Lamivudine prophylaxis against reinfection in liver transplantation for hepatitis B cirrhosis

Liver transplantation for hepatitis B virus. Pre-emptive and peri-operative prophylaxis

In the past, reinfection of the graft by hepatitis B virus (HBV) after liver transplantation for HBV-related liver disease was often followed by severe liver damage and reduced survival. The long-term administration of hepatitis B immunoglobulin (HBIG) dramatically reduced this risk. However, this procedure was ineffective in most patients with active viral replication pre-transplant. The use of lamivudine in the pre-transplant setting partially solved this problem. The emergence of resistant mutants to lamivudine was also solved by the addition of adefovir. At present, combination therapy by oral antivirals pre-transplant and HBIG plus the same drugs post-transplant achieves nearly 100% of protection against graft reinfection. In a recent study, a new intravenous HBIG, Niuliva has shown high efficacy in achieving protective anti-HBs levels after liver transplantation for HBV-related liver diseases, as well as a good safety profile. Using combination therapies, the doses of HBIG can be reduced or even stopped after several weeks or months post-transplant, continuing with oral antivirals alone. The recently introduced antivirals achieve a very high antiviral potency and low risk of resistance. This may further increase the efficacy in preventing graft reinfection in the post-liver transplantation setting.

The option of liver transplantation for hepatitis B: where are we?

Combination therapy with hepatitis B immunoglobulin (HBIG) plus nucleos(t)ide analogue have reduced the rate of hepatitis B virus (HBV) recurrence post-transplantation to less than 10% at long-term. HBV recurrence diagnosed after 3 years post-transplantation is extremely rare. Considering the cost and the constraints of HBV prophylaxis it was suggested to decrease the amount of HBIG given and possibly to discontinue HBIG administration. The additional debate was on the need to maintain or not any HBV prophylaxis at long-term or to maintain monoprophylaxis with one or two nucleos(t)ide analogues or to administer HBV vaccine: The supporters of this strategy argued that HBV recurrence can be easily controlled by administration of nucleos(t)ide analogues. However, it was shown that 50-80% of patients maintain HBV DNA in the liver, serum or peripheral mononuclear blood cells long-term after transplantation. In patients receiving monoprophylaxis with nucleos(t)ide analogues the risk of HBV reinfection increases with time due to HBV mutant strains. Vaccine protocols used to replace HBIG prophylaxis gave disappointing results. Combination protocols using low-doses of intramuscular HBIG plus nucleos(t)ide analogues have been associated with a low rate of HBV reinfection. In conclusion, long-term prophylaxis should be maintained in most patients except those with anti-HBs seroconversion.

Liver transplantation in viral hepatitis: prevention of recurrence

End-stage liver disease caused by the hepatitis B and C viruses (HBV and HCV) are major indications for liver transplantation. Outcome depends largely on the prevention of allograft reinfection. The advent of long-term hepatitis B immune globulin administration and the introduction of new antiviral agents were a major breakthrough in the management of these patients. Today, survival after orthotopic liver transplantation (OLT) is similar to that of patients transplanted for HBsAg-negative liver disease, and the risk of recurrence is below 10%. In contrast, HCV reinfection is almost constant and significantly impairs patient and graft survival. Factors that may influence disease severity and consequently progression of HCV graft injury remain unclear. Pre-transplantation and prophylactic post-transplantation antiviral treatments are limited by low applicability and poor tolerance. Treatment of established graft lesions with combination therapy gave promising results, with sustained virological response in 25-45% of patients, but indications, modality and duration of treatment should be assessed.

A randomized study of adefovir dipivoxil in place of HBIG in combination with lamivudine as post-liver transplantation hepatitis B prophylaxis

Prior to effective prophylaxis, liver transplantation for hepatitis B virus (HBV)-related disease was frequently complicated by recurrence, which could be severe and rapidly progressive. Combination hepatitis B immunoglobulin (HBIG) and lamivudine prophylaxis reduces this rate of recurrence to <5% at 5 years; however, HBIG administration is costly and inconvenient. We conducted a multicenter randomized study of adefovir dipivoxil substitution for low-dose intramuscular (IM) HBIG in patients without HBV recurrence at least 12 months posttransplantation for HBV-related disease. Thirty-four patients were randomized, 16 to adefovir (1 patient withdrew consent at 3 months and is not considered in the results) and 18 to continue HBIG. All continued lamivudine. Groups were well matched by age, sex, and time since transplantation (median, 4.5 years), and background virological risk for HBV recurrence (30% of patients in the adefovir group, 24% in the HBIG group having detectable HBV DNA at transplantation). All patients were alive at study completion without recurrence. One patient in the adefovir group became hepatitis B surface antigen-positive at 5 months but was persistently HBV DNA undetectable via polymerase chain reaction (sensitivity 14 IU/mL) over the following 20 months. Median creatinine was not significantly changed over the course of the study in either group. One patient in the adefovir group with a background of diabetic and hypertensive nephropathy (baseline creatinine 150 micromol/L) developed increased creatinine leading to dose reduction and ultimately cessation of adefovir at 15 months. Yearly cost of combination adefovir/lamivudine prophylaxis was $8,290 versus $13,718 IM HBIG/lamivudine.

CONCLUSION

Compared with combination HBIG plus lamivudine prophylaxis, combination adefovir plus lamivudine provides equivalent protection against recurrent HBV infection but with better tolerability and less cost.

