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

[Liver transplantation for complications of hepatitis B]

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

Treatment of hepatitis B and C after liver transplantation. Part 1, hepatitis B

The outcome of OLT for HBV-related liver disease is dependent on the prevention of allograft re-infection. Over the past decade, major advances have been made in the management of HBV transplant candidates. The advent of long-term hepatitis B immune globulin (HBIG) administration as a prophylaxis against HBV recurrence, and the introduction of new antiviral agents against HBV infection, such as lamivudine (LAM), were a major breakthrough in the management of these patients. Results of OLT for HBV infection are similar to those achieved with other indications. Pre-OLT antiviral treatment such as LAM can suppress HBV replication before OLT and thus decrease the risk of re-infection of the graft. Combination prophylaxis with LAM and HBIG after transplantation highly effectively reduces the rate of HBV re-infection, even in HBV replicative cirrhotic patients. The optimal HBIG protocol in the LAM era is yet to be defined: dosing of HBIG, routes of administration, and possibility of stopping HBIG. Several antiviral drugs have been developed for the management of HBV infection on the graft, so outcome is currently good.

Management of HBV Infection in Liver Transplantation Patients

In the absence of preventative therapy, reinfection of allografts with hepatitis B virus (HBV) after orthotopic liver transplantation (OLT) resulted in dismal allograft and patient survival. Major advances in the management of HBV-infected recipients of OLT during the past 15 years have steadily reduced the rate of reinfection, resulting in improved outcomes. Initially, long-term use of hepatitis B immune globulin (HBIG) as a source of anti-HBs antibodies was effective in preventing or delaying reinfection. Lamivudine monotherapy made it possible to suppress HBV replication prior to OLT, markedly decreasing the risk of reinfection. Although lamivudine monotherapy used before and after OLT could prevent reinfection, its effectiveness was limited by progressive development of lamivudine-resistant mutant infections. Combination therapy with HBIG and lamivudine after OLT reduced both HBV recurrence and the risk of lamivudine resistance even in patients with active HBV replication. Introduction of adefovir provided a safe, alternative oral antiviral able to treat effectively lamivudine-resistant mutants HBV. Available strategies to prevent reinfection have resulted in OLT outcomes for HBV-infected patients comparable to those for patients transplanted for non-HBV indications. In the future, combination therapies of HBIG and both nucleoside and/or nucleotide agents will undoubtedly be optimized. Development of new drugs to treat HBV will increase opportunities to combine agents to enhance safety, efficacy and prevent emergence of HBV escape mutants. New vaccines and adjuvants may make it possible to generate anti-HBs in immunosuppressed patients, eliminating the need for HBIG.

Nucleoside analogues and other antivirals for treatment of hepatitis B in the peritransplant period

Chronic HBV infection is a common cause of advanced liver disease that is associated with substantial mortality. Furthermore, chronic hepatitis B was historically a controversial indication for liver transplantation because of a low post-transplant survival, with graft infection being the major contributor to adverse outcomes. The initial use of hepatitis B immune globulin as prophylaxis, followed later by combined therapy with lamivudine, markedly reduced viral recurrence and improved the survival of patients transplanted for acute or chronic hepatitis B with liver failure. Lamivudine alone can also be used for long-term prophylaxis against de novo HBV infection that can be transmitted by organs from donors positive for anti-HBc or anti-HBs. When used in patients with decompensated chronic hepatitis B with cirrhosis, lamivudine has been shown to improve clinical manifestations, prolong pretransplant survival, and defer, or even obviate, the need for transplantation. Despite prophylaxis, viral mutations with breakthrough reinfection may occur and lead to liver failure. The recently approved adefovir dipivoxil, which is active against lamivudine-resistant mutation, and other nucleoside analogs that are in various phases of development, offer hope as rescue therapy for viral recurrence. Other therapeutic alternatives in the future may include gene therapy and immune interventions.

