Complete weaning off immunosuppression in HCV liver transplant recipients is feasible and favourably impacts on the progression of disease recurrence

Operational tolerance after liver transplantation

The achievement of an immunosuppression (IS)-free state after transplantation represents the ultimate goal of any immunosuppressive regimen. While clinical operational tolerance (COT) remains the exception after other types of solid organ transplantation, several cases of COT have been described after liver transplantation (LT). Overall, the experience gained so far worldwide demonstrates that COT can be achieved safely in one quarter of selected individuals, irrespective of the immunological background of donor and recipient, patient age, indication for LT, study endpoint, length of the weaning period and of pre/post-weaning follow-up, presence or not of chimerism. However, most transplant physicians still believe that the achievement of COT is still out of reach for the majority of LT recipients because of the potential risk for transplant survival, the non-randomized nature of most of the studies reported so far, and the selective nature of the patients enrolled in such studies, making them non-representative of the whole population of LT recipients. Despite these concerns, the present article demonstrates that this attitude is potentially no longer justified, given the growing evidence that a permanent and stable IS-free state can be achieved in a proportion of individuals who have received a LT for non-immune mediated liver diseases.

Requirement of protocol biopsy before and after complete cessation of immunosuppression after liver transplantation

BACKGROUND

Operational tolerance is defined as long-term acceptance of a transplanted organ after complete cessation of immunosuppression (IS), but may not always protect against antigen-dependent changes in graft morphology.

METHOD

IS free patients after living-donor liver transplantation (LDLT) underwent protocol biopsy (tolerance group [Gr-Tol]) and were evaluated for rejection and fibrosis. The degree of fibrosis was compared with those in the patients on maintenance IS group (Gr-IS) and the base line normal liver group (Gr-BS). When bridging fibrosis or progression of fibrosis was observed, IS was reintroduced or increased in Gr-Tol or in the patients in the weaning process.

RESULTS

Neither acute nor chronic rejection was observed. The degree of fibrosis, however, was significantly greater in Gr-Tol than those in Gr-IS and Gr-BS. In Gr-Tol, the number of graft infiltrating FOXP3 cells was significantly increased, the interval between LDLT and biopsy plus the donor age was significantly longer, and recipient age at LDLT was significantly younger, compared with those in Gr-IS. However, none of these three parameters correlated with the degree of fibrosis. In 7 of 11 patients in whom IS was reintroduced or increased, the improvement of fibrosis was observed by the subsequent biopsy.

CONCLUSION

Grafts of operationally tolerant patients after LDLT did not exhibit acute or chronic rejection, but they exhibited fibrosis. It remains elusive whether fibrosis observed in tolerant grafts is antigen dependent. The finding that after [corrected] the reintroduction or the increase of IS fibrosis was improved supported the possibility that fibrosis in operationally tolerant patients was antigen dependent.

Long-term management of immunosuppression after pediatric liver transplantation: is minimization or withdrawal desirable or possible or both?

PURPOSE OF REVIEW

The aim is to review available data regarding the risks and benefits of indefinite immunosuppression against attempted immunosuppression withdrawal for children who have undergone liver transplantation.

RECENT FINDINGS

Emerging data suggest that conventional immunosuppression practices may well be responsible for a substantial proportion of the long-term mortality and morbidity burden borne by pediatric liver transplant recipients. The cumulative risk of chronic kidney disease, infection, malignancy, and cardiovascular risk factors such as hypertension, diabetes, and hyperlipidemia appear to threaten the health and well being of children more than that of acute or chronic allograft rejection. In parallel, single-center experiences have suggested that gradual immunosuppression withdrawal can be done safely with higher success rates in pediatric compared with adult liver transplant recipients. The coalescence of these two data streams has engendered substantial interest in systematic exploration of the safety and efficacy of immunosuppression withdrawal in conjunction with a vigorous scientific effort to elucidate an immunologic signature predictive of successful withdrawal.

