Lamivudine prophylaxis against reinfection in liver transplantation for hepatitis B cirrhosis

Advances in antiviral therapy

Multiple agents for the treatment and prevention of viral illnesses have been developed during the past few years. While in many cases this has been in direct response to the human immunodeficiency virus type 1 epidemic, a number of new antiviral agents are relevant to the practice of general pediatrics. This article reviews recent advances in the therapy of some common and a few unusual viral illnesses of children. The indication and efficacy of the newly developed agents valacyclovir, famciclovir, cidofovir, oral and intraocular ganciclovir, adefovir, respiratory syncytial virus immune globulin, palivizumab, and imiquimod are discussed, as well new uses of acyclovir, lamivudine, and ribavirin. Many of the antivirals discussed, including valacyclovir and cidofovir, have not yet been studied in children, but they hold promise for improving the treatment of pediatric viral infections.

Treatment of chronic hepatitis B virus infection: an Asia-Pacific perspective

Chronic hepatitis B infection is a serious health threat in the Asia-Pacific area. A consensus meeting on the treatment of chronic hepatitis B infection was conducted in Hong Kong, in August 1997. It was generally agreed that treatment of chronic hepatitis B infection should be based on the understanding of the natural history of chronic hepatitis B infection. To date, interferon alpha is the only Food and Drug Administration (FDA)-approved form of therapy for chronic hepatitis B infection. The overall response in Asian patients is unsatisfactory: approximately 15-20% will clear hepatitis B e antigen, but less than 5% will clear hepatitis B surface antigen. Newer immunomodulatory therapies are under trial. In contrast, nucleoside analogues, such as lamivudine (pending FDA approval) and famciclovir, have been shown to be potent suppressors of hepatitis B viral replication; however, their role as monotherapy in the treatment of chronic hepatitis B infection remains to be defined. Also, the issues of resistance to nucleoside analogues and withdrawal rebound need to be carefully studied. The future direction of therapy in chronic hepatitis B infection is probably a combination of nucleoside analogues or nucleoside analogues with immunomodulatory therapy.

Mutations in hepatitis B DNA polymerase associated with resistance to lamivudine do not confer resistance to adefovir in vitro

To determine whether adefovir is active against lamivudine-resistant hepatitis B virus (HBV), the inhibition constants of adefovir diphosphate and lamivudine triphosphate for wild-type and mutant human HBV DNA polymerases, which contain amino acid substitutions associated with lamivudine resistance, were compared. Recombinant wild-type and mutant human HBV DNA polymerases were expressed and substantially purified using a baculovirus expression system and immunoaffinity chromatography. HBV DNA polymerase mutants M552I, M552V, and L528M/M552V showed resistance to lamivudine triphosphate with inhibition constants (Ki) increased by 8.0-fold, 19.6-fold, and 25.2-fold compared with that of wild-type HBV DNA polymerase. However, these mutants remained sensitive to adefovir diphosphate with the inhibition constants increasing by 1.3-fold and 2.2-fold or decreasing by 0.79-fold. The L528M single mutation, identified in patients with increasing HBV DNA levels during therapy with famciclovir, also remained sensitive to adefovir diphosphate with the inhibition constant increased by only 2.3-fold.

Inhibition of human hepatitis B virus replication by AT-61, a phenylpropenamide derivative, alone and in combination with (-)beta-L-2',3'-dideoxy-3'-thiacytidine

AT-61, a member of a novel class of phenylpropenamide derivatives, was found to be a highly selective and potent inhibitor of human hepatitis B virus (HBV) replication in four different human hepatoblastoma cell lines which support the replication of HBV (i.e., HepAD38, HepAD79, 2.2.15, and transiently transfected HepG2 cells). This compound was equally effective at inhibiting both the formation of intracellular immature core particles and the release of extracellular virions, with 50% effective concentrations ranging from 0.6 to 5.7 microM. AT-61 (27 microM) was able to reduce the amount of HBV covalently closed circular DNA found in the nuclei of HepAD38 cells by >99%. AT-61 at concentrations of >27 microM had little effect on the amount of viral RNA found within the cytoplasms of induced HepAD38 cells but reduced the number of immature virions which contained pregenomic RNA by >99%. The potency of AT-61 was not affected by one of the mutations responsible for (-)-beta-L-2', 3'-dideoxy-3' thiacytidine (3TC) resistance in HBV, and AT-61 acted synergistic with 3TC to inhibit HBV replication. AT-61 (81 microM) was not cytotoxic or antiproliferative to several cell lines and had no antiviral effect on woodchuck or duck HBV, human immunodeficiency virus type 1, herpes simplex virus type 1, vesicular stomatitis virus, or Newcastle disease virus. Therefore, we concluded that the antiviral activity of AT-61 is specific for HBV replication and most likely occurs at one of the steps between the synthesis of viral RNA and the packaging of pregenomic RNA into immature core particles.

Resolution of recurrent hepatitis B in two liver transplant recipients treated with famciclovir

Recurrent hepatitis B infection after orthotopic liver transplantation remains problematic despite prophylaxis with hepatitis B immune globulin (anti-HBs IgG). Recently, famciclovir (an oral nucleoside analog) has been shown to have potent antiviral activity against hepatitis B in vitro as well as in patients with chronic hepatitis B. We present two patients who developed recurrent hepatitis B after orthotopic liver transplantation and were treated with famciclovir, 500 mg t.i.d. Both patients subsequently responded with marked improvement in biochemical liver tests and histology, with subsequent loss of hepatitis B surface antigen. Famciclovir is a useful agent in the treatment of hepatitis B in the liver transplant recipient.

