Anti-HCV human immunoglobulins for the prevention of graft infection in HCV-related liver transplantation, a pilot study

Monoclonal anti-envelope antibody AP33 protects humanized mice against a patient-derived hepatitis C virus challenge

End-stage liver disease (ESLD) caused by hepatitis C virus (HCV) infection is a major indication for liver transplantation. However, immediately after transplantation, the liver graft of viremic patients universally becomes infected by circulating virus, resulting in accelerated liver disease progression. Currently available direct-acting antiviral therapies have reduced efficacy in patients with ESLD and prophylactic strategies to prevent HCV recurrence are still highly needed. In this study, we compared the ability of two broadly reactive monoclonal antibodies (mAbs), designated 3/11 and AP33, recognizing a distinct, but overlapping, epitope in the viral E2 glycoprotein to protect humanized mice from a patient-derived HCV challenge. Their neutralizing activity was assessed using the HCV pseudoparticles and cell-culture-derived HCV systems expressing multiple patient-derived envelopes and a human-liver chimeric mouse model. HCV RNA was readily detected in all control mice challenged with a patient-derived HCV genotype 1b isolate, whereas 3 of 4 AP33-treated mice were completely protected. In contrast, only one of four 3/11-treated mice remained HCV-RNA negative throughout the observation period, whereas the other 3 had a viral load that was indistinguishable from that in the control group. The increased in vivo efficacy of AP33 was in line with its higher affinity and neutralizing capacity observed in vitro.

CONCLUSIONS

Although mAbs AP33 and 3/11 target the same region in E2, only mAb AP33 can efficiently protect from challenge with a heterologous HCV population in vivo. Given that mAb AP33 efficiently neutralizes viral variants that escaped the humoral immune response and reinfected the liver graft of transplant patients, it may be a valuable candidate to prevent HCV recurrence. In addition, our data are valuable for the design of a prophylactic vaccine.

Impact of lipids and lipoproteins on hepatitis C virus infection and virus neutralization

Hepatitis C virus (HCV) infections represent a major global health problem. End-stage liver disease caused by chronic HCV infection is a major indication for liver transplantation. However, after transplantation the engrafted liver inevitably becomes infected by the circulating virus. Direct acting antivirals are not yet approved for use in liver transplant patients, and limited efficacy and severe side effects hamper the use of pegylated interferon combined with ribavirin in a post-transplant setting. Therefore, alternative therapeutic options need to be explored. Viral entry represents an attractive target for such therapeutic intervention. Understanding the mechanisms of viral entry is essential to define the viral and cellular factors involved. The HCV life cycle is dependent of and associated with lipoprotein physiology and the presence of lipoproteins has been correlated with altered antiviral efficacy of entry inhibitors. In this review, we summarise the current knowledge on how lipoprotein physiology influences the HCV life cycle. We focus especially on the influence of lipoproteins on antibodies that target HCV envelope proteins or antibodies that target the cellular receptors of the virus. This information can be particularly relevant for the prevention of HCV re-infection after liver transplantation.

Antiviral prophylaxis for the prevention of chronic hepatitis C virus in patients undergoing liver transplantation

BACKGROUND

It is not clear whether prophylactic antiviral therapy is indicated to improve patient and graft survival in patients undergoing liver transplantation for chronic decompensated hepatitis C virus (HCV) infection.

OBJECTIVES

To compare the benefits and harms of different prophylactic antiviral therapies for patients undergoing liver transplantation for chronic HCV infection.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1, 2013), MEDLINE, EMBASE, and Science Citation Index Expanded to February 2013.

SELECTION CRITERIA

Only randomised clinical trials irrespective of language, blinding, or publication status and comparing various prophylactic antiviral therapies (alone or in combination) in the prophylactic treatment of patients undergoing liver transplantation for chronic HCV infection.

DATA COLLECTION AND ANALYSIS

Two authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) or hazard ratio (HR) with 95% confidence intervals (CI) using the fixed-effect and the random-effects models based on available case analysis.

