Adefovir dipivoxil alone or in combination with lamivudine in patients with lamivudine-resistant chronic hepatitis B

Entecavir: a new treatment for chronic hepatitis B infection

Hepatitis B virus can cause both acute and chronic liver disease in humans. Entecavir, a new, potent, orally administered guanosine analog for the treatment of chronic hepatitis B, has recently approved in the USA and Europe. Monotherapy with entecavir in nucleoside-naive patients has been associated with statistically superior histological improvement, greater reduction in hepatitis B virus-DNA levels, and improved normalization of alanine aminotransferase levels when compared with lamivudine. After 2 years of treatment, viral resistance to entecavir has not developed in the antiviral-naive patient population. Similar findings in terms of efficacy have also been observed in patients with lamivudine-resistant hepatitis B virus. The use of entecavir in the lamivudine-resistant patient population could lead to the development of entecavir-resistant mutants at the rate of 9% by 2 years. Entecavir is well tolerated with a good safety profile and should be considered as primary therapy for chronic hepatitis B. Entecavir may also be considered for use in the lamivudine-resistant patient at twice the dose recommended for nucleoside-naive patients, with the recognition that virologic breakthrough could develop.

Intracellular metabolism and in vitro activity of tenofovir against hepatitis B virus

Tenofovir is an acyclic nucleotide analog with activity against human immunodeficiency virus (HIV) and hepatitis B virus (HBV). Tenofovir disoproxil fumarate (tenofovir DF), a bis-alkoxyester prodrug of tenofovir, is approved for the treatment of HIV and is currently being developed to treat chronic hepatitis B. In this report, we further characterize the in vitro activity of tenofovir against HBV as well as its metabolism in hepatic cells. We show that tenofovir is efficiently phosphorylated to tenofovir diphosphate (TFV-DP) in both HepG2 cells and primary human hepatocytes. TFV-DP has a long intracellular half-life (95 h) and is a potent and competitive inhibitor of HBV polymerase (Ki = 0.18 microM). Tenofovir has a 50% effective concentration of 1.1 microM against HBV in cell-based assays, and potency is improved > 50-fold by the addition of bis-isoproxil progroups. Tenofovir has previously demonstrated full activity against lamivudine-resistant HBV in vitro and clinically. Here we show that the major adefovir resistance mutation, rtN236T, confers three- to fourfold-reduced susceptibility to tenofovir in cell culture; the clinical significance of this susceptibility shift has not yet been determined. The rtA194T HBV polymerase mutation recently identified in tenofovir DF-treated HIV/HBV-coinfected patients did not confer in vitro resistance to tenofovir as a single mutation or in a lamivudine-resistant viral background. Overall, the antiviral and metabolic profile of tenofovir supports its development for the treatment of chronic hepatitis B.

Multiplex locked nucleic acid probes for analysis of hepatitis B virus mutants using real-time PCR

Current methods of detecting hepatitis B virus (HBV) mutations are time consuming, labor intensive, and not suitable for screening large numbers of samples. A multiplex real-time PCR approach presented in this article is a hepatitis B virus quantification method that employs the SYBR Green I dye in conjunction with wild-type HBV sequence-specific locked nucleic acid (LNA) probes. The three short LNA probes distinguished the wild-type strain or three groups of mutants (rt173, rt180/rt181, and rt202/rt204) depending on perfect-match hybrids or mismatch within one template simultaneously. Primers labeled with quencher minimized the background signals. This sensitive approach could quantify 10(2) copies of HBV virus, and as low as 1% mutants among 10(4) copies of wild-type HBV could be identified. The technique is handy and convenient, requiring only 3.5 h to analyze 30 hepatitis B surface antigen-positive serum samples. The HBV isolates were confirmed by direct sequencing. Our data indicate that real-time PCR with SYBR Green I dye is a reliable, rapid, and convenient technique for HBV quantification. Furthermore, by incorporating fluorescent LNA probes, this technique becomes handy in identifying and classifying mutations in the HBV polymerase gene. Being sensitive, specific, accurate, rapid, and convenient in nature, this technique could be a suitable diagnostic tool with wide application particularly in cases in which large volumes of clinical samples are handled.

Hepatitis B Virus Replication and Liver Disease Progression: The Impact of Antiviral Therapy

Chronic hepatitis B virus (HBV) infection is a serious health issue worldwide. The presence of HBV replication markers — hepatitis B e antigen (HBeAg) or HBV DNA — is associated with continuing hepatitis activity or intermittent hepatitis flares and subsequent disease progression, including hepatic decompensation and development of liver cirrhosis or hepatocellular carcinoma (HCC). Long-term (>10 years) prospective studies in patients ≥30 years of age have shown that HBeAg seropositivity is associated with increased risk of disease progression, and the risk of cirrhosis and HCC begins to increase at an HBV DNA level of 104 copies/ml. Therefore, elimination of HBV, or at least sustained or maintained suppression of HBV, is the key to reducing hepatitis and thereby halting or preventing disease progression. Therapy with interferon-α or a direct antiviral agent has been shown to reduce the risk of cirrhosis and prevent further disease worsening. In both the woodchuck hepatitis model and in HBV patients, maintained suppression of HBV replication by a direct antiviral agent may reduce the progression to HCC. However, the efficacy of current antiviral therapy is still far from satisfactory. The ability to achieve a high rate of sustained or maintained HBV suppression with a low risk of drug resistance would be the ultimate goal in the treatment of chronic HBV infection.

Tenofovir for patients with lamivudine-resistant hepatitis B virus (HBV) infection and high HBV DNA level during adefovir therapy

Incomplete virological response to adefovir dipivoxil (ADV) has been observed in patients with lamivudine-resistant hepatitis B virus (HBV) infection and may be associated with developing resistance and disease progression. We therefore investigated whether the efficacy of viral suppression could be improved by replacing ADV with tenofovir disoproxil fumarate (TDF). Twenty patients with chronic HBV infection (18 HBeAg+), viral breakthrough during lamivudine therapy, and persistent viral replication (>10(4) copies/mL) after 15 months of ADV monotherapy (range 4-28 months) were treated with TDF 300 mg daily and were retrospectively analyzed. A screening for nucleoside/nucleotide analogue resistance mutations within the HBV polymerase gene was performed in all patients by direct sequencing. Within a median of 3.5 months, application of TDF led to undetectable HBV DNA in 19 of 20 patients, as demonstrated by suppression of HBV DNA below the detection limit of 400 copies/mL. Initially elevated ALT levels had normalized in 10 of 14 patients by the end of follow-up (median 12 months, range 3-24 months). Four patients lost HBeAg, after 3, 4, 5, and 16 months, and one patient seroconverted to anti-HBs after 16 months of TDF therapy. Lamivudine-associated mutations (rtV173L, rtL180M, rtM204V/I) could be detected in 6 patients at baseline of TDF, but this obviously did not influence the response. ADV-resistant mutations were not detected. No side effects were reported. In conclusion, these preliminary observations strongly suggest that TDF might be a highly effective rescue drug for HBV-infected patients with altered responsiveness to treatment with lamivudine and ADV.