Genome-wide scanning in inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are multifactorial traits involving both environmental and genetic factors. In order to identify the IBD susceptibility genes, two groups of strategies have been developed. In the candidate gene approach, a specific hypothesis is tested by usually investigating the prevalence of specific alleles in groups of affected and control individuals with no familial relationship. Such association studies are powerful and straightforward. However, they are limited by possible recruitment biases and a multitesting problem due to the large number of possible candidate genes. Furthermore, they rely on the existence of a founder effect. In the genome scanning searches, no prior assumption is made on the susceptibility genes. The studies are based on cosegregation (or linkage) analyses performed on families with several affected members. Their drawbacks are the lack of statistical power and the low resolution of the localization. Nonetheless, using genome-wide screens, two IBD loci have been localized by several independent groups on chromosomes 12 and 16. Additional IBD loci have been proposed by individual groups on chromosomes 1, 3, 4, 7, 11, 15 and X. In order to gain wide acceptance, the latter localizations are to be confirmed by additional independent studies. Identification of IBD susceptibility genes would represent a key step in the understanding of the pathogenic mechanism of these diseases. However, in complex disorders, genes are only a part of the risk factors. Epidemiological studies looking for environmental factors are thus complementary of the genetic approach.

Biodistribution, stability, and antiviral efficacy of liposome-entrapped phosphorothioate antisense oligodeoxynucleotides in ducks for the treatment of chronic duck hepatitis B virus infection

This study investigated the feasibility of using liposomes to increase the hepatic delivery and antiviral efficacy of phosphorothioate antisense oligodeoxynucleotides (PS-ODN) for the in vivo treatment of hepatitis B virus (HBV) infection. Ducks infected with duck hepatitis B virus (DHBV) were used as the model. We studied the stability of an antisense PS-ODN in duck plasma, its integrity during the process of liposome entrapment, its in vivo biodistribution, plasma clearance, and excretion. In addition, the intrahepatic distribution of a labeled free and liposome-entrapped ODN was also investigated. The results of our studies show that: 1) phosphorothioate ODN remain stable during the process of liposome entrapment; 2) are stable in duck plasma for many hours; 3) are rapidly cleared from the plasma when injected intravenously; 4) intravenous injection of antisense ODNs entrapped within liposomes enhances delivery of the ODN to the liver; and 5) inhibit DHBV replication. Serum DHBV DNA levels fell rapidly, with a corresponding decrease in intrahepatic viral replicative intermediates at the end of the 5-day study period. Although inhibition of viral replication and a fall in the target protein was observed, a marked inhibition of viral replication was also observed with high doses of a random-sequence ODN. Thus, it is not certain that inhibition of viral replication was entirely through an antisense mechanism. Therefore, liposomes may be effective vehicles to improve the delivery of antisense oligonucleotides to the liver for the therapy of hepatotropic viruses.

Liver transplantation in Asia: Problems and practice

Liver transplantation in Asia has been difficult to establish due to: a reluctance in Asians to donate organs; a lack of financial support; and the predominance of hepatitis B in the population, which effectively reduces the number of cadaveric organs. To overcome the problem of organ shortage, living-related liver transplantation for paediatric patients was rapidly established initially at Kyoto University, Japan, and then in several centres in Asia. Living-related liver transplantation was extended to adults using the left lobe in 1994 and using the right lobe in 1996. Up to May 1998, 785 liver transplantations had been performed in major centres in Asia with a patient survival rate approaching 80%. To overcome the problem of hepatitis B viral infection, lamivudine is now used peri-operatively. Lamivudine is shown to be very effective in preventing graft reinfection. Of the 15 patients who received lamivudine and liver transplantation at Queen Mary Hospital, hepatitis B surface antigen (HBsAg) disappeared in 11 patients and hepatitis B virus DNA was not detectable in any of them. Two patients had a reappearance of HBsAg after an initial loss, but their liver grafts were not affected by hepatitis. Compared with hepatitis B immunoglobulin, lamivudine is definitely cheaper and more convenient. In conclusion, even though there are major obstacles to liver transplantation in Asia, steady progress is being made. Hopefully, when the number of cadaveric grafts increases in future, an increasing number of patients can benefit.

Genetics of inflammatory bowel disease. A personal view on progress and prospects

Clinical, epidemiological and molecular data reported in the last 5 years have provided strong evidence that genetic factors are important in susceptibility to both Crohn's disease and ulcerative colitis. The model of disease inheritance which best fits the epidemiological data is that Crohn's disease and ulcerative colitis are related polygenic diseases. However, genetic heterogeneity is likely to be extensive, and may well underlie the variability in clinical presentation associated with inflammatory bowel disease. Considerable progress has already been made in identifying potential disease susceptibility loci using the technique of genome-wide scanning. There is optimism that international collaborative studies will allow fine mapping of the loci implicated on chromosomes 16 and 12. The identification of novel susceptibility genes has become a realistic goal for investigators. Once this has been achieved, there are likely to be immediate clinical benefits, both in understanding disease pathophysiology, and in disease management.