MAIN RESULTS

A total of 501 liver transplant recipients undergoing liver transplantation for chronic HCV infection were randomised in 12 trials to various experimental interventions and control interventions. The proportion of genotype I varied between 49% and 100% in the seven trials that reported the genotype. Only one or two trials were included under each comparison. All the trials were of high risk of bias. Ten trials including 441 liver transplant recipients provided data for this review.There were no significant differences in the 90-day mortality (1 trial; 81 participants; 5/35 (adjusted proportion: 14.2%) in interferon group versus 5/46 (10.9%) in control group; RR 1.31; 95% CI 0.41 to 4.19); mortality at maximal follow-up (2 trials; 105 participants; 7/47 (adjusted proportion: 14.8%) in interferon group versus 10/58 (17.2%) in control group; RR 0.86; 95% CI 0.36 to 2.08); long-term mortality (1 trial; 81 participants; HR 0.45; 95% CI 0.13 to 1.56); mortality at maximal follow-up (1 trial; 54 participants; 1/26 (3.9%) in pegylated interferon group versus 2/28 (7.1%) in control group; RR 0.54; 95% CI 0.05 to 5.59); 90-day mortality (1 trial; 115 participants; 5/55 (9.1%) in pegylated interferon plus ribavirin group versus 3/60 (5.0%) in control group; RR 1.82; 95% 0.46 to 7.25); 90-day mortality (3 trials; 53 participants; 3/37 (adjusted proportion: 4.3%) in HCV antibody group versus 1/16 (6.3%) in placebo group; RR 0.69; 95% CI 0.15 to 3.11); or 90-day mortality (2 trials; 31 participants; 2/14 (adjusted proportion: 16.2%) in HCV antibody high-dose group versus 1/17 (5.9%) in HCV antibody low-dose group; RR 2.75; 95% CI; 0.30 to 25.35). There were no significant differences in the retransplantation at maximal follow-up (2 trials; 105 participants; 2/47 (adjusted proportion: 4.0%) in interferon group versus 2/58 (3.4%) in control group; RR 1.17; 95% CI 0.22 to 6.2); 90-day retransplantation (1 trial; 18 participants; 1/12 (8.3%) in HCV antibody group versus 0/6 (0%) in control group; RR 1.71; 95% CI 0.09 to 32.93); or 90-day retransplantation (1 trial; 12 participants; 1/6 (17.7%) in HCV antibody high-dose group versus 0/6 (0%) in HCV antibody low-dose group; RR 3.00; 95% CI 0.15 to 61.74). There were no significant differences in serious adverse events, graft rejection, worsening of fibrosis, or HCV recurrence between intervention and control groups in any of the comparisons that reported these outcomes. None of the trials reported quality of life, liver decompensation, intensive therapy unit stay, or hospital stay. Life-threatening adverse events were not reported in either group in any of the comparisons.

AUTHORS' CONCLUSIONS

There is currently no evidence to recommend prophylactic antiviral treatment to prevent recurrence of HCV infection either in primary liver transplantation or retransplantation. Further randomised clinical trials with adequate trial methodology and adequate duration of follow-up are necessary.

Strategies to reduce hepatitis C virus recurrence after liver transplantation

Hepatitis C virus (HCV) is a major health problem that leads to chronic hepatitis, cirrhosis and hepatocellular carcinoma, being the most frequent indication for liver transplantation in several countries. Unfortunately, HCV re-infects the liver graft almost invariably following reperfusion, with an accelerated history of recurrence, leading to 10%-30% of patients progressing to cirrhosis within 5 years of transplantation. In this sense, some groups have even advocated for not re-transplanting this patients, as lower patient and graft outcomes have been reported. However, the management of HCV recurrence is being optimized and several strategies to reduce post-transplant recurrence could improve outcomes, decrease the rate of re-transplantation and optimize the use of available grafts. Three moments may be the focus of potential actions in order to decrease the impact of viral recurrence: the pre-transplant moment, the transplant environment and the post-transplant management. In the pre-transplant setting, it is not well established if reducing the pre transplant viral load affects the risk for HCV progression after transplant. Obviously, antiviral treatment can render the patient HCV RNA negative post transplant but the long-term benefit has not yet been fully established to justify the cost and clinical risk. In the transplant moment, factors as donor age, cold ischemia time, graft steatosis and ischemia/reperfusion injury may lead to a higher and more aggressive viral recurrence. After the transplant, discussion about immunosuppression and the moment to start the treatment (prophylactic, pre-emptive or once-confirmed) together with new antiviral drugs are of interest. This review aims to help clinicians have a global overview of post-transplant HCV recurrence and strategies to reduce its impact on our patients.

