Adefovir treatment in posttransplant hepatitis B virus infection resistant to lamivudine plus hepatitis B virus immunoglobulin

Current management of hepatitis B virus infection before and after liver transplantation

The progress in treatment against hepatitis B virus (HBV) has substantially improved the outcome of all HBV-infected patients. We systematically reviewed the existing data in the management of HBV transplant patients in order to assess the optimal regimen in the pretransplant setting, for post-transplant prophylaxis and for therapy of HBV recurrent infection. All data suggest that an effective pretransplant anti-HBV therapy prevents post-transplant HBV recurrence. Pretransplant therapy has been based on lamivudine with addition of adefovir upon lamivudine resistance, but the use of newer, potent high-genetic barrier agents is expected to improve long-term efficacy. Moreover, it may lead to improvement of liver function, which sometimes removes the need for transplantation, although more objective criteria for removal from waiting lists are required. After liver transplantation, the combination of HBV immunoglobulin and one nucleos(t)ide analogue, mostly lamivudine, is currently the best approach, almost eliminating the probability of HBV recurrence. Treatment of post-transplant HBV recurrence has been mainly studied with lamivudine, but it will be most effective with entecavir and tenofovir, which have a low risk of resistance. In conclusion, the newer anti-HBV agents improve the treatment of HBV both pretransplant and post-transplant. HBV immunoglobulin is still used in combination with an anti-HBV agent for post-transplant prophylaxis. Monoprophylaxis with one of the new anti-HBV agents might be possible, particularly in patients preselected as having a low risk of HBV recurrence, but further data are needed and strategies to ensure compliance must be used.

Adefovir dipivoxil therapy in liver transplant recipients for recurrence of hepatitis B virus infection despite lamivudine plus hepatitis B immunoglobulin prophylaxis

BACKGROUND

Treatment of post-transplantation recurrence of hepatitis B virus (HBV) infection despite prophylaxis with hepatitis B immunoglobulin (HBIG) and lamivudine combination therapy is not easy. Because HBV reinfection has a severe course and could result in graft failure in liver transplant recipients, prompt medication is essential. Herein is reported the authors' experience with adefovir dipivoxil (AD) therapy in 11 liver transplant recipients who had HBV reinfection despite the administration of lamivudine and HBIG.

METHOD

Two-hundred and nine patients underwent liver transplantation (100 deceased donor liver transplantations [DDLT], 109 living donor liver transplantation [LDLT]) due to chronic hepatitis B infection between April 1997 and May 2005 in Ege University Medical School, Liver Transplantation Unit. Patients had prophylaxis with lamivudine and low-dose HBIG combination after liver transplantation. Treatment of recurrence consisted of AD 10 mg once a day and lamivudine 300 mg/daily and HBIG was discontinued in those patients.

RESULTS

In total there were 11 HBV recurrences: five occurred in DDLT recipients and six in LDLT recipients, at a median follow up of 18 months (range, 6-48 months). In one of 11 patients, pretransplant HBV-DNA and HBeAg were positive. Three patients had a severe course and one patient had fibrosing cholestatic hepatitis. After AD treatment, HBV-DNA level decreased in all patients and became negative in seven patients. Two patients died due to hepatocellular carcinoma recurrence after 12 and 14 months of follow up. Serum creatinine level increased mildly in one patient and no other side-effect was observed, and all patients continued therapy.

CONCLUSION

Adefovir dipivoxil is a safe, effective treatment option for post-transplant HBV recurrence even among patients with fibrosing cholestatic hepatitis caused by lamivudine-resistant HBV.