Virological Response and Incidence of Adefovir Resistance in Lamivudine-Resistant Patients Treated with Adefovir Dipivoxil

Background and aims

The incidence of adefovir dipivoxil (ADV) resistance in patients with lamivudine (3TC)-resistant mutants who received ADV therapy remains unclear. The aims of this study were to determine the virological response to ADV, the incidence and the risk factors of ADV resistance, and the associated factors of initial virological response (IVR) in lamivudine-resistant patients.

Patients and methods

Forty-six consecutive lamivudine-resistant chronic hepatitis B patients treated with ADV for more than 12 months with or without 3TC overlapping were prospectively examined for virological response and adefovir resistance.

Results

IVR was documented in 24 (52.2%) of patients. Of the 46 patients, 11 had ADV resistance (5 rtN236T, 5 rtA181T, 1 rtA181T and rtN236T). The cumulative incidence of ADV resistance at month 6, 12, 18 and 24 was 0%, 6.5%, 24.6% and 38.3% respectively. Compared with those without ADV resistance, patients with ADV resistance had a significantly higher rate of liver cirrhosis. Based on Cox regression analysis, the significant risk factor of ADV resistance was younger age (OR=0.92, 95% CI=0.86–0.99, P=0.023) and liver cirrhosis (OR=5.3, 95% CI=1.12–25.09, P=0.036). In addition, patients with ADV resistance were associated with higher HBV DNA levels and lower HBV DNA reduction in first 6 months of ADV treatment than those without ADV resistance.

Conclusion

Only half of our patients achieved IVR on ADV treatment. The incidence of ADV resistance was high in 3TC-resistant patients treated with ADV.

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A double-blind randomized trial of adefovir dipivoxil in Chinese subjects with HBeAg-positive chronic hepatitis B

Four hundred and eighty Chinese subjects with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) were enrolled in a multicenter, double-blind, randomized, placebo-controlled study of adefovir dipivoxil (ADV) 10 mg once daily. There was a significant difference in reduction of serum hepatitis B virus (HBV) DNA after 12 weeks between subjects who received ADV and those who received the placebo (3.4 and 0.1 log10 copies/mL, respectively, P < .001). Further reductions in serum HBV DNA and increases in the proportion of subjects with an HBV DNA level of at most 10(5) copies/mL, with HBV DNA undetectable, and with ALT normalization were observed in ADV-treated subjects at week 52 (median HBV DNA reduction of 4.5 log(10) copies/mL, 67% with HBV DNA <or= 10(5) copies/mL, 28% with HBV DNA undetectable, and 79% with ALT normalization). Subjects who initially received ADV lost some treatment benefit after being rerandomized to the placebo in week 40. Subjects with YMDD mutant HBV at baseline had virological, biochemical, and serological responses to treatment that were similar to those of subjects with wild-type HBV. The incidence of clinically adverse events was similar in nature and severity between the treatment groups, and there was no evidence of renal toxicity. No adefovir-related HBV mutations were identified. In conclusion, treatment with ADV 10 mg daily over 52 weeks was safe and effective in Chinese subjects with HBeAg-positive CHB and did not lead to the emergence of drug resistance. The study is continuing for an additional 4 years with all subjects on open-label ADV 10 mg daily.

Entecavir for treatment of lamivudine-refractory, HBeAg-positive chronic hepatitis B

BACKGROUND & AIMS

Lamivudine treatment is associated with frequent development of resistant hepatitis B virus (HBV) and loss of treatment benefit. In preclinical and phase II studies, entecavir demonstrated potent antiviral activity against lamivudine-resistant HBV.

METHODS

In this phase III, double-blind trial, hepatitis B e antigen-positive patients who were refractory to lamivudine therapy (persistent viremia or documented YMDD mutations while receiving lamivudine) were randomized to switch to entecavir 1 mg daily (n = 141) or continue lamivudine 100 mg daily (n = 145) for a minimum of 52 weeks. Two coprimary end points were assessed at 48 weeks: histologic improvement and a composite end point (HBV branched DNA <0.7 MEq/mL and alanine aminotransferase [ALT] <1.25 times the upper limit of normal).

RESULTS

Histologic improvement occurred in 55% (68/124) of entecavir-treated vs 28% (32/116) of lamivudine-treated patients (P < .0001). More patients on entecavir than lamivudine achieved the composite end point: 55% (77/141) vs 4% (6/145), respectively (P < .0001). Mean change from baseline in HBV DNA was -5.11 log(10) copies/mL for entecavir-treated patients and -0.48 log(10) copies/mL for lamivudine-treated patients (P < .0001). Virologic rebound because of entecavir resistance substitutions occurred in 2 of 141 of entecavir-treated patients, and genotypic evidence of resistance was detected in 10 patients. The safety profile of entecavir was comparable to lamivudine with fewer ALT flares on treatment.

CONCLUSIONS

In patients with lamivudine-refractory chronic hepatitis B, switching to entecavir provides superior histologic improvement, viral load reduction, and ALT normalization compared with continuing lamivudine, with a comparable adverse event profile.

Overlap lamivudine treatment in patients with chronic hepatitis B receiving adefovir for lamivudine-resistant viral mutants

Adefovir dipivoxil is effective against lamivudine-resistant hepatitis B virus (HBV) strains. Whether short-term overlap lamivudine is beneficial remains unknown, particularly in patients with decompensated chronic hepatitis B. We enrolled 30 patients who underwent 48-week adefovir treatment (10 mg daily) for exacerbation of hepatitis B, associated with lamivudine-resistant mutants. Nineteen (63.3%) patients had baseline evidence of hepatic decompensation. Lamivudine was combined for <or=1 month in eight (group I), 2-5 months in 10 (group II) and >or=6 months in 12 (group III). We analysed their serial alanine aninotransferase (ALT) levels, Child-Pugh (CP) score, serum viral load and lamivudine-resistant strains. We found that serum ALT became normalized in 20 (66.7%) and HBV-DNA decreased to <or=100 copies/mL in eight (26.7%) at the end of the 48-week treatment. The log(10) reduction of serum HBV-DNA was significantly smaller in group I patients compared with group II and III patients at week 24 and 48 of treatment [median (range): 3.0 (1.5-5.6) vs 4.5 (1.5-7.4), P = 0.032; and 3.4 (0.9-4.7) vs 5.2 (2.2-7.7), P = 0.008 respectively]. In contrast, the virologic responses at the end of the 48-week therapy were similar between group II and III patients. The improvement in serum ALT and CP score at week 48 was similar irrespective of baseline decompensation, liver cirrhosis and the duration of overlap lamivudine therapy. Our findings suggested that an overlap of lamivudine for >or=2 months might lead to better virological but not biochemical outcomes in patients receiving adefovir for lamivudine-resistance HBV. As our sample size was small and the study was not randomly controlled, further studies are needed.