Hepatitis C therapy: other players in the game

Therapies in addition to the direct-acting antiviral agents (DAA) under evaluation for chronic hepatitis C include host targets such as cyclophilin inhibitors and immunomodulators. Both passive and therapeutic vaccines hold promise for the future. Although the numbers of drug categories and individual agents are increasing, only a handful of the non-DAAs seem to be ready to move on to phase III trials. New interferon agents are in development, and ribavirin variants are still under consideration. The role of the other players in the overall armamentarium against hepatitis C virus is still evolving.

Antiviral prophylactic intervention for chronic hepatitis C virus in patients undergoing liver transplantation

BACKGROUND

It is not clear whether prophylactic antiviral therapy is indicated in patients undergoing liver transplantation for chronic decompensated hepatitis C virus (HCV) infection.

OBJECTIVES

To compare the benefits and harms of different prophylactic anti-viral therapies for patients undergoing liver transplantation for chronic HCV infection.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until August 2010.

SELECTION CRITERIA

Only randomised clinical trials irrespective of language, blinding, or publication status and comparing various prophylactic antiviral therapies (alone or in combination) in the prophylactic treatment of patients undergoing liver transplantation for chronic HCV infection.

DATA COLLECTION AND ANALYSIS

Two authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) or hazard ratio (HR) with 95% confidence intervals (CI) using the fixed-effect and the random-effects models based on available case analysis.

MAIN RESULTS

A total of 477 liver transplant recipients undergoing liver transplantation for chronic HCV infection were randomised in eleven trials to various interventions and controls. The proportion of genotype I varied between 49% to 88% in the five trials that reported the genotype. Only one or two trials were included under each comparison. All the trials were of high risk of bias. There was no significant differences in the patient survival, graft rejection, re-transplantation, or HCV recurrence between intervention and control groups in any of the comparisons that reported these outcomes. None of the trials reported liver decompensation, primary graft non-function, intensive therapy unit stay, hospital stay, or quality of life. Life-threatening adverse events were not reported in either group in any of the comparisons. Up to 91% of patients required reduction in dose and up to 36% of patients required cessation of treatment in the various comparisons because of adverse events or because of patient's choice to stop treatment.

AUTHORS' CONCLUSIONS

There is currently no evidence to recommend prophylactic antiviral treatment to prevent recurrence of HCV infection either in primary liver transplantation or re-transplantation. Further randomised clinical trials with adequate trial methodology and adequate duration of follow-up are necessary.

Liver transplantation for hepatitis B and C virus-related cirrhosis: mid-term results

Hepatitis C virus (HCV) recurrence after orthotopic liver transplantation (OLT) is almost universal; cirrhosis develops in up to 30% of cases. Currently there is interest in the midterm outcomes of HCV patients with concomitant hepatitis B virus (HBV) infection among OLT recipients. We therefore retrospectively analyzed our database of patients who underwent OLT for HCV-HBV-related cirrhosis. Between April 1992 and December 2008, 350 patients underwent OLT, including 20 (5.7%) transplanted for HBV-HCV cirrhosis. We assessed patient and graft survivals at 1 and 5 years, as well as the progression of fibrosis. Protocol liver biopsies were available yearly after OLT. The survival curves were analyzed by the Kaplan-Meier approach and chronic hepatitis evaluated according to the Ishak scoring system. At a median follow-up of 68.4 +/- 53 months, the 1- and 5-year patient and graft survival rates were 80% and 70%, respectively. The 5-year fibrosis progression rate was 0.17 +/- 0.08 units of fibrosis. The only patient who developed histologic cirrhosis within 10 years of follow-up showed a lamivudine-resistant HBV recurrence. Patients transplanted for HBV-HCV coinfection showed a lower fibrosis progression rate compared with HCV monoinfected subjects.

Human liver transplantation as a model to study hepatitis C virus pathogenesis

Hepatitis C is a leading etiology of liver cancer and a leading reason for liver transplantation. Although new therapies have improved the rates of sustained response, a large proportion of patients (approximately 50%) fail to respond to antiviral treatment, thus remaining at risk for disease progression. Although chimpanzees have been used to study hepatitis C virus biology and treatments, their cost is quite high, and their use is strictly regulated; indeed, the National Institutes of Health no longer supports the breeding of chimpanzees for study. The development of hepatitis C virus therapies has been hindered by the relative paucity of small animal models for studying hepatitis C virus pathogenesis. This review presents the strengths of human liver transplantation and highlights the advances derived from this model, including insights into viral kinetics and quasispecies, viral receptor binding and entry, and innate and adaptive immunity. Moreover, consideration is given to current and emerging antiviral therapeutic approaches based on translational research results.

