for chronic hepatitis B patients. In this open-label study we randomly assigned 125 CHB patients to receive 0.5 mg of entecavir (n = 56) or 10mg of adefovir (n = 69) once daily for 48 weeks. HBV DNA, ALT and HBeAg were quantified at baseline and at 0, 24, 48 weeks. At week 24 and 48, more patients in entecavir group than in adefovir group achieved undetectable serum HBV DNA level (68% vs 35%, 84% vs 49%, P < 0.05). The percentage of patients with normal ALT level in the two groups at week 48 was similar (100% vs 94%, P > 0.05). Among the HBeAg positive patients, more patients in entecavir group than in adefovir group had HBeAg loss at week 24 and 48 (23% vs 7%, 44% vs 15%, P < 0.05). The ratio of HBeAg seroconversion was similar in the two groups at week 24 (18% vs 7%, P > 0.05), but more patients in entecavir group than in adefovir group achieved HBeAg seroconversion at week 48 (33% vs 12%, P < 0.05). The retreated patients in the entecavir group had a higher chance to achieve undetectable serum HBV DNA level (79% vs 34%, P < 0.05), HBeAg loss (42% vs 17%, P > 0.05), and seroconversion (26% vs 17%, P > 0.05), than these in the adefovir group. The safety profiles and adverse event profiles were similar in the two groups. Compared to adefovir, entecavir is more potent to suppress HBV replication.

Treatment Efficacy of Clevudine, Entecavir and Lamivudine in Treatment-naive Patients with HBeAg-Positive Chronic Hepatitis B

clevudine is a potent antiviral agent that has demonstrated efficacy in patients with chronic hepatitis B. This study compared the efficacy of clevudine (C), entecavir (E) and lamivudine (L) in treatment-naive patient with HBeAg-positive chronic hepatitis B. a total of 146 treatment-naive patients with HBeAg-positive chronic hepatitis B received clevudine, entecavir or lamivudine. C group (n=39) received 30 mg of clevudine, E group (n=39) received 0.5 mg of entecavir and L group (n=68) received 100 mg of lamivudine once a day for more than 48 weeks. The efficacy analysis estimated the mean changes of the HBV DNA levels as a virologic response, the normalization of the ALT levels (less than 35 IU/L) as a biochemical response and loss of HBeAg or seroconversion as a serologic response. The serum HBV DNA level was quantified by hybrid capture and real-time PCR assay. before the administration of clevudine, entecavir and lamivudine, the mean HBV DNA and ALT levels and the gender and age were well balanced among the three groups (p>0.05). For the virologic response at 48 weeks, the mean changes of the HBV DNA levels from baseline of the C, E and L groups were -3.8+/-2.2, -4.5+/-1.9 and -2.5+/-2.1 log copies/mL. C and E group showed superior antiviral activity compared to that of L group (p<0.0001), but no significant differences in antiviral response were noted between C and E groups. For the biochemical response at 48 weeks, the normalization of the ALT levels (less than 35 IU/L) among the C, E and L groups was 82%, 74% and 71%, respectively (p=0.46). The rates of undetectable serum HBV DNA (less than 300 copies/mL) of the C, E and L groups were 39%, 69% and 27%, respectively (p<0.0001). For the serologic response at 48 weeks, the loss of HBeAg was 13%, 31% and 24% and the seroconversion was 10%, 23% and 17%, respectively. There was no difference of efficacy among the three groups regarding ALT normalization or serologic response (p>0.05). Viral breakthrough in C group was noted at 24 weeks (5%) and 48 weeks (21%), but no biochemical breakthrough was noted. The elevation of the serum CK level was noted in only 1 patient of group C at 48 weeks (2.56%) after therapy. For the patients without or with liver cirrhosis (LC), C and E group showed superior antiviral activity compared to that of the L group, but the antiviral activity was more effective in non- LC group than LC group (p<0.0001 vs p=0.036). clevudine therapy compared with lamivudine for 48 weeks showed significantly potent antiviral efficacy in treatment-naive patients with HBeAg-positive chronic hepatitis B, and especially in the non-LC patients. However, the antiviral efficacy of clevudine was similar to that of entecavir even though taking into account relatively short follow up period and retrospective study.