Management of chronic hepatitis B virus infection: current perspectives for the nurse practitioner

PURPOSE

To address the clinical management of chronic hepatitis B virus (HBV) infection.

DATA SOURCES

Studies from the National Library of Medicine that examine the natural history, prevention, and antiviral therapy of chronic HBV infection, with emphasis on recent studies.

CONCLUSIONS

Chronic infection with HBV is a frequent cause of cirrhosis, liver cancer, and liver-related mortality worldwide. Strategies to prevent infection, screen for liver cancer in HBV carriers, and treat chronic hepatitis B are all important in managing this disorder.

IMPLICATIONS FOR PRACTICE

Much can be done to prevent and treat infection. Both classes of drugs to treat hepatitis B, nucleoside analogues and interferons, have advantages and disadvantages. Selection of therapy should be based on biochemical, histological, and virological parameters as well as consideration of several practical issues.

Management of drug-resistant chronic hepatitis B

Lamivudine, adefovir, and entecavir are safe and effective orally administered inhibitors of hepatitis B virus (HBV) replication, but drug-resistant strains of HBV with point mutations in the HBV polymerase gene are being reported with prolonged treatment that can lead to viral rebound and serum alanine aminotransferase flares. Salvage treatment with antiviral agents including investigational nucleoside/nucleotide analogues is available but highlights the limitations and hazards of sequential antiviral monotherapy for chronic HBV. Studies of pegylated interferon combined with an antiviral agent or dual nucleoside/nucleotide combination therapy are awaited to minimize the incidence of drug-resistant HBV and improve long-term outcomes.

Diagnosis and management of allograft failure

The article focuses on diagnosis and management of allograft failure in four main categories: (1) ischemic-reperfusion injury (primary nonfunction), (2) technical complications (hepatic artery and portal vein thrombosis), (3) chronic rejection, and (4) recurrent disease. It also discusses the complex problems involved in retransplantation for allograft failure.

In vitro characterization of the anti-hepatitis B virus activity and cross-resistance profile of 2',3'-dideoxy-3'-fluoroguanosine

The fluorinated guanosine analog 2',3'-dideoxy-3'-fluoroguanosine (FLG) was shown to inhibit wild-type (wt) hepatitis B virus (HBV) replication in a human hepatoma cell line permanently expressing HBV. Experiments performed in the duck model of HBV infection also showed its in vivo antiviral activity. In this study, we investigated the mechanism of inhibition of FLG on HBV replication and its profile of antiviral activity against different HBV or duck hepatitis B virus (DHBV) drug-resistant mutants. We found that FLG-triphosphate inhibits weakly the priming of the reverse transcription compared to adefovir-diphosphate in a cell-free system assay allowing the expression of an enzymatically active DHBV reverse transcriptase. It inhibits more potently wt DHBV minus-strand DNA synthesis compared to lamivudine-triphosphate and shows a similar activity compared to adefovir-diphosphate. FLG-triphosphate was most likely a competitive inhibitor of dGTP incorporation and a DNA chain terminator. In Huh7 cells transiently transfected with different HBV constructs, FLG inhibited similarly the replication of wt, lamivudine-resistant, adefovir-resistant, and lamivudine-plus-adefovir-resistant HBV mutants. These results were consistent with those obtained in the DHBV polymerase assay using the same drug-resistant polymerase mutants. In conclusion, our data provide new insights in the mechanism of action of FLG-triphosphate on HBV replication and demonstrate its inhibitory activity on drug-resistant mutant reverse transcriptases in vitro. Furthermore, our results provide the rationale for further clinical evaluation of FLG in the treatment of drug-resistant virus infection and in the setting of combination therapy to prevent or delay drug resistance.

Variant of hepatitis B virus with primary resistance to adefovir

The reverse-transcriptase inhibitor lamivudine (Zeffix, GlaxoSmithKline) is often used to treat chronic infection with hepatitis B virus (HBV) until resistance develops. Treatment may then be switched to the reverse-transcriptase inhibitor adefovir (Hepsera, Gilead), which has a lower frequency of resistance. Here, we describe three cases of primary adefovir resistance that were sensitive to tenofovir (Viread, Gilead). All three cases involved a rare HBV variant with a valine at position 233 of the reverse-transcriptase domain instead of isoleucine (rtI233V), as in the wild-type virus. This HBV variant also displayed resistance to adefovir and sensitivity to tenofovir in vitro.

The current management of HBV drug resistance

Lamivudine and adefovir have potent inhibitory effects on hepatitis B virus (HBV) replication. Although short-term therapy is feasible in a selected subgroup of patients, prolonged therapy is required for sustained suppression in the majority of patients. However, HBV species with mutations in the tyrosine-methionine-aspartate-aspartate (YMDD) locus of the HBV RNA-dependent DNA polymerase (rtM204 I/V) conferring resistance to lamivudine may emerge after 9-10 months therapy. The incidence increases with duration of therapy up to 70% after 5 years lamivudine therapy. Serum alanine aminotransferase (ALT) elevation and HBV DNA rebound ( I log) occur in >90% of the patients with rtM204 I/V during continued lamivudine therapy. Marked flare of serum ALT may occur, sometimes severe, and may be complicated with decompensation or even fatality. The initial clinical and histologic improvement may also reverse after emergence of rtM204 IN Studies do suggest that stopping seems better than continuing lamivudine therapy. Limited data show that interferon therapy seems ineffective. Add-on adefovir therapy is effective in suppressing rtM204 I/V in both compensated and decompensated patients. Switching to adefovir monotherapy is effective and safe even in cirrhotic patients with decompensation. The overall incidence of adefovirresistant rtN236T and A181V is low, being 0 after one year and 5.9% after 3 years' therapy. The impact of adefovir resistance is less clear but is responsive to lamivudine therapy. In conclusion, monitoring of viral breakthrough to start effective intervention is mandatory during direct antiviral therapy.