Genetics of inflammatory bowel disease. The candidate gene approach: susceptibility versus disease heterogeneity

Ulcerative colitis and Crohn's disease are complex diseases of unknown etiology. Several genes are involved in the susceptibility. These genes are necessary to suffer from these diseases but not sufficient. Environmental factors trigger the inflammatory response. Evidence is accumulating that this response is abnormal in these patients. Therefore, the study of genes that are involved in the regulation of the inflammation may help to clarify the pathogenesis of the disease. The working hypothesis is that HLA and cytokine gene polymorphisms, of extreme importance in the regulation of inflammation, contribute to determining the heterogeneity of the disease and the prognosis. In this case, the candidate genes are those involved in the regulation of the immune response of the host. These studies may be of great importance in the tailoring of an appropriate treatment for particular subgroups of patients. A premise for the success of these studies is to use a solid classification, which should take into account the dynamic process and the natural evolution of the disease; to use a carefully selected and ethnically matched group of healthy controls, and to use the advanced molecular biological typing techniques. In the present article, this concept is explored by taking into account some of the recent findings obtained with the HLA and cytokine gene polymorphisms in inflammatory bowel diseases. The results support the concept that these gene polymorphisms are of greater importance in determining the severity of the disease than in determining the susceptibility to suffer from the disease. From this point of view, these studies are complementary and a necessary addition to studies using the whole genome approach in the effort to understand the genetics of these chronic multifactorial diseases.

Treatment of chronic hepatitis B with lamivudine in renal transplant recipients

BACKGROUND

Lamivudine is a potent inhibitor of hepatitis B virus replication. Little has been reported about the efficacy and safety of lamivudine in the treatment of chronic hepatitis B in the setting of renal transplantation.

METHODS

Two patients were treated for chronic hepatitis B with lamivudine and subsequently underwent renal transplantation. Four other patients were treated with lamivudine for reactivation of hepatitis B after renal transplantation. Chronic hepatitis B was proven histologically in all the patients. The doses of lamivudine ranged from 100 to 150 mg/day. Hepatic enzyme and viral markers were monitored.

RESULTS

Lamivudine was well tolerated for a median duration of 8 months (range, 4-14 months) without significant side effects. Viral replication was suppressed, as evidenced by negative conversion of serum hepatitis B virus DNA in all the patients. Hepatic enzyme was also normalized. Modification of doses of immunosuppressant regimen was not required in using lamivudine in all patients. One patient experienced acute rejection and responded to solumedrol pulse therapy with normalization of graft function. Normal graft function was maintained in other patients while they were treated with lamivudine.

CONCLUSION

Lamivudine was a safe and effective therapy for activated hepatitis B in renal transplant recipients in the short term.

Quantitative hepatitis B virus DNA assessment by the limiting-dilution polymerase chain reaction in chronic hepatitis B patients: evidence of continuing viral suppression with longer duration and higher dose of lamivudine therapy

Lamivudine, a novel cytosine analogue, exhibits potent antiviral activity against hepatitis B virus (HBV) in vitro and in vivo. The standard HBV DNA hybridization assay used in phase II clinical studies has a low sensitivity, the detection limit of HBV DNA levels being approximately 10(7) genome equivalents per ml (geq ml-1). In this work we used a semiquantitative polymerase chain reaction (PCR) assay (detection limit approximately 10(3) geq ml-1) to determine HBV DNA levels during a 24-week study of lamivudine in 51 stable chronic hepatitis B patients who were positive for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg). Patients were randomly allocated to receive oral doses of 25, 100 or 300 mg lamivudine once daily. At week 24 the median serum concentration of HBV DNA had fallen from 10(8) to 10(4) geq ml-1, a 4-log median reduction. A trend towards more profound suppression of viral replication with an increased dose of lamivudine was observed. After 12 weeks of therapy, 12% of patients had an HBV DNA level that was undetectable in the PCR assay; this increased to 26% after 24 weeks, while in an additional 20% of patients, HBV DNA decreased to the level of detection of the PCR assay. We conclude that a 24-week course of lamivudine decreases serum HBV DNA to the level of PCR detection in 46% of patients. Such additional viral suppressive activity with higher doses and more protracted lamivudine may be of clinical utility prior to liver transplantation. Further studies are needed to define the degree of virus suppression required in clinical practice, and methods are required to increase the efficacy of virus suppression.

The M539V polymerase variant of human hepatitis B virus demonstrates resistance to 2'-deoxy-3'-thiacytidine and a reduced ability to synthesize viral DNA

The cytosine analog 2'-deoxy-3'-thiacytidine (3TC) has been shown to be an effective treatment for chronic hepatitis B virus (HBV) infection. However, several liver transplant patients who were undergoing treatment with 3TC for HBV infection experienced a breakthrough of virus while on 3TC. The predominant virus found in these patients' sera contained either a valine or isoleucine for the methionine in the highly conserved YMDD nucleotide binding site in the HBV polymerase. To determine the biological relevance of the Met-to-Val substitution, we mutated a plasmid that contained a cDNA copy of the HBV pregenomic RNA such that when virus replication occurred during transient transfection of HepG2 cells, an M539V polymerase variant was produced. We found that in transiently transfected cells, this variant was approximately 330-fold less sensitive to the antiviral effects of 3TC and produced 7-fold less viral DNA than the wild type.