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

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

Clinical efficacy of entecavir therapy and factors associated with treatment response in naïve chronic hepatitis B patients

Entecavir is a potent and selective guanosine analogue that has demonstrated a significant antiviral efficacy against hepatitis B virus (HBV). The aim of this study was to characterize the response to entecavir and to examine the factors affecting that response. We administered 0.5 mg of entecavir once daily for more than 12 months to 114 naive chronic hepatitis B (CHB) patients. We measured the levels of liver enzymes, serological markers, and serum HBV DNA at 3-month interval. Normalization of serum alanine aminotransferase levels was observed in 68.5% (76/114), 74.6% (85/114), and 81.6% (62/76) of patients after 6, 12, and 24 months of therapy, respectively. HBV DNA levels of <50 copies/mL (as evaluated by polymerase chain reaction) were observed in 43.9% (50/114), 71.1% (81/114), and 85.5% (65/76) of patients after 6, 12, and 24 months, respectively. Viral breakthrough was not observed. The rates of HBeAg loss and seroconversion were 43.5% (27/62) and 14.5% (9/62), respectively, after 12 months of therapy, and 56.4% (22/39) and 15.4% (6/39) after 24 months. The independent factor associated with PCR negativity was early virologic response (EVR; HBV DNA <2,000 copies/mL after 3 months of therapy, P<0.001). The independent factors predicting HBeAg loss were found to be serum albumin levels (P=0.041) and EVR (P=0.005). Entecavir induced excellent biochemical and virologic responses in naive CHB patients. EVR was an independent factor for predicting HBV PCR negativity and HBeAg loss.

M1916 Three-Years of Continuous Entecavir Treatment in Chinese Patients Who Had Previously Failed Lamivudine: Results from Studies ETV-056 and −050

entecavir (ETV)-treated patients from Chinese study ETV-023 enrolled in a long-term rollover study ETV-050. We present efficacy and safety results in a cohort of patients from ETV studies -023 and -050 who received 3 years of continuous therapy with ETV. Methods: The Chinese ETV-continuous cohort consists of HBeAg(+)/(−) nucleoside-naive ETV patients from ETV study -023 who (a) had a virologic non-response after completing 52 weeks of blinded dosing, or (b) had not achieved consolidated response after 96 weeks of therapy, or (c) had a virologic breakthrough during the year 2 of dosing, and (d) enrolled into ETV-050 with a treatment gap 35 days. In ETV-050, patients were treated with 1mg of ETV. The proportions of patients with HBVDNA <300 copies/mL by PCR, ALT normalization, HBeAg loss, and HBeAg seroconversion were evaluated among patients with evaluable samples at Week-144. Safety for all treated patients in this cohort was also evaluated. Results: The Chinese ETV-continuous cohort consists of 160 patients. Efficacy parameters for patients who completed 3 years of therapy are presented in the table below. The safety profile of ETV was consistent with previously reported experience. Conclusions: High proportions of Chinese nucleoside-naive patients who received continuous treatment with ETV for 3 years had suppression of viral replication and ALT normalization. Continued therapy also resulted in additional patients experiencing HBeAg loss and HBeAg seroconversion.

Absence of a Pharmacokinetic Interaction Between Entecavir and Adefovir

This study evaluated the effect of entecavir on the pharmacokinetics of adefovir and the effect of adefovir on the pharmacokinetics of entecavir using a fixed-sequence crossover design in healthy adult subjects. Subjects received 10 mg of adefovir once daily on days 1 to 4, 1 mg of entecavir on days 5 to 14, and 1 mg of entecavir plus 10 mg of adefovir on days 15 to 24. Pharmacokinetic assessments were performed on days 4 and 24 for adefovir and on days 14 and 24 for entecavir. The geometric mean ratios (90% confidence interval) for area under the plasma concentration-time curve in 1 dosing interval, peak plasma concentration, and 24-hour postdose plasma concentration of entecavir when coadministered with adefovir and of adefovir when coadministered with entecavir were within the prespecified 0.80 to 1.25 no-effect range. Entecavir and adefovir were well tolerated when administered in combination. Therefore, the pharmacokinetic data generated in this study indicate that entecavir and adefovir can be coadministered without the need for dosage adjustment.