[Liver transplantation for chronic hepatitis B]

Liver transplantation for hepatitis B represents 5-10 % of all liver transplantations performed in Europe. The prognosis after liver transplantation is related to the efficacy of prophylaxis of HBV graft reinfection. The risk of HBV reinfection is directly related to the HBV viral load at transplantation. HBV prophylaxis after transplantation with long-term administration of anti-HBS immune globulins (HBIG) or with monoprophylaxis with lamivudine can reduce significantly the risk of HBV recurrence mainly in patients without active HBV replication. Antivirals such as lamivudine, adefovir, entecavir or tenofovir can control HBV replication in patients with decompensated HBV cirrhosis waiting for transplantation. However, there is a risk of HBV viral breakthrough during nucleo (t) side antiviral treatment. The use of an antiviral alone or in combination should take into account the antiviral efficacy and the risk of viral resistance. The post-transplant combination of antiviral therapy and HBIG prophylaxis is very effective in reducing the rate of HBV reinfection to less than 10 % even in patients with HBV replication at transplantation. In the absence of active viral replication at transplantation, the possibilty to discontinue HBIG prophylaxis at long-term after transplantation with maintenance of antiviral treatment or HBV vaccination is in evaluation. The use of new antiviral therapies (nucleos(t)ide analogues) has dramatically improved the prognosis of patients with HBV reinfection of the graft. The current 5-year survival after liver transplantation for HBV related liver disease is 85 %. In conclusion, the prophylaxis of HBV reinfection combining antiviral therapy prior to transplantation, and combination of HBIG and antiviral therapy post-transplantation is effective in reducing the rate of HBV reinfection to less than 10 %.

Liver transplantation for hepatitis B: what is the best hepatitis B immune globulin/antiviral regimen?

1. Prophylaxis using the combination of lamivudine and high-dose intravenous hepatitis B immunoglobulin (approximately 10,000 IU monthly) reduces the long-term risk of recurrence of hepatitis B in hepatitis B surface antigen-positive transplant recipients to 5% to 10%. However, this therapy is expensive and inconvenient for patients. 2. Recent studies have shown that similar results can be obtained, at far less cost, with much lower doses of intramuscular hepatitis B immune globulin (400-800 IU monthly) in combination with pretransplant and posttransplant lamivudine therapy. 3. The development of lamivudine resistance pre-transplant can lead to hepatic decompensation and increases the risk of posttransplant recurrence in patients receiving hepatitis B immune globulin/lamivudine prophylaxis. Newer nucleos(t)ide analogues with lower resistance rates such as entecavir, adefovir, and tenofovir should therefore replace lamivudine in hepatitis B prophylaxis. 4. Combination therapy with these newer agents and low-dose intramuscular hepatitis B immune globulin is likely to be the most cost effective hepatitis B immune globulin-containing regimen for the prevention of hepatitis B recurrence post-transplant. 5. Some form of hepatitis B virus prophylaxis needs be continued indefinitely post-transplant. However, the use of antivirals with very low rates of drug resistance will make it possible to stop hepatitis B immune globulin therapy in many patients currently receiving hepatitis B immune globulin/nucleos(t)ide combination therapy.

Management of patients with decompensated hepatitis B virus associated [corrected] cirrhosis

1. Hepatitis B virus replication is associated with a severe outcome in patients with decompensated cirrhosis. 2. Viral suppression induced by antivirals results in a clinical improvement that allows liver transplantation to be delayed or avoided. 3. Early treatment intervention is mandatory in patients with decompensated cirrhosis because of the delay in the restoration of liver functions. 4. Lamivudine is no longer the drug of choice because the initial enthusiasm has been tempered by the high rate of resistance development. 5. Early add-on therapy with adefovir allows us to rescue lamivudine resistance, but its use may be limited by nephrotoxicity. 6. Studies are ongoing with the newer generation of antivirals (telbivudine, tenofovir, entecavir, and emtricitabine) in monotherapy or in combination to determine the best strategy for achieving rapid and prolonged suppression of viral replication. These improved strategies should enhance treatment success enough to obtain clinical stabilization, to delay or prevent the need for transplantation, and to reduce the risk of hepatitis B virus recurrence on the graft.AASLD.

Hepatitis B reactivation after chemotherapy: two decades of clinical research

Hepatitis due to hepatitis B virus reactivation after cytotoxic or immunosuppressive therapy is a serious cause of liver-related morbidity and mortality. With the characterization of the underlying pathogenesis, much progress in the management of this important clinical problem has been made in the past 2 decades. By year 2008, it is mandatory to screen for hepatitis B surface antigen status before initiating intensive chemotherapy or immunosuppressive therapy. All those who are hepatitis B surface antigen positive should be started on preemptive nucleos(t)ide analogues. However, there remains important issues, such as the type and duration of nucleos(t)ide analogue therapy, which need to be understood. As not all hepatitis B surface antigen-positive patients will suffer from HBV reactivation, it is therefore useful to identify risk factors related to HBV reactivation so that patients will not be treated unnecessarily with nucleos(t)ide analogues. To date, a high baseline level of viral replication, as reflected by high serum HBV DNA level, positive serum hepatitis B e antigen, and a high intrahepatic covalently closed circular DNA level, is the most important predictor for HBV reactivation. Recently, there has been an increased awareness of reactivation of occult hepatitis B virus, especially in hepatitis B virus endemic area, such as the Asia-Pacific region. Careful epidemiological study will be needed to clarify the impact of occult hepatitis B infection in patients treated with cytotoxic or immunosuppressive therapy.

Viral persistence after liver transplantation for hepatitis B virus: a cross-sectional study

BACKGROUND

Prophylaxis to prevent recurrent HBV infection in liver transplant (LT) recipients has evolved over time, and we manage patients who receive lamivudine monoprophylaxis, lamivudine with HBV immunoglobulin (HBIg), and lamivudine and adefovir with HBIg.

METHODS

Serum was examined with sensitive assays to detect the persistence of HBV, and to identify mutations that might confer resistance to the antiviral prophylaxis. Forty patients were studied, and sera were collected 20 days to 13.3 years after LT.