Hepatitis C virus infection and immunomodulatory therapies

Hepatitis C virus (HCV) infection remains a large-scale and significant health concern. The combination of subcutaneously administered pegylated interferon and oral ribavirin is the FDA-approved regimen for the treatment of chronic HCV infection. Combination therapy may result in a sustained virologic response leading to HCV eradication, with a reduction in risk for cirrhosis, hepatic decompensation, and hepatocellular carcinoma. However, the combination of PEG-IFN and ribavirin does not universally result in cure in all patients who undergo treatment. In this article, the authors discuss immunomodulatory therapies and clinical trials in the treatment of HCV infection.

Polyclonal immunoglobulins from a chronic hepatitis C virus patient protect human liver-chimeric mice from infection with a homologous hepatitis C virus strain

The role of the humoral immune response in the natural course of hepatitis C virus (HCV) infection is widely debated. Most chronically infected patients have immunoglobulin G (IgG) antibodies capable of neutralizing HCV pseudoparticles (HCVpp) in vitro. It is, however, not clear whether these IgG can prevent a de novo HCV infection in vivo and contribute to the control of viremia in infected individuals. We addressed this question with homologous in vivo protection studies in human liver-urokinase-type plasminogen activator (uPA)(+/+) severe combined immune deficient (SCID) mice. Chimeric mice were loaded with chronic phase polyclonal IgG and challenged 3 days later with a 100% infectious dose of the acute phase H77C virus, both originating from patient H. Passive immunization induced sterilizing immunity in five of eight challenged animals. In the three nonprotected animals, the HCV infection was attenuated, as evidenced by altered viral kinetics in comparison with five control IgG-treated animals. Plasma samples obtained from the mice at viral challenge neutralized H77C-HCVpp at dilutions as high as 1/400. Infection was completely prevented when, before administration to naïve chimeric mice, the inoculum was pre-incubated in vitro at an IgG concentration normally observed in humans.

CONCLUSION

Polyclonal IgG from a patient with a long-standing HCV infection not only displays neutralizing activity in vitro using the HCVpp system, but also conveys sterilizing immunity toward the ancestral HCV strain in vivo, using the human liver-chimeric mouse model. Both experimental systems will be useful tools to identify neutralizing antibodies for future clinical use.

New drugs for hepatitis C virus

No new therapy has been approved for the treatment of chronic hepatitis C in the last 5 years in the USA since the approval of pegylated interferon (IFN)-alpha(2a) and ribavirin. Multiple new drugs are currently in development and are expected to be approved for use in the USA and/or the EU by 2011-2013. Although the mechanism of action of pegylated IFN and ribavirin are not completely known, it is likely that they will continue to be used in combination regimens for a number of years. Direct antivirals are likely to be the first new drugs to be used in combination with pegylated IFN and ribavirin. Viral resistance will prove to be a significant barrier and require that consolidation therapy with at least 24 weeks of pegylated IFN and ribavirin be used to successfully prevent the selection or emergence of resistant variants. Numerous other compounds, such as ribavirin analogs, long-acting IFNs, hepatoprotectants and immunomodulators, are in development and may replace the drugs that are used currently. The combination of direct antivirals, such as protease and polymerase inhibitors, may rapidly follow in development, as has occurred in HIV drug therapy.

Longer survival of liver transplant recipients with hepatitis virus coinfections

Hepatitis virus coinfections [HBV plus HCV coinfection (HBV/HCV) or HBV plus HDV coinfection (HBV/HDV)] may progress more rapidly to cirrhosis than hepatitis B or C monoinfections in immunocompetent patients. Only limited information is available on the outcome of coinfected patients after liver transplantation. We studied survival rates of 204 patients with viral hepatitis transplanted at our center between 1972 and 1997. HBV/HDV and HBV/HCV coinfections were present in 23 and nine individuals, respectively, while 97 patients had monoinfection by HCV and 75 had HBV monoinfection. Survival of coinfected patients was significantly longer than that of monoinfected patients (14.4 +/- 0.9 vs. 8.5 +/- 0.6 yr; p = 0.0003). The same was true for graft survival (p = 0.0002). In Cox's regression, viral coinfection (p = 0.0001), absence of hepatocellular carcinoma (HCC) (p = 0.00001) and no retransplantation (p = 0.02) were independently associated with patient survival. After exclusion of patients with HCC (n = 62), survival of coinfected patients was still significantly longer than that of monoinfected individuals (p = 0.002). The improved outcome was similar for both HBV/HDV and HBV/HCV coinfections. In contrast to immunocompetent patients, individuals with multiple hepatitis virus infections had an improved outcome after liver transplantation. Thus, viral coinfections may be associated with ameliorated courses of diseases under certain conditions.