Prophylaxis against hepatitis B recurrence following liver transplantation using combination lamivudine and hepatitis B immune globulin

Patients undergoing liver transplantation for hepatitis B-related liver disease are prone to recurrence. The mainstay of prophylaxis has been passive immunotherapy with hepatitis B immune globulin (HBIG). Antiviral therapy with lamivudine has proven effective in lowering hepatitis B virus (HBV) DNA and improving histology in patients with hepatitis B infection; its role in prophylaxis against hepatitis B recurrence following liver transplantation is under investigation. Viral breakthrough and resistance, however, are a significant problem with monotherapy with either HBIG or lamivudine. The efficacy of combination lamivudine/HBIG prophylaxis has not been reported. Fourteen patients underwent transplantation for decompensated liver disease owing to hepatitis B. Lamivudine (150 mg p.o./d) was begun before transplantation in 10 patients, including 4 who were HBV DNA-positive. In addition, 1 patient was HBV DNA-positive when transplanted. HBIG was given perioperatively and continued thereafter; treatment with lamivudine was maintained or initiated at the time of transplantation and continued indefinitely. The median follow-up was 387 days. Actuarial 1-year patient and graft survival was 93% (1 patient died of unrelated causes). At a median interval of 28 days following lamivudine treatment, all 5 HBV DNA-positive patients cleared HBV DNA from the serum; 1 went on to clear hepatitis B surface antigen (HBsAg), before transplantation, at day 148 of lamivudine treatment. By the highly sensitive polymerase chain reaction (PCR), at a median of 346 days (range, 130-525 days) following transplantation, all 13 surviving patients had no detectable serum HBV DNA. Lamivudine suppresses HBV replication in patients awaiting liver transplantation. At a median follow-up of 1.1 years, combination prophylaxis with lamivudine and HBIG prevented hepatitis B recurrence following liver transplantation.

Current results and evolving indications for liver transplantation in children

Liver transplantation continues to be successful and effective treatment for acute and chronic liver failure, and many important lessons have been learned. The development of innovative operative techniques has much reduced the waiting list mortality rate and has extended transplantation to younger and sicker children and to those with functionally normal livers who may benefit from auxiliary liver transplantation. The incidence and range of postoperative complications have improved with increased medical and surgical expertise. As information on long-term outcome for liver transplantation is gained, it is clear that many children will benefit from early elective liver transplantation before the development of significant growth or psychosocial retardation. Early transplantation is also indicated in children with cirrhosis and intrapulmonary shunting or cystic fibrosis with moderate lung disease. During the same period, evolving medical therapy has altered the natural history, patient selection, and timing of transplantation in children with tyrosinaemia type I, primary bile acid disorders, neonatal haemochromatosis, and potentially, cystic fibrosis. It is now clear that children with significant multisystem disease, such as mitochondrial disorders or severe systemic oxalosis, are no longer suitable candidates for liver transplantation. The successful development of liver transplantation has brought good quality life to many children and their families. There are still many lessons to learn and there are future challenges such as the ever-increasing problems of donor scarcity and the search for potent but less toxic immunosuppressive agents.

The identification and development of antiviral agents for the treatment of chronic hepatitis B virus infection

Hepatitis B virus (HBV) is the leading cause of chronic hepatitis throughout the world. Notwithstanding the availability of a safe and effective vaccine, the world prevalence of HBV has not declined significantly, thus resulting in the need for a selective antiviral agent. HBV is a small, partially double-stranded DNA virus which replicates through an RNA intermediate. Most efforts to develop anti-HBV agents have been targeted to the viral DNA polymerase which possesses reverse transcriptase activity. Currently, the most promising anti-HBV agents are nucleoside analogs which interfere with viral DNA replication. Although earlier nucleoside analogs such as vidarabine (ara-A) and fialuridine (FIAU) have displayed unacceptable toxicities, newer analogs such as lamivudine (3TC), bis-POM PMEA (GS-840), lobucavir, and BMS-200,475 have demonstrated clinical utility. In particular, the use of lamivudine has generated considerable interest in the development of other L-enantiomeric nucleoside analogs for use against HBV. Here, we provide an overview of HBV structure and replication strategy and discuss the use of cell culture systems, in vitro viral polymerase systems, and animal models to identify and evaluate anti-HBV agents. We also discuss the various classes of nucleoside analogs in terms of structure, mechanism of action, status in clinical development, ability to select for resistant HBV variants, and use in combination therapies. Finally, we present a discussion of novel antiviral approaches, including antisense and gene therapy, and address the various challenges to successful anti-HBV chemotherapeutic intervention.

Lamivudine treatment of chronic hepatitis B

Several new nucleoside analogues have 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 have been completed. The sustained HBeAg seroconversion rate in patients who have received 100 mg lamivudine increases from 17% after a year of treatment to 27% after 2 years of treatment. Histological improvement has been noted in 38%-52% of lamivudine-treated patients, exceeding the improvement seen in placebo recipients. Similar histological improvement has been noted in anti-HBe-positive, DNA- positive patients. Lamivudine 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 reduce the burden of infected hepatocytes in the liver, and to prevent relapse. The drug is generally well tolerated with few direct adverse events. Genotypic mutations have been observed in 23% (range 13-32%). In a study in Asian patients treated for two years the incidence of these mutants increased to 38% (as detected by PCR). Loss of susceptibility to 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. Copyright 1998 John Wiley & Sons, Ltd.