Hepatitis B in liver transplant recipients

1. The use of low-dose immunosuppressive therapy along with pre- and posttransplantation nucleos(t)ide therapy and posttransplantation hepatitis B immunoglobulin (HBIG) has yielded marked improvements in survival. 2. Lamivudine (Epivir-HBV), adefovir (Hepsera), entecavir (Baraclude), tenofovir (Viread), emtricitabine (Emtriva), and the combination drugs tenofovir + emtricitabine (Truvada) and abacavir + lamivudine (Epzicom) are effective nucleos(t)ide antiviral agents that, in some cases, may help reverse liver disease sufficiently to avoid transplant. 3. In posttransplantation patients, virus suppression with some combination of HBIG and the nucleos(t)ide agents may prevent graft loss and death or the need for a second transplant. 4. In both the pre- and posttransplantation setting, the goal of hepatitis B virus management is complete virus suppression. 5. The use of low-dose intramuscular HBIG is evolving, with studies showing that dosing and cost can be reduced by 50-300% with a customized approach. 6. Elimination of HBIG from the treatment paradigm is currently under evaluation and may be possible with the use of newer medications that have no or low resistance rates. 7. Although there is growing evidence that some types of combination therapy may decrease the chance that drug resistance will develop and increase the likelihood of long-term success in preventing graft loss and death, additional research will be required to determine which combinations will work well in the long term, and which will not.

Where does adefovir stand amongst newly developed antivirals: from pharmacology to virology

Adefovir, an acyclic nucleotide analog of adenosine monophosphate, has demonstrated potent activities against several viruses in vitro. Since 2002, the diester prodrug of this molecule, adefovir dipivoxil, has been approved as a well-tolerated and efficacious treatment for chronic hepatitis B. It is the first nucleotide analog to be approved for this indication and it is now challenged by several other molecules that also inhibit hepatitis B virus replication. In this article, we analyze the strengths and limitations of adefovir in the context of hepatitis B treatment and consider the other alternatives in the treatment of this difficult-to-treat chronic disease. Adefovir dipivoxil has offered a real opportunity for patients who developed lamivudine resistance and were facing a therapeutic deadlock; the next challenge for clinicians will be to offer the best therapeutic strategy to limit the inexorable selection of resistant strains.

Prevention and treatment of recurrent Hepatitis B after liver transplantation: the current role of nucleoside and nucleotide analogues

The Hepatitis B virus (HBV) is a DNA virus that can cause both acute and chronic liver disease in humans. Approximately 350–400 million people are affected worldwide and up to one million deaths occur annually from cirrhosis and hepatocellular carcinoma. When cirrhosis and liver failure develop, the definitive treatment of choice remains orthotopic liver transplantation (OLT). In the past, an unacceptable HBV recurrence rate with a high rate of graft loss was noted. The use of Hepatitis B immunoglobulin (HBIG) has resulted in improved patient and graft survival rates. The addition of the nucleoside analog Lamivudine (LAM) to HBIG has improved these survival curves to an even greater degree. Prolonged use of LAM will almost invariably lead to the development of viral mutations resistant to the drug. There are now several other nucleoside and nucleotide analogs (Adefovir, Entecavir, Tenofovir, and Truvada) available for the clinician to utilize against these resistant strains. It should be possible to prevent recurrence in most, if not all, post-transplant patients and also to significantly reduce viral loads with normalization of transaminases in those who have developed recurrent infection. The antiviral regimen should be robust and minimize the risk of breakthrough mutations. A prudent approach may be the implication of combination antiviral therapy. This review summarizes the efficacy of previous regimens utilized to prevent and treat recurrent HBV following OLT. Particular attention will be paid to the newer nucleoside and nucleotide analogs and the direction for future strategies to treat HBV in the post transplant setting.

Synthesis and in vitro anti-hepatitis B and C virus activities of ring-expanded ('fat') nucleobase analogues containing the imidazo[4,5-e][1,3]diazepine-4,8-dione ring system

As part of our structure-activity relationship studies, we report here the synthesis and in vitro anti-HBV and anti-HCV activities of a number of ring-expanded ('fat') nucleobases containing the imidazo[4,5-e][1,3]diazepine-4,8-dione ring system. One of the compounds, ZP-88, exhibited a good activity/toxicity profile against HBV by inhibition of the synthesis of extracellular virion release (EC(50)=1.7microM, CC(50)=286microM, SI=168) and intracellular HBV replication intermediates (EC(50)=8.4microM, CC(50)=286microM, SI=34) in cultured human hepatoblastoma 2.2.15 cells. By contrast, most of the compounds tested against HCV had only marginal activity/toxicity profile, although that was still better than that of the reference compound ribavirin.