Hepatitis C immune globulin (human) for the prevention of viral recurrence after liver transplantation

Immunoglobulin therapy has been used extensively in the treatment of infectious diseases. Hepatitis B immunoglobulin (HBIg) reduces the onset of infection in post-percutaneous exposure to Hepatitis B virus (HBV) and in infants of hepatitis B surface antigen (HBsAg)-positive mothers; it also significantly reduces the risk of recurrent HBV infection in liver transplant recipients, thus increasing the survival rate of this population. Prior to 1990, when plasma donors were not screened for the hepatitis C virus (HCV) antibody, the prevalence of HCV viremia after a liver transplant was found to be lower in those patients receiving HBIg containing anti-HCV antibodies. Phase I trials with chimpanzees demonstrated the ability of hepatitis C immune globulin (human) to decrease hepatic inflammation and to neutralize the HCV antibody, but this effect was not sustained over time. Phase I/II human studies have currently been unable to replicate the animal studies, but further trials are planned.

Approach to recurrent hepatitis C following liver transplantation

Hepatitis C-associated liver failure is the most common indication for liver transplantation. Histologic evidence of recurrence is apparent in approximately 50% of hepatitis C virus (HCV)-infected recipients in the first postoperative year. Approximately 10% of HCV-infected recipients will die or lose their allograft due to hepatitis C-associated allograft failure. HCV-infected recipients who undergo retransplantation have 5-year patient and graft survival rates that are broadly similar to those for transplant recipients who are not HCV infected. Although the choice of calcineurin inhibitor, mycophenolate mofetil, or both has not been clearly shown to affect histologic recurrence of hepatitis C, higher cumulative exposure to corticosteroids is associated with increased mortality and more severe histologic recurrence. In contrast to treatment of non-HCV-infected recipients, treatment of HCV-infected transplant recipients for acute cellular rejection is associated with attenuated patient survival. Steroid-resistant rejection with or without the use of T-cell-depleting therapies is associated with a greater than fivefold increased risk of mortality in HCV-infected liver transplant recipients. Pegylated interferon with or without ribavirin should be considered for treatment of recipients with histologically apparent recurrence of hepatitis C before total bilirubin exceeds 3 mg/dL. The role of hepatitis C immunoglobulin and new immunosuppressive agents in the management of hepatitis C after transplant continues to evolve.

New therapies: oral inhibitors and immune modulators

Several new classes of antiviral drugs are undergoing development and should change the way that hepatitis C virus infection is treated in the future. It is likely that combinations of drugs that target different points in the viral replication and disease processes will prove most successful. It is hoped that such combinations will improve the efficacy, tolerability, and duration of antiviral treatment for this disease.

[Management of hepatitis C virus infection in liver transplantation]

Because of graft reinfection and recurrence of the primary disease in the graft, patients who undergo transplantation due to cirrhosis caused by chronic hepatitis C virus (HCV) infection have a poorer long-term prognosis than non-HCV-infected transplant recipients. Apart from antiviral therapy, which can occasionally eradicate HCV infection before transplantation, there are no effective measures to prevent graft reinfection. Pre-transplantation antiviral therapy, however, is of limited applicability with currently available drugs. After liver transplantation, 2 options can be used to prevent graft loss due to HCV progression: early treatment in the first 4-6 weeks when there is still no evidence of histological injury and treatment of established HCV infection. Early antiviral therapy is limited not only by its scarce applicability but also by poor tolerability and limited effectiveness (sustained virological response in approximately 20-30% of patients). Treatment of established HCV infection, especially in patients with evidence of disease progression in biopsy, is the most cost-effective alternative with an efficacy of around 35-45% when pegylated interferon combined with ribavirin is used. Adverse effects, such as cytopenia and even induction of rejection, are the main limitation and lead to premature withdrawal in 30% of patients.