Resistance of human hepatitis B virus to reverse transcriptase inhibitors: from genotypic to phenotypic testing

The treatment of HBV infected patients with analogues of nucleos(t)ides, including lamivudine and adefovir dipivoxil, has significantly increased the rate of anti-HBe seroconversion and therefore reduced the impact of chronic hepatitis B (CHB) on liver disease. Altogether, these antivirals have offered novel options for the treatment of patients who did not respond to previous therapy with interferon alpha, the only available treatment against CHB until 1998. However, therapies using analogues of nucleos(t)ides have been confronted with viral resistances which are often associated to with worsening of liver disease. Drug resistance is conferred by the appearance of one or several mutations within the HBV polymerase gene. These mutations confer to the mutant viral population a phenotypic advantage over the wild-type pretherapeutic viral quasispecies, as they induce a reduction of drug susceptibility of mutant strains in vivo. This reduction of drug susceptibility can be as well measured in vitro, i.e in cell culture, using phenotypic assays. The detection of these mutations has become of crucial importance to better adapt clinical option to the virological status of the patient. Genotypic and more recently phenotypic assays have been developed and both assays can be used for drug resistance testing. Genotypic assay gives information about already characterized mutations associated with viral resistance, while phenotypic testing measures the overall drug susceptibility of patient-derived viral strains in cell culture. These assays are described and their potential use in the clinical setting is discussed.

Antiviral therapy of chronic hepatitis B

Treatment of chronic hepatitis B remains a clinical challenge. Long-term viral suppression is a major goal of antiviral therapy to improve the clinical outcome of the patients. Antiviral treatment of chronic hepatitis B relies currently on immune modulators such as interferon alpha and its pegylated form, and viral polymerase inhibitors. Because of the slow kinetics of viral clearance and the spontaneous viral genome variability, viral mutants resistant to nucleoside analogs may be selected. However, the development of new antiviral agents is rapidly improving the offing of therapy of chronic hepatitis B. These new therapeutic advances are reviewed in this manuscript.

Pegylated IFN-α 2b added to ongoing lamivudine therapy in patients with lamivudine-resistant chronic hepatitis B

AIM: To investigate the role of pegylated-interferon (IFN) α-2b in the management of patients with lamivudine-resistant chronic hepatitis B.

METHODS: Twenty consecutive anti-HBe positive patients were treated with pegylated IFN α-2b (100 μg sc once weekly) for 12 mo. There was no interruption in lamivudine therapy. Hematology, liver biochemistry, serum HBV DNA levels were detected by PCR, and vital signs were also assessed. Liver histology was assessed in some patients at entry and at wk 52 for comparison.

RESULTS: Nine patients (45%) had a partial virological end-treatment response; seven patients (35%) showed complete virological end-treatment response. Eight patients (40%) showed biochemical end-treatment response. There was a trend for higher virological response rates in patients who had previously responded to IFN and relapsed compared to IFN non-responders (four out of seven patients vs none out of six patients, respectively; P = 0.1). Patients without virological end-treatment response showed significant worsening of fibrosis [median score 2 (range, 1 to 3) vs median score 3 (range, 1 to 4)], in the first and second biopsy respectively (P = 0.014), whereas necroinflammatory activity was not significantly affected. Patients with complete or partial virological end-treatment response did not show any significant changes in histological findings, possibly due to the small number of patients with paired biopsies (n = 5). Nevertheless, after 12 mo of follow-up, only one patient (5%) showed sustained virological response and only 2 patients (10%) showed sustained biochemical response. Two patients (10%) discontinued pegylated IFN both after 6 mo of treatment due to flu-like symptoms.

CONCLUSION: Pegylated IFNα-2b, when added to ongoing lamivudine therapy in patients with lamivudine-resistant chronic hepatitis B, induces sustained responses only in a small minority of cases.

Hepatitis B virus (HBV) reactivation with immunosuppressive therapy in rheumatic diseases: assessment and preventive strategies

Understanding of the natural history and basic biology of hepatitis B virus (HBV) has increased greatly in recent years. In view of this, the following are reviewed here: (a) recent advances in HBV biology pertinent to the rheumatic disease population; (b) the risks of HBV reactivation in patients with rheumatic disease undergoing immunosuppression; and (c) potential strategies to manage these risks.

Personal view: the management of chronic hepatitis B infection

There are two new nucleoside analogues available for the management of chronic hepatitis B, adefovir and entecavir, and several more in development. In addition, pegylated interferon has become available. Large-scale population studies have re-emphasized the significance of viral load in predicting a poor outcome over the longer term. These new developments have prompted a reassessment of the indications and objectives of therapy for chronic hepatitis B. Hepatitis B virus deoxyribonucleic acid, rather than alanine aminotransferase should be the prime indication for therapy. Hepatitis B e antigen seroconversion can be achieved in 30-40% of treated patients whatever agent is used. However, it takes longer for nucleoside analogues to achieve the same seroconversion rates as interferon. In anti-HBe-positive disease long-term therapy is required for most patients because the relapse rate after withdrawal of therapy is very high, irrespective of the agent used. Viral resistance limits the use of lamivudine, and to a lesser extent adefovir. Resistance to entecavir has so far only been described in pre-existing lamivudine resistance. Although therapy with combinations of nucleoside analogues has not been investigated to any extent, this is the only way to reduce the emergence or resistance, and studies are urgently needed.

Switching to adefovir monotherapy after emergence of lamivudine-resistant mutations in patients with liver cirrhosis

Switching to adefovir (ADV) monotherapy is effective in patients with lamivudine (LAM)-resistant hepatitis B virus (HBV) mutations (rtM204 I/V). However, it was recommended to continue LAM therapy for months after starting ADV therapy for safety concern. The safety and efficacy of switching to ADV monotherapy was examined in compensated and decompensated patients with liver cirrhosis. The clinical, biochemical and virological responses were compared between ADV monotherapy in 18 cirrhotic patients and ADV add-on LAM therapy in 10 comparable cirrhotic patients with LAM-resistant rtM204 I/V. After switching to ADV monotherapy, Child-Pugh's score, serum alanine aminotransferase (ALT), bilirubin, albumin and HBV DNA levels improved significantly (P < 0.01). Serum HBV DNA response, defined as HBV DNA decreased to below 10(5) copies/mL or > or =2 log(10) reduction form baseline, was achieved in all patients. A transient ALT flare without concurrent changes in serum bilirubin or prothrombin time was observed in only two patients (11%). The efficacy and safety profile was similar to those with ADV add-on LAM therapy. In conclusion, switching to ADV monotherapy after emergence of LAM-resistant rtM204 I/V is effective and safe in cirrhotic patients, even in those with hepatic decompensation. To stop LAM and switch to ADV in patients with breakthrough is a reasonably safe and cost-effective approach.