Efficacy of lamivudine in controlling hepatitis B virus recurrence after liver transplantation

BACKGROUND

Indication of liver transplantation for patients infected with hepatitis B virus (HBV) remains controversial because of the high incidence of posttransplant HBV recurrence and aggressive involvement of the allograft. In this article, we provide evidence that the introduction of lamivudine may favorably alter the prognosis of these patients.

METHODS

Lamivudine was used in 40 HBV-infected adult patients suffering from chronic end-stage liver disease who underwent liver transplantation. The drug was used in the following settings: failure of prolonged passive immunoprophylaxis, elective conversion from immunoprophylaxis, de novo posttransplant HBV infection, and primary treatment with lamivudine which started before and continued after transplantation. Twenty patients (50%) had viral replication at the time lamivudine was started. Posttransplant and antiviral treatment follow-ups were 8-64 months (median follow-up: 27.5 months) and 9-39 months (median follow-up: 19 months), respectively.

RESULTS

The patient and graft survival rates were 97.5% (39/40). Thirty-three patients (82.5%) have remained free of viral recurrence. In the seven re-infected patients, the manifestations of HBV involvement of the allograft have been mild. There have been no side effects related to lamivudine, and the treatment is substantially less costly than with other anti-HBV agents.

CONCLUSIONS

Compared with historic series utilizing other modalities of treatment, the use of lamivudine has, so far, yielded superior results. This drug may be an important acquisition for antiviral prophylaxis in HBV-infected liver recipients. Because of the risk of viral mutations, however, efforts should proceed to achieve more efficacious methods for prevention and control of HBV recurrence.

Emergence and takeover of YMDD motif mutant hepatitis B virus during long-term lamivudine therapy and re-takeover by wild type after cessation of therapy

Treatment of hepatitis B virus (HBV) with lamivudine is effective in suppressing virus replication and results in reduced inflammatory activity. However, the emergence of lamivudine-resistant mutant virus, with amino acid substitution in the YMDD motif of DNA polymerase, has been reported. We report the emergence and takeover of YMDD mutant and re-takeover by wild type during and after long-term lamivudine therapy. YMDD mutants were detected in five patients who showed DNA breakthrough (HBV DNA becoming detectable after a period of DNA negativity), which occurred after 9 to 14 months of lamivudine therapy. Four of five mutants had amino acid sequence YIDD, and the remaining mutant had YVDD. Patients with high HBV-DNA titer and/or hepatitis B e antigen tended to develop breakthrough (P = .038). Using a sensitive and specific polymerase chain reaction (PCR)-based method developed in this study, the emergence of YMDD mutants was detected 1 to 4 months before DNA breakthrough, but not detected in any of the pretreatment sera. The mutants were predominant at breakthrough, but were replaced by wild-type virus 3 to 4 months after cessation of therapy in the two patients who discontinued therapy. One of these patients had a relapse of hepatitis. Mutant continued to replicate in the remaining three patients who continued to receive treatment, and relapse occurred in only one of these patients. Our results suggest that the replication of YMDD mutant viruses is less than wild type and is re-overtaken by wild type after cessation of therapy. Re-administration of lamivudine, possibly combined with other antiviral therapy, might be useful in some patients experiencing hepatitis with lamivudine-resistant variants.

Improved clinical outcomes with liver transplantation for hepatitis B-induced chronic liver failure using passive immunization

OBJECTIVE

The goals were to summarize the results of liver transplantation for chronic hepatitis B disease (HBV) at the University of Virginia, correlate pretransplant viral markers with posttransplant hepatitis B immunoglobulin (HBIg) requirements, and identify the relation between viral protein in the liver and clinical reinfection.

SUMMARY BACKGROUND DATA

Liver transplantation is an accepted treatment for end-stage liver disease from chronic HBV infection, although lifelong antiviral treatment (with HBIg or antiviral agents) is still necessary. Patients with evidence of active viral replication (detectable serum HBV-DNA or e antigen) at the time of transplant have a higher rate of allograft infection. Whether clinically stable patients receiving HBIg immunoprophylaxis have detectable viral products in their grafts remains unknown.

METHODS

Forty-four transplants performed for HBV disease at the University of Virginia since March 1990 were reviewed. Most patients underwent aggressive passive immunoprophylaxis with HBIg to maintain serum HBV surface antibody (HBsAb) levels > or =500 IU/l for the first 6 months after the transplant, and > or =150 IU/l thereafter. Patients had viral markers quantified, underwent pharmacokinetic analysis of HBsAb levels to adjust dosing, and were biopsied routinely every 3 to 6 months and when indicated.

RESULTS

Forty-four transplants were performed in 39 patients. Actual 1-year and 3-year graft survival was 95% and 81%, respectively, and 1-year and 3-year patient survival was 98% and 96%, respectively. After the adoption of indefinite HBIg prophylaxis, nine grafts became infected (all in recipients positive for HBV e antigen). Three occurred within 8 weeks of transplantation and were associated with a short HBsAb half-life and a wild-type virus. Six occurred >8 months after the transplant, and most of these were associated with viral mutation. Quantification of pretransplant markers was an overall poor predictor of HBIg requirements after the transplant. Immunohistochemistry demonstrated transient low-level expression of core protein in the liver in 23% of patients without serum or clinical evidence of recurrent hepatitis.

