Efficacy and safety of induction therapy with rabbit antithymocyte globulins in liver transplantation for hepatitis C

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.

Perioperative effects of high doses of intraoperative thymoglobulin induction in liver transplantation

AIM: To describe our single-centre experience in liver transplantation (LT) with the infusion of high perioperative thymoglobulin doses. The optimal dosage and timing of thymoglobulin^® [antithymocyte globulin (ATG)] administration during LT remains controversial. Cytokine release syndrome, haemolytic anaemia, thrombocytopenia, neutropenia, fever and serum sickness are potential adverse effects associated with ATG infusion.

METHODS: Between December 2009 and December 2010, 16 adult non-randomized patients (ATG group), receiving a liver graft from a deceased donor, received an intraoperative infusion (4-6 h infusion) of thymoglobulin (3 mg/kg, ATG: Thymoglobuline^®). These patients were compared (case control approach) with 16 patients who had a liver transplant without ATG treatment (control group) to evaluate the possible effects of intraoperative ATG infusion. The matching parameters were: Sex, recipient age (± 5 years), LT indication including viral status, MELD score (± 5 points), international normalized ratio and platelet count (as close as possible). The exclusion criteria for both groups included the following: Multi-organ or living donor transplant, immunosuppressive therapy before transplantation, contraindications to the administration of any thymocyte globulin, human immunodeficiency virus seropositivity, thrombocytopenia [platelet < 50000/μL] or leukopenia [white blood cells < 1000/μL]. The perioperative side effects (haemodynamic alterations, core temperature variations, colloids and crystalloids requirements, and surgical time) possibly related to ATG infusion and the thromboelastographic (TEG) evaluation of the ATG effects on coagulation, blood loss and blood product transfusion were analysed during the operation and the first three postoperative days.

RESULTS: Intraoperative ATG administration was associated with longer surgical procedures [560 ± 88 min vs 480 ± 83 min (control group), P = 0.013], an intraoperative core temperature more than 37 °C (50% of ATG patients vs 6.2% of control patients, P = 0.015), major intraoperative blood loss [3953 ± 3126 mL vs 1419 ± 940 mL (control group), P = 0.05], higher red blood cell [2092 ± 1856 mL ATG group vs 472 ± 632 mL (control group), P = 0.02], fresh frozen plasma [671 ± 1125 mL vs 143 ± 349 mL (control group), P = 0.015], and platelet [374 ± 537 mL vs 15.6 ± 62.5 mL (control group), P = 0.017] transfusion, and a higher requirement for catecholamines (0.08 ± 0.07 μg/kg per minutes vs 0.01 ± 0.38 μg/kg per minutes, respectively, in the ATG and control groups) for haemodynamic support. The TEG tracings changed to a straight line during ATG infusion (preanhepatic and anhepatic phases) in 81% of the patients from the ATG group compared to 6.25% from the control group (P < 0.001). Patients from the ATG group compared to controls had higher post-op core temperatures (38 °C ± 1.0 °C vs 37.3 °C ± 0.5 °C; P = 0.02), an increased need of noradrenaline (43.7% vs 6.25%, P = 0.037), received more platelet transfusions (31.5% vs 0%, P = 0.04) and required continuous renal replacement therapy (4 ATG patients vs none in the control group; P = 0.10). ATG infusion was considered the cause of a fatal anaphylactic shock and of a suspected adverse reaction that led to intravascular haemolysis and acute renal failure.

CONCLUSION: The side effects and the coagulation imbalance observed in patients receiving a high dosage of ATG suggest caution in the use of thymoglobulin during LT.

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.

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.

Antibody induction versus corticosteroid induction for liver transplant recipients

BACKGROUND

Liver transplantation is an established treatment option for end-stage liver failure. To date, no consensus has been reached on the use of immunosuppressive T-cell specific antibody induction compared with corticosteroid induction of immunosuppression after liver transplantation.

OBJECTIVES

To assess the benefits and harms of T-cell specific antibody induction versus corticosteroid induction for prevention of acute rejection in liver transplant recipients.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index Expanded, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) on 30 September 2013 together with reference checking, citation searching, contact with trial authors and pharmaceutical companies to identify additional trials.

SELECTION CRITERIA

We included all randomised clinical trials assessing immunosuppression with T-cell specific antibody induction versus corticosteroid induction in liver transplant recipients. Our inclusion criteria stated that participants within each included trial should have received the same maintenance immunosuppressive therapy.