Lamivudine monotherapy in HBeAg-negative chronic hepatitis B: prediction of response-breakthrough and long-term clinical outcome

BACKGROUND

Factors that predict response and breakthrough phenomenon to lamivudine monotherapy in patients with HBeAg-negative chronic hepatitis B have not been well defined.

AIM

To determine pre-treatment and on treatment variables that predict initial response and breakthrough in patients with HBeAg-negative chronic hepatitis B receiving long-term lamivudine.

METHODS

Seventy-nine patients, with chronic HBeAg-negative hepatitis B, who received lamivudine for a median of 31 months were included in the study.

RESULTS

Initial virologic and biochemical response was observed in 73 (92%) and 70 (89%) patients, respectively, while 34 (47%) and 15 (21%) patients developed virological and biochemical breakthrough, respectively. High levels of necroinflammation in liver biopsy were associated with a higher probability of initial virological and biochemical response. Patients with pre-treatment serum hepatitis B virus DNA concentrations of more than 10(6) copies/mL were three times more likely to develop virologic breakthrough. Two patients died, one with baseline cirrhosis because of liver failure during biochemical breakthrough while the second death was liver and treatment unrelated.

CONCLUSIONS

In HBeAg-negative chronic hepatitis B, initial response to lamivudine therapy is associated with necroinflammation, while baseline serum hepatitis B virus DNA exceeding 10(6) copies/mL is a strong predictor for breakthrough because of drug-resistant mutations. Severe complications are uncommon and are associated with biochemical breakthrough and pre-existing cirrhosis.

High rates of progressive hepatic functional deterioration whether lamivudine therapy is continued or discontinued after emergence of a lamivudine-resistant mutant: a prospective randomized controlled study

BACKGROUND

The management of patients with lamivudine-resistant mutants remains challenging, and no clear evidence has been presented concerning the discontinuation of lamivudine.

METHODS

Seventy-four patients with lamivudine-resistant mutants were prospectively enrolled and randomized; 37 patients continued (group A) and 37 patients discontinued lamivudine therapy (group B). The median follow-up was 20 months.

RESULTS

Serum albumin levels were reduced and prothrombin time was prolonged in both groups versus baseline (P = 0.015 and 0.045, respectively). Four patients in group A (10.8%) and six in group B (16.2%) experienced hepatitis flare, but the difference was not significant (P > 0.05). Multivariate analyses identified a younger age as a risk factor for hepatitis flare (P = 0.021). Seven (18.9%) decompensations occurred in group A and five (13.5%) in group B, which was not a significant difference (P > 0.05). Multivariate analyses revealed higher alanine aminotransferase and a lower platelet count as risk factors for hepatic decompensation (P = 0.001 and 0.001, respectively). The patients whose platelet count was <65 000/microl experienced hepatic decompensations more frequently (50%) than those with platelet counts >65 000/microl (13.2%) during follow-up (P = 0.05).

CONCLUSIONS

The clinical course of group B was not significantly different from that of group A. Therefore, the discontinuation of lamivudine may be a feasible option when other antiviral agents active against lamivudine-resistant mutants are unavailable.

Anti-hepatitis B virus efficacy of tenofovir disoproxil fumarate in HIV-infected patients

Tenofovir disoproxil fumarate (TDF) has shown in vitro activity against both HIV and hepatitis B virus (HBV). We retrospectively evaluated the efficacy of TDF (300 mg/d), administered as a part of anti-retroviral therapy, in a large cohort of HIV/HBV-coinfected patients. Sixty-five HIV/HBV-coinfected patients who received TDF for at least 6 months with serum HBV DNA levels above 2.3 log10 copies/mL at TDF initiation and who had stored serum samples before and during TDF therapy were included. Serum HBV DNA was measured on stored samples. The median follow-up period was 12 (Q1-Q3: 8-17) months. Serum hepatitis B e antigen (HBeAg) was positive in 54 patients (83.1%). Fifty-two patients (80.0%) were receiving lamivudine (LAM) (150 mg twice a day), and 68.8% had documented LAM resistance at baseline. Among HBeAg-positive patients, the median reduction from baseline (8.17; Q1-Q3 = 7.30-8.30 log10 copies/mL) of serum HBV DNA was 4.56 log10 copies/mL (Q1-Q3 = 3.33-5.55) (P < .0001). In HBeAg-negative patients, serum HBV DNA decline from baseline (4.83; Q1-Q3 = 2.69-6.40 log10 copies/mL) was 2.53 log10 copies/mL (Q1-Q3 = 0.39-4.10). At the end of the study, HBV DNA became undetectable in 29.6% and 81.6% of the HBeAg-positive and HBeAg-negative patients, respectively. Serum HBeAg became negative in 4 patients, 2 of whom acquired serum hepatitis B e antibody. In conclusion, this retrospective analysis demonstrates the efficacy of TDF against wild-type, presumed precore mutants and LAM-resistant HBV when used as a part of anti-retroviral therapy in HIV-coinfected patients.

[Liver transplantation for complications of hepatitis B]

In the absence of prophylaxis, there is an elevated risk of virus recurrence after liver transplantation required because of chronic hepatitis B. Regardless of prophylaxis, the risk of recurrence is associated with pre-graft viral load. Long-term prophylaxis by hepatitis B immune globulin (HBIG) significantly reduces the risk of recurrence, especially if there was no pre-graft viral replication. Use of antiviral agents such as lamivudine, adefovir, tenofovir, and entecavir, control HBV replication in patients with decompensation of cirrhosis while awaiting transplantation and in patients with HBV recurrence post-graft. The risk of emergence of resistant strains limits the use of these antiviral agents. The choice of one or several combined antiviral agents depends on their resistance profiles. Combining antiviral agents and HBIG after transplantation can reduce the risk of HBV recurrence to less than 10%, even in patients with viral replication pre-graft. If there was no detectable viral load pre-graft, withdrawal of HBIG should be considered at some point, while continuing an antiviral agent or after anti-HBV vaccination.

Clinical and virological effects during two years of ongoing adefovir dipivoxil in the treatment of lamivudine-resistant chronic hepatitis B infection

OBJECTIVE

Our aim was to evaluate the efficacy and safety of adding adefovir to lamivudine therapy for hepatitis B virus (HBV)-infected patients resistant to Ramivudine.