Prevention of and treatment for hepatitis B virus infection after liver transplantation in the nucleoside analogues era

Post-transplant prophylaxis with hepatitis B immune globulin (HBIG) has significantly reduced hepatitis B virus (HBV) recurrence rates, but it is rather ineffective in patients with pretransplant viremia. Moreover, long-term HBIG administration is very expensive and may be associated with emergence of escape HBV mutants. Lamivudine has been widely used in the management of HBV transplant patients. Pretransplant lamivudine lowers HBV viremia, decreasing the risk of post-transplant HBV recurrence, but to try and minimize development of resistant HBV strains, it should start within the last 6 months of the anticipated transplantation timing. Preemptive post-transplant lamivudine monotherapy is associated with progressively increasing HBV recurrence rates, but combined therapy with lamivudine and HBIG at relatively low dosage is currently the most effective approach in this setting, even in HBV-DNA-positive patients, who also receive lamivudine in the pretransplant period. The most frequent therapy for post-transplant HBV recurrence is lamivudine, but the increasing resistance rates represent a rather challenging problem. Adefovir dipivoxil and entecavir are currently the most promising agents for lamivudine-resistant HBV strains. All these advances in anti-HBV therapy have made HBV liver disease an indication for liver transplantation irrespective of viral replication status, a complete turn around from 10 years ago.

Successful treatment of fibrosing cholestatic hepatitis using adefovir dipivoxil in a patient with cirrhosis and renal insufficiency

Fibrosing cholestatic hepatitis is a deleterious manifestation of hepatitis B virus infection in immunocompromised patients. Without treatment, this condition is usually fatal within weeks of onset. Liver retransplantation has not been successfully performed to date, and treatment intervention was generally unsuccessful before the advent of adefovir dipivoxil. However, concerns have been expressed about the use of this agent in patients who are renally compromised. A 40-year-old liver transplant recipient with hepatitis B virus reinfection, resistance to lamivudine, and fibrosing cholestatic hepatitis complicated by terminal renal impairment and spontaneous bacterial peritonitis was treated with adefovir dipivoxil 10 mg after every dialysis. Since initiating treatment with adefovir dipivoxil 10 mg, a dramatic virologic and clinical improvement was observed in this patient. The patient returned to work full-time within 6 months of starting adefovir dipivoxil without the need for liver retransplantation. Serum HBV DNA (Amplicor HBV; Roche Diagnostics, Basle, Switzerland) decreased by 6 log(10) copies/mL and became negative (< 400 copies/mL) within 8 weeks of treatment and remains negative at the last available assessment. The patient continues to require renal dialysis, but is generally well. Creatinine clearance improved from 8 mL/min to 16 mL/min during the course of treatment. No adverse events related to adefovir dipivoxil were observed. Adefovir dipivoxil resulted in significant clinical improvement in this patient with hepatitis B virus-induced fibrosing cholestatic hepatitis, despite the presence of renal impairment and lamivudine resistance.

Oral ganciclovir for treatment of lamivudine-resistant hepatitis B virus infection: a pilot study

Although liver disease seems to be stable in most patients who are infected with lamivudine-resistant mutant hepatitis B virus (HBV) in the short term, it may progress to more-advanced disease in some patients. In our pilot study, we investigated the efficacy of oral ganciclovir for the treatment of lamivudine-resistant HBV infection. Six patients infected with lamivudine-resistant HBV (3 patients had decompensated cirrhosis and 3 had chronic active hepatitis without cirrhosis) were included. Ganciclovir was administered at a dosage of 3 g daily for 6 months. Four of 6 patients completed the 6-month treatment period. Two patients with cirrhosis completed only 2 months of ganciclovir treatment because they died of cirrhosis complications. None of the patients had a > or =2-log(10) reduction of HBV DNA and complete alanine aminotransferase normalization at the end of their treatment regimens. In conclusion, 6 months of ganciclovir treatment is not effective for suppression of lamivudine-resistant HBV infection.