DATA COLLECTION AND ANALYSIS

We used RevMan for statistical analysis of dichotomous data with risk ratio (RR) and of continuous data with mean difference (MD), both with 95% confidence intervals (CIs). We assessed risk of systematic errors (bias) using bias risk domains with definitions. We used trial sequential analysis to control for random errors (play of chance).

MAIN RESULTS

We included 10 randomised trials with a total of 1589 liver transplant recipients, which studied the use of T-cell specific antibody induction versus corticosteroid induction. All trials were with high risk of bias. We compared any kind of T-cell specific antibody induction versus corticosteroid induction in 10 trials with 1589 participants, including interleukin-2 receptor antagonist induction versus corticosteroid induction in nine trials with 1470 participants, and polyclonal T-cell specific antibody induction versus corticosteroid induction in one trial with 119 participants.Our analyses showed no significant differences regarding mortality (RR 1.01, 95% CI 0.72 to 1.43), graft loss (RR 1.12, 95% CI 0.82 to 1.53) and acute rejection (RR 0.84, 95% CI 0.70 to 1.00), infection (RR 0.96, 95% CI 0.85 to 1.09), hepatitis C virus recurrence (RR 0.89, 95% CI 0.79 to 1.00), malignancy (RR 0.59, 95% CI 0.13 to 2.73), and post-transplantation lymphoproliferative disorder (RR 1.00, 95% CI 0.07 to 15.38) when any kind of T-cell specific antibody induction was compared with corticosteroid induction (all low-quality evidence). Cytomegalovirus infection was less frequent in patients receiving any kind of T-cell specific antibody induction compared with corticosteroid induction (RR 0.50, 95% CI 0.33 to 0.75; low-quality evidence). This was also observed when interleukin-2 receptor antagonist induction was compared with corticosteroid induction (RR 0.55, 95% CI 0.37 to 0.83; low-quality evidence), and when polyclonal T-cell specific antibody induction was compared with corticosteroid induction (RR 0.21, 95% CI 0.06 to 0.70; low-quality evidence). However, when trial sequential analysis regarding cytomegalovirus infection was applied, the required information size was not reached. Furthermore, diabetes mellitus occurred less frequently when T-cell specific antibody induction was compared with corticosteroid induction (RR 0.45, 95% CI 0.34 to 0.60; low-quality evidence), when interleukin-2 receptor antagonist induction was compared with corticosteroid induction (RR 0.45, 95% CI 0.35 to 0.61; low-quality evidence), and when polyclonal T-cell specific antibody induction was compared with corticosteroid induction (RR 0.12, 95% CI 0.02 to 0.95; low-quality evidence). When trial sequential analysis was applied, the trial sequential monitoring boundary for benefit was crossed. We found no subgroup differences for type of interleukin-2 receptor antagonist (basiliximab versus daclizumab). Four trials reported on adverse events. However, no differences between trial groups were noted. Limited data were available for meta-analysis on drug-specific adverse events such as haematological adverse events for antithymocyte globulin. No data were available on quality of life.

AUTHORS' CONCLUSIONS

Because of the low quality of the evidence, the effects of T-cell antibody induction remain uncertain. T-cell specific antibody induction seems to reduce diabetes mellitus and may reduce cytomegalovirus infection when compared with corticosteroid induction. No other clear benefits or harms were associated with the use of T-cell specific antibody induction compared with corticosteroid induction. For some analyses, the number of trials investigating the use of T-cell specific antibody induction after liver transplantation is small, and the numbers of participants and outcomes in these randomised trials are limited. Furthermore, the included trials are heterogeneous in nature and have applied different types of T-cell specific antibody induction therapy. All trials were at high risk of bias. Hence, additional randomised clinical trials are needed to assess the benefits and harms of T-cell specific antibody induction compared with corticosteroid induction for liver transplant recipients. Such trials ought to be conducted with low risks of systematic error and of random error.

Pharmacology and toxicology of mycophenolate in organ transplant recipients: an update