RESULTS

Overall, HBV DNA was detected in serum of 67.5% of patients (8 of 10 of lamivudine monoprophylaxis patients, 15 of 24 of those receiving lamivudine and HBIg, and 4 of 6 of those receiving lamivudine, adefovir and HBIg). Thus, HBV infection persists for most of the patients despite successful prophylaxis after LT. Of those patients with detectable serum HBV DNA, three of eight of the lamivudine monoprophylaxis group had sequences associated with resistance to lamivudine (YMDD mutants), compared with only 1 of 15 of the lamivudine and HBIg cohort. Three of the lamivudine and HBIg cohort had the I126A Hepatitis B surface antigen escape variant. In those serum HBV DNA-positive patients who were receiving lamivudine, adefovir, and HBIg, only one of four had YMDD mutant, and none had Hepatitis B surface antigen escape variants. None of the 40 patients suffered clinical HBV recurrence.

CONCLUSIONS

Our observations imply that the selection of resistant virus may be essential, but is not sufficient to cause overt failure of prophylaxis with development of clinical disease. It seems likely that the patients' immune response contributes, at least partially, to the long-term control of infection in these patients.

Living donor liver transplantation for hepatitis B cirrhosis

BACKGROUND AND AIM

Living donor liver transplantation (LDLT) has particular advantages for Turkey where hepatitis B virus (HBV) infection is the most common cause of cirrhosis, both because LDLT circumvents the difficulties encountered in the emerging world in providing deceased donor organs, and because it allows preemptive antiviral therapy. The aim of this study was to review one institution's experience with LDLT in patients with chronic HBV infection.

METHODS

A total of 109 patients with chronic HBV infection underwent LDLT between September 1999 and June 2005, of whom 40 were coinfected with hepatitis D virus and 23 had hepatocellular carcinoma. Antiviral prophylaxis was attempted in all, beginning prior to transplantation with lamivudine or adefovir, and continuing after transplantation with low dose intramuscular hyperimmune B immunoglobulin (HBIg) plus lamivudine or adefovir.

RESULTS

In a median follow up of 20 months (range 1-66 months), there was no donor mortality. One-year recipient survival was 90%, and in total 16 recipients died. None of the deaths was related to HBV. Recurrence of HBV infection was detected by reappearance of serum hepatitis B surface antigen in six patients (5.5%) at 5, 8, 12, 17, 34 and 46 months after transplantation, respectively. There was no influence of donor hepatitis B core antibody status on the likelihood of recurrence of HBV in the allograft.

CONCLUSION

The results indicate that LDLT with antiviral treatment and low dose HBIg provides excellent results for donors and recipients.

Recurrent viral liver disease (hepatitis B and C) after liver transplantation

Hepatitis C represents more than 35% of liver transplant candidates worldwide. Meanwhile, hepatitis B continues to be an important cause of end-stage liver disease and hepatocellular carcinoma in Asia and Africa. Recurrent viral liver disease is a significant event after liver transplantation and continues to be one of the main causes of graft dysfunction and loss in the middle and long-term follow-up. Mechanisms of liver reinfection and disease recurrence vary between these two viruses and pre-emptive as well as the therapeutic approaches are different. Hepatitis B patients can be managed with immune globulin immediately after liver transplant and various agents such as nucleotide and nucleoside analogues can be associated. As a result, disease recurrence has been delayed or prevented in these patients. Individuals transplanted for hepatitis C are known to have universal reinfection and a high rate of disease recurrence has been reported in the literature. Strategies to treat hepatitis C recurrence are limited to the use of pegylated interferon and ribavirin when disease is demonstrated histologically and biochemically, although other strategies have been described with limited or no success. We herein review the mechanisms of disease recurrence and the current as well as the future therapeutic approaches to prevent and to treat these diseases.

Prophylaxis of Recurrent Hepatitis B in Chinese Patients After Liver Transplantation Using Lamivudine Combined With Hepatitis B Immune Globulin According to the Titer of Antibody to Hepatitis B Surface Antigen

BACKGROUND/AIMS

We sought to determine the outcomes of long-term use of lamivudine combined with hepatitis B immune globulin according to the titer of antibody to hepatitis B surface antigen in preventing recurrent hepatitis B in Chinese patients after liver transplantation.

METHODS

Eighty-five patients with detectable hepatitis B envelope antigen in serum before liver transplantation were retrospectively enrolled in the study. Twenty-eight patients used lamivudine monotherapy as a control group. Fifty-seven patients used lamivudine combined with hepatitis B immune globulin therapy according to the titer of antibody to hepatitis B surface antigen.

RESULTS

In the lamivudine monotherapy group, seven patients had recurrent hepatitis B after transplantation, with 1-, 2-, and 3-year recurrence rates of 10.70%, 21.90%, and 25.8%, respectively. In the combination therapy group, three patients had recurrent hepatitis B after transplantation, with 1-, 2-, and 3-year recurrence rates of 0.00%, 5.50%, and 13.40% (P = .03). YMDD mutants were detected in 6 of the 10 patients with recurrent hepatitis B. HBV-DNA load before transplantation was significantly associated with recurrent hepatitis B after transplantation in the overall patients (P = .04).

CONCLUSIONS

Long-term use of lamivudine combined with hepatitis B immune globulin, according to the titer of antibody to hepatitis B surface antigen was efficacious and cost effective to prevent recurrent hepatitis B in Chinese patients after liver transplantation.