Management of Recurrent Hepatitis C in Liver Transplant Recipients

Recurrent HCV infection is universal in liver transplant recipients who are viremic pretransplant. The rate of histologic disease progression after transplantation is more rapid, and the risk of cirrhosis by 5 to 10 years is about 30%. Several donor, recipient, and viral factors have been associated with worse post-transplant outcomes in recipients with recurrent hepatitis C. Whether or not HCV-infected recipients of live donor grafts have worse out-comes compared with deceased donor graft recipients is controversial. To maximize the long-term survival of recipients with HCV infection, eradication of infection is the ultimate goal. Treatment of recurrent HCV after liver transplantation can be undertaken at several different time points: (1) prophylactically, at the time of transplantation; (2) pre-emptively, in the early post-transplant period; and (3) after established recurrent histologic disease is present. Prophylactic therapy for HCV infection has no established role at present, but studies are ongoing. Preemptive therapy using IFN and RBV has resulted in variable SVR rates (9%-43%) and is generally poorly tolerated, especially if the patient has advanced liver disease pretransplantation. Treatment of established recurrent HCV disease with combination PEGIFN and RBV is associated with a SVR in about 30% to 35% of patients overall but is limited by high rates of dose reduction or drug discontinuation. In conclusion, successful HCV eradication in the post-transplant setting is difficult with current treatment options, but it is possible. Determination of the optimal doses of antiviral drugs in transplant patients and improvements in drug tolerability may be important first steps in achieving enhanced response rates. There is a need for new drugs in this population that have greater efficacy and a better safety profile.

Management of hepatitis C in liver transplant recipients

Recurrent hepatitis C virus (HCV) disease is the leading cause of graft loss in liver transplant recipients with pre-transplant HCV infection. While natural history is variable, median time to recurrent cirrhosis is less than a decade. Factors contributing to risk of recurrence and rate of fibrosis progression are only partially known. Older donor age, treatment of acute rejection, cytomegalovirus infection and high pre-transplant viral load are most consistently linked with worse outcomes. Whether these factors can be modified to positively impact on HCV disease progression is unknown. The main therapeutic approach for patients with recurrent HCV disease has been the treatment with interferon and ribavirin (RBV) once recurrent disease is documented or progressive. Efficacy is lower than in nontransplant patients and tolerability, especially of RBV, is a major limitation. Stable or improved fibrosis scores are seen in the majority of sustained responders. Optimal dose, duration and timing of treatment have not been determined. Alternative strategies under study include pre-transplant treatment of decompensated cirrhotics, preemptive antiviral therapy started within weeks of transplantation and prophylactic therapy using HCV antibodies. Ongoing studies may establish a future role for alternative treatment approaches. Additionally, limited overall efficacy of interferon-based therapy in the transplant setting highlights the urgent need for new drug therapies.

A randomized, open-label study to evaluate the safety and pharmacokinetics of human hepatitis C immune globulin (Civacir) in liver transplant recipients

Chronic hepatitis C is the most common indication for liver transplantation, but viral recurrence is universal and progressive graft injury occurs in most recipients. Our aim was to assess the safety, pharmacokinetics (PK), and antiviral effects of high doses of a human hepatitis C antibody enriched immune globulin product (HCIG) in patients undergoing liver transplantation for chronic hepatitis C. This was a multicenter, randomized, open-label, controlled trial conducted at 4 transplant centers in the United States. A total of 18 patients with chronic hepatitis C, who underwent liver transplantation, were randomized to receive low-dose HCIG (75 mg/kg) or high-dose HCIG (200 mg/kg), or no treatment. A total of 17 infusions of HCIG were administered in each treated patient over 14 weeks using a time-dependent dosing strategy based on the PK of anti-hepatitis B immune globulin in liver transplant recipients. Hepatitis C virus levels, liver enzymes, and liver biopsies were obtained serially throughout the study period. PK profiles of HCV antibodies were determined on days 4, 10, and 98. HCIG infusions were safe and tolerated. The infusion rate could not be maximized because of symptoms for 18% to 30% of the doses. The half-life of HCIG was extremely short immediately after transplantation but was gradually prolonged. In the high-dose group, serum alanine aminotransferase (ALT) levels normalized in most subjects and no patient developed hepatic fibrosis. However, serum HCV RNA levels were not suppressed at either dose. In conclusion, HCIG, an anti-HCV enriched immune globulin product, appears to be safe in patients with chronic hepatitis C undergoing liver transplantation. Further studies are required to determine whether the drug has beneficial effects in this group of patients.

