Hot-topic debate on hepatitis C virus: the type of immunosuppression matters

Impact of anti-thymocyte globulin during immunosuppression induction in patients with hepatitis C after liver transplantation

BACKGROUND

Induction immunosuppression with anti-thymocyte globulin (ATG) provides potential benefits after liver transplantation (LT). However, its use in patients with LT and hepatitis C (HCV) is controversial.

AIM

To evaluate the 1- and 2-year patient survival and HCV recurrence rate in patients receiving ATG during the induction phase of immunosuppression (IPI) after LT.

METHODS

A total of 49 patients undergoing their first LT for HCV were randomized to receive ATG during IPI. Patient survival and HCV recurrence were determined at 1 and 2 years. The frequency of acute cellular rejection (ACR), infections, and neoplasms was also evaluated.

RESULTS

Twenty-six patients were randomized to receive ATG (Arm-1) and 23 to standard induction therapy (Arm-2). Those given ATG had lower HCV recurrence (26.9 vs 73.9 %, p = 0.001). The 1- and 2-year patient survival rates were similar for both arms (p = 0.33). Infections occurred in 46.1 % subjects in Arm-1 and 34.7 % in Arm-2 (p = 0.562). There was a greater proportion of fungal infections in Arm-1 (19.2 vs 0 %, p = 0.032).

CONCLUSIONS

ATG during the IPI was associated with lower frequency of recurrence of HCV in patients undergoing LT. This, however, did not affect the 1- and 2-year survival and the frequency of ACR, infections, or neoplasms.

Impact of immunosuppression minimization and withdrawal in long-term hepatitis C virus liver transplant recipients

AIM: To investigate the effects of different immunosuppressive regimens and avoidance on fibrosis progression in hepatitis C virus (HCV) liver transplant (LT) recipients.

METHODS: We retrospectively compared the liver biopsies of well-matched HCV LT recipients under calcineurin inhibitors (CNI group, n = 21) and mycophenolate (MMF group, n = 15) monotherapy, with those patients who successfully withdrawn immunosuppression (IS) therapy from at least 3 years (TOL group, n = 10). To perform the well-matched analysis, all HCV transplanted patients from December 1993 were screened. Only those HCV patients who reached the following criteria were considered for the analysis: (1) at least 3 years of post-operative follow-up; (2) patients with normal liver graft function under low dose CNI monotherapy (CNI group); (3) patients with normal liver graft function under antimetabolite (Micophenolate Mofetil or coated mycophenolate sodium) monotherapy (MMF group); and (4) recipients with normal liver function without any IS. We excluded from the analysis recipients who were IS free or under monotherapy for < 36 mo, recipients with cirrhosis or with unstable liver function tests.

RESULTS: Thirty six recipients were enrolled in the study. Demographics, clinical data, time after LT and baseline liver biopsies were comparable in the three groups. After six years of follow-up, there was no worsening of hepatic fibrosis in the MMF group (2.5 ± 1.5 Ishak Units vs 2.9 ± 1.7 Ishak Units, P = 0.5) and TOL group (2.7 ± 10.7 vs 2.5 ± 1.2, P = 0.2). In contrast, a significant increase in the fibrosis score was observed in the CNI group (2.2 ± 1.7 vs 3.9 ± 1.6, P = 0.008). The yearly fibrosis progression rate was significantly worse in the CNI group (0.32 ± 0.35) vs MMF group (0.03 ± 0.31, P = 0.03), and TOL group (-0.02 ± 0.27, P = 0.02). No differences have been reported in grading scores for CNI group (2.79 ± 1.9, P = 0.7), MMF group (3.2 ± 1.5, P = 0.9) and TOL group (3.1 ± 1.4, P = 0.2). Twenty four patients were treated with low dose ribavirin (8 TOL, 7 MMF, 9 CNI). The hepatitis C titers were comparable in the three groups. No episodes of rejection have been reported despite differences of liver function test in the three groups during the observational period.

CONCLUSION: IS withdrawal and MMF monotherapy is safe and seems to be associated with the slowest fibrosis progression in HCV LT recipients.

Post-liver transplant hepatitis C virus recurrence: an unresolved thorny problem

Hepatitis C virus (HCV)-related cirrhosis represents the leading cause of liver transplantation in developed, Western and Eastern countries. Unfortunately, liver transplantation does not cure recipient HCV infection: reinfection universally occurs and disease progression is faster after liver transplant. In this review we focus on what happens throughout the peri-transplant phase and in the first 6-12 mo after transplantation: during this crucial period a completely new balance between HCV, liver graft, the recipient's immune response and anti-rejection therapy is achieved that will deeply affect subsequent outcomes. Nearly all patients show an early graft reinfection, with HCV viremia reaching and exceeding pre-transplant levels; in this setting, histological assessment is essential to differentiate recurrent hepatitis C from acute or chronic rejection; however, differentiating the two patterns remains difficult. The host immune response (mainly cellular mediated) appears to be crucial both in the control of HCV infection and in the genesis of rejection, and it is also strongly influenced by immunosuppressive treatment. At present no clear immunosuppressive strategy could be strongly recommended in HCV-positive recipients to prevent HCV recurrence, even immunotherapy appears to be ineffective. Nonetheless it seems reasonable that episodes of rejection and over-immunosuppression are more likely to enhance the risk of HCV recurrence through immunological mechanisms. Both complete prevention of rejection and optimization of immunosuppression should represent the main goals towards reducing the rate of graft HCV reinfection. In conclusion, post-transplant HCV recurrence remains an unresolved, thorny problem because many factors remain obscure and need to be better determined.

