Lamivudine prophylaxis against reinfection in liver transplantation for hepatitis B cirrhosis

HBV genotypic resistance to lamivudine in kidney recipients and hemodialyzed patients

BACKGROUND

Lamivudine is a potent inhibitor of human immunodeficiency virus reverse transcriptase and hepatitis B virus (HBV) DNA polymerase. Its overall efficiency is clearly hampered by relapse at discontinuation and by risk of genotypic resistance. We describe herein the first cases of HBV resistance to lamivudine in kidney recipients and hemodialyzed patients.

METHODS

We analyzed 26 HBV-infected kidney recipients and five hemodialyzed patients treated with lamivudine who became serum HBV DNA-negative (by Digene test). The biological and virological follow-up identified breakthrough as defined by the reappearance of serum HBV DNA. In two cases of breakthrough, HBV DNA was amplified and sequenced through the polymerase domain, including the YMDD motif, before the beginning of treatment and at time of breakthrough to determine genotypic mutations.

RESULTS

Ten breakthroughs (reappearance of serum HBV DNA) were observed after a median follow-up of 11 months in eight kidney recipients and two hemodialyzed patients after a median duration of treatment of 16.5 (from 4 to 31) months of treatment. Previous HBe/anti-HBe seroconversion was not observed in the patients who escaped. In two kidney recipients, the comparison of HBV-DNA sequences before the treatment and after the breakthrough identified in one case a mutation of the highly conserved YMDD motif (YVDD), whereas in the second case, no genotypic mutation was observed in the sequenced region.

CONCLUSION

We report the first cases of HBV genotypic resistance to lamivudine in kidney recipients and hemodialysis patients. Genotypic resistance is observed after 4-31 months of therapy. The YMDD mutation does not account for all cases of virological escape.

Indications for liver transplantation in patients with chronic hepatitis B and C virus infection and hepatocellular carcinoma

Patients with chronic hepatitis B virus (HBV) infection were not accepted for liver transplantation in Asia in the past because the hepatitis B immune globulin (HBIG) used to prevent post-transplantation recurrence was very expensive and it was generally believed that Asians with hepatitis B fared worse than Caucasians after liver transplantation. The availability of lamivudine has altered the indication of liver transplantation for these patients. Twenty-five Chinese patients with chronic HBV infection were given lamivudine as primary prophylaxis against HBV re-infection before transplantation. Five patients died within 40 days of transplantation. After a median follow-up period of 14 months (range, 5-39), 17 patients had lost serum HBsAg from 4 days to 27 months post transplantation, but it reappeared in three patients 4-12 months later. Antibody to HBsAg was detected periodically in the serum of 1 patients who had lost HBsAg. At the last follow-up, six patients were HBsAg-positive and HBV DNA was detected in only one of them. The indication for liver transplantation for chronic hepatitis C virus (HCV) infection is not as strict as for patients with chronic HBV infection because the long-term survival is similar to that of non-hepatitis C patients, even though re-infection by HCV in the recipients is nearly universal. The main issue in the selection of patients with HCV for liver transplantation is therefore identification of criteria that can predict re-infection and development of cirrhosis. These include factors such as multiple episodes of rejection, use of OKT3, pre-transplant viral load and genotype, but reports are not consistent and so there are no well-defined selection criteria. The selection criteria for patients with hepatocellular carcinoma are now well defined. Many studies have confirmed that a tumour > 5 cm, and showing vascular invasion, and poor differentiation adversely affects survival. In practice, only patients with a tumour < 5 cm and Child's C cirrhosis are accepted for liver transplantation. Transarterial oily chemoembolization and intralesional alcohol injection are used to control or down-stage the tumour while patients wait for a cadaveric liver graft.

Lamivudine for hepatitis B in liver transplantation: a single-center experience

BACKGROUND

Liver transplantation for hepatitis B virus (HBV) has been associated with a high rate of reinfection and graft failure. Lamivudine, a potent inhibitor of HBV replication, has been shown to prevent viral recurrence after transplantation.

METHODS

The effectiveness of lamivudine monotherapy for the management of HBV recurrence after liver transplantation was assessed. Lamivudine was used in three patient groups: (1) patients started before transplantation and continued after transplantation (n = 13); (2) patients treated after transplantation (n = 15); and (3) patients with de novo hepatitis B after transplantation (n = 4).

RESULTS

Median follow-up on lamivudine was 24 months. Active viral replication (HBV-DNA+) was seen in 17 (53%) of 32 at treatment initiation. All lost HBV-DNA at a mean of 2.4+/-1.6 months after lamivudine initiation. Twenty-six (81%) patients remain free of viral recurrence. Six (19%) patients have evidence of breakthrough infection with the YMDD mutant of HBV, two of whom progressed to graft failure. All four patients in group 1 who developed breakthrough had evidence of hepatitis B surface antigen expression in the explanted liver by immunohistochemistry despite being serum HBV-DNA negative before transplantation. No difference was observed among the three groups in DNA clearance or breakthrough rates.

CONCLUSIONS

Lamivudine achieves viral DNA clearance in almost all patients. Expression of viral antigens in the liver seems to identify patients at risk of developing HBV-DNA recurrence. Disease-free survival of 81% at 22 months is similar to data with hepatitis B immunoglobulin therapy. Given the safe clinical profile and high efficacy in the prevention of disease recurrence, lamivudine will favorably change the outlook of liver transplantation for HBV.

Mapping genes for polygenic disorders: considerations for study design in the complex trait of inflammatory bowel disease

While the methodology for the mapping of Mendelian disorders is well established, the practical and theoretical steps required for successful gene identification in a complex trait are still difficult to predict. A number of analytical models and simulations based on repetitive drawings from predefined statistical distributions are available. To supplement these analytical models, we developed an integrated simulation approach by directly simulating entire populations under a disease model based on epidemiological data. Random mating, nonoverlapping populations and the absence of differential fitness were assumed. Samples were drawn from these homogeneous and heterogeneous populations and analyzed with established analysis tools. We investigated the properties of linkage and association studies in inflammatory bowel disease - modeled as a six-locus polygenic disorder - as an example of this approach. In nonparametric linkage studies, lod scores varied widely, with the median required sample size depending on the locus-specific relative sibling risk. A fine mapping resolution <4 cM was found to require nonparametric lod scores >10. Family-based association studies (TDT test) and case-control studies showed a similar sensitivity and can identify risk loci in populations with moderate levels of linkage disequilibrium in sample sizes of 500-800 triplets. Case-control association studies were prone to false-positive results if applied in heterogeneous populations, with the false-positive rate increasing with sample size because population heterogeneity is detected with increasing power.