This review aims to provide an update of the literature on the pharmacology and toxicology of mycophenolate in solid organ transplant recipients. Mycophenolate is now the antimetabolite of choice in immunosuppressant regimens in transplant recipients. The active drug moiety mycophenolic acid (MPA) is available as an ester pro-drug and an enteric-coated sodium salt. MPA is a competitive, selective and reversible inhibitor of inosine-5'-monophosphate dehydrogenase (IMPDH), an important rate-limiting enzyme in purine synthesis. MPA suppresses T and B lymphocyte proliferation; it also decreases expression of glycoproteins and adhesion molecules responsible for recruiting monocytes and lymphocytes to sites of inflammation and graft rejection; and may destroy activated lymphocytes by induction of a necrotic signal. Improved long-term allograft survival has been demonstrated for MPA and may be due to inhibition of monocyte chemoattractant protein 1 or fibroblast proliferation. Recent research also suggested a differential effect of mycophenolate on the regulatory T cell/helper T cell balance which could potentially encourage immune tolerance. Lower exposure to calcineurin inhibitors (renal sparing) appears to be possible with concomitant use of MPA in renal transplant recipients without undue risk of rejection. MPA displays large between- and within-subject pharmacokinetic variability. At least three studies have now reported that MPA exhibits nonlinear pharmacokinetics, with bioavailability decreasing significantly with increasing doses, perhaps due to saturable absorption processes or saturable enterohepatic recirculation. The role of therapeutic drug monitoring (TDM) is still controversial and the ability of routine MPA TDM to improve long-term graft survival and patient outcomes is largely unknown. MPA monitoring may be more important in high-immunological recipients, those on calcineurin-inhibitor-sparing regimens and in whom unexpected rejection or infections have occurred. The majority of pharmacodynamic data on MPA has been obtained in patients receiving MMF therapy in the first year after kidney transplantation. Low MPA area under the concentration time from 0 to 12 h post-dose (AUC0-12) is associated with increased incidence of biopsy-proven acute rejection although AUC0-12 optimal cut-off values vary across study populations. IMPDH monitoring to identify individuals at increased risk of rejection shows some promise but is still in the experimental stage. A relationship between MPA exposure and adverse events was identified in some but not all studies. Genetic variants within genes involved in MPA metabolism (UGT1A9, UGT1A8, UGT2B7), cellular transportation (SLCOB1, SLCO1B3, ABCC2) and targets (IMPDH) have been reported to effect MPA pharmacokinetics and/or response in some studies; however, larger studies across different ethnic groups that take into account genetic linkage and drug interactions that can alter a patient's phenotype are needed before any clinical recommendations based on patient genotype can be formulated. There is little data on the pharmacology and toxicology of MPA in older and paediatric transplant recipients.

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.

Impact of immunosuppressive regimen on survival of kidney transplant recipients with hepatitis C

BACKGROUND

Hepatitis C virus (HCV) infection is common among end-stage renal disease patients receiving hemodialysis and a kidney transplant. HCV-positive kidney transplant recipients have worse clinical outcomes than those who are HCV negative. The optimal immunosuppressive regimen in this group of patients remains uncertain.

METHODS

Using data obtained from the Organ Procurement and Transplantation Network/Scientific Registry of Transplant Recipients, we studied the impact of induction and maintenance immunosuppression on risk of patient death, with death-censored graft failure and death with a functioning graft as secondary endpoints. Cox regression analysis was used to estimate hazard ratios (HR) adjusted for donor, recipient, and transplant variables. A total of 3708 HCV-positive and 75,629 HCV-negative kidney transplant recipients were analyzed.

RESULTS

Patient survival was negatively affected by HCV-positive serology. Among HCV-positive kidney transplant recipients, a reduced HR for patient death was observed with the use of induction therapy (HR=0.75, 95% CI 0.61-0.90, P=0.003) and with the use of mycophenolate mofetil (HR=0.77, 95% CI 0.64-0.92, P=0.005).

CONCLUSIONS

In kidney transplant recipients with HCV-positive serology, the use of antibody induction did not negatively affect patient survival and the use of mycophenolate mofetil as part of maintenance immunosuppression was associated with better patient survival.

Serum sickness following rabbit antithymocyte-globulin induction in a liver transplant recipient: case report and literature review

Thymoglobulin (Genzyme, Cambridge, MA) is an antithymocyte globulin preparation used for induction immunosuppression therapy in solid organ transplantation. It is being utilized with increasing frequency in orthotopic liver transplantation (OLT) in an effort to minimize or delay the use of calcineurin inhibitors due to their inherent nephrotoxicity. Experience with thymoglobulin in OLT remains limited. We report a case of serum sickness in a patient who received thymoglobulin following OLT. The patient experienced intermittent fevers, polyarthralgia, and acute renal failure 9 days after completion of thymoglobulin administration. The patient's symptoms resolved rapidly and completely with a course of intravenous steroids. We review a set of diagnostic criteria for serum sickness and emphasize the importance of early recognition of the process. Early treatment of serum sickness with steroids or plasmapheresis is highly effective and can reduce unnecessary morbidity from this unusual sequela of induction immunosuppression with antithymocyte globulin.