Antithymocyte globulin induction therapy in hepatitis C-positive liver transplant recipients

Current Use of Immunosuppression in Liver Transplantation

Since the first successful liver transplant in 1967, immunosuppression has allowed liver transplantation to become the standard treatment of end-stage liver disease. Over the decades, the rates of rejection have decreased, and patient survival outcomes have significantly improved in large part due to the introduction and advancements of immunosuppression medications. However, the adverse effects associated with long-term immunosuppression have created new challenges facing liver transplantation and added significantly to posttransplantation morbidity. This review presents the data and rationale for immunosuppression approaches, addresses the main controversies related to immunosuppression in liver transplantation, and explores some of the newer advancements in immunosuppressive drug therapy.

Superior Patient and Graft Survival in Adult Liver Transplant with Rabbit Antithymocyte Globulin Induction: Experience with 595 Patients

OBJECTIVES

The use of induction therapy in liver transplant is debatable. We aimed to compare clinical outcomes of different induction protocols in liver transplant recipients.

MATERIALS AND METHODS

This was a retrospective cohort analyses using the University of Washington Transplant Database from January 2005 to May 2012 for adult (≥ 18 y old) primary liver transplant patients. All patients received induction therapy. Maintenance immunosuppressive agents were tacrolimus or tacrolimus-mycophenolate mofetil. Primary endpoints were acute cellular rejection, patient survival, and graft survival. In patients with chronic hepatitis C, the degree of histologic inflammation or fibrosis at 1 year was assessed. Cox proportional hazards models were constructed to evaluate variables associated with both patient and graft survival.

RESULTS

We identified 595 patients: 322 patients received rabbit antithymocyte globulin and 273 received interleukin 2 receptor blocker. Acute cellular rejection was higher in patients who received interleukin 2 receptor blocker than in patients who received rabbit antithymocyte globulin (27% vs 18%; P < .03). Both patient survival at 1 year (95% vs 90%), 3 years (92% vs 87%), and 5 years (86% vs 80%) and graft survival at 1 year (93% vs 88%), 3 years (90% vs 86%), and 5 years (83% vs 78%) were superior with rabbit antithymocyte globulin than with the interleukin 2 receptor blocker (P < .002). In patients with hepatitis C virus, type of induction therapy did not have any effect on the timing of hepatitis C virus recurrence. At 1 year after transplant, 33.3% in the rabbit antithymocyte globulin group had grade 3/4 inflammation and 10.2% had stage 3/4 fibrosis, compared with 16.8% and 4.8% in the interleukin 2 receptor blocker group (P ≤ .002 and not significant). Female recipient, Model for End-Stage Liver Disease score, hepatocellular carcinoma, and high preoperative serum creatinine levels were associated with less favorable patient and graft survival.

CONCLUSIONS

Rabbit antithymocyte globulin is associated with lower rejection rate and improved patient and graft survival in liver transplant. Type of therapy affects the degree of histologic hepatitis C virus recurrence.

Antithymocyte Globulin Induction Therapy in Liver Transplant: Old Drug, New Uses

OBJECTIVE

To review the use of rabbit antithymocyte globulin (rATG) induction therapy in liver transplant recipients.

DATA SOURCES

A MEDLINE literature search (inception to March 2016) was conducted using the search terms rabbit antithymocyte globulin, liver transplantation, and induction References from extracted sources were further searched for any relevant, missed data sources.

STUDY SELECTION AND DATA EXTRACTION

All English-language randomized and observational studies were included.

DATA SYNTHESIS

A total of 9 studies were included in this review evaluating rATG's use for induction therapy. All studies were single-center analyses. rATG induction is utilized to delay calcineurin inhibitor initiation and to minimize or avoid steroids. Patients receiving rATG induction tended to have improved renal function compared with patients not receiving induction. Overall, rejection rates tended to be lower in recipients administered rATG. Regimens varied in each study, with most recipients receiving 2 to 3 doses of induction therapy.