PATIENTS AND METHODS

Among 17 studied patients, 7 had chronic active HBV infection and 10 were posttransplant with HBV infection (9 with de novo HBV). They received lamivudine plus adefovir therapy for 2 years. We assessed reductions in serum HBV-DNA and alanine aminotransferase (ALT) levels, loss of HBeAg (in HBeAg+ cases), and HBsAg clearance.

RESULTS

A virological response, as defined by HBV-DNA below the cut off by hybridization, was observed in 12 (70.6%) patients and loss of HBeAg in 4 (44.4%) of the 9 initially HBeAg-positive cases. A biochemical response, defined as a decreased serum ALT to the normal range, occurred in 4 (26.7%) patients. Median serum creatinine increased in 3 of 15 (20%) patients, excluding those on hemodialysis. There were two noteworthy cases of sustained HBsAg seroconversion with adefovir (11.8%): one patient with de novo HBV infection posttransplantation and positive hepatitis C virus-RNA serology, and one patient with decompensated HBV cirrhosis in whom viral replication ceased, making him eligible for transplantation.

CONCLUSIONS

Currently, adefovir is an effective rescue therapy that broadens the existing range of options for patients with lamivudine-resistant chronic hepatitis B infection, particularly those with decompensated cirrhosis awaiting a liver graft, and those with recurrent posttransplantation HBV. The relatively small biochemical response seen in these patients may be attributable to the high prevalence of concomitant hepatitis C virus infection (41%).

Reactivation of hepatitis B virus with rituximab

Rituximab has become a useful drug for the treatment of non-Hodgkin's lymphoma (NHL) and such autoimmune diseases as idiopathic thrombocytopenic purpura and rheumatoid arthritis. When combined with cytotoxic agents, rituximab showed synergistic effects for the treatment of NHL. In such treatment, hepatitis B virus (HBV) reactivation is a crucial complication when patients are treated with immunosuppressive or chemotherapeutic agents. Despite its treatment efficacy, several studies have pointed out unusual viral infections after its administration that resulted in fatal hepatitis due to HBV reactivation. In the cases at the authors' institute, the authors analysed the kinetics of HBV antibodies, HBV-reactivation timing, and the prophylactic efficacy of lamivudine. The authors reviewed their cases and the previous literature to clarify the characteristics of HBV-reactivated patients who were administered rituximab.

HBV plus HCV, HCV plus HIV, HBV plus HIV

Coinfection of hepatitis C virus (HCV), hepatitis B virus (HBV), and HIV is common due to shared modes of transmission. These coinfections accelerate the course of chronic liver disease and facilitate progression to cirrhosis and hepatocellular carcinoma. The viral interactions between these viruses are complex, and their treatment may be challenging for clinicians.

Therapy of hepatitis B -- viral suppression or eradication?

The practicing clinician is currently faced with a number of treatment options for chronic hepatitis B. Beginning in 1998 with the licensing of lamivudine and subsequently adefovir, the treatment paradigm shifted from 4 to 6 months of conventional alfa interferon to a year of nucleoside analog therapy. However, prolonged treatment with nucleoside analogs is often needed to optimize virological response. Recently, a 48-week regimen of pegylated interferon for hepatitis B e antigen (HBeAg)-positive and HBeAg-negative chronic hepatitis B has been shown to be effective, and long-term nucleoside analog therapy has been demonstrated to maintain viral suppression. These findings have added to the complexity of decision-making and have raised questions about whether a finite course of pegylated interferon or nucleoside analog therapy, with possible long-term maintenance, is better as first-line therapy. Each of these fundamentally different approaches has advantages and limitations, and both have a place in the therapeutic armamentarium against chronic hepatitis B. Long-term therapy with nucleoside analogs, however, raises a number of practical concerns that have not been fully addressed as of yet. I will present evidence in support of the recommendation that antiviral therapy should ideally be directed toward achieving the highest rate of viral clearance with the shortest interval of treatment.

Looking to the future: new agents for chronic hepatitis B

New antiviral agents are currently being developed to treat patients with chronic hepatitis B. Both pegylated interferon alfa-2a and entecavir are now approved for the treatment of hepatitis B while telbivudine, tenofovir, emtricitabine, and pegylated interferon alfa-2b are in clinical development. Successive advances have resulted in more profound suppression of hepatitis B replication, a reduction in breakthrough resistance, and an increase in the frequency of attainment of virologic, serologic, biochemical, and histologic clinical endpoints.

Advancing patient care: integrating new data

Physicians involved in the management of patients with chronic hepatitis B infection are frequently faced with complex clinical issues concerning the diagnosis, investigation, and treatment of patients. Guidelines exist within the literature that help with decision making; however, in practice individual nuances are often encountered necessitating decisions that go beyond the current guidelines. Following presentation of the available data, a panel of expert hepatologists and gastroenterologists sought to identify and solve challenges that are faced by clinicians in the daily management of patients with chronic hepatitis B infection. The following summary provides an overview of the outcome of these discussions. Because of the complexities of clinical management, the recommendations reflect the opinion of the majority; however, many recommendations were not unanimous. Furthermore, the recommendations that follow are limited to adult patients; the treatment of children was not discussed. A number of issues were identified, and statements concerning possible management strategies that could be applied were developed.

Cost-effectiveness analysis of lamivudine and adefovir dipivoxil in the treatment of patients with HBeAg-negative chronic hepatitis B

AIM

To estimate the cost-effectiveness over a 4-year duration of lamivudine and adefovir dipivoxil for patients with hepatitis B 'e' antigen-negative chronic hepatitis B.

METHODS

A decision analysis model has been used to perform a cost-effectiveness analysis of lamivudine and adefovir dipivoxil from the perspective of the Spanish Public Health System. Data were obtained from clinical trials.

RESULTS

For the base-case, the total estimated cost per patient treated with lamivudine or adefovir dipivoxil for 4 years was 11,457 and 21,939 respectively. Virological response at year 4 for the lamivudine arm was 40.4% and 78.0% for the adefovir dipivoxil arm. The average cost-effectiveness ratio (cost per responding patient at year 4) was 28,375 for the lamivudine arm and 28,132 for the adefovir dipivoxil arm. The incremental cost-effectiveness ratio of adefovir dipivoxil vs. lamivudine (cost per additional responding patient with adefovir dipivoxil) was 27,872, demonstrating that this cost was slightly lower than the average cost-effectiveness ratios of adefovir dipivoxil or lamivudine. The sensitivity analysis demonstrated that the factors that most influence the cost-effectiveness were the response to adefovir dipivoxil and lamivudine at year 4.