Prevention of hepatitis B virus recurrence after liver transplantation

Liver transplantation for hepatitis B virus (HBV)-related liver disease has changed from a contraindication to outcomes comparable with non-HBV-related liver transplantations during the last two decades. Mainly the implementation of immunoprophylaxis with hepatitis B immunoglobulin (HBIG) and the use of nucleoside analogs such as lamivudine and adefovir account for this dramatic change. The standard of care in most centers today consists of lamivudine treatment in replicating hepatitis B pre-orthotopic liver transplantation (OLT) and a combination regimen of lamivudine and HBIG post-OLT. With adefovir, a potent antiviral drug became available in recent years that allows for the treatment of patients with lamivudine-resistant tyrosine-methionine-aspartate-aspartate (YMDD)-mutant HBV. In the transplantation setting, first studies indicate that a triple prophylactic therapy consisting of lamivudine, adefovir, and HBIG will become the standard of care for YMDD-mutant-related hepatitis B. With new drugs emerging for the treatment of chronic HBV, there is optimism for new options also in the transplant setting.

[The prophylaxis against post-liver-transplant hepatitis B re-infection]

OBJECTIVE

To review the prophylaxis against post-liver transplantation hepatitis B reinfection with anti-hepatitis B immunoglobulin and nucleoside analogues.

METHOD

A bibliographic search was carried out using Pubmed, entering the following key words: hepatitis B and liver transplantation and (hepatitis B hyperimmune globulin and lamivudine and adefovir dipivoxil) up to June 2006. The initial search was filtered using the terms clinical trial, randomized clinical trial and review. The data contained in selected studies were reviewed.

RESULTS

A total of 53 works were found. Prophylaxis with anti-HB immunoglobulin and lamivudine is the best strategy for avoiding recurrence of the hepatitis B virus in patients undergoing hepatic transplants; achieving very low reinfection rates (0-10%) with follow up periods of between 1-5 years. There is a great degree of variability (dose, duration and method of HBIg administration) in the prophylactic protocols reviewed. The use of low doses of anti-HB immunoglobulin (administered intravenously followed by intramuscular administration, or administered intramuscularly from the anhepatic stage), and lamivudine in patients who receive transplants with a low risk of recurrence, shows prophylactic efficacy comparable to the use of high doses of anti-HB immunoglobulin. Furthermore, it implies a considerable reduction in costs.

CONCLUSIONS

The availability of suitably designed clinical trials is required to design a more cost-effective protocol and reduce variability.

HBsAg level at time of liver transplantation determines HBsAg decrease and anti-HBs increase and affects HBV DNA decrease during early immunoglobulin administration

BACKGROUND/AIMS

Administration of hepatitis B immunoglobulin (HBIG) initially after liver transplantation of hepatitis B patients is considered important to prevent reinfection reliably. However, dosing schedules differ considerably between centers. We measured HBsAg, anti-HBs and HBV DNA kinetics to create a rational basis for dosing schemes.

METHODS

Thirteen patients (group A) received 10,000 IU HBIG in the anhepatic phase followed by 10,000 IU daily until HBsAg became negative, whereas five patients (group B) received 20,000 IU followed by 5000 IU every 30 min.

RESULTS

HBsAg levels at time of transplantation ranged from 0.12 to 12,990 IU/ml. Correlations between initial HBsAg and HBIG required to decrease HBsAg below 1 IU/ml were high in groups A and B (r=0.97, p<0.001; r=1.00, p<0.001), as were correlations between initial HBsAg and HBIG required to raise anti-HBs above 1000 IU/l (r=0.94, p<0.001; r=1.00, p<0.001). In 11 HBV DNA-positive patients, DNA levels became negative in seven, and dropped by 2.5 log10 (mean) in the other four patients during immunoglobulin administration.

CONCLUSIONS

In conclusion, required HBIG doses to decrease HBsAg and raise anti-HBs are determined by HBsAg levels at time of transplantation, not by HBV DNA levels. Shortened HBIG dosing intervals accelerate HBsAg decrease and anti-HBs increase. HBV DNA decreases rapidly during HBIG administration in most patients.

Adefovir dipivoxil for wait-listed and post-liver transplantation patients with lamivudine-resistant hepatitis B: final long-term results

Wait-listed (n = 226) or post-liver transplantation (n = 241) chronic hepatitis B (CHB) patients with lamivudine-resistant hepatitis B virus (HBV) were treated with adefovir dipivoxil for a median of 39 and 99 weeks, respectively. Among wait-listed patients, serum HBV DNA levels became undetectable (<1,000 copies/mL) in 59% and 65% at weeks 48 and 96, respectively. After 48 weeks, alanine aminotransferase (ALT), albumin, bilirubin, and prothrombin time normalized in 77%, 76%, 60%, and 84% of wait-listed patients, respectively. Among posttransplantation patients, serum HBV DNA levels became undetectable in 40% and 65% at weeks 48 and 96, respectively. After 48 weeks, ALT, albumin, bilirubin, and prothrombin time normalized in 51%, 81%, 76%, and 56% of posttransplantation patients, respectively. Among wait-listed patients who underwent on-study liver transplantation, protection from graft reinfection over a median of 35 weeks was similar among patients who did (n = 34) or did not (n = 23) receive hepatitis B immunoglobulin (HBIg). Hepatitis B surface antigen was detected on the first measurement only in 6% and 9% of patients who did or did not receive HBIg, respectively. Serum HBV DNA was detected on consecutive visits in 6% and 0% of patients who did or did not receive HBIg, respectively. Treatment-related adverse events led to discontinuation of adefovir dipivoxil in 4% of patients. Cumulative probabilities of resistance were 0%, 2%, and 2% at weeks 48, 96, and 144, respectively. In conclusion, adefovir dipivoxil is effective and safe in wait-listed or posttransplantation CHB patients with lamivudine-resistant HBV and prevents graft reinfection with or without HBIg.

Lamivudine plus low-dose hepatitis B immunoglobulin to prevent recurrent hepatitis B following liver transplantation

BACKGROUND AND AIMS

High-dose intravenous hepatitis B immunoglobulin (HBIG) may prevent recurrent hepatitis B virus (HBV) infection, but the cost has limited its widespread use in countries with endemic HBV infection. We report on long-term safety and efficacy of an alternative strategy of very low doses (400-800 IU/month) of intramuscular (IM) HBIG plus lamivudine.