Treatment of recurrent hepatitis C after liver transplantation

Chronic hepatitis C virus (HCV) infection is the most common indication for liver transplantation in the United States and Europe, and more than 20,000 patients worldwide have undergone transplantation for complications of chronic hepatitis C. In North America, HCV accounts for 15% to 50% of the liver transplants performed in United States transplant programs. To maximize the long-term survival of liver transplant recipients who have HCV infection, eradication of infection is the ultimate goal. Pretransplant antiviral therapy with the goal of achieving viral eradication before transplantation is a consideration in some patients, especially those who have mildly decompensated liver disease. This article focuses on the management of liver transplant recipients who have HCV infection at the time of transplantation. Prophylactic and preemptive therapies, as well as treatment of established recurrent disease, are the strategies reviewed.

Management of hepatitis C virus infection in the setting of liver transplantation

1. Posttransplantation recurrence of hepatitis C virus infection is a universal phenomenon with a highly variable natural history. 2. Approximately 10% to 25% of hepatitis C virus- infected recipients of liver allografts will develop cirrhosis within 5 years' after transplantation. 3. The 1-year actuarial risk of hepatic decompensation after recurrence of cirrhosis approximates 42%. 4. Some of the factors associated with aggressive recurrence include donor and recipient age, recent year of transplantation, recipient gender and race, the use of antithymocyte globulin, and high dose of corticosteroids. 5. Highly aggressive recurrent hepatitis C virus infection leading to cirrhosis fares poorly after retransplantation in the presence of hyperbilirubinemia and renal failure, with a 1-year survival of approximately 40%. 6. Elevated serum aminotransferases are a poor indicator or recurrent disease. 7. Current sustained virological response after combination pegylated alpha interferon and ribavirin treatment is approximately 25%. 8. There is no consensus on initiation time point, duration of treatment, or dosage. Given immunosuppression, at least 48 weeks of therapy is a reasonable approach. 9. Treatment for 48 weeks is cost effective. Incremental cost-effectiveness ratio for men aged 55 years is $29,100 per life-year saved.

New therapies for chronic hepatitis C virus infection

Chronic hepatitis C infection is associated with significant morbidity and mortality in addition to substantial social and health-related costs. Since the identification of the virus and determination of the HCV genome over a decade ago, considerable progress has been made in the treatment of chronic hepatitis C infection. However, the current standard combination of interferon-based therapies and ribavirin is effective in only 50% of patients. In addition, this combination is expensive, requires lengthy periods of administration, and is associated with significant side effects. Furthermore, no effective preventive measure, such as vaccination, is currently available. A number of newer therapies, including protease and helicase inhibitors, ribozymes, antisense therapies, and therapeutic vaccines, are in preclinical and clinical development and may significantly enhance existing therapeutic options for the future.

Prophylactic and preemptive therapies for hepatitis C virus-infected patients undergoing liver transplantation

1. Preclinical data from chimpanzees and studies in hepatitis B virus/hepatitis C virus (HCV) coinfected transplant recipients suggest prophylactic HCV antibody therapy may have a role in the prevention of HCV recurrence. 2. There are insufficient data available to evaluate the efficacy of this therapeutic approach. A small study found no benefit. Other ongoing studies using alternative antibody preparations and more intensive dosing schedules are underway. 3. Preemptive antiviral therapy, started within the first 4 weeks posttransplantation and prior to the onset of clinical signs and symptoms, is effective in some patients (5-33%) and is not associated with an increased risk of acute rejection. Tolerability of antiviral agents in the early posttransplantation period may be a factor limiting treatment efficacy. 4. It is unclear whether the preemptive antiviral treatment is superior to delaying treatment until recurrent disease is present and controlled trials addressing this issue are needed.

Treatment of hepatitis C virus infection in the allograft

1. Recurrence of hepatitis C virus (HCV) in the graft is associated with a reduced quality of life and worse graft survival. 2. Pretransplantation, the severity of HCV recurrence may be reduced by reducing the pretransplantation load, by avoiding the use of organs from older donors, and by reducing the ischemic times. The effect of split livers on recurrence rates is uncertain. 3. The optimal immunosuppression regime has not been established but a heavy induction regime and treatment for acute rejection are associated with more viral replication and more graft damage. 4. Presently, there is no convincing evidence for preemptive treatment of HCV. 5. There are many studies on the effect of interferon with and without ribavirin for the treatment of HCV hepatitis. However, few are prospective, randomized, and controlled. 6. The current best treatment is with pegylated interferon and ribavirin; the dose and duration of treatment need to be established. Side-effects of treatment are common and reduction/withdrawal is frequent, but the regime is cost-effective. 7. The role of newer treatments remains to be established.