SUMMARY

There is a concerted effort within the transplant community to identify biomarkers that can accurately predict the success of immunosuppression withdrawal after liver transplantation. Freedom from lifelong immunosuppression is likely to yield considerable benefit, particularly for children who face the longest lifetime horizons.

Immunoregulatory profiles in liver transplant recipients on different immunosuppressive agents

We compared peripheral blood immunophenotyping in 31 adult liver transplant recipients on differing long-term immunosuppressive (IS) monotherapy with and without peri-transplantation alemtuzumab (AL) induction. All patients had been stable on monotherapy with either sirolimus (SRL) (n = 10) or without SRL (tacrolimus (TAC) (n = 10), mycophenolate mofetil (MMF) (n = 11)) for more than 6 months. Five-color flow cytometry for putative "regulatory" T and dendritic cells as well as serum assays for soluble HLA-G (sHLA-G) were performed. The SRL monotherapy group had significantly higher percentages of CD4+CD25(high+)Foxp3+ T cells (1.3 +/- 1.0) compared with the non-SRL group (0.7 +/- 0.6) (p = 0.04). The SRL effect was even higher in a subset with prior AL induction and no prior hepatitis C or rejection (1.7 +/- 0.2) compared with all other subgroups (0.7 +/- 0.6) (p = 0.02). TAC patients showed significantly higher "regulatory" DC2:DC1 ratios (10 +/- 7.6) compared with non-TAC patients (4.1 +/- 2.3) (p = 0.04). Although sHLA-G levels appeared higher in TAC patients, the differences were not statistically significant. In conclusion, IS monotherapy provides an opportunity to investigate regulatory roles of individual agents. SRL maintenance and prior AL induction in subsets of patients appeared to show a regulatory T cell immunophenotype. However, TAC patients may have other regulatory characteristics, supporting the need for larger, prospective studies to clarify differences.

Long-term antiviral therapy for recurrent hepatitis C after liver transplantation in nonresponders: biochemical, virological, and histological impact

More than 50% of patients with a recurrent posttransplant hepatitis C virus infection fail to respond to antiviral treatment. The aim of this study was to evaluate the interest of a long-term antiviral treatment maintained for more than 48 weeks. Seventy treated patients, with a histological follow-up > 1 year, were enrolled in this observational, retrospective study. The duration of antiviral treatment, tolerance, and occurrence of virological, biochemical, and histological responses were recorded. Thirty-two patients were nonresponders after 48 weeks of treatment. Combined antiviral therapy was maintained for >12 months in 26 and for >18 months in 21. Twelve patients had to discontinue their treatment. At 48 weeks, the rates of virological response and sustained virological response were 37% and 24.3%, respectively; at the end of the follow-up, they were 48.5% and 35.7%. Virological response was significantly associated with a higher incidence of biochemical and histological response, regardless of its time of occurrence (before or after 6 months). Even in the absence of virological response, the rate of progression of fibrosis was significantly slowed in patients treated for more than 6 months. Our results show the feasibility, safety, and efficacy of long-term antiviral therapy in nonresponder patients with a recurrent posttransplant hepatitis C virus infection.

Monitoring of human liver and kidney allograft tolerance: a tissue/histopathology perspective

Several factors acting together have recently enabled clinicians to seriously consider whether chronic immunosuppression is needed in all solid organ allograft recipients. This has prompted a dozen or so centers throughout the world to prospectively wean immunosuppression from conventionally treated liver allograft recipients. The goal is to lessen the impact of chronic immunosuppression and empirically identify occasional recipients who show operational tolerance, defined as gross phenotype of tolerance in the presence of an immune response and/or immune deficit that has little or no significant clinical impact. Rare operationally tolerant kidney allograft recipients have also been identified, usually by single case reports, but only a couple of prospective weaning trials in conventionally treated kidney allograft recipients have been attempted and reported. Pre- and postweaning allograft biopsy monitoring of recipients adds a critical dimension to these trials, not only for patient safety but also for determining whether events in the allografts can contribute to a mechanistic understanding of allograft acceptance. The following is based on a literature review and personal experience regarding the practical and scientific aspects of biopsy monitoring of potential or actual operationally tolerant human liver and kidney allograft recipients where the goal, intended or attained, was complete withdrawal of immunosuppression.