Long-term prognosis after resection of hepatocellular carcinoma associated with hepatitis B-related cirrhosis

PURPOSE

The optimum management of hepatocellular carcinoma (HCC) associated with cirrhosis has not yet been clarified. Very few data are available in the literature regarding the prognosis after resection of HCC associated with hepatitis B virus (HBV)-related cirrhosis. This study evaluated the long-term results and prognostic factors after resection of HCC complicating HBV-related cirrhosis.

PATIENTS AND METHODS

One hundred forty-six patients with HBV-related Child's A or B cirrhosis who had undergone resection of HCC over a 10-year period were prospectively studied for long-term results. They were compared with 155 noncirrhotic patients with HBV-related HCC resected in the same period.

RESULTS

The overall survival results of cirrhotic patients after resection of HCC were comparable to those of noncirrhotic patients (5-year survival, 44.3% v 45.6%, respectively; P =.216), but the former group had significantly smaller tumors. Stratified according to tumor size, the survival results were similar between cirrhotic and noncirrhotic patients with tumors </= 5 cm (5-year survival, 60.7% v 61.7%, respectively; P =.327) but were worse in cirrhotic compared with noncirrhotic patients with tumors greater than 5 cm (5-year survival, 27.8% v 39.5%, respectively; P =.034). Stage by stage, there were no significant differences in survival results between cirrhotic and noncirrhotic patients. Preoperative serum AST level greater than 100 IU/L (P =.004), perioperative transfusion (P =.015), and venous invasion (P <.001) were independent adverse prognostic factors.

CONCLUSION

The prognosis after resection of HCCs less than 5 cm in patients with compensated HBV-related cirrhosis was comparable to that of noncirrhotic patients, which suggests that surgical resection may be considered a first-line treatment for these patients. Patients with underlying active hepatitis as indicated by a high preoperative transaminase level are less favorable candidates for resection. Further studies are needed to define the relative roles of resection and transplantation for HCC associated with hepatitis B cirrhosis.

Hepatitis B immunoglobulin discontinuation followed by hepatitis B virus vaccination: A new strategy in the prophylaxis of hepatitis B virus recurrence after liver transplantation

It is widely agreed that hepatitis B virus immunoglobulin (HBIG) should be administered for at least 12 months to patients transplanted for hepatitis B virus (HBV)-related diseases to prevent HBV recurrence. No data are available, however, on how long this treatment should be used, and most centers currently administer HBIG on a life-long basis. Herein, we report the results of a new prophylactic strategy aiming at the discontinuation of HBIG treatment and consisting of the administration of double dose recombinant HBV vaccine (0, 1-, and 6-month schedule) to liver transplant recipients fulfilling the following criteria: (1) liver transplantation for conditions related to nonreplicative HBV infection (hepatitis B surface antigen [HBsAg] positive, hepatitis B e antigen [HBeAg] negative, and HBV DNA negative); (2) at least 18 months of HBIG administration; and (3) no HBV infection recurrence, normal or slightly altered liver graft function, and low-grade immunosuppression at the time of vaccination. Seventeen patients received HBV vaccination and 14 of them (82%) developed protective serum titers of anti-HBs (>10 IU/L). Six patients seroconverted after a first course of vaccination, whereas 8 patients required a second course (3 additional doses of vaccine). Responding patients were followed for a median of 14 months (range, 3-50) after seroconversion. During this period no HBV recurrence occurred and in only 2 patients a decrease of anti-HBs titers below 10 UI/L was observed. Our data suggest that in selected liver transplant recipients, posttransplantation HBV vaccination may be a useful and cost-effective strategy in the prophylaxis of HBV recurrence, allowing the discontinuation of life-long HBIG treatment.

Antiviral chemotherapy for the treatment of hepatitis B virus infections

Approximately 5% of the world's human population have an increased risk for developing liver cancer and cirrhosis as a direct consequence of chronic infection with the hepatitis B virus (HBV). Antiviral chemotherapy remains the only option for controlling infection in these individuals, for whom the current licensed hepatitis B vaccines provide no benefit. Interferon (IFN)-alpha has proven benefit in a well-defined group of those with hepatitis B but has made little impact on the global burden of chronic liver disease. The development of more effective chemotherapy for treatment of chronic hepatitis B infection has proven to be extremely challenging, the result of both virus- and host-dependent factors, which will be reviewed in this article. Past attempts to treat chronic hepatitis B infection using nucleoside analogues were disappointing, but more recently, several nucleoside (or nucleotide) analogues have been identified that are potent and selective inhibitors of HBV replication. These agents fall into two broad categories: (1) nucleoside/nucleotides that have modified sugar residues in either cyclic or acyclic configurations and (2) stereoisomers of nucleosides in the "unnatural" L-configuration. Of the analogues that have been used clinically, representatives of the first category are purine derivatives, e.g., adefovir dipivoxil and famciclovir, whereas representatives of the second category are pyrimidine derivatives, such as lamivudine.

Viral hepatitis A, B, and C

Mankind probably has known viral hepatitis for many centuries; however, the major and most dramatic developments in our knowledge of these diseases have taken place during the second half of the 20th century. During this relatively short period of time, the infectious nature of hepatitis A, B, and C has been proven, leading to their identification and description. The advent of serologic markers has provided the means for establishing the diagnosis. Epidemiologic studies have provided important information that led to exciting achievements in detection and prevention of transmission. Molecular biology studies and cell culture techniques have established our knowledge of the viral genomes, and led to the development of specific vaccines for hepatitis A and B. Anti-viral therapy has been developed and aggressive combination therapy has emerged as a promising strategy for chronic hepatitis B and C. This article reviews some of the main fields of progress and achievement related to viral hepatitis A, B, and C in the 20th century.