CONCLUSIONS

An excellent outcome is possible after liver transplantation for chronic HBV disease using HBIg dosed by pharmacokinetic parameters. Currently, quantification of pretransplant serum markers of the HBV antigen load does not predict the intensity of posttransplant treatment required for good clinical outcomes. Because HBV is not eradicated from the patient, some form of indefinite antiviral therapy continues to be warranted.

Hepatitis B Virus Antiviral Drug Resistance: From the Laboratory to the Patient

The development and application of nucleoside (and nucleotide) analogues for the treatment of chronic hepatitis B infection will transform the management of this condition. For instance, treatment with lamivudine effects a dramatic and measurable reduction of serum virus titre. This is associated with biochemical and histological improvements. Unfortunately, for the majority, replication resumes when treatment is withdrawn. Prolongued lamividine treatment may be associated with the emergence of drug-resistant species with specific polymerase mutations. Compared with the observed rate for the development of drug resistance observed during monotherapy of HIV infection, resistance is slow to emerge during treatment of hepatitis B. The rate of emergence might be dependent on the rate of infected hepatocyte turnover, which is extremely variable in chronic HBV infection (and significantly slower than infected lymphocyte turnover during HIV infection). Preliminary data suggest that pretreatment serum virus titre may be an important predictor of the development of drug resistance, an observation consistent with pre-existance of the resistant virus in the hepatitis B virus quasispecies. Akin to developments in antiviral treatment of HIV infection, further progress in the treatment of chronic hepatitis B will depend on the development of drugs for use in combination therapy.

Nucleoside analogue therapy in fibrosing cholestatic hepatitis--a case report in an HBsAg positive renal transplant recipient

A 45-year-old HBsAg carrier (HBeAb positive with normal liver function tests) underwent renal transplantation for mesangioproliferative glomerulonephritis. Sixteen months later he developed jaundice. Investigations showed he remained HBeAb positive, but HBV-DNA levels were 99 pg/ml, indicating active replication of a HBV pre-core mutant. He was commenced on lamivudine therapy with a subsequent rapid fall in HBV-DNA levels to 2.8 pg/ml, but liver function tests continued to deteriorate and he developed hepatorenal failure. Liver biopsy showed fibrosing cholestatic hepatitis. He underwent liver transplantation, which was complicated by lactic acidosis. Lamivudine was withdrawn and HBV prophylaxis with HB immunoglobulin was commenced. Unfortunately he died 38 days post-transplant of surgical complications with no evidence of HBV recurrence. We discuss the use of nucleoside analogues in fibrosing cholestatic hepatitis and review the literature.

Transient emergence of hepatitis B variants in a patient with chronic hepatitis B resistant to lamivudine

BACKGROUND

Lamivudine is a cytosine nucleoside analogue that inhibits hepatitis B virus replication. Resistance to lamivudine monotherapy has been reported in patients who received lamivudine to prevent recurrent hepatitis B virus infection after liver transplantation. No cases of resistance have been described in patients who did not clear HBV DNA during lamivudine therapy.

METHODS

We report the case of an adult patient with chronic HBeAg-positive hepatitis B who had a hepatitis flare during lamivudine therapy. The patient did not respond to lamivudine and, at 4 months of treatment, developed a significant serum alanine aminotransferase elevation. Alanine aminotransferase levels remained elevated for 4 months and returned to baseline spontaneously. Lamivudine therapy was administered for 1 year (52 weeks) and after withdrawal, alanine aminotransferase levels remained elevated.

RESULTS

Sequencing studies of HBV DNA at week 52 showed the emergence of a lamivudine-resistant variant associated with two point mutations in the hepatitis B virus polymerase gene: one mutation led to amino acid substitution of methionine to valine at residue 552, in the highly conserved tyrosine-methionineaspartate-aspartate motif, part of the active site of the polymerase; the second mutation consisted of a substitution of leucine to methionine at residue 528. At week 54 of follow-up, both mutations were undetectable.

CONCLUSION

This observation demonstrates the transient emergence of HBV variants in the course of therapy in a patient resistant to lamivudine therapy.