METHODS

Australian and New Zealand patients who received low-dose HBIG plus lamivudine following liver transplantation for HBV-related end-stage liver disease were studied. Prior to transplantation, patients with detectable serum HBV DNA received lamivudine 100 mg daily. Posttransplantation, all patients received lamivudine 100 mg daily plus IM HBIG 400 or 800 IU daily for 1 week then monthly thereafter. Serum HBV DNA levels were measured prior to lamivudine, at transplantation, and at 12 months posttransplantation. Serum titers of antibody to HBV surface antigen were measured at 1, 3, and 12 months posttransplantation.

RESULTS

Between February 1996 and October 2004, 147 patients received low-dose HBIG plus lamivudine. Thirty-one percent were hepatitis B e antigen positive, and 85% were HBV DNA+ prior to transplantation. The median duration of pretransplantation lamivudine was 92 days (range, 1-1775). Median follow-up posttransplantation was 1860 days. Kaplan-Meier patient survival was 92% at 1 year and 88% at 5 years. The actuarial risk of HBV recurrence was 1% at 1 year and 4% at 5 years. Baseline HBV DNA titer was associated with HBV recurrence.

CONCLUSION

Low-dose IM HBIG plus lamivudine provides safe and effective long-term prophylaxis against recurrent HBV at <10% the cost of the high-dose regimen.

Short-term high-dose followed by long-term low-dose hepatitis B immunoglobulin and lamivudine therapy prevented recurrent hepatitis B after liver transplantation

Hepatitis B immunoglobulin (HBIg) and lamivudine combination has been accepted as the best way to control hepatitis B recurrence after liver transplantation. However, the optimal dose of HBIg and the target titer of hepatitis B surface antibody (HBsAb) remain unclear. We report our satisfactory experience with high-dose HBIg in the early period followed by low-dose HBIg with lamivudine. Subjects comprised five patients with fulminant hepatitis (FH) and 18 patients with liver cirrhosis (LC) who underwent liver transplantation. HBIg at a dosage of 200 IU/kg per day was administered for one week postoperatively. Thereafter, HBIg was administered only for HBsAb titer <100 IU/L. After six months, HBIg was withdrawn in FH and administered in LC only for HBsAb titer <10 IU/L. Lamivudine was administered to two FH and all LC cases. Although two patients with LC showed transient hepatitis B surface antigen (HBsAg) recurrence, all patients remained HBsAg-negative at the final follow-up date. This method allows reliable and cost-effective control of hepatitis B recurrence.

Management of recurrent viral hepatitis B and C after liver transplantation

Liver transplant teams are often faced with the challenges of managing viral recurrence after liver transplantation. Hepatitis C virus (HCV) remains the most challenging viral disease in the transplant community. Strategies to prevent and delay viral recurrence have slowly developed over the past 5 years. Hepatitis B virus (HBV), previously a contraindication for liver transplantation due to recurrence and cholestasis with allograft failure, is now one of the more favorable indications for liver transplantation as a result of current therapeutic options. This review investigates the up-to-date information on treatment outcomes for HCV and HBV in the period following liver transplant.

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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.

[Viral hepatitides infections in transplant recipients]

Hepatitis C (HCV) and hepatitis B (HBV) -related end-stage liver disease are the most common indications for liver transplantation (LTx) in our area. Recurrent HCV infection is universal after LTx and although histological recurrence is variable, the rate of disease progression is more rapid than in non-immunosuppressed patients and this impact graft and patient survival. All anti-HCV treatment strategies have shown limited efficacy so, at the present time, HCV reinfection after LTx represents the most important clinical problem in the follow-up. Regarding HBV, the most important factor in viral recurrence in the allograft is the presence of active viral replication at the time of LTx. The best patient selection (in non-replicative phase), the indefinite use of hyperimmune anti-hepatitis B immunoglobulin and the use of the new antiviral drugs have made possible a significant improvement in graft and patient survival.

[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.

Established and emerging therapies for the treatment of viral hepatitis

Patients who are chronically infected with either hepatitis B or C viruses run the risk of developing cirrhosis and hepatocellular carcinoma in later life. Antiviral treatment offers the only means of interrupting this progression. To date, recombinant interferon alpha and the nucleos(t)ide analogues lamivudine and adefovir dipivoxil are the only licensed drugs for the treatment of chronic hepatitis B, whilst recombinant or pegylated interferons in combination with ribavirin are the ones used for chronic hepatitis C virus infections. The efficacy of these treatments, reasons for treatment failure, drug resistance and future options are discussed in the present review.

Hepatitis B and Liver Transplantation

Liver transplantation is the treatment of choice for patients with liver failure secondary to chronic hepatitis B. However, liver transplantation is complicated by the risk of recurrent hepatitis B virus infection, which significantly impairs graft and patient survival. The main risk factor for the development of recurrent hepatitis B virus infection is the virus load at the time of transplantation. The development of antiviral medications, such as lamivudine and adefovir, and the implementation of effective prophylactic regimens using hepatitis B immune globulin have significantly improved the outcomes of hepatitis B after liver transplantation. However, current approaches continue to be hampered by the extremely high cost of treatment and the emergence of drug-resistant viral mutations. Ongoing studies are necessary to establish the most cost-effective approaches to prevent recurrent hepatitis B virus infection after liver transplantation.

Timing of lamivudine administration according to Child class in patients with decompensated cirrhosis

BACKGROUND

Few clinical trials have investigated the use of lamivudine (LAM) in patients with decompensated cirrhosis related to chronic hepatitis B. The aim of the present study was to evaluate the efficacy of extended LAM treatment and to determine the timing of LAM administration in patients with decompensated cirrhosis.