Outcome of lamivudine resistant hepatitis B virus infection in the liver transplant recipient

BACKGROUND

In many transplant centres lamivudine is an important component of prophylaxis against, and treatment of, hepatitis B virus (HBV) graft infection. Drug resistant HBV species with specific polymerase mutations may emerge during lamivudine treatment.

AIMS

To examine the clinical consequences of graft infection by lamivudine resistant virus.

METHODS

The clinical course of four liver transplant patients who developed graft infection with lamivudine resistant virus was reviewed. The response of HBV infection to reduction of immunosuppression and to manipulation of antiviral therapy was assessed. For each patient, serum viral titre was measured and the viral polymerase gene was sequenced at multiple time points.

RESULTS

High serum titres were observed following emergence of the lamivudine resistant species. Wild type HBV re-emerged as the dominant serum species after lamivudine withdrawal. All patients developed liver failure, and onset of liver dysfunction was observed when resistant virus was the dominant serum species. In three patients, liver recovery was observed when immunosuppression was stopped and when alternative antivirals were given. Wild type virus appeared to respond to ganciclovir, and to reintroduction of lamivudine. For one patient, introduction of famciclovir was associated with clinical, virological, and histological response.

CONCLUSIONS

Failure of lamivudine prophylaxis may identify patients at special risk for the development of severe graft infection. Treatment of graft reinfection should include reduction of immunosuppression, and systematic exposure to alternative antivirals. Viral quantitation and genetic sequencing are essential components of therapeutic monitoring.

Hepatitis B

The management of acute HBV infection is supportive. Specific treatment is not indicated for HBV carriers because they often have no evidence of liver injury, and, further, do not respond to currently available therapies. Interferon monotherapy is best indicated for patients with chronic replicating HBV infection and evidence of chronic hepatitis. There is an increased likelihood of clearing HBsAg with interferon monotherapy as compared to lamivudine. Lamivudine is an oral nucleoside analog that is better tolerated than interferon. The clinical situations for its use are far more than interferon monotherapy. Lamivudine should be used in patients with decompensated cirrhosis and also in transplantation, both before and after transplantation. The post-transplant use of hepatitis B immune globulin (HBIG) and lamivudine combination therapy may be better for recipients who are identified in a replicative phase prior to transplantation. Hepatitis B coinfection with one or more viruses, HCV, HDV, or HIV, may occur. Both interferon and lamivudine have been useful in these patients. However, the data are sparse and heterogeneous. Therapy with one or both drugs will have to be tailored to the clinical situation. Combination therapy with immunomodulatory and/or antiviral drugs are what we will be looking toward in the future.

Novel patterns of amino acid mutations in the hepatitis B virus polymerase in association with resistance to lamivudine therapy in japanese patients with chronic hepatitis B

Lamivudine is effective in suppressing replication of hepatitis B virus (HBV). However, the emergence of HBV variants resistant to lamivudine is a concern. Lamivudine resistance has been attributed mainly to a substitution of isoleucine or valine for methionine at residue 550 (M550I or M550V) in the catalytic site of the virus polymerase. A substitution of methionine for leucine at residue 526 (L526M) has also been identified. To examine such virus genotypic mutations in Japanese patients, we studied five patients with chronic hepatitis B, who showed HBV breakthrough while on a 1-year lamivudine treatment. The entire nucleotide and deduced amino acid sequences of the proposed reverse transcriptase domain of the polymerase gene were determined on HBV DNA amplified by polymerase chain reaction from patient sera collected at the start and at the end of therapy. The HBV sequences from all five patients were of genotype C. In four patients, a substitution of valine or isoleucine for leucine at residue 426, which has not been reported previously, emerged in combination with M550I. One also harbored L526M. In the remaining patient, an alteration of leucine to methionine at residue 428 co-occurred with M550V. Longitudinal study of the mutations showed that the two or three mutations in each patient emerged almost simultaneously 4 weeks before or at the time of breakthrough and were replaced by wild-type virus after completing the therapy. Our results indicate that occurrence of HBV polymerase mutations at residue 426 in combination with M550I is frequent in Japanese or genotype C virus-in- fected patients who develop resistance to lamivudine.

Lamivudine therapy in patients undergoing liver transplantation for hepatitis B virus precore mutant-associated infection: high resistance rates in treatment of recurrence but universal prevention if used as prophylaxis with very low dose hepatitis B immune globulin

Recurrent hepatitis B virus (HBV) infection remains a major cause of morbidity and mortality after liver transplantation. Recently, antiviral therapy, such as lamivudine, has become available for prophylaxis against HBV reactivation posttransplantation and for the treatment of HBV recurrent disease. We report our initial experience with lamivudine therapy in patients with precore mutant-associated HBV infection undergoing liver transplantation (n = 29). Outcomes were compared in three patient groups: group 1, precore mutant HBV infection not receiving lamivudine (n = 10); group 2, recurrent precore mutant HBV infection posttransplantation subsequently treated with lamivudine (n = 10); and group 3, HBV precore mutant patients undergoing liver transplantation and receiving lamivudine and low-dose hepatitis B immune globulin (HBIG) from the time of transplantation (n = 9). In group 1, HBV recurred in 9 of 10 patients, with subsequent graft loss in all 9 patients. In group 2, all patients developed HBV recurrence at a mean of 7.3 months posttransplantation and started lamivudine therapy at a median of 16 months posttransplantation. Follow-up on lamivudine therapy was for a median of 11 months. Six of these 10 patients developed mutations in the HBV polymerase gene associated with lamivudine resistance. There were two liver failure-related deaths in this group. In group 3 patients, there was one death from graft-versus-host disease. The remaining 8 patients have been followed up for a mean of 15.6 months posttransplantation, and all remain hepatitis B surface antigen negative and HBV DNA negative. In conclusion, lamivudine therapy in association with low-dose HBIG is effective in preventing HBV reactivation posttransplantation. Rescue therapy with lamivudine in patients with HBV recurrence is only moderately effective, with a 60% lamivudine resistance rate in patients treated for longer than 6 months.