CONCLUSION

Long-term treatment with adefovir dipivoxil is a cost-effective strategy in patients with chronic hepatitis B 'e' antigen-negative hepatitis.

Traitement de l’hépatite chronique B

Chronic hepatitis B develops in 3 phases: immune tolerance, where viral replication is strong and there is little or no fibrosis; immune activity phase with low viral replication and rapidly developing fibrosis as well as an elevated risk of cirrhosis; low viral replication and remission, with a risk, nonetheless, of reactivation. Antiviral treatment is indicated in patients with moderate or severe levels of either fibrosis or activity (necrotic and inflammatory lesions). Standard interferon treatment produces a prolonged response rate on the order to 20-40%; side effects are frequent but generally mild and reversible when treatment stops. Pegylated interferon (standard interferon conjugated with polyethylene glycol) has substantially better efficacy and comparable tolerance. Lamivudine (a nucleoside analog) has several advantages over interferon: oral administration, excellent tolerance, and rapid antiviral effect. Its principal disadvantage is the frequency of resistant mutations. Adefovir and entecavir have oral administration, are well tolerated and associated with a low incidence of resistance. They induce a sustained response after withdrawal of therapy in only a minority of patients and therefore the treatment needs to be indefinitely administered in the majority of patients.

Virologic response and resistance to adefovir in patients with chronic hepatitis B

BACKGROUND

The incidence and risk factors for adefovir-resistant HBV have not been clearly defined.

AIMS

To characterize the virologic response to adefovir, to determine the rate of adefovir resistance and to explore factors associated with initial virologic response (IVR) and adefovir resistance.

METHODS

All hepatitis B patients who received adefovir for > or =6 months at our center were prospectively monitored for virologic response and adefovir resistance.

RESULTS

Forty three patients were included; mean treatment duration was 18 months (range 6-45). Thirty four (79%) patients had prior lamivudine. IVR was observed in 44% patients and associated with higher pretreatment ALT (P = 0.05) and the absence of HBeAg (P = 0.02). Six (14%) patients were found to have adefovir-resistant mutations. The cumulative probability of genotypic resistance to adefovir at month 24 was 22%. Patients with adefovir resistance were more likely to have been switched from lamivudine to adefovir monotherapy (P = 0.01), to be older (P = 0.04), and to be infected with HBV genotype D (P = 0.02).

CONCLUSIONS

Roughly 50% of patients failed to achieve IVR on adefovir. The cumulative probability of adefovir resistance at 2 years was 22%. Our data suggest that combination of lamivudine and adefovir may prevent emergence of adefovir resistance in patients with lamivudine-resistant HBV.

Therapeutic options for chronic hepatitis B: considerations and controversies

Five agents are currently approved for the treatment of chronic hepatitis B infection. This article will discuss the three agents for which the most extensive data are available; interferon (IFN), lamivudine, and adefovir, while the following article by Dr. Jules Dienstag will discuss the recently marketed agents, entecavir and peginterferon alfa-2a. The advantages of IFN are its finite duration of therapy (4-6 months), lack of emergence of resistance, and durability of response. On the negative side, response to IFN is less durable in patients with HBeAg-negative chronic hepatitis B virus (HBV). Also, use of IFN is limited by adverse effects and the mode of administration (daily to thrice-weekly subcutaneous injection). Lamivudine and adefovir are orally administered and have good tolerability and safety. Even in patients who experience a marked decrease in serum HBV DNA and loss of HBeAg, oral therapy needs to be continued for at least 6 months, to avoid the risk of reappearance of HBeAg and viremia. Rates of HBeAg seroconversion to anti-HBe-positivity increase with duration of lamivudine or adefovir therapy. The likelihood of development of resistance to lamivudine and associated viral breakthrough limits its long-term use. In patients with HBeAg-negative chronic hepatitis B, long-term therapy is usually required, as off-treatment relapse is common. The emergence of resistance to adefovir is delayed and infrequent, hence adefovir may be preferred in patients requiring long-term therapy.

Successful rescue therapy with tenofovir in a patient with hepatic decompensation and adefovir resistant HBV mutant

BACKGROUND

Prolonged adefovir therapy exposes to the emergence of adefovir resistant hepatitis B virus mutants. Initial reports of the rtN236T mutation showed preserved sensitivity to lamivudine; however, complex mutations are emerging with reduced susceptibility to lamivudine.

CASE PRESENTATION

After 2 years of therapy, a cirrhotic patient developed the rtN236T and rtA181T adefovir resistant mutations. He had been previously treated with lamivudine, developed lamivudine resistance and, despite good compliance, had an incomplete response to adefovir. Adefovir resistance resulted in viral breakthrough with hepatitis flare-up and liver decompensation. Tenofovir had an excellent antiviral effect allowing sustained control of viral replication and reversal of hepatic failure.

CONCLUSION

In patients with cirrhosis, adefovir resistance can lead to severe hepatitis. Tenofovir appears to be an effective treatment of adefovir resistant mutants. Incomplete control of viral replication with adefovir requires monitoring for viral resistance and should prompt a change in antiviral treatment.

Novel Approaches to New Therapies for Hepatitis B Virus Infection

Hepatitis B is one of the most prevalent viral diseases in the world. It leads to chronic liver disease in 10% of infected individuals, putting them at an increased risk for liver-related morbidity and mortality from complications of cirrhosis and hepatocellular carcinoma. Despite the success of universal hepatitis B vaccination in many countries, this disease remains a major public health problem, resulting in more than 500,000 deaths per year. Although the current therapy for chronic hepatitis B (CHB) is effective, it is not optimal; novel approaches to the management of CHB are needed. An improved understanding of virus-host interactions, advances in gene therapy, the development of molecular therapies targeted at different stages of the hepatitis B virus life cycle, and new insights into various approaches of immune modulation will lead to the development of better therapeutic agents for the management of CHB. These advances herald a new era of combination therapy. In this review, we will discuss emerging therapies and potential mechanisms, and highlight the promises and pitfalls of these new treatment strategies.