Using transcriptional profiling to develop a diagnostic test of operational tolerance in liver transplant recipients

A fraction of liver transplant recipients are able to discontinue all immunosuppressive therapies without rejecting their grafts and are said to be operationally tolerant to the transplant. However, accurate identification of these recipients remains a challenge. To design a clinically applicable molecular test of operational tolerance in liver transplantation, we studied transcriptional patterns in the peripheral blood of 80 liver transplant recipients and 16 nontransplanted healthy individuals by employing oligonucleotide microarrays and quantitative real-time PCR. This resulted in the discovery and validation of several gene signatures comprising a modest number of genes capable of identifying tolerant and nontolerant recipients with high accuracy. Multiple peripheral blood lymphocyte subsets contributed to the tolerance-associated transcriptional patterns, although NK and gammadeltaTCR+ T cells exerted the predominant influence. These data suggest that transcriptional profiling of peripheral blood can be employed to identify liver transplant recipients who can discontinue immunosuppressive therapy and that innate immune cells are likely to play a major role in the maintenance of operational tolerance in liver transplantation.

The Tor Vergata weaning off immunosuppression protocol in stable HCV liver transplant patients: the updated follow up at 78 months

BACKGROUND

We report the update of the Tor Vergata immunosuppression (IS) weaning protocol in stable hepatitis C virus (HCV) liver transplant (LT) recipients.

METHODS

The weaning off IS was attempted in 34 patients who had received a LT 63.5+/-20.1 month earlier, for HCV-related end stage liver disease. Patients were observed over a period of 6.5 years. During this time, yearly protocol liver biopsies were performed. Primary endpoints were determined as the feasibility of weaning off IS and its impact on the long term disease progression. Secondary endpoints were defined as the impact on patient morbidity and quality of life.

RESULTS

Of the 8 originally tolerant patients, 7 remain alive and in good condition, while 1 died of severe HCV recurrence 10 years post-LT and 6 years after complete removal of IS. Four out of 26 intolerant individuals died of HCV recurrence (2x), lung carcinoma (1x) and acute myocardial infarction (1x), after a mean follow up period from LT of 115 (range 100-124). The 10-year survival from LT was comparable (89% vs. 87.5%). Liver graft pathology showed no significant differences between the two groups in terms of staging, fibrosis progression rate, and grading. Quantitative HCV RNA assay showed a significant non-logarithmic difference between the two groups (p = 0.03). The two groups were comparable in terms of liver function tests and lipid profile, whereas they differed with regards to glycaemia. While all tolerant individuals were euglicemic, 11 intolerant individuals developed new onset diabetes that required specific treatment (p = 0.03). Finally, significantly more intolerant patients are suffering from either cardiovascular (14/22 vs. 0/7, p = 0.01) or infectious diseases (13/22 vs. 0/7, p = 0.01).

CONCLUSIONS

After a 6.5-year follow up, the complete withdrawal of IS in HCV LT recipient remains safe and beneficial to patients, because it reduces the IS-related morbidity and increases the quality of life. The impact on HCV disease recurrence is less marked than after 3.5 years.

Hepatitis C and liver transplantation: enhancing outcomes and should patients be retransplanted

Hepatitis C (HCV)-related end-stage liver disease is the most common indication for liver transplantation. Safe expansion of the donor pool with improved rates of deceased donation and more widespread use of living and extended criteria donation are likely to decrease wait list mortality. In addition, improved antiviral treatments and a better understanding of the delicate balance between under- and over-immunosuppression in this population are needed. Finally, when recurrent advanced fibrosis occurs, the criteria for patient selection for retransplantation remain widely debated. This article reviews the literature on these topics and the work being done in each area to maximize outcomes in patients receiving transplants for HCV-related cirrhosis.

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.