Liver transplantation for chronic hepatitis B infection with the use of combination lamivudine and low-dose hepatitis B immune globulin

Current protocols for prophylaxis against allograft reinfection after liver transplantation for chronic hepatitis B virus (HBV) infection include the administration of large doses of hepatitis B immune globulin (HBIG), with considerable associated economic costs. Monotherapeutic prophylaxis with lamivudine has been complicated by the development of resistant strains of HBV. We studied the effectiveness of a posttransplantation prophylaxis protocol using combination lamivudine and low-dose HBIG in 7 consecutive patients with chronic HBV infection, 4 of whom were serum HBV DNA positive before pretransplantation lamivudine therapy. All patients were serum HBV DNA negative at transplantation and received lamivudine, 100 mg/d, posttransplantation. HBIG, 2170 IU, was administered intramuscularly intraoperatively and daily for 14 days. Maintenance HBIG therapy consisted of 2170 IU intramuscularly twice weekly, tapered to every 2 to 4 weeks by 12 months posttransplantation. Target serum HBIG (HBV surface antibody) titers were less than 500 IU/L for 6 months, then greater than 300 IU/L until 12 months posttransplantation. Induction serum HBIG titers were determined daily in 5 patients, and both serum HBIG and hepatitis B surface antigen were determined every 4 weeks in all patients. One patient died 61 days posttransplantation; the surviving patients (n = 6) were followed up for a mean of 532 days (range, 395 to 648 days). No patient has developed allograft reinfection. In the induction period, a target HBIG titer of greater than 500 IU/L was not achieved until a mean of 6.8 days (range, 5 to 10 days). In the maintenance period, all patients achieved the target HBIG titer. This suggests combination lamivudine and low-dose HBIG is effective in preventing allograft reinfection by HBV.

Intramuscular hepatitis B immune globulin combined with lamivudine for prophylaxis against hepatitis B recurrence after liver transplantation

Immunoprophylaxis using intravenous (IV) hepatitis B immune globulin (HBIG) decreases the recurrence of hepatitis B virus (HBV) infection after orthotopic liver transplantation (OLT). However, IV HBIG is expensive, has significant side effects, and is inconvenient to administer. An alternative approach for prophylaxis using intramuscular (IM) HBIG and oral lamivudine was prospectively evaluated in this study. Ten consecutive patients with cirrhosis with HBV infection who underwent OLT were included in this study. Nine of 10 patients received lamivudine, 150 mg/d, for an average duration of 8.6 months before OLT. Two of 10 patients with detectable HBV DNA at the time of OLT received 10,000 U (45 mL) of IV HBIG daily for 7 consecutive days, followed by 5 mL of IM HBIG weekly for the next 3 weeks, then every 3 weeks. The other 8 patients were HBV DNA negative at OLT and received one dose of IV HBIG (45 mL) during surgery, followed by 5 mL of IM HBIG weekly for 4 weeks, then every 3 weeks. All patients received lamivudine, 150 mg/d, after OLT. During a mean follow-up of 15.6 months, 9 of 10 patients achieved a protective hepatitis B surface antibody (HBsAb) titer greater than 200 IU/L and had no evidence of HBV recurrence. One patient failed to develop an adequate HBsAb titer and developed histological and virological evidence of recurrence. One patient died unrelated to HBV recurrence. Our preliminary data suggest that this combination prophylaxis with IM HBIG and lamivudine is effective and potentially cost saving.

New antiviral agents for the therapy of chronic hepatitis B virus infection

The development of new antiviral strategies for the treatment of chronic hepatitis B remains a major goal since hepatitis virus (HBV) is resistant to interferon treatment as well as to new nucleoside analogs. HBV is a small DNA virus that replicates its genome via a reverse transcription step. The viral polymerase has been the main viral target that was studied to design new antiviral treatments. Active research has led to the discovery of new nucleoside analogs that are potent inhibitors of the viral reverse transcriptase. Among them, lamivudine has also proven antiviral efficacy in clinical trials with a sustained inhibition of viral replication. However, due to the kinetics of viral clearance, long-term antiviral therapy is necessary to eradicate viral infection. These prolonged regimens are associated with the emergence of drug-resistant strains that harbor mutations in the viral polymerase gene within the conserved B and C domains. New approaches using combinations of nucleoside analogs or other strategies, such as immune intervention (DNA vaccine, stimulation of the TH1 response ) or gene therapy (antisense oligonucleotides, dominant negative mutants), should therefore be evaluated in animal models to optimize the current antiviral protocols.

Role of lamivudine in the treatment of chronic hepatitis B virus infection

OBJECTIVE

To examine the evidence regarding the therapeutic effectiveness of lamivudine in the treatment of chronic hepatitis B virus (HBV) infection in immunocompetent patients.

DATA SOURCES

Using chronic hepatitis B and lamivudine as MeSH headings, MEDLINE was searched from 1966 to September 1998 for all published randomized controlled trials evaluating lamivudine in chronic HBV infection. Relevant articles from selected bibliographies were also retrieved.

STUDY SELECTION

Only randomized, single- and double-blind trials in human HBV carriers published in the English language were included.

DATA SYNTHESIS

Evidence from the controlled trials suggests that lamivudine has a therapeutic effect in suppressing HBV replication in immunocompetent patients. Lamivudine 100 mg/d appears to suppress HBV replication in as many as 97% of patients within two weeks after the initiation of therapy and is capable of suppressing histologic damages. However, viral suppression is effective only during the therapy; on discontinuation of lamivudine therapy, most patients return to the pretreatment condition. Viral resistance to lamivudine has been observed. Most patients with chronic HBV infection appear to tolerate 100 mg/d of lamivudine therapy.

CONCLUSIONS

Evidence has shown that oral lamivudine 100 mg/d will produce rapid and significant suppression of viral replication in immunocompetent patients with chronic HBV infections. Treatment periods up to one year have been effective and well tolerated. The suppression of viral replication may not be sustained after cessation of lamivudine therapy, and very few patients have complete elimination of HBV during therapy. Therefore, long treatment periods may be necessary. Efficacy and tolerability of treatment beyond one year need to be investigated. Resistance to lamivudine has been reported in patients receiving therapy. A combination anti-HBV regimen using lamivudine and other agents with different mechanisms of action should be investigated to maximize the elimination of the viral infection while minimizing or preventing damage to the liver cells and tissues and the development of viral resistance.