CONCLUSIONS

rATG induction therapy may lead to improved renal function and lower rejection rates following liver transplant. The use of this medication can help avoid unwanted adverse effects from other immunosuppression agents. Because of the potential benefits with this induction agent, rATG may have a larger role in induction therapy for liver transplant recipients.

Selection and use of immunosuppressive therapies after liver transplantation: current German practice

In recent years, immunosuppression (IS) after liver transplantation (LT) has become increasingly diversified as the choice of agents has expanded and clinicians seek to optimize the balance of immunosuppressive potency with the risk of adverse events in individual patients. Calcineurin inhibitors (CNIs) are the primary agents used for patients undergoing liver transplantation. Other therapeutic agents like interleukin-2 receptor antagonists are not universally administered, but can be considered for the delay or reduction in CNI exposure. An early addition of mycophenolate mofetil (MMF) or the mTOR inhibitor everolimus also allows for the reduction in the CNI dose. To reduce the risk of malignancy, in particular of skin tumors, as well as to prevent the deterioration of renal function, everolimus-based therapy may be advantageous. Apart from patients with autoimmune hepatitis, steroids are withdrawn within 3-6 months after transplantation. Overall, immunosuppression can only be standardized in a limited proportion of patients due to specific clinical requirements and risk factors. Future studies should attempt to refine accurate individualization of the immunosuppressive regimen in specific difficult-to-treat patient subpopulations.

New directions for rabbit antithymocyte globulin (Thymoglobulin(®)) in solid organ transplants, stem cell transplants and autoimmunity

In the 30 years since the rabbit antithymocyte globulin (rATG) Thymoglobulin^® was first licensed, its use in solid organ transplantation and hematology has expanded progressively. Although the evidence base is incomplete, specific roles for rATG in organ transplant recipients using contemporary dosing strategies are now relatively well-identified. The addition of rATG induction to a standard triple or dual regimen reduces acute cellular rejection, and possibly humoral rejection. It is an appropriate first choice in patients with moderate or high immunological risk, and may be used in low-risk patients receiving a calcineurin inhibitor (CNI)-sparing regimen from time of transplant, or if early steroid withdrawal is planned. Kidney transplant patients at risk of delayed graft function may also benefit from the use of rATG to facilitate delayed CNI introduction. In hematopoietic stem cell transplantation, rATG has become an important component of conventional myeloablative conditioning regimens, following demonstration of reduced acute and chronic graft-versus-host disease. More recently, a role for rATG has also been established in reduced-intensity conditioning regimens. In autoimmunity, rATG contributes to the treatment of severe aplastic anemia, and has been incorporated in autograft projects for the management of conditions such as multiple sclerosis, Crohn’s disease, and systemic sclerosis. Finally, research is underway for the induction of tolerance exploiting the ability of rATG to induce immunosuppresive cells such as regulatory T-cells. Despite its long history, rATG remains a key component of the immunosuppressive armamentarium, and its complex immunological properties indicate that its use will expand to a wider range of disease conditions in the future.

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 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.

Management of recurrent hepatitis C in orthotopic liver transplant recipients

End-stage liver disease and hepatocellular carcinoma from chronic hepatitis C are the most common indications for orthotopic liver transplantation and the incidence of both are projected to increase over the next decade. Recurrent hepatitis C virus infection of the allograft is associated with an accelerated progression to cirrhosis, graft loss, and death. This article presents an overview of the natural history of hepatitis C virus recurrence in liver transplant recipients and guidance on optimal management strategies.