Natural history of hepatitis C and outcomes following liver transplantation

Hepatitis C-associated liver failure is the most common indication for liver transplantation and the infection recurs nearly universally following transplantation. Histologic evidence of recurrence is apparent in approximately 50% of HCV-infected recipients in the first postoperative year. Approximately 10% of HCV-infected recipients will die or lose their allograft secondary to hepatitis C-associated allograft failure in the medium term. HCV-infected recipients who undergo retransplantation experience 5-year patient and graft survival rates that are similar to recipients undergoing retransplantation who are not HCV-infected. While the choice of calcineurin inhibitor or the use of azathioprine have not been clearly shown to affect histologic recurrence of hepatitis C or the frequency of rejection in HCV-infected recipients, cumulative exposure to corticosteroids is associated with increased mortality, higher levels of HCV viremia, and more severe histologic recurrence. In contrast to non-HCV-infected recipients, treatment for acute cellular rejection is associated with attenuated patient survival among recipients with hepatitis C. The development of steroid-resistant rejection is associated with a greater than 5-fold increased risk of mortality in HCV-infected liver transplant recipients. In lieu of large studies in a posttransplant population, therapy with pegylated IFN (+/- ribavirin) should be considered in recipients with histologically apparent recurrence of hepatitis C before total bilirubin exceeds 3 mg/dl. The role of hepatitis C immunoglobulin and new immunosuppression agents in the management of posttransplant hepatitis C infection is still evolving.

Hepatitis C virus in the human liver transplantation model

Hepatitis C virus-related liver failure is the single leading indication for liver transplantation, and the study of HCV in the transplant setting has enhanced the understanding of the natural history of disease and putative mechanisms by which HCV causes liver injury. In a subset of patients, allograft cirrhosis develops within a few years after transplantation, and recent findings suggest these individuals are immunologically impaired compared with individuals with mild HCV recurrence at long-term follow-up. Fig. 9 shows a conceptual paradigm of mechanisms potentially involved in shaping HCV outcome after transplantation. It is possible that relative antiviral control by innate and adaptive immune responses (to maintain HCV replication below a certain threshold) prevents direct cytopathic injury and induction of oxidative stress and apoptosis of cells. Additional phenomena that may contribute to induction of apoptosis (eg, genetic polymorphisms within the donor organ. CMV coinfection, and ischemic-preservation injury) may augment the initial cascade of liver injury. Recruitment to the allograft of nonspecific cells may decrease viral replication by way of noncytolytic mechanisms or augment viral replication (eg, Th2 phenotype) and direct cytopathic injury. The immune response is likely insufficiently vigorous to keep viral replication under control, but may maintain chronic liver injury. The liver transplant model is unique in that distinct phenotypic outcomes can be observed over a short period of time. A consideration of the temporal evolution of different mechanisms is also important, because mechanisms that initially predominate may become less important over time, and conversely, as suggested with the inverse correlation between viral load at 5 years and allograft fibrosis, new immune responses may emerge that modify the host-virus interaction. Prospective characterization of the immunoregulatory and virologic mechanisms involved in the liver transplantation model hopefully will help unravel the causal basis of reported associations, lead to the development of highly specific therapeutic strategies, and ultimately diminish the rate of graft loss from recurrent disease.

Treatment of recurrent hepatitis C

1. Treatment of established recurrent hepatitis C with interferon-alpha monotherapy does not achieve sustained virologic response (SVR). 2. Treatment of established recurrent hepatitis C with combination interferon plus ribavirin achieves SVR rates of 17% to 27%, but dropout rates approach 30%. 3. Pretransplant prophylaxis against recurrent hepatitis C with combination interferon plus ribavirin is poorly tolerated in patients with decompensated hepatitis C cirrhosis. 4. Posttransplant prophylaxis with combination interferon plus ribavirin prevents both recurrent viremia and hepatitis in 15% to 20% of patients, but dropout rates approach 50%. 5. Hepatitis C virus genotype is the best predictor of response to antiviral prophylaxis and treatment of recurrent hepatitis C. 6. Interferon-alpha therapy is not associated with an increased risk of allograft rejection in liver transplant recipients. 7. Ribavirin therapy is associated with increased hemolysis in liver transplant recipients. 8. Preliminary data suggest pegylated interferon monotherapy will have similar efficacy but better tolerability than combination interferon plus ribavirin. 9. In a recent study, posttransplant immunoprophylaxis with polyclonal hepatitis C immunoglobulin had no effect on recurrent viremia or hepatitis.