Long-term ganciclovir therapy for hepatitis B virus infection after liver transplantation

BACKGROUND/AIMS

Hepatitis B virus (HBV) disease on a liver graft is associated with florid viral replication and graft failure. The aim of this study performed between 1992 and 1995 was to investigate the safety and efficacy of long-term intravenous ganciclovir for HBV infection in liver transplant recipients.

METHODS

Twelve patients with HBV re-infection and four with de novo HBV infection were studied. HBV DNA was positive in all (median titer: 437.5 pg/ml) and HBeAg was positive in seven. Intravenous ganciclovir was started after a median of 14.5 months from HBsAg positivation and continued for a median of 10 months.

RESULTS

A complete response with HBV DNA negativation was seen in ten cases, a partial response with a decrease of more than 50% of initial HBV DNA levels in four and no response in two. Overall tolerance was good. Among the ten complete responders, two seroconverted for both HBsAg and HBeAg and one for HBsAg alone. Among these ten patients, three were re-transplanted for liver failure: two of them are alive; three had a viral breakthrough during treatment; and four remained HBV DNA negative: two are alive and two died. Partial responders and nonresponders were treated with other antiviral agents and three were re-transplanted, two of them are alive. Overall 12 out of 16 patients (75%) survived with a median follow up of 46 months.

CONCLUSIONS

Long-term intravenous ganciclovir can persistently inhibit HBV DNA replication in liver transplant recipients and is well tolerated. Further evaluation should be encouraged, especially for HBV recurrence after first-line treatments.

Lamivudine therapy for hepatitis B infection

BACKGROUND

Several new antiviral agents have recently been developed which can inhibit hepatitis B replication by at least two logs. Lamivudine is the most widely studied of these new agents. Extensive phase II and III studies in patients with chronic hepatitis B are in progress, or have been completed. The sustained HBeAg seroconversion rate in patients who have received 100 mg lamivudine rate increase from 17% at year one to 27% after 2 years. Early treatment results have suggested that lamivudine improves hepatic histology in patients with chronic hepatitis B, and can prevent recurrence of hepatitis B after liver transplantation. It is likely that in the absence of immune clearance to accelerate elimination of infected hepatocytes, inhibitors of virus replication such as lamivudine will need to be administered for a long period to substantially reduce the burden of infected hepatocytes in the liver, and prevent relapse. Histological improvement has been noted in between 38% and 52% of lamivudine-treated patients, exceeding the improvement seen in placebo recipients. Lamivudine has also been assessed in anti-HBe positive, HBV DNA positive patients. Preliminary results show that 65% of lamivudine recipients become HBV DNA negative and have normal serum aminotransferases after a year of treatment. The drug is generally well tolerated with few direct adverse events. Genotypic mutations have been observed in 11% after 1 year of treatment, but this percentage doubles after 2 years of therapy. Loss of susceptibility lamivudine has been found to be due to reverse transcriptase amino acid substitutions. Lamivudine is likely to be reserved for patients with replicative hepatitis B infection with active chronic hepatitis, and/or active cirrhosis. Both HBeAg and anti-HBe positive patients are benefited, as may be patients with cirrhosis.

Use of the hepatitis B virus recombinant baculovirus-HepG2 system to study the effects of (-)-beta-2',3'-dideoxy-3'-thiacytidine on replication of hepatitis B virus and accumulation of covalently closed circular DNA

(-)-Beta-2',3'-Dideoxy-3'-thiacytidine (lamivudine [3TC]) is a nucleoside analog which effectively interferes with the replication of hepatitis B virus (HBV) DNA in vitro and in vivo. We have investigated the antiviral properties of 3TC in vitro in HepG2 cells infected with recombinant HBV baculovirus. Different types of information can be obtained with the HBV baculovirus-HepG2 system because (i) experiments can be carried out at various levels of HBV replication including levels significantly higher than those that can be obtained from conventional HBV-expressing cell lines, (ii) cultures can be manipulated and/or treated prior to or during the initiation of HBV expression, and (iii) high levels of HBV replication allow the rapid detection of HBV products including covalently closed circular (CCC) HBV DNA from low numbers of HepG2 cells. The treatment of HBV baculovirus-infected HepG2 cells with 3TC resulted in an inhibition of HBV replication, evidenced by reductions in the levels of both extracellular HBV DNA and intracellular replicative intermediates. The effect of 3TC on HBV replication was both dose and time dependent, and the reductions in extracellular HBV DNA that we observed agreed well with the previously reported efficacy of 3TC in vitro. As expected, levels of HBV transcripts and extracellular hepatitis B surface antigen and e antigen were not affected by 3TC. Importantly, the HBV baculovirus-HepG2 system made it possible to observe for the first time that CCC HBV DNA levels are lower in cells treated with 3TC than in control cells. We also observed that the treatment of HepG2 cells prior to HBV baculovirus infection resulted in a slight increase in the efficacy of 3TC compared to treatments starting 24 h postinfection. The treatment of HepG2 cells with the highest concentration of 3TC tested in this study (2 microM) prior to the initiation of HBV replication markedly inhibited the accumulation of CCC DNA, whereas treatment with the same concentration of 3TC at a time when CCC HBV DNA pools were established within the cells was considerably less effective. In addition, our results suggest that in HepG2 cells, non-protein-associated relaxed circular HBV DNA and particularly CCC HBV DNA are considerably more resistant to 3TC treatment than other forms of HBV DNA, including replicative intermediates and extracellular DNA. We conclude from these studies that the HBV baculovirus-HepG2 system has specific advantages for drug studies and can be used to complement other in vitro model systems currently used for testing antiviral compounds.

Association of lamivudine resistance in recurrent hepatitis B after liver transplantation with advanced hepatic fibrosis

BACKGROUND

Orthotopic liver transplantation (OLT) in patients with hepatitis B virus (HBV) infection is known to be associated with a high recurrence rate and poor prognosis. Lamivudine, a nucleoside analogue, is a potent inhibitor of HBV replication, but it is associated with a 14-39% rate of resistance.