Management of hepatitis C virus in the transplant patient

Hepatitis C virus (HCV) is a leading cause of chronic hepatitis, with 170 to 190 million people infected worldwide. The treatment of choice for patients who have HCV-related cirrhosis with or without hepatocellular carcinoma is liver transplantation. Virologic recurrence is constant after transplantation and results in chronic hepatitis in the vast majority. HCV infection now can be cured in a substantial proportion of liver transplant recipients. This review highlights the available strategies to improve outcome, including modification of factors that affect disease progression and the efficacy of antiviral therapy.

Multiparameter immune profiling of operational tolerance in liver transplantation

Immunosuppressive drugs can be completely withdrawn in up to 20% of liver transplant recipients, commonly referred to as 'operationally' tolerant. Immune characterization of these patients, however, has not been performed in detail, and we lack tests capable of identifying tolerant patients among recipients receiving maintenance immunosuppression. In the current study we have analyzed a variety of biological traits in peripheral blood of operationally tolerant liver recipients in an attempt to define a multiparameter 'fingerprint' of tolerance. Thus, we have performed peripheral blood gene expression profiling and extensive blood cell immunophenotyping on 16 operationally tolerant liver recipients, 16 recipients requiring on-going immunosuppressive therapy, and 10 healthy individuals. Microarray profiling identified a gene expression signature that could discriminate tolerant recipients from immunosuppression-dependent patients with high accuracy. This signature included genes encoding for gammadelta T-cell and NK receptors, and for proteins involved in cell proliferation arrest. In addition, tolerant recipients exhibited significantly greater numbers of circulating potentially regulatory T-cell subsets (CD4+ CD25+ T-cells and Vdelta1+ T cells) than either non-tolerant patients or healthy individuals. Our data provide novel mechanistic insight on liver allograft operational tolerance, and constitute a first step in the search for a non-invasive diagnostic signature capable of predicting tolerance before undergoing drug weaning.

Switch to 1.5 grams MMF monotherapy for CNI-related toxicity in liver transplantation is safe and improves renal function, dyslipidemia, and hypertension

Although mycophenolate mofetil (MMF) monotherapy has been successfully used in liver transplant recipients suffering from calcineurin-inhibitor (CNI)-related chronic toxicity, still no consensus has been reached on its safety, efficacy and tolerability. We attempted the complete weaning off CNI in 42 individuals presenting chronic renal dysfunction and/or dyslipidemia and/or arterial hypertension and simultaneously introduced 1.5 gm/day MMF. CNI could be completely withdrawn in 41 cases. A total of 32 (75%) patients are currently on <or=1.5 gm/day of MMF. Mean follow-up from the introduction of MMF is 31.5 months and mean length of follow-up from the beginning of MMF monotherapy is 27.3 months. Renal function improved in 31/36 (89%) cases. Blood levels of cholesterol and triglycerides decreased in 13 of 17 (76%) and 15 of 17 (89%) patients, respectively. Arterial hypertension improved in 4 of 5 (80%) cases. A total of 8 patients showed a single episode of fluctuation of liver function tests during tapering off CNI. This feature was interpreted as an acute rejection (AR), based on the resolution of the clinical setting after escalation of MMF daily dose to 2 gm. A further patient developed a biopsy-proven AR insensitive to MMF adjustment, requiring reinstitution of the CNI dose. No deaths or major toxicity requiring MMF discontinuation occurred. In conclusion, low dose MMF monotherapy is safe, effective, and well tolerated.

Clinical tolerance following liver transplantation: long term results and future prospects

The ongoing quest of achieving clinical transplantation tolerance has been fueled, in large part, by the success of solid organ transplantation. Long term morbidity following transplantation now is primarily related to complications of immunosuppression (IS) such as malignancy, drug toxicity, or infection. This report provides long term follow-up on a large cohort of operationally tolerant patients, provides clinical guidelines to be considered in IS withdrawal, and identifies future prospects for achieving consistent clinical tolerance following liver transplantation (LT).