Review article: use of induction therapy in liver transplantation

Induction therapy is used relatively infrequently in liver transplantation, but developments in induction regimens and strategies for their use are prompting a re-examination of its benefits. Rabbit antithymocyte globulin (rATG) induces protracted, dose-dependent lymphocytopenia with preferential reconstitution of regulatory T-lymphocytes. Non-depleting interleukin-2 receptor antagonists (IL-2RA) act selectively on activated T-lymphocytes with a shorter duration of effect. IL-2RA induction with delayed and reduced calcineurin inhibitor (CNI) exposure appears to preserve efficacy, while more aggressive CNI minimisation has been attempted successfully using rATG. Steroid-free tacrolimus monotherapy with rATG or IL-2RA induction is effective if adequate tacrolimus exposure is maintained. Early concerns that addition of induction to a conventional maintenance regimen could lead to accelerated progression of hepatitis C disease, or to an increased risk of hepatocellular cancer recurrence, now appear unfounded using modern regimens. Similarly, with routine use of systemic prophylaxis, recent prospective and retrospective data have not shown a higher rate of infections overall, or cytomegalovirus infection specifically, using rATG or IL-2RA induction. Historical evidence that lymphocyte-depleting agents increased the risk of non-Hodgkin lymphoma has not been confirmed for rATG. Wider use of induction in liver transplantation is now merited, using individualized strategies to support reduced CNI exposure or steroid-free immunosuppression.

Association of preoperative parameters with postoperative mortality and long-term survival after liver transplantation

BACKGROUND

The ability of Child-Turcotte-Pugh (CTP) or Model for End-Stage Liver Disease (MELD) scores to predict recipient survival after liver transplantation is controversial. This analysis aims to identify preoperative parameters that might be associated with early postoperative mortality and long-term survival after liver transplantation.

METHODS

We studied a total of 15 parameters, using both univariate and multivariate models, among adults who underwent primary liver transplantation.

RESULTS

A total of 458 primary adult liver transplants were performed. Fifty-seven (12.44%) patients died during the first 3 postoperative months and composed the early mortality group. The remaining 401 patients composed the long-term patient survival group. The parameters that were identified through univariate analysis to be associated with early postoperative mortality were CTP score, MELD score, bilirubin, creatinine, international normalized ratio and warm ischemia time (WIT). In all multivariate models, WIT retained its statistical significance. The 10-year long-term survival was 65%. The parameters that were identified to be independent predictors of long-term survival were the recipient's sex (improved survival in women, p = 0.005), diagnosis of hepatocellular cancer (p=0.015) and recipient's age (p=0.024).

CONCLUSION

Either CTP or MELD score, in conjunction with WIT, might have a role in predicting early postoperative mortality after liver transplantation, whereas the recipient's sex and the absence of hepatocellular cancer are associated with improved long-term survival.

The difference in the fibrosis progression of recurrent hepatitis C after live donor liver transplantation versus deceased donor liver transplantation is attributable to the difference in donor age

Hepatitis C recurs universally after liver transplantation (LT). Whether its progression differs after live donor liver transplantation (LDLT) and deceased donor liver transplantation (DDLT) is still debated. We retrospectively analyzed 201 consecutive LTs performed at our institution for hepatitis C-related end-stage liver disease between April 2000 and December 2005 (46 LDLTs and 155 DDLTs). Patients were followed with protocol biopsies for medians of 29 (LDLT) and 39 months (DDLT; P = 0.7). Although overall graft and patient survival did not differ, the mean fibrosis stage (Metavir) was significantly higher at 12 to 48 months post-LT (all P < 0.05), and the rate of fibrosis progression tended to be faster after DDLT than LDLT (0.19 versus 0.11 stage/year, P = 0.05). In univariate analysis, donor age, cold ischemic time, and DDLT were significantly associated with a fibrosis stage > or = 1 at 1 year and a fibrosis stage of 3 or 4 at 2 years post-LT. In multivariate analysis, however, donor age was the sole variable independently associated with both surrogate outcomes. Thus, donor age > 45 years carried a relative risk of 8.17 (confidence interval = 2.6-25.5, P = 0.001) for reaching fibrosis stage 3 or 4 at 2 years post-LT. In conclusion, donor age, rather than the transplant approach, determines the progression of recurrent hepatitis C after LT. LDLT, allowing for the selection of younger donors, may particularly benefit hepatitis C patients.