METHODS

A total of 17 patients were treated with LAM 100 mg/day. The mean duration of follow up was 28 +/- 8.4 months (range: 14-42 months). All patients were evaluated for evidence of clinical, biochemical and serologic replication of hepatitis B virus (HBV) infection. There were 12 patients with Child class B and five with Child class C.

RESULTS

Ten of 17 patients (58.2%) responded to LAM treatment. Of the breakthrough patients, six (86%) had YMDD motif variants. Clinical improvement was observed in nine out of 10 responders (90%), six of the seven breakthrough patients (86%) and five of six patients with YMDD variant DNA. Mean time to achieve a 2-point reduction in Child-Pugh-Turcotte score was 14 months in patients with Child class C, compared with 5.9 months in those with Child class B (P < 0.001). Mean time required to gain a 0.5 g/dL increment in albumin was 14 months in Child class C and 5.8 months in Child class B. Hepatitis B e antigen (HBeAg) seroconversion was achieved in five of 13 HBeAg-positive patients at the last follow up and during the follow-up period.

CONCLUSION

Long-term administration of LAM for patients with decompensated cirrhosis is effective. Earlier LAM administration in Child class B patients led to improved clinical outcomes.

Failure of hepatitis B vaccination in patients receiving lamivudine prophylaxis after liver transplantation for chronic hepatitis B

BACKGROUND/AIMS

Lamivudine prophylaxis against hepatitis B virus (HBV) reinfection after liver transplantation is associated with recurrence due to escape mutants.

METHODS

Fifty-two patients on lamivudine prophylaxis at a median of 412 days (median, 370-2040 days) after transplantation for chronic HBV-related liver disease received two courses of an accelerated schedule of double-dose recombinant HBV vaccine. Before vaccination, all patients were seronegative for HBsAg, anti-HBs and HBV DNA (by qPCR). Three intramuscular doses of vaccine (40 microg each) were administered monthly and another identical course was repeated after 3 months. Lamivudine (100mg/day) was continued throughout the study.

RESULTS

After the first course, two patients developed a weak response (anti-HBs titre of 12 mIU/mL) that disappeared rapidly. One early responder developed anti-HBs (27 mIU/mL) again after the second course but the other did not. Two other patients developed response (anti-HBs titre of 17 and 103 mIU/mL, respectively) giving an overall response rate of 7.7%. The antibody level declined rapidly. At the end of the study, one patient who did not respond had developed viral breakthrough which was treated with adefovir dipivoxil therapy.

CONCLUSIONS

Active immunization with two courses of double-dose recombinant HBV vaccine has limited efficacy in patients receiving lamividine prophylaxis after liver transplantation.

Is Hepatitis B Immunoglobulin Prophylaxis Needed for Liver Transplantation in the Era of New Antivirals?

Chronic infection with hepatitis B virus (HBV) is one of the most common causes of cirrhosis of the liver and hepatocellular carcinoma worldwide, frequently requiring liver transplantation. Other nonliver organ transplants get infected de novo or through reactivation from previous active or inactive infections. With significant improvements in the surgical techniques and immunosuppressive regimens over the last 20 years, organ transplantation has become the most effective and lifesaving therapy for patients with chronic renal failure, cirrhosis, hepatocarcinoma, and heart failure. Until recently chronic HBV infection was considered a formal contraindication for liver transplantation, since recurrence of infection without prophylaxis occurs in 75% to 90% of the patients, with significant morbidity and mortality and few therapeutic alternatives. However, the introduction of hepatitis B immunoglobulin (HBIG) a decade ago to reduce the risk of reinfection of liver grafts, and more recently the availability of nucleoside analogues with few side effects and easy administration, have led to a dramatic improvement in patient outcomes with a risk of long-term HBV reinfection of less than 10% with combined HBIG and lamivudine prophylaxis. Chronic HBV infection in kidney, heart, and other organs has become a serious long-term problem and one of the most frequent and important comorbidities affecting graft and patient survival. Fortunately the introduction of nucleoside analogues allows significant control of viral replication and prevents progression of liver disease and other organ damage. In the present article we discuss the current indications for HBV prophylaxis and treatment prior to and after organ transplantation, as well as the most cost-effective way to apply different regimens to reduce side effects and improve survival and quality of life after transplantation.

Liver Transplantation for Children: Red Cross Children's Hospital Experience

BACKGROUND

The liver transplant program for infants and children at the Red Cross Children's Memorial Hospital is the only established pediatric service in sub-Saharan Africa. Since 1985, 250 infants and children have been assessed and 155 accepted for transplantation.

METHODS

Since 1987, 76 children (range 6 months to 14 years) have had 79 liver transplants, with biliary atresia being the most frequent diagnosis. The indications for transplantation include biliary atresia (n = 44), metabolic (n = 7), fulminant hepatic failure (n = 10), redo transplants (n = 3), and other (n = 15). Three combined liver/kidney transplants have been performed. Forty-nine were reduced-size transplants with donor: recipient weight ratios ranging from 2:1 to 11:1, and 29 children weighed < 10 kg.

RESULTS

Fifty-six (74%) patients survived 3 months to 12 years posttransplant. Cumulative 1- and 5-year patient survival data are 79% and 70%, respectively. However, with the introduction of prophylactic intravenous gancyclovir and the exclusion of hepatitis B virus (HBV) IgG core Ab-positive donors, the projected 5-year pediatric survival has been >80%. Early (<1 month) post-liver-transplant mortality was low, but included: primary malfunction (n = 1); inferior vena cava thrombosis (n = 1); bleeding esophageal ulcer (n = 1); and sepsis (n = 1). Late morbidity and mortality was mainly due to infections: de novo hepatitis B (5 patients, 2 deaths); Epstein-Barr virus (EBV)-related posttransplantation lymphoproliferative disease (12 patients, 7 deaths); and cytomegalovirus disease (10 patients, 5 deaths). Tuberculosis (TB) treatment in three patients was complicated by chronic rejection (n = 1) and TB drug-induced subfulminant liver failure (n = 1).