Entecavir versus lamivudine for HBeAg positive and negative chronic hepatitis B

Entecavir versus lamivudine for patients with HBeAg-negative chronic hepatitis B. Lai CL, Shouval D, Lok AS, Chang TT, Cheinquer H, Goodman Z, DeHertogh D, Wilber R, Zink RC, Cross A, Colonno R, Fernandes L; BEHoLD AI463027 Study Group. BACKGROUND Entecavir is a potent and selective antiviral agent that has demonstrated efficacy in phase 2 studies in patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B. METHODS In this phase 3, double-blind trial, we randomly assigned 648 patients with HBeAg-negative chronic hepatitis B who had not previously been treated with a nucleoside analogue to receive 0.5mg of entecavir or 100mg of lamivudine once daily for a minimum of 52 weeks. The primary efficacy end point was histologic improvement (a decrease by at least two points in the Knodell necroinflammatory score, without worsening of fibrosis). RESULTS Histologic improvement after 48 weeks of treatment occurred in 208 of 296 patients in the entecavir group who had adequate baseline liver-biopsy specimens that could be evaluated (70%), as compared with 174 of 287 such patients in the lamivudine group (61%, P =0.01). More patients in the entecavir group than in the lamivudine group had undetectable serum hepatitis B virus (HBV) DNA levels according to a polymerase-chain-reaction assay (90% vs. 72%, P P =0.045). The mean reduction in serum HBV DNA levels from baseline to week 48 was greater with entecavir than with lamivudine (5.0 vs. 4.5 log [on a base-10 scale] copies per milliliter, P CONCLUSIONS Among patients with HBeAg-negative chronic hepatitis B who had not previously been treated with a nucleoside analogue, the rates of histologic improvement, virologic response, and normalization of alanine aminotransferase levels were significantly higher at 48 weeks with entecavir than with lamivudine. The safety profile of the two agents was similar, and there was no evidence of viral resistance to entecavir. (ClinicalTrials.gov number, NCT00035789.). [Abstract reproduced by permission of N Engl J Med 2006;354:1011–1020] A comparison of entecavir and lamivudine for HBeAg-positive chronic hepatitis B. Chang TT, Gish RG, de Man R, Gadano A, Sollano J, Chao YC, Lok AS, Han KH, Goodman Z, Zhu J, Cross A, DeHertogh D, Wilber R, Colonno R, Apelian D; BEHoLD AI463022 Study Group. BACKGROUND Entecavir is a potent and selective guanosine analogue with significant activity against hepatitis B virus (HBV). METHODS In this phase 3, double-blind trial, we randomly assigned 715 patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B who had not previously received a nucleoside analogue to receive either 0.5mg of entecavir or 100mg of lamivudine once daily for a minimum of 52 weeks. The primary efficacy end point was histologic improvement (a decrease by at least two points in the Knodell necroinflammatory score, without worsening of fibrosis) at week 48. Secondary end points included a reduction in the serum HBV DNA level, HBeAg loss and seroconversion, and normalization of the alanine aminotransferase level. RESULTS Histologic improvement after 48 weeks occurred in 226 of 314 patients in the entecavir group (72%) and 195 of 314 patients in the lamivudine group (62%, P =0.009). More patients in the entecavir group than in the lamivudine group had undetectable serum HBV DNA levels according to a polymerase-chain-reaction assay (67% vs. 36%, P P =0.02). The mean reduction in serum HBV DNA from baseline to week 48 was greater with entecavir than with lamivudine (6.9 vs. 5.4 log [on a base-10 scale] copies per milliliter, P P =0.33). No viral resistance to entecavir was detected. Safety was similar in the two groups. CONCLUSIONS Among patients with HBeAg-positive chronic hepatitis B, the rates of histologic, virologic, and biochemical improvement are significantly higher with entecavir than with lamivudine. The safety profile of the two agents is similar, and there is no evidence of viral resistance to entecavir. (ClinicalTrials.gov number, NCT00035633.). [Abstract reproduced by permission of N Engl J Med 2006;354:1001–1010]

Entecavir versus Lamivudine for Patients with HBeAg-Negative Chronic Hepatitis B

Entecavir is a potent and selective antiviral agent that has demonstrated efficacy in phase 2 studies in patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B. In this phase 3, double-blind trial, we randomly assigned 648 patients with HBeAg-negative chronic hepatitis B who had not previously been treated with a nucleoside analogue to receive 0.5 mg of entecavir or 100 mg of lamivudine once daily for a minimum of 52 weeks. The primary efficacy end point was histologic improvement (a decrease by at least two points in the Knodell necroinflammatory score, without worsening of fibrosis). Histologic improvement after 48 weeks of treatment occurred in 208 of 296 patients in the entecavir group who had adequate baseline liver-biopsy specimens that could be evaluated (70 percent), as compared with 174 of 287 such patients in the lamivudine group (61 percent, P=0.01). More patients in the entecavir group than in the lamivudine group had undetectable serum hepatitis B virus (HBV) DNA levels according to a polymerase-chain-reaction assay (90 percent vs. 72 percent, P<0.001) and normalization of alanine aminotransferase levels (78 percent vs. 71 percent, P=0.045). The mean reduction in serum HBV DNA levels from baseline to week 48 was greater with entecavir than with lamivudine (5.0 vs. 4.5 log [on a base-10 scale] copies per milliliter, P<0.001). There was no evidence of resistance to entecavir. Safety and adverse-event profiles were similar in the two groups. Among patients with HBeAg-negative chronic hepatitis B who had not previously been treated with a nucleoside analogue, the rates of histologic improvement, virologic response, and normalization of alanine aminotransferase levels were significantly higher at 48 weeks with entecavir than with lamivudine. The safety profile of the two agents was similar, and there was no evidence of viral resistance to entecavir. (ClinicalTrials.gov number, NCT00035789.).