Changes in viral loads of lamivudine-resistant mutants and evolution of HBV sequences during adefovir dipivoxil therapy

The addition of adefovir dipivoxil (ADV) to ongoing lamivudine therapy is effective against lamivudine-resistant virus in patients with hepatitis B virus (HBV) infection. We studied 39 patients who received ADV added to lamivudine for breakthrough hepatitis. We determined early viral changes (12 weeks) in YMDD mutants (rtM204I [YIDD sequence], rtM204V [YVDD]) and rtL180M in all 39 patients as well as amino acid changes in the polymerase reverse transcriptase (rt) region and precore/core promoter mutations in 15 patients who received long-term treatment (more than 1 year). Changes in rtM204I and rtL180M viral loads were greater than that of the rtM204V, albeit statistically insignificant. Moreover, the greatest change in viral load was seen for rtM204I without hepatitis B e antigen (HBeAg). The precore mutant was replaced with wild-type virus in three of eight patients after 1 year of added ADV therapy. Compared to baseline with lamivudine therapy only, new amino acid mutations were seen in the rt region at baseline with ADV in seven patients. At 1 year after ADV coadministration, the YMDD motif was replaced with wild-type (rt204M) in two patients, in whom mutations were fewer and of a different type. We conclude that the rtM204I may be more sensitive to ADV in vivo. ADV tended to select wild-type virus from precore mutants. Moreover, viruses that were wild-type in the rt region reappeared after 1 year of ADV coadministration in some patients.

Efficacy and safety of adefovir dipivoxil in kidney recipients, hemodialysis patients, and patients with renal insufficiency

BACKGROUND

This study analyzes the biochemical, serological, and virological efficacy and the safety of adefovir dipivoxil in patients with renal disturbances.

METHODS

Twelve patients with lamivudine-resistant hepatitis B virus (HBV) chronic infection were treated for a median time of 15 (3-19) months. The daily dosage was 10 mg initially and then adjusted according to renal function.

RESULTS

Median (range) ALT values remained stable: 55 (13-117) and 37 (17-266) UI/L. After the 12th month, the median decline in serum HBV DNA was from 8.76 (6.3-9.7) to 2.97 (1.15-5.65) log10 Eq/ml (median decline of -5.5 log10). No virologic breakthrough was observed. One of the six HBeAg-positive patients lost HBe Ag but without HBe seroconversion; none had HBs Ag loss. There were no significant clinical and biochemical adverse effects. In the 11 nonhemodialysed patients, the creatinine clearance significantly improved from 70 (30-100) to 88 (38-125) ml/mn (P=0.01) and the mean serum creatinine levels increased only slightly from 114 (91-839) to 130 (81-561) micromol/ml (NS). Serum phosphorus remained stable. The urinary level of protein decreased from 0.16 (0.08-8.63) to 0.12 (0.01-0.74) g/day (NS).

CONCLUSIONS

Adefovir dipivoxil is safe for the treatment of chronic hepatitis B in patients with varying degrees of renal dysfunction and lamivudine-resistant HBV and results in biochemical and virological efficacy similar to that reported in the general population.

Complications in treating chronic hepatitis B in patients with HIV

The management of chronic hepatitis B virus (HBV) poses specific problems in the presence of HIV infection, as therapeutic approaches have to consider both HBV and HIV. There are currently four drugs approved for the treatment of chronic HBV: IFN-alpha, lamivudine, adefovir and entecavir. Furthermore, the dual antiviral activity against HIV and HBV of antiretrovirals such as tenofovir and emtricitabine broadens the armamentarium against HBV in the HIV-coinfected population. Nucleotide analogues adefovir and tenofovir have the advantage of a higher genetic barrier for resistance when compared with the nucleoside analogues lamivudine and emtricitabine. Fortunately, the two families do not share resistance mutations, allowing salvage therapy and the consideration of combination therapy for drug-naive individuals. Although response to IFN-alpha is poorer in HBV/HIV-coinfected patients compared with HBV-monoinfected individuals, the more potent pegylated forms of IFN-alpha have brought new hopes.

Adefovir-resistant hepatitis B can be associated with viral rebound and hepatic decompensation

BACKGROUND/AIMS

The susceptibility of adefovir-resistant hepatitis B virus (HBV) mutants is only reduced by 3-10-fold in in vitro studies, suggesting that virologic breakthrough and clinical deterioration are unlikely. The aim of this study was to describe the clinical course of patients with adefovir-resistant HBV infection.

METHODS

Testing for adefovir-resistant mutations was performed on patients who had a suboptimal response or virologic breakthrough on adefovir. Adefovir-resistant mutations were detected using a line probe assay and direct sequencing of the HBV P-gene.

RESULTS

Eight male patients with pre-existing lamivudine resistance or breakthrough (mean age 47+/-13 years) were found to have adefovir-resistant mutations rtA181V/T or rtN236T. Baseline median ALT was 66 IU/L (range, 27-1161) and median HBV DNA 7.9 log10 copies/ml (range, 6-8.3). At the time of adefovir resistance (mean of 20+/-9 months), HBV DNA increased to > or = 5 log10 copies/ml in 7 patients. After detection of adefovir resistance, hepatic decompensation occurred in 2 patients, 1 of whom died. Salvage therapy with lamivudine, entecavir or tenofovir was given to 7 patients and a reduction in HBV DNA by > or = 3 log10 was seen in 3 patients.

CONCLUSIONS

In conclusion, adefovir resistance can be associated with significant viral rebound and hepatic decompensation which may be fatal.

Adefovir rapidly suppresses hepatitis B in HBeAg-negative patients developing genotypic resistance to lamivudine

Progression of hepatitis B in patients with lamivudine-resistant strains is slowed down by adefovir dipivoxil (ADV). Whether the time point of ADV administration (genotypic vs. phenotypic resistance) influences the outcome of therapy is unknown. We compared the outcome of ADV therapy in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B patients with genotypic and phenotypic resistance to lamivudine. Ten milligrams of ADV was administered daily for 2 years to 46 HBeAg-negative patients at the time of phenotypic resistance (group A, >6 log(10) copies/mL of hepatitis B virus [HBV] DNA and high alanine aminotransferase [ALT] levels) and 28 patients at the time of genotypic resistance (group B, 3-6 log(10) copies/mL of HBV-DNA and normal ALT). HBV DNA was assessed every 2 months using Versant 3.0 assay, and lamivudine resistance was confirmed via INNO-LiPA assay in all patients. By month 3, HBV DNA tested negative in all patients from group B compared with only 20 (46%) in group A (P < .0001). The 2-year rates of virological response were 100% in the former patients and 78% in the latter ones (P < .0001). ALT levels remained persistently normal in all group B patients, whereas in group A patients they normalized at rates of 50% at month 6 (P < .0001), 72% at month 12 (P < .01), and 93% at month 24. None of the patients developed ADV resistance or ADV-related side effects. In conclusion, to optimize antiviral treatment in HBeAg-negative patients selecting resistant strains to lamivudine, ADV should be added to lamivudine as soon as genotypic resistance is detected.