METHODS

We report on four patients who underwent OLT for HBV infection. In all cases, the HBV infection recurred in the grafted liver and was treated with lamivudine (100 mg daily) on a compassionate-use basis. The patients were monitored closely for serum liver enzymes, hepatitis B surface antigen and HBV DNA (by hybridization). Liver biopsy was performed before and after lamivudine therapy. HBV DNA was amplified from serum for each patient and sequenced through a conserved polymerase domain, the tyrosine-methionine-aspartate-aspartate (YMDD) locus.

RESULTS

All four patients exhibited lamivudine resistance 9-20 months after initiation of the drug. In all patients with a clinically mild disease, liver histology findings (12-24 months after lamivudine therapy) showed progressive fibrosis as compared to biopsies performed before lamivudine therapy, with a significant increase (> or =2 points) in the Knodell score in three patients. Moreover, two patients exhibited worsening of the necroinflammatory process. A mutation at the YMDD motif of the HBV polymerase gene was detected in all cases.

CONCLUSIONS

Lamivudine resistance frequently occurs in patients with recurrent HBV infection after OLT and is associated with advanced hepatic fibrosis and necroinflammatory process. A combination of antiviral therapies may be necessary.

Natural and iatrogenic variation in hepatitis B virus

The existence of HBV as quasispecies is thought to be favoured by the infidelity of HBV RT, which would account for the emergence of the many natural mutants with point substitutions. RT infidelity may also underlie the hypermutation phenomenon. Indeed, the oft-reported point mutation in the preC gene that leads to failure of HBeAg synthesis may be driven by a hypermutation-related mechanism. The presence of mutants with deletions and insertions involving single nucleotides and oligonucleotides at specific positions in the genome, and of mutants with deletions of even longer stretches particularly in the C gene, suggests that other mutagenic mechanisms operate. Candidates include slippage during mispairing between template and progeny DNA strand, the action of cellular topoisomerase I, and gene splicing using alternative donor and acceptor sites. Natural substitutions, deletions or insertions involving the Cp/ENII locus in the X gene can significantly alter the extent of viral replicative activity. Similar mutations occurring at other locations of Cp/ENII, and at B-cell epitope sites of the S gene are associated with failure to detect serological markers of HBV infection. HBV variation can also arise from recombination between coinfecting strains. S gene mutations that become evident following HBIG administration and HBV vaccination are all point substitutions, as are mutations in functional RT domains of the P gene after treatment with viral RT-inhibitory drugs. Widespread and long-term use of prophylactic and therapeutic agents may potentially generate serologically occult HBV variants that might become difficult to eradicate.

Lamivudine. A review of its therapeutic potential in chronic hepatitis B

Lamivudine is a deoxycytidine analogue that is active against hepatitis B virus (HBV). In patients with chronic hepatitis B, lamivudine profoundly suppresses HBV replication. Clinically significant improvements in liver histology and biochemical parameters were obtained with lamivudine in double-blind, randomised, trials in hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis B and compensated liver disease. After 52 weeks of treatment, relative to placebo (< or = 25%), significantly more Chinese (56%) or Western patients (52%) treated with lamivudine 100 mg/day had reductions of > or = 2 or more points in Knodell necro-inflammatory scores. Moreover, significantly fewer lamivudine 100 mg/day than placebo recipients had progressive fibrosis in liver biopsies (< or = 5 vs > or = 15%) and fewer lamivudine- than placebo-treated patients progressed to cirrhosis (1.8 vs 7.1%). More lamivudine 100 mg/day than placebo recipients acquired antibodies to HBeAg after 52 weeks (16 vs 4% in Chinese patients and 17 vs 6% in Western patients). ALT levels normalised in significantly more lamivudine than placebo recipients enrolled in these trials. In HBeAg-negative, HBV DNA positive patients with compensated liver disease enrolled in a double-blind, randomised study, HBV DNA levels were suppressed to below the limit of detection (< 2.5 pg/ml) and ALT levels normalised in 63% and 6% of patients treated with lamivudine 100 mg/day or placebo for 24 weeks. Clinically significant improvements in liver histology were obtained in 60% of patients treated with lamivudine for 52 weeks in this study. Lamivudine 100 mg/day for 52 weeks produced similar or significantly greater improvements in liver histology and ALT levels than 24 weeks' treatment with lamivudine plus interferon-alpha. In liver transplant candidates with chronic hepatitis B and end-stage liver disease, lamivudine 100 mg/day alone, or in combination with hepatitis B immune globulin, generally suppressed HBV replication and appeared to protect the grafted liver from reinfection. Lamivudine 100 mg/day suppressed viral replication and improved liver histology in liver transplant recipients with recurrent or de novo chronic hepatitis B. Lamivudine 300 or 600 mg/day reduced HBV replication in HIV-positive patients. The incidence of adverse events in patients with chronic hepatitis B and compensated liver disease treated with lamivudine 100 mg/day or placebo for 52 to 68 weeks was similar. 3.1- to 10-fold increases in ALT over baseline occurred in 13% of patients during treatment with lamivudine 100 mg/day or placebo for 52 weeks. Post-treatment ALT elevations were more common in lamivudine than placebo recipients; however, these generally resolved spontaneously; < or = 1.5% of lamivudine- or placebo-treated patients experienced hepatic decompensation.

CONCLUSION

Lamivudine inhibits HBV replication, reduces hepatic necro-inflammatory activity and the progression of fibrosis in patients with chronic hepatitis B, ongoing viral replication and compensated liver disease including HBeAg-negative patients. The drug also suppresses viral replication in liver transplant recipients and HIV-positive patients. Thus, lamivudine is potentially useful in a wide range of patients with chronic hepatitis B and ongoing viral replication.

Absence of mutations in the YMDD motif/B region of the hepatitis B virus polymerase in famciclovir therapy failure

BACKGROUND/AIMS

Nucleoside analogues such as lamivudine and famciclovir are potent drugs for treatment of chronic hepatitis B virus infection. Breakthrough infections during lamivudine therapy are associated with mutations in the YMDD motif and putative B region of the HBV polymerase. This study investigated whether failure of famciclovir therapy is also associated with presence or emergence of particular mutations in the HBV polymerase.

METHODS

We analyzed longitudinally the sequence of the priming and polymerase domain in seven patients with primary non-response to therapy and two patients with a breakthrough during therapy. Two patients who responded to therapy served as a control.