Nucleoside analogues for chronic hepatitis B: antiviral efficacy and viral resistance

Nucleoside analogues have been recently introduced in the management of chronic hepatitis B virus (HBV) infection. They mainly act by inhibition of HBV polymerase activity resulting in decrease of viral replication. They are administered orally, and most of them have an excellent tolerance and safety profile. Lamivudine is the only nucleoside analogue licensed for chronic hepatitis B. It has potent activity against HBV, and a 12-month course achieves clearance of hepatitis B e antigen (HBeAg) in 20-30% of HBeAg-positive patients and both biochemical and virological remission in more than 65-70% of HBeAg-negative chronic hepatitis B patients. Famciclovir and ganciclovir are less effective, whereas other nucleoside or nucleotide analogues, such as adefovir, entecavir, and emtricitabine, are currently under evaluation. Prolonged effective antiviral therapy is required for eradication of chronic HBV infection, but long-term treatment with nucleoside analogues has been found to be associated with progressively increasing rates of viral resistance because of emergence of resistant HBV mutant strains. Virological breakthroughs usually develop after the first 6 months of lamivudine monotherapy, and their rate ranges between 15% and 30% at 12 months and exceeds 50% after 3 yr of therapy. Resistant HBV mutant strains harbor point mutations in the HBV polymerase gene and predominantly in the well-conserved YMDD motif. Although resistant HBV strains may have impaired replication capacity compared with the wild HBV, their clinical significance has not been completely clarified yet. No significant biochemical or clinical event may develop in some cases, whereas severe biochemical breakthroughs with or without deterioration of liver function may develop in others. To date, there is no proven effective therapy for the resistant HBV mutant strains, although adefovir and entecavir seem to be interesting candidates.

Chronic hepatitis B: current and future treatment options

Hepatitis B, a major viral infection that can lead to cirrhosis and hepatocellular carcinoma, is the ninth most common cause of death worldwide. Prevention of hepatitis B virus transmission is key to reducing the spread of this serious condition. Management of chronic hepatitis B requires significant knowledge of approved pharmacotherapeutic agents and their limitations. Today, agents approved by the Food and Drug Administration for this infection are interferon-alpha-2b and lamivudine. Newer agents are being developed and hold promise: adefovir, famciclovir, ganciclovir, lobucavir, entecavir, emtricitabine, L-deoxythymidine, clevudine, a therapeutic vaccine, and thymosin alpha-1. Therapeutic options for managing hepatitis infection after liver transplantation are also evolving. These include hepatitis B immunoglobulin and nucleoside analogues.

A concise update on the status of liver transplantation for hepatitis B virus: the challenges in 2002

Significant improvements in both patient and graft survival after orthotopic liver transplantation (OLT) for hepatitis B virus (HBV)-related liver failure have been made during the last decade. Recurrence of HBV infection has decreased, even in high-risk patients. Despite ongoing progress, challenges remain for the next millennium, including the determination of cost-effective dosing strategies, treatment of HBV infection in liver transplant recipients, and ramifications of the use of new antiviral agents, specifically, the appearance of resistant strains. This review summarizes the relevant history of OLT for chronic viral hepatitis B, details accepted preventive and therapeutic treatments, and discusses ongoing experimental trials. Emphasis also is placed on new approaches in transplantation as they impact on the care of HBV-infected patients.

Diagnosis and management of pre-core mutant chronic hepatitis B

Chronic hepatitis due to pre-core hepatitis B virus (HBV) mutants presents as hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB). HBeAg-negative CHB represents a late phase in the natural course of chronic HBV infection that develops after HBeAg loss and seroconversion to anti-HBe. It is usually associated with pre-core stop codon mutation at nucleotide 1896 (mainly selected in non-A HBV genotypes), but also with other pre-core changes or with mutations in the basic core promoter region (mainly in HBV genotype A). In chronic HBV infections, pre-core mutants can be detected both in patients with HBeAg-negative CHB and in inactive hepatitis B surface antigen (HBsAg) carriers. The diagnosis of HBeAg-negative CHB is based on HBsAg positivity, HBeAg negativity, and mainly on increased alanine aminotransferase (ALT) and serum HBV-DNA levels and exclusion of other causes of liver disease. The differential diagnosis between patients with CHB and inactive HBsAg carriers can be made only by close follow-up of aminotransferase activity and viraemia levels, although the cut-off level of serum HBV DNA has not been definitely determined. IgM anti-HBc levels have also been suggested as an index that increases the diagnostic accuracy for transient hepatitis flares, while liver biopsy confirms the diagnosis and evaluates the severity of the liver disease. Interferon-alpha (IFN-alpha) and lamivudine are the two drugs that have been tried, mainly in the management of HBeAg-negative CHB. A 12-month course of IFN-alpha achieves sustained biochemical remission in about 20% of patients, which has been associated with improvement in the long-term outcome of this subset. A 12-month course of lamivudine is rather ineffective, maintaining remission in less than 15% of patients after cessation of therapy. Long-term lamivudine is associated with progressively increasing rate of virological and subsequent biochemical breakthroughs due to YMDD mutants, with approximately 30% of patients remaining in remission in the third year of therapy. Several other antiviral agents are currently being evaluated in this setting with combined regimens being the most reasonable step for the near future.