Operational tolerance in clinical liver transplantation: emerging developments

There is still little understanding of the immune events that occur in transplant patients as they develop a relationship with their graft alloantigens. Though, there is an enormous interest and motivation in inducing specific unresponsiveness to organ allografts in order to allow minimization or complete withdrawal of immunosuppression in the recipient, given that life-long immunosuppressive treatment entails a high risk of infectious and metabolic complications, malignancies, and drug-specific toxicity. Clinical tolerance is defined as stable normal graft function in the total absence of a requirement for maintenance immunosuppression. Effective clinical tolerance has been reported more frequently in liver transplant recipients than after transplantation of other organs, as the liver is an immune-privileged organ for several mechanisms, most of which still remain unclear. According to the English medical literature, cautious, carefully supervised weaning of immunosuppressive drugs in controlled trials is not unreasonable, especially when monitored by protocol biopsies. The five centers in which the weaning has been attempted have reported a similar degree of success (1 out of 4 patients) and no harm to the patient over the short-term. Though, long-term follow-up has been lacking and, at present, there are no reliable immunological parameters that enable patients who can be withdrawn from immunosuppressants without the risk of rejection to be identified. To achieve that goal, appropriate collaboration and interaction between clinicians, immunologists and other basic scientists are desirable, as well as the creation of an international, maybe intercontinental, registry for tolerant patients.

An appraisal of tolerance in liver transplantation

Human liver allografts have a lower susceptibility to rejection than other organs. In addition, in some liver transplant recipients immunosuppressive drugs can be completely withdrawn, and these patients are considered as 'operationally' tolerant. Careful scrutiny of accumulated clinical experience indicates that elective immunosuppressive drug weaning is feasible in almost 20% of selected liver transplant recipients. This is associated with an incidence of 12% to 76% of acute cellular rejection, but these episodes are commonly mild and often resolve by return to baseline immunosuppression (IS), many times without the need to administer steroid boluses. Study of tolerance in liver transplantation (LT) has been hampered by confusion regarding the definitions of rejection and tolerance, and by the absence of prospective studies correlating results of immune monitoring assays and clinical outcome. Thus, we lack a clinically validated treatment-stopping rule capable of predicting the success of IS withdrawal and this procedure has to be performed on a 'trial and error' basis. The search for an accurate means to identify allograft tolerance among immunosuppressed recipients should become a priority in LT research. This information would provide a biological basis for guiding IS withdrawal protocols and for the implementation of tolerance-promoting strategies in LT.

Treating hepatitis C infection in liver transplant recipients

Chronic infection with hepatitis C virus (HCV) is a growing problem worldwide, with up to 300 million individuals infected, and those with chronic infection are at risk for cirrhosis and hepatocellular carcinoma. HCV infection is the most common indication for liver transplantation in the United States and Europe. Unfortunately, although transplantation is effective for treating decompensated cirrhosis and limited hepatocellular carcinoma associated with hepatitis C, HCV reinfection is virtually the rule among transplant recipients. Reinfection of the graft is associated with more rapidly progressive disease, with a median time to cirrhosis of 8 to 10 yr. Unfortunately, treatment of chronic HCV in liver transplant recipients is suboptimal. Combination therapy with interferon (pegylated and nonpegylated forms) plus ribavirin appears to provide maximum benefits. Drug therapy is usually administered for recurrent disease. No prophylactic therapy is available. Preemptive regimens offer no distinctive advantages over treatments begun for recurrent disease. Overall, treatment is poorly tolerated, with frequent need for dose reductions, especially from cytopenias, and drug discontinuations in up to 50% of patients. Optimizing drug doses is important in maximizing sustained virological response rates. Future therapies may include ribavirin alternatives with lower rates of anemia, alternative interferons with lower rates of cytopenias, and new antiviral drugs that can be used alone or in combination with either interferon or ribavirin to enhance sustained virological response rates and improve tolerability. Liver Transpl 12:1192-1204, 2006. (c) 2006 AASLD.