A Comparison of Entecavir and Lamivudine for HBeAg-Positive Chronic Hepatitis B

Entecavir is a potent and selective guanosine analogue with significant activity against hepatitis B virus (HBV). In this phase 3, double-blind trial, we randomly assigned 715 patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B who had not previously received a nucleoside analogue to receive either 0.5 mg of entecavir or 100 mg of lamivudine once daily for a minimum of 52 weeks. The primary efficacy end point was histologic improvement (a decrease by at least two points in the Knodell necroinflammatory score, without worsening of fibrosis) at week 48. Secondary end points included a reduction in the serum HBV DNA level, HBeAg loss and seroconversion, and normalization of the alanine aminotransferase level. Histologic improvement after 48 weeks occurred in 226 of 314 patients in the entecavir group (72 percent) and 195 of 314 patients in the lamivudine group (62 percent, P=0.009). More patients in the entecavir group than in the lamivudine group had undetectable serum HBV DNA levels according to a polymerase-chain-reaction assay (67 percent vs. 36 percent, P<0.001) and normalization of alanine aminotransferase levels (68 percent vs. 60 percent, P=0.02). The mean reduction in serum HBV DNA from baseline to week 48 was greater with entecavir than with lamivudine (6.9 vs. 5.4 log [on a base-10 scale] copies per milliliter, P<0.001). HBeAg seroconversion occurred in 21 percent of entecavir-treated patients and 18 percent of those treated with lamivudine (P=0.33). No viral resistance to entecavir was detected. Safety was similar in the two groups. Among patients with HBeAg-positive chronic hepatitis B, the rates of histologic, virologic, and biochemical improvement are significantly higher with entecavir than with lamivudine. The safety profile of the two agents is similar, and there is no evidence of viral resistance to entecavir. (ClinicalTrials.gov number, NCT00035633.).

Ｌａｍｉｖｕｄｉｎｅ耐性ウイルスに対してＥｎｔｅｃａｖｉｒを投与したＢ型慢性肝炎例から検出された新たなＥｎｔｅｃａｖｉｒ耐性ウイルス

Entecavir (ETV) exhibits potent antiviral activity in patients chronically infected with wild-type or lamivudine-resistant hepatitis B virus (HBV). Among the patients treated in phase II ETV clinical trials, one patient for whom previous therapies had failed exhibited virologic breakthrough while on ETV. Isolates from this patient were analyzed genotypically for emergent substitutions in HBV reverse transcriptase (RT). After 135 weeks of lamivudine therapy, patient received 0.5 mg of ETV for 52 weeks followed by 1.0 mg of ETV continuously. Viral rebound occurred at 84 weeks after ETV was started. The lamivudine RT substitutions rtH55R, rtL180M and rtM204V were present at study entry, and the additional substitutions rtS202G and rtL269I emerged during ETV treatment.

Potent efficacy of entecavir (BMS-200475) in a duck model of hepatitis B virus replication.

The ability of entecavir (ETV) to inhibit Duck hepatitis B virus (DHBV) infection in duck hepatocytes and ducklings was examined using lamivudine (3TC) as a comparator drug. ETV exhibited antiviral activity (50% effective concentration [EC(50)], 0.13 nM) in DHBV-infected duck hepatocytes that was >1,000-fold more potent than that of 3TC (EC(50), 138 nM). A 21-day treatment of ducklings with 1 mg of ETV per kg of body weight per day by oral gavage resulted in a mean reduction of log(10) 3.1 in serum DHBV DNA levels. Daily treatment with 0.1 mg of ETV/kg was nearly as effective, achieving an average viral DNA level decrease of log(10) 2.1. Reducing the daily dose of ETV to only 0.01 mg/kg resulted in an average viral DNA level decrease of log(10) 0.97. Daily treatment with 25 mg of 3TC/kg resulted in an average viral DNA level decrease of log(10) 0.66, compared to the log(10) 0.20 drop seen for ducklings given the vehicle alone. ETV was also more effective in decreasing the DHBV DNA levels in duck livers after 21 days of treatment, causing average drops of log(10) 1.41, log(10) 0.76, and log(10) 0.26 for dose levels of 1.0, 0.1, and 0.01 mg/kg, respectively, compared to a decrease of log(10) 0.06 for 3TC at a dose level of 25 mg/kg. Levels of viral covalently closed circular DNA in the treatment group receiving 1 mg of ETV/kg were reduced compared to those in the vehicle-treated group. ETV and 3TC were both well tolerated in all treated animals. These results show that ETV is a highly potent and effective antiviral in the DHBV duck model.