RESULTS

The YMDD motif and the B region were conserved in all isolates. V-->I changes at position 555 just downstream of the YMDD motif were observed before and during therapy in a virus subpopulation of two patients with a primary non-response. In patients with a breakthrough, 378-V-->I and 424-N-->D mutations emerged in the N terminal part of the polymerase domain during follow-up. Lamivudine rescue therapy initiated in four patients, including a patient infected with YMDD(555-V-->I) variants, efficiently reduced viremia.

CONCLUSIONS

These data indicate that failure of famciclovir therapy can occur independently of mutations in the YMDD motif or B region of the HBV polymerase and provide a rationale for rescue therapy with lamivudine.

Retransplantation of the liver for recurrent hepatitis B virus infection: the Paul Brousse experience

Recurrent hepatitis B virus (HBV) infection of the liver graft is characterized by a severe outcome and high level of HBV replication. For many investigators, retransplantation appears contraindicated because of constant recurrence and a high mortality. We report our experience in this setting. Between January 1985 and December 1995, 10 patients who underwent retransplantation for HBV graft reinfection were studied. According to the antiviral treatment administered after HBV recurrence on the first liver graft and the protocol of antiviral prophylaxis after retransplantation, two groups were defined: group 1 underwent retransplantation before January 1992 (n = 5), and group 2 underwent retransplantation after January 1992 (n = 5). At the time of reinfection, serum HBV DNA was positive in all patients, hepatitis Be antigen (HBeAg) was positive in 6 patients. Antiviral therapy was administered to 7 patients (group 1, adenine arabinoside mono phosphate [ara-Amp; n = 3]; group 2, ara-Amp [n = 5], ganciclovir [n = 4]). After retransplantation, long-term antibody to HB surface antigen (anti-HBs) immunoglobulins were administered to achieve an anti-HBs titer greater than 100 IU/L in group 1 and to achieve an anti-HBs titer greater than 500 IU/L associated with prophylactic intravenous ganciclovir administration (5 mg/kg three times weekly) for 2 years in group 2. In group 1, all patients died, either perioperatively or secondary to HBV recurrence (1 year survival, 0%). In group 2, 1 patient died 50 months after retransplantation of HBV cirrhosis on the second graft, and 4 patients remained HBsAg negative at a mean of 41 months (range, 24 to 68 months) after retransplantation. The prognosis of retransplantation for HBV recurrence was dramatically improved by the administration of antiviral therapy before retransplantation and the maintenance of a high anti-HBs level combined with antiviral therapy after retransplantation.

Mutations in the hepatitis B virus polymerase gene associated with antiviral treatment for hepatitis B

Significant advances have been made, during the last 5 years, in the treatment of chronic hepatitis B. Several new antiviral agents: lamivudine, famciclovir, lobucavir and adefovir, have been shown to be safe and effective in inhibiting hepatitis B virus (HBV) replication. These compounds can be administered orally and are well tolerated. However, virus clearance is uncommon after short courses (<6 months) of therapy. Lamivudine and famciclovir have been evaluated in Phase III clinical trials in patients with chronic hepatitis B as well as in liver transplant recipients. Unfortunately, drug-resistant mutants involving the HBV polymerase gene, leading to breakthrough infection, have been reported in some patients who have received long courses (>/= 12 months) of treatment. The incidence, clinical outcome and biological significance of these mutants will be reviewed.

Multicenter study of lamivudine therapy for hepatitis B after liver transplantation. Lamivudine Transplant Group

Hepatitis B after liver transplantation is often fatal, and no proven medical therapy exists for this condition. We chose to study the potential efficacy of lamivudine therapy for patients with chronic hepatitis B after liver transplantation. Fifty-two patients with chronic hepatitis B after liver transplantation were treated in an open label, multicenter study. Each had detectable hepatitis B virus (HBV) DNA in serum and 45 (87%) had detectable serum hepatitis B e antigen before treatment. Patients were treated for 52 weeks with lamivudine (100 mg daily). The primary endpoint was undetectability of HBV DNA; secondary endpoints included normalization of serum alanine transaminase (ALT) levels, disappearance of hepatitis B e antigen, and improvement in liver histology. After treatment, 60% of patients had undetectable HBV DNA by solution hybridization assay, 14 (31%) of the initially positive patients lost hepatitis B e antigen; hepatitis B surface antigen was undetectable in 3 (6%); and serum ALT levels normalized in 71%. Blinded histological assessments showed improvement in the histological activity index (P =.007 for periportal necrosis,.001 for lobular necrosis, and.013 for portal inflammation). YMDD variants of HBV, potentially associated with drug resistance, were detected in 14 (27%) of the patients. Repeat liver biopsies in 7 patients with the mutated virus were unchanged in 2, improved in 2, and worse in 3. We conclude that lamivudine is a potentially effective therapy for hepatitis B after liver transplantation.

High pre-treatment serum hepatitis B virus titre predicts failure of lamivudine prophylaxis and graft re-infection after liver transplantation

BACKGROUND/AIMS

Orthotopic liver transplantation has an established role for the treatment of patients with chronic liver failure secondary to hepatitis B virus (HBV) infection. Unfortunately, recurrent infection of the graft can be associated with aggressive disease, and with diminished graft and patient survival. Currently, the role of nucleoside analogues for prevention of graft re-infection is being evaluated. Preliminary results are encouraging, but treatment failure has been associated with emergence of drug-resistant virus.

METHODS

We have studied ten consecutive patients who received lamivudine prophylaxis for prevention of HBV graft reinfection. Sequential sera, collected prelamivudine then during treatment before and after liver transplantation, were examined. Conventional serological markers were measured, as were serum viral DNA levels with a sensitive quantitative polymerase chain reaction assay.

RESULTS

Lamivudine treatment effected a reduction in serum HBV levels, but six patients still had measurable viral DNA at the time of transplantation. Five patients developed graft re-infection with lamivudine-resistant virus. Resistant virus emerged 8 to 15 months post-transplant. The likelihood of emergence of resistant virus was related to the pre-treatment serum HBV titre. Persistent serum viral DNA positivity and evidence of graft re-infection during the early post-transplant period did not predict the subsequent emergence of resistant virus.