CONCLUSIONS

Despite limited resources, a successful pediatric program has been established with good patient and graft survival figures and excellent quality of life. Shortage of donors due to HBV and human immunodeficiency virus (HIV) leads to significant waiting list mortality and infrequent transplantation.

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.

Liver transplantation for HBV and management of reinfection

Follicular non-Hodgkin's lymphoma (NHL) represents the most common indolent lymphoma with a median survival of 10 years. A new prognostic index (FLIPI) provides prognostic information at diagnosis and at relapse. Initial treatments combining monoclonal antibody therapy using rituximab with chemotherapy appear to increase the response rate and decrease the risk of relapse with little increase in toxicity. Promising phase III trial results demonstrating improvements in outcome using rituximab have recently been reported. A number of phase II trials have also demonstrated encouraging activity combining radiolabeled antibodies in sequence with chemotherapy. The role of high-dose therapy and autologous transplantation is becoming more defined, with improvements in progression-free survival observed in the upfront and relapsed setting. The application of allogeneic transplantation, once restricted to young otherwise healthy patients has shown encouraging activity in older, relapsed, and refractory patients using nonmyeloablative conditioning regimens. These new treatment options make the management of newly diagnosed patients both exciting and a challenge.

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.

Effects of long-term lamivudine therapy in renal-transplant patients

BACKGROUND

Following renal transplantation (RT), chronic immunosuppression is associated in hepatitis B virus (HBV) (+) patients with a flare-up of the disease, which might be harmful in the long term.

OBJECTIVES

We report on the effect of long-term lamivudine therapy given at an initial daily dose of 100mg in 18 HBV (+) RT patients.

RESULTS

When lamivudine therapy was commenced, 14 patients (77%) had an increase in their aspartate (AST) and alanine (ALT) aminotransferase levels. During a mean follow-up, under treatment, of 36.5 +/- 3.5 months (up to 66 months), 10 patients (55%) had a sustained partial (HBV DNA < 4 x 10(5)copies/ml) (n = 4) or complete (HBV DNA < 400 copies/ml) (n = 6) virological response. Overall, 12 virological breakthroughs were observed. Of those who were HBe Ag(+) prior to lamivudine therapy (n = 4), one seroconverted to HBe Ab during therapy. At the last follow-up, AST and ALT levels were normal in 13 patients. When liver biopsy was repeated during treatment (n = 15), the virological responders showed a significant decrease in total Knodell score from 10 +/- 0.6 to 7 +/- 1 (P = 0.04), but no significant change in the stage of fibrosis. Conversely, in those patients with high HBV DNA titers, there were no significant changes in the total Knodell score or in the grade of fibrosis.

CONCLUSION

In conclusion, lamivudine therapy is safe in HBV(+)ve renal-transplant patients. However, even if the full and partial virological response rates are still high (55%) in the long term, relapse or primary non-responses occur. The implementation of alternative efficient strategies is warranted.

Current therapies for chronic hepatitis B virus infection

Patients who are chronically infected with the hepatitis B virus are at an increased risk of developing cirrhosis, hepatic decompensation and hepatocellular carcinoma. Therapeutic intervention offers the only means of interrupting this progression. Currently there are three licensed agents for the treatment of chronic hepatitis B virus infection. These are interferon-alpha, an immunomodulator, and two synthetic nucleos(t)ide analogs, namely lamivudine (Epivir, GlaxoSmithKline) and adefovir dipivoxil (Hepsera, Gilead Sciences). This review aims to summarize current experience with these drugs in the treatment and management of patients with chronic hepatitis B virus infection, their efficacy, and current problems of drug resistance. An outline of future treatment perspectives is also included.

Hepatitis B and hepatitis C viruses in liver transplantation

Liver transplantation (LT) for end-stage liver disease (ESLD) secondary to hepatitis viruses has evolved rapidly during the last two decades. ESLD secondary to hepatitis C virus (HCV) accounts for approximately 50% of LT in the United States and Europe. Despite the decrease in the number of new HCV infections, the prevalence of advanced HCV-related liver disease is steadily increasing. In light of the near universal recurrence of posttransplantation HCV infection and our limited ability to treat recurrent disease, transplantation is in danger of being overrun by viral hepatitis, unless effective strategies can be used to treat disease, expand the donor pool of available organs, and prevent disease recurrence. In the early 1980s, results of LT for chronic hepatitis B virus infection were hampered by recurrent infection and subsequent allograft failure. However, with the introduction of passive immunoprophylaxis with hepatitis B immunoglobulin and treatment with potent nucleoside analogs, there has been a resurgence of LT for hepatitis B virus-related ESLD. Despite the wide acceptance of LT as a therapy for ESLD, there is little consensus on the appropriate immunosuppressive regimens, and prophylactic and therapeutic treatments vary widely from one center to another. This review summarizes available data and highlights appropriate strategies to improve outcomes.

Prevention of hepatitis B virus recurrence after living donor liver transplantation

The emergence of lamivudine-resistant hepatitis B mutations is a major complication during pretransplantation treatment. The proper time to begin Lamivudine before transplantation is not yet known. Twenty-six patients received preoperative lamivudine treatment followed by combined lamivudine and hepatitis B immunoglobulin after transplantation up to December 2002. The length of preoperative lamivudine treatment ranged from 13 to 200 days (mean, 52 +/- 37 days). Hepatitis B virus-DNA was positive in 22 of 26 (84.6%) patients before preoperative lamivudine prophylaxis and persistently positive among only 4 of 22 patients (18%) who at transplantation did not show a viral mutation. In all patients, hepatitis B virus-DNA became negative immediately after transplantation. At a median follow-up of 34 months, neither a hepatitis B recurrence nor a mutation had occurred in any patient. The ability to schedule the proper time for preoperative lamivudine prophylaxis is an advantage of living donor liver transplantation.