Hepatitis viruses and liver transplantation

Acute and chronic liver diseases related to hepatitis viruses are the main indications for liver transplantation. The risk of viral reinfection after transplantation is the main limiting factor in these indications. The risk of viral B reinfection is: 80% in the absence of prophylaxis; is related to the presence of active viral B replication prior to transplantation; is higher in patients with chronic liver disease, rather than with fulminant hepatitis; and is higher in patients with hepatitis B virus (HBV)-related liver disease alone rather than in those with HBV-hepatitis delta virus (HDV) infection. Post-transplant long-term passive antibody to hepatitis B (anti-HB) immunoprophylaxis reduces the risk of HBV recurrence to 30% in patients with HBV cirrhosis, and to less than 10% in those with fulminant hepatitis B. Patients with HBV-HDV liver disease receiving passive anti-HB immunoprophylaxis are at low risk of HBV recurrence (10-15%), but at high risk of HDV recurrence (80%). However, HDV reinfection of the graft has no clinicopathological consequence in the absence of concomitant HBV reinfection. The five year survival of patients transplanted for HBV cirrhosis and for HDV cirrhosis at the Hepatobiliary Center, Hôpital Paul Brousse is 72% and 85%, respectively. Hepatitis B virus reinfection of the graft is characterized by a high level of viral replication, and a chronic outcome. Antiviral treatments such as ganciclovir, adenine arabinoside monophosphate, famcyclovir, and lamivudine have a place after transplantation and may stop HBV replication, ganciclovir, famcyclovir and lamivudine should be continued for several months and in some cases indefinitely. Hepatitis C virus reinfection is almost constant, assessed by the persistence of hepatitis C virus (HCV)-RNA in the serum in 90% of cases. Acute lobular hepatitis appeared in 75% of patients at a median of 4 months post transplantation with a range of between 23 days and 4 years. In our series, the 5 year actuarial rate of HCV acute hepatitis on the graft, chronic hepatitis, and cirrhosis, is 75, 60, and 8%, respectively. Hepatitis C virus RNA level is dramatically increased after transplantation and seems to correlate with the occurrence of acute hepatitis on the graft. A positive relation between genotype 1b and prevalence and severity of HCV hepatitis on the graft have been suggested in European series. There is no demonstrated way to prevent HCV reinfection. The use of interferon for the treatment of HCV hepatitis on the graft was disappointing due to a poor antiviral effect and the occurrence of chronic rejection episodes in some patients. Promising results of the combination of interferon and ribavirine have been reported and need confirmation. The 5 year survival of patients transplanted for viral C cirrhosis at the Hepatobiliary Center, Hôpital Paul Brousse is 78%. In conclusion, patients with HBV cirrhosis and without HBV replication are candidates for liver transplantation. Long-term passive anti-HB prophylaxis is the best way to prevent HBV recurrence. Patients with HBV replication should be included in protocols using combinations of antiviral treatments and passive anti-HB immunoprophylaxis. Viral C reinfection is frequent, but medium-term survival is good. However, long-term graft and patient survival remains unknown and methods to prevent and treat HCV reinfection on the graft are needed.

Alteration of the dismal natural history of fibrosing cholestatic hepatitis secondary to hepatitis B virus with the use of lamivudine

BACKGROUND

Fibrosing cholestatic hepatitis (FCH) is a severe form of hepatitis B virus (HBV) infection occurring as either primary allograft reinfection after liver transplantation for HBV or as severe HBV reactivation induced by immunosuppression in patients with previously latent infection. Without treatment, FCH is universally fatal within a few months of diagnosis. Some improvement has been reported with long-term ganciclovir, with and without foscarnet, but an effective and easily available treatment has not yet been reported.

METHODS

We report the prolonged survival of a renal transplant recipient who developed histologically confirmed FCH 6 months after transplantation and was treated with lamivudine.

RESULTS

At the time of diagnosis, the patient had jaundice, ascites, and a serum HBV-DNA level of 3868 pg/ml. Lamivudine was instituted 2 months later, and after 6 months of treatment, the HBV-DNA level was undetectable with the serum bilirubin within the normal range. Twelve months after the diagnosis of FCH, the patient remains stable without progression of liver dysfunction.

CONCLUSION

Our experience demonstrates that lamivudine therapy can improve the dismal natural history of FCH.

Recurrence-free long-term survival after liver transplantation for hepatitis B using interferon-alpha pretransplant and hepatitis B immune globulin posttransplant

OBJECTIVE

The authors determined whether pretransplant reduction of hepatitis B virus (HBV) load using alpha-interferon-2b (IFN) and passive immunoprophylaxis using hepatitis B immunoglobulin (HBIg) posttransplantation can prevent HBV recurrence in patients undergoing liver transplantation (LT) for HBV cirrhosis.

SUMMARY BACKGROUND DATA

Liver transplantation in patients with HBV cirrhosis is associated with a high rate of recurrence and reduced survival. In patients with evidence of replicating virus (HBV-DNA or hepatitis B e antigen [HBeAg]-positive serum or both), recurrence is nearly universal. Passive immunoprophylaxis with HBIg alone is not effective in preventing HBV recurrence posttransplant, especially in patients with evidence of active viral replication pretransplant. Higher doses of HBIg posttransplant has reduced recurrence rates to 30% to 50%. Lamivudine, a nucleoside analogue that has shown early promise, also is associated with significant HBV recurrence. The authors report a reliable method of preventing viral recurrence in patients even with evidence for active HBV replication pretransplant.

METHODS

Pretransplant patients with evidence of replicating HBV were given IFN starting at 1 million IU 3 times per week subcutaneously. This dose was increased to 2 and then 3 million IU 3 times per week when patient's side effects permitted and was maintained until the patient underwent a LT. All patients were tested every 4 weeks for hepatitis B surface antigen (HBsAg), HBeAg, and HBV-DNA. When patients became negative for HBeAg and HBV-DNA, they were listed for LT. Patients that were only HBsAg positive were listed immediately and received a LT without prior IFN treatment. Post-LT, all patients began receiving HBIg 2000 IU (10 mL) daily from days 1 to 20 and then weekly for the first 2 years. After 2 years, all patients received 2000 IU (10 mL) monthly. Additional HBIg immunoprophylaxis was given during intense immunosuppression for rejection. Posttransplant serum was tested for HBsAg, HBeAg, and HBV-DNA in all patients 1 week, 1 month, and every 3 months thereafter. Liver biopsies were done at least yearly and when liver enzymes were abnormal and were always tested for HBsAg and HBcAg by immunoperoxidase.