CONCLUSIONS

Our observations suggest that the resistant species may be present in the viral quasispecies in the serum and liver of patients with high-level replication prior to lamivudine exposure. The resistant species can persist during lamivudine treatment prior to transplantation, and emerge following transplantation. These observations suggest strategies which might prevent the emergence of drug-resistant species, and imply that graft re-infection may be a preventable phenomenon.

Efficacy of lamivudine in patients with hepatitis B virus precore mutant infection before and after liver transplantation

OBJECTIVE

Hepatitis B virus (HBV) precore mutant infection is associated with a more severe liver disease and a poorer response to interferon. We evaluated the efficacy and tolerance of lamivudine to induce complete and sustained suppression of viral replication in seven patients infected with HBV precore mutant (HBeAg-/HBeAb+/HBV DNA+) (in three patients mutation at codon 1896 was detected by direct sequencing).

METHODS

Of the seven patients, five had decompensated HBV cirrhosis in a replicative phase and were liver transplant candidates (Group A) and two patients underwent orthotopic liver transplantation (OLT) for HBV liver cirrhosis and developed recurrent HBV infection in the grafted liver (Group B). Lamivudine 100 mg daily was administered orally for a period of 6-75 wk.

RESULTS

After 6-8 wk lamivudine therapy was well tolerated and successfully suppressed HBV replication to an undetectable serum level of HBV DNA by polymerase chain reaction in six patients. In Group A, two patients underwent successful OLT with no evidence of HBV reinfection 2-14 months later. Lamivudine was continued after OLT with no episodes of rejection. Three patients died before a suitable liver could be found (one remained serum HBV DNA+ after 6 wk of lamivudine therapy). In Group B, 9-14 months after lamivudine therapy both patients developed lamivudine resistance (increased liver enzymes, reappearance of serum HBsAg and HBV DNA [by hybridization]). In both patients liver histology had progressed and in both, mutation at codon 552 of the HBV polymerase gene was detected.

CONCLUSIONS

Lamivudine is well tolerated in patients with decompensated liver cirrhosis due to HBV precore mutant infection who are liver transplant candidates. In four patients (80%) potent suppression of viral replication was detected, allowing OLT to be performed. However, post-OLT, a resistant mutant developed under lamivudine therapy. Combination therapy with other antiviral agents should be evaluated to discourage the emergence of lamivudine-resistant mutants.

YMDD motif in hepatitis B virus DNA polymerase influences on replication and lamivudine resistance: A study by in vitro full-length viral DNA transfection

Recently, lamivudine used to treat patients with hepatitis B virus (HBV) infection was revealed to have potent antiviral activity. However, HBV resistance to lamivudine has been reported and shown to have amino acid substitutions in the methionine residue of the conserved tyrosine (Y), methionine (M), aspartate (D), aspartate (D) motif of RNA-dependent DNA polymerase. To explore the consequences of substitutions in this motif (YMDD), we made 7 variants by substituting the methionine of the YMDD motif with isoleucine (I), valine (V), alanine (A), leucine (L), lysine (K), arginine (R), and threonine (T). Replication ability of these variants was evaluated by transfection into human hepatoma cells. Sensitivity to lamivudine was tested for replication-competent variants. Four variants with hydrophobic substitutions (I, V, A, and L) remained replication-competent, whereas 3 others with hydrophilic substitutions (K, R, and T) exhibited impaired replication. Of the 4 replication-competent variants, 2 (I and V) were resistant, and 2 (A and L) were sensitive to lamivudine. Because the polymerase and the surface gene overlap, the introduction of these mutations affected the secretion of hepatitis B surface antigen (HBsAg), namely 4 variants (I, V, L, and R) secreted HBsAg, whereas 3 variants (A, K, and T) did not. Our study elucidated that only one amino acid substitution in the YMDD motif was sufficient to cause lamivudine resistance in vitro. As a result of replication competence and lamivudine sensitivity, only viruses having YIDD or YVDD sequences may appear during treatment with lamivudine. This in vitro system could be used to study HBV mutations, replication competence, and their susceptibility to antivirals.

Liver transplantation for chronic viral hepatitis

A better understanding of the mechanism of viral replication and of viral transmission has led to improved results with OLTx for patients with end-stage liver disease caused by viral hepatitis. Patients with hepatitis-B-related liver disease who are HBV-DNA negative can expect excellent survival after OLTx with long-term HBIG therapy. Patients coinfected with HDV who are HBV-DNA negative can also expect an excellent rate of survival. HBV-DNA-positive patients may benefit from the addition of lamivudine to the prophylactic regimen both before and after OLTx. De novo HBV infections generally have a very benign course. Lamivudine has proven to be very effective in the treatment of both de novo and recurrent HBV infection after OLTx; however, resistance can develop. Allografts from donors with antibodies to HBV can be used most effectively when directed to recipients who also harbor HBV antibodies. The recurrence of HCV infection after OLTx is universal; however, the 5-year survival rate in patients who received OLTx for HCV-related liver disease is not diminished. Although a few patients experience an aggressive recurrence of HCV infection after OLTx, prognostic indicators have not been determined to allow for identification of these patients. Alpha-interferon does not seem to be effective in the treatment of recurrent HCV infection after OLTx. Trials with combination alpha-interferon-ribavirin are underway. Retransplantation for HCV-related allograft failure can be performed safely in patients if performed before the onset of other organ system failure. Finally, anti-HCV-positive recipients of allografts from anti-HCV-positive donors have an excellent 5-year survival rate.

Treatment of chronic hepatitis B: new antiviral therapies

Chronic hepatitis B infection is the most important cause of cirrhosis and hepatocellular carcinoma worldwide. Interferon-alpha has been shown to be effective in approximately one third of patients, and response seems to be sustained in long-term follow-up studies in Western countries. New treatments using lamivudine and other nucleoside analogues such as famciclovir, lobucavir, and adfovir showed promising results although sustained suppression of viral replication is unusual after discontinuation of therapy. The results of recent clinical studies using these nucleoside analogues are discussed in detail in this review. Other important issues such as drug resistance and the role of combination therapy are also addressed.