Outcomes in liver transplant recipients with hepatitis B virus: resistance and recurrence patterns from a large transplant center over the last decade

Hepatitis B virus (HBV) recurrence following liver transplantation (LTx) has been controllable primarily with the use of hepatitis B immune globulin (HBIg) and lamivudine (LAM). However, HBV resistance to LAM and/or HBIg has become an increasing problem prompting the use of newer antiviral agents. The purpose of our study was to investigate the association between therapy, HBV breakthrough, and allograft / patient survival in HBV-positive liver transplant recipients. We performed a retrospective review of the medical records of patients that were transplanted for HBV from June 1994 to May 2003. A total of 92 patients, positive for either hepatitis B surface antigen (HBsAg) or HBV deoxyribonucleic acid (DNA) pretransplant, received LAM monotherapy or HBIg (6 months) plus LAM therapy post-liver transplant. HBV breakthrough post-LTx was noted in 14 patients. All patients had detectable HBV DNA prior to liver transplantation; none of the patients that were HBV DNA negative prior to transplant had detectable HBV DNA posttransplant. Of these 14, 9 patients (64%) were switched from LAM to adefovir dipivoxil (ADF) and 5 patients (36%) to tenofovir disoproxil fumarate (TNV). In conclusion, pre-LTx HBV viremia should be considered in planning post-LTx prophylaxis. Trials to evaluate oral antiviral agents in combination with or without HBIg therapy are needed.

Outcomes of liver transplantation for hepatitis B: a single-center study of 35 patients

BACKGROUND

Results of liver transplantation (LT) for hepatitis B (HBV) have improved in the past decade but recently drug resistance has been described, the clinical significance of which is unclear. The aims of this study were to evaluate outcomes of LT for HBV and describe the prevalence of drug resistance.

METHODS

A retrospective chart analysis and review of the organ transplant database was performed to identify all patients transplanted for HBV between December 1982 and April 2004 who survived more than 3 months.

RESULTS

Thirty-five patients were transplanted for HBV during this period: 27 men and 8 women. Median age at LT was 48.8 years (range 18.9 to 74.3). Four patients were transplanted for fulminant liver failure and 31 for decompensated cirrhosis. Intramuscular HBIG was administered to 8 patients and intravenous HBIG to 32 patients, data were unavailable for three patients. Lamivudine was prescribed for 18 patients (58%) pre-OLT and for 31 patients (88.6%) post-LT. Drug-resistant HBV developed in two patients (5.71%) receiving lamivudine and HBIG. Adefovir substitution resulted in improvement in liver function tests, in HBV DNA and in histology in both patients. Twenty-five patients are currently alive with and 1-year survival of 95% and a 5-year survival of 75%. Causes of death were respiratory failure (n = 3), metastatic cancer of unknown primary (n = 2), renal failure (n = 2), sepsis (n = 1), cerebrovascular accident (n = 1), and cerebral edema (n = 1).

CONCLUSIONS

LT for HBV shows survival rates comparable to other liver transplant recipients. Lamivudine resistance was rare in this series but responded to adefovir substitution.

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Evolving strategies to prevent HBV recurrence

1. Long-term prophylaxis with hepatitis B immune globulin (HBIG) significantly reduces the risk for hepatitis B virus (HBV) recurrence and increases survival. Patients with HBV cirrhosis and / or positive HBV DNA at the time of transplantation have a high risk for recurrence despite HBIG prophylaxis. 2. Pre-orthotopic liver transplantation (OLT) antiviral treatment using lamivudine (LAM) can suppress HBV replication before transplantation and may induce clinical improvement in a subset of patients. Adefovir dipivoxil (ADV) may serve as "rescue" therapy for patients with LAM resistance; its place as first-line therapy requires further evaluation. 3. Combination prophylaxis with LAM and HBIG prevents HBV recurrence in 90% to 100% of patients who undergo transplantation for hepatitis B. The optimal HBIG protocol in the "nucleoside-nucleotide analog era" remains to be determined. The place of ADV or LAM as first-line posttransplant antiviral therapy in combination with HBIG requires further studies. 4. Future research should test new protocols using lower HBIG doses given intravenously (IV) or intramuscularly (IM) alone or in combination with antiviral agents and identify patients in whom HBIG prophylaxis can be stopped safely or replaced by antiviral agents or vaccination.

Adefovir dipivoxil: review of a novel acyclic nucleoside analogue

Adefovir dipivoxil (ADF) is a novel acyclic nucleoside analogue that has recently been approved for the treatment of chronic hepatitis B virus (HBV). Adefovir was initially assessed at higher doses for the treatment of human immunodeficiency virus (HIV) infection. However, in these studies, nephrotoxicity proved a dose-limiting side effect. Large randomised controlled studies have recently shown that ADF results in histological, virological and biochemical improvement in both hepatitis B e antigen (HBeAg)-positive and HBeAg-negative chronic HBV. While the rate of HBeAg seroconversion at 1 year (12%) was lower than both lamivudine and interferon, this increases with prolonged treatment. The clinical improvements occurred without serious side effects or the development of resistance at the dose of 10 mg daily, in treatment trials of up to 2 years, although resistance has now been observed. In addition, the drug is efficacious in HBV/HIV co-infection and hepatitis B-infected liver transplant recipients, particularly in those who have developed lamivudine resistance. ADF can be added as a treatment option to existing treatment options (interferon-alpha and lamivudine) and assumes a role in the ongoing management of chronic HBV. The optimal use of ADF as either a monotherapy or as part of combination therapy requires further assessment.