Clinically relevant sequence-based genotyping of HBV, HCV, CMV, and HIV

The term 'genotyping' describes the genetic characterization of a genome. The genotype analysis is performed to identify mutations that differentiate one individual or strain from another. The mutations may confer resistance to specific antiviral drugs or they may simply allow classification of a strain as to 'type' and 'subtype'. There are four human viruses for which genotype information is clinically useful. Hepatitis B virus (HBV) infections are being treated with antiretroviral drugs and resistance after prolonged treatment is common. Since HBV cannot be cultured, the only method of detecting resistance-conferring mutations in the genome is a genotypic analysis. Hepatitis C virus (HCV) infection can be cured by treatment with the combination of interferon and ribavirin but certain strains of virus are more resistant to treatment than others. The current recommendations are that all HCV type 1 infections be treated for 12 months whereas other types may be successfully treated in 6 months. Since interferon treatment may have significant side effects, the determination of HCV genotype is an important aspect of this therapeutic regimen. Treatment of cytomegalovirus (CMV) disease with nucleoside analogues occasionally results in resistant virus with mutations in the phosphotransferase gene (UL97) and/or the DNA polymerase gene (UL54) that can be tested with phenotypic or genotypic assays. Since CMV grows very slowly, it may be more clinically useful to perform a rapid genotypic assay although only the UL97 gene can be efficiently genotyped. Finally, the virus for which genotyping has become the standard of care, human immunodeficiency virus type 1 (HIV-1) can now be genotyped routinely by many clinical virology labs experienced with molecular amplification methods and automated DNA sequencing technology. All currently-available antiretroviral drugs are directed against either the protease or reverse transcriptase genes of HIV-1 and the mutations within these genes that confer resistance have been well described. Sequence-based genotyping methods are not necessarily the best approach for routine genotyping of these four viruses, but sequencing is the gold standard from which other methods are developed and against which they are compared.

Combination chemotherapy for hepatitis B virus: the path forward?

Hepatitis B virus (HBV) was identified as a cause of viral hepatitis more than 30 years ago and hepatitis B vaccines have been available for almost 20 years, but HBV infection continues to be a global health problem, responsible for about 1.2 million deaths annually. By the end of this year, almost 400 million people--about 5% of the world's population and more than ten times the number infected with human immunodeficiency virus (HIV)--will be infected with HBV. Chemotherapy remains the only treatment option for controlling chronic HBV infection once acquired, but none of the many different chemotherapeutic strategies used in the past has proven consistently successful. Prospects for successful treatment of HBV have improved dramatically during the past decade due to the development of new, well tolerated and efficacious anti-HBV drugs, and to advances in our understanding of HBV replication and pathogenesis. The newer anti-HBV drugs are capable of reducing viral loads very rapidly, but the initial response is invariably followed by very much slower elimination of residual virus. As more effective anti-HBV drugs become available, the emergence of drug resistance during the slower phase of HBV elimination will probably become the most significant obstacle in the way of eventual control of HBV infection. Experience with HIV indicates that combination chemotherapy may suppress or eliminate drug resistance and methods for pre-clinical and clinical assessment of anti-HBV drug combinations are being developed. Basic research into mechanisms of drug action and interaction should assist in the design and optimisation of combination chemotherapy for HBV infection, for which additional new anti-HBV drugs will undoubtedly be required in future.