Immunosuppression minimization vs. complete drug withdrawal in liver transplantation

Despite the increase in long-term survival, liver transplant recipients still exhibit higher morbidity and mortality than the general population. This is in part attributed to the lifelong administration of immunosuppression and its associated side effects. Several studies reported in the last decades have evaluated the impact of immunosuppression minimization in liver transplant recipients, but results have been inconsistent due to the heterogeneity of study designs and insufficient sample sizes. On the other hand, complete immunosuppression withdrawal has proven to be feasible in approximately 20% of carefully selected liver transplant recipients, especially in older patients and those with longer duration after transplantation. The long-term risks and clinical benefits of this strategy, however, also need to be clarified. As a consequence, and despite the general perception that a large proportion of liver recipients are over-immunosuppressed, it is currently not possible to derive evidence-based guidelines on how to manage long-term immunosuppression to improve clinical outcomes. Large clinical trials of drug minimization and/or withdrawal focused on clinically-relevant long-term outcomes are required. Development of personalized medicine tools and a deeper understanding of the pathogenesis of idiopathic inflammatory graft lesions will be pre-requisites to achieve these goals.

Immunosuppression in HCV-positive liver-transplant recipients

PURPOSE OF REVIEW

The purpose of this review is to evaluate the historical and recent literature as it pertains to current immunosuppression regimens in hepatitis C virus (HCV)-positive (+) liver-transplant recipients.

RECENT FINDINGS

Recent findings suggest that there are unique differences between HCV transplant recipients and non-HCV transplant recipients, not only in the graft's inflammatory response, but also to the treatments used to prevent and combat rejection.

SUMMARY

HCV (+) transplant recipients present unique challenges. Over the years, there has been progress but there is clearly no consensus regarding the optimal immunosuppressive medications or drug regimens; however, there continues to be advancements in the management of patients with HCV. Though current studies do not provide clear evidence as to optimal immunosuppression, they do identify questions ideally addressed by large, randomized controlled trials.

Immunomodulating options for liver transplant patients

Much has changed since the early years of liver transplantation. Improvements in post-transplant survival are largely due to more selective and less toxic immunosuppression regimens and advances in operative and perioperative care. This has allowed liver transplantation to become an extremely successful treatment option for patients with endstage liver disease. Beginning with cyclosporine, a cyclic endecapeptide of fungal origin and the first of the calcineurin inhibitors to find widespread use, immunosuppressive regimens have evolved to include additional calcineurin inhibitors, steroids, mTOR inhibitors, antimetabolites and antibodies, mostly targeting T-cell activation. This review will present currently available immunosuppressive agents used in the perioperative period of liver transplantation, as well as maintenance treatments, tailoring therapeutic strategies for specific populations, and advances in immune monitoring and tolerance.

Hepatitis C virus recurrence and immunosuppression-free state after liver transplantation

HCV-related disease is the most common indication for liver transplantation (LT). HCV recurrence, which is almost universal, has a significant impact on patient and graft survival after LT and still represents a great unsolved issue for the liver transplant community. Several treatment strategies have been proposed. Since antiviral therapy has limited efficacy and can be administrated only in selected transplant recipients and additionally that immunosuppressive drugs have a negative impact on HCV re-infection, the achievement of an immunosuppression-free state after LT could play a central role in the avoidance of rapid HCV recurrence.

The adverse pharmacology of calcineurin inhibitors and their impact on hepatitis C recurrence after liver transplantation: implications for clinical practice

Calcineurin inhibitors are widely used as maintenance immunosuppressants in solid-organ transplantation to minimize the risk of allograft rejection. Although the use of these agents has transformed the outcomes for patient and graft survival, this has come at a cost, notably the well-known adverse events of nephrotoxicity and metabolic abnormalities, to name a few. Over the last decade, tremendous interest has also focused on the impact of these medications on the replication of hepatitis C virus (HCV), with cyclosporine in particular having a negative effect on viral replication in vitro. Although small retrospective studies suggested that there may be a beneficial effect with cyclosporine on the progression of recurrent HCV and response to interferon, these findings have not been validated in several well-designed randomized controlled trial studies. The authors will review the pharmacology and pharmacokinetics of these well-known drugs and discuss the impact of these medications on the natural history of HCV recurrence after liver transplantation.

Viral hepatitis in liver transplantation

Liver transplantation is the only alternative for patients with end-stage liver disease. Viral hepatitis B and C are among the most common causes of cirrhosis and hepatocellular carcinoma and a frequent indication for liver transplantation. Hepatitis B virus immunoglobulin and nucleot(s)ide analogues have facilitated the management of patients with hepatitis B who have received liver transplants and resulted in excellent long-term outcomes. On the contrary, recurrence of hepatitis C is the main cause of graft loss in most transplant programs. Current therapeutic approaches are far from optimal, because sustained virologic responses are only achieved in one-third of treated patients, and adverse effects are common and severe. However, the rapid development of direct-acting antivirals against hepatitis C virus will change the management of this disease and in a few years prevent graft infection with this virus.