RESULTS

Thirteen patients with decompensated HBV cirrhosis were transplanted. Pretransplant, eight patients had evidence of active viral replication at the initial assessment (HBeAg or HBV-DNA-positive serum or both). All eight were successfully treated with IFN (median duration, 24 weeks; range, 8-53) and converted to a negative status before transplantation. Side effects from IFN were minimal and well tolerated, except in one patient who required 6 million IU to convert to a nonreplicating status. The five patients that were only HBsAg positive were not treated with IFN pretransplant. After surgery, HBIg given as described achieved consistently serum levels greater than 1000 IU/L. Twelve of the 13 patients are alive with normal liver function and without serologic evidence of HBV recurrence at a median follow-up of 32 months (range, 9-56 months). None have evidence of HBV recurrence as measured by serum HBsAg/HBeAg/HBV-DNA at recent follow-up. The sera of the seven longest survivors has tested negative for HBV-DNA using the polymerase chain reaction method. In addition, a liver biopsy was obtained in six of these patients, the results of which also tested negative for HBV-DNA using polymerase chain reaction. Liver biopsy specimens have been negative for the presence of HBsAg and HBcAg by immunoperoxidase staining in all 12 patients.

CONCLUSION

A reduction of viral load pretransplant with IFN and posttransplant HBIg prevents recurrence of hepatitis B and permits LT for HBV cirrhosis, even in patients with evidence of replicating virus. The IFN pretransplant was well tolerated, and the small frequent dosing of HBIg posttransplant did not cause side effects while achieving serum levels > 1000 IU/L.

Identification of BMS-200475 as a potent and selective inhibitor of hepatitis B virus

BMS-200475 is a novel carbocyclic 2'-deoxyguanosine analog found to possess potent and selective anti-hepatitis B virus (anti-HBV) activity. BMS-200475 is distinguished from guanosine by replacement of the natural furanose oxygen on the sugar moiety with an exo carbon-carbon double bond. In the HepG2 stably transfected cell line 2.2.15, BMS-200475 had a 50% effective concentration (EC50) of 3.75 nM against HBV, as determined by analysis of secreted HBV DNA. Structurally related compounds with adenine, iodouracil, or thymine base substitutions were significantly less potent or were inactive. Direct comparison of the antiviral activities of BMS-200475 with those of a variety of other nucleoside analogs, including lamivudine (EC50 = 116.26 nM), demonstrated the clearly superior in vitro potency of BMS-200475 in 2.2.15 cells. Intracellular HBV replicative intermediates were uniformly reduced when cells were treated with BMS-200475, but rebounded after treatment was terminated. The concentration of BMS-200475 causing 50% cytotoxicity in 2.2.15 cell cultures was 30 microM, approximately 8,000-fold greater than the concentration required to inhibit HBV replication in the same cell line. Treatment with BMS-200475 resulted in no apparent inhibitory effects on mitochondrial DNA content.

Hepatitis-B-virus resistance to lamivudine given for recurrent infection after orthotopic liver transplantation

BACKGROUND

Orthotopic liver transplantation for end-stage hepatitis-B-virus (HBV) infection is commonly complicated by recurrence of HBV. Lamivudine, a cytosine nucleoside analogue, has been shown to suppress HBV infection. We report the development of resistance to lamivudine in three patients who underwent transplantation for end-stage liver disease secondary to hepatitis B.

METHODS

Two of the patients received lamivudine for recurrent HBV infection after transplantation, whereas the third patient began treatment 1 month before transplantation in an attempt to prevent HBV recurrence after transplantation. The three patients initially responded well to treatment, but viral recurrence occurred after 9-10 months of treatment in all patients. HBV DNA was amplified from serum and sequenced through a conserved polymerase domain-the tyrosine, methionine, aspartate, aspartate (YMDD) locus. We assessed the susceptibility of HBV to lamivudine by infecting primary human hepatocytes with serum taken before the start of treatment and after recurrence in varying concentrations of lamivudine.

FINDINGS

DNA sequencing showed a common mutation within the YMDD locus of the HBV polymerase gene in all patients during lamivudine treatment. In hepatocyte cultures infected with pretreatment serum, HBV DNA concentrations were reduced to less than 6% of those in control cultures by addition of lamivudine in concentrations as low as 0.03 mumol/L. By contrast, in cultures treated with serum taken after recurrence, HBV DNA concentrations did not fall below 20% of control values, even with lamivudine at 30 mumol/L.

INTERPRETATION

Resistance to lamivudine has been reported in HIV patients with mutations in the YMDD locus of the polymerase gene. Our findings indicate a common mechanism of lamivudine resistance for HIV and HBV that involves similar point mutations in homologous domains of the viral polymerases.

Hepatitis B virus and liver transplantation: concepts in antiviral prophylaxis

Liver transplantation remains problematic in patients with end-stage liver disease secondary to chronic hepatitis B virus (HBV) infection. Recurrent hepatitis is almost universal in those patients who are HBV DNA-positive prior to transplantation. Prophylactic hepatitis B immune globulin can be given to reduce the rate of hepatitis B recurrence in patients who are HBV DNA-negative prior to transplantation. More recently novel antiviral drugs such as lamivudine or famciclovir have been used specifically to inhibit hepatitis B viral replication. However, the development of drug-resistant viral mutants have been observed. Further studies are needed to investigate these drugs more extensively, particularly to assess whether combination therapy may be a more effective means of controlling viral recurrence in patients transplanted for chronic HBV infection.