Daclizumab induction therapy associated with tacrolimus-MMF has better outcome compared with tacrolimus-MMF alone in pediatric living donor liver transplantation

Meta-analysis of few small studies in orphan diseases

Meta-analyses in orphan diseases and small populations generally face particular problems, including small numbers of studies, small study sizes and heterogeneity of results. However, the heterogeneity is difficult to estimate if only very few studies are included. Motivated by a systematic review in immunosuppression following liver transplantation in children, we investigate the properties of a range of commonly used frequentist and Bayesian procedures in simulation studies. Furthermore, the consequences for interval estimation of the common treatment effect in random-effects meta-analysis are assessed. The Bayesian credibility intervals using weakly informative priors for the between-trial heterogeneity exhibited coverage probabilities in excess of the nominal level for a range of scenarios considered. However, they tended to be shorter than those obtained by the Knapp-Hartung method, which were also conservative. In contrast, methods based on normal quantiles exhibited coverages well below the nominal levels in many scenarios. With very few studies, the performance of the Bayesian credibility intervals is of course sensitive to the specification of the prior for the between-trial heterogeneity. In conclusion, the use of weakly informative priors as exemplified by half-normal priors (with a scale of 0.5 or 1.0) for log odds ratios is recommended for applications in rare diseases. © 2016 The Authors. Research Synthesis Methods published by John Wiley & Sons Ltd.

Current developments in pediatric liver transplantation

In 1953, the pioneer of human orthotopic liver transplantation (LT), Thomas E Starzl, was the first to attempt an orthotopic liver transplant into a 3 years old patient suffering from biliary atresia. Thus, the first LT in humans was attempted in a disease, which, up until today, remains the main indication for pediatric LT (pLT). During the last sixty years, refinements in diagnostics and surgical technique, the introduction of new immunosuppressive medications and improvements in perioperative pediatric care have established LT as routine procedure for childhood acute and chronic liver failure as well as inherited liver diseases. In contrast to adult recipients, pLT differs greatly in indications for LT, allocation practice, surgical technique, immunosuppression and post-operative life-long aftercare. Many aspects are focus of ongoing preclinical and clinical research. The present review gives an overview of current developments and the clinical outcome of pLT, with a focus on alternatives to full-size deceased-donor organ transplantation.

Interleukin-2 receptor antagonists for pediatric liver transplant recipients: a systematic review and meta-analysis of controlled studies

IL-2RA are frequently used as induction therapy in liver transplant recipients to decrease the risk of AR while allowing the reduction of concomitant immunosuppression. The exact association with the use of IL-2RA, however, is uncertain. We performed a systematic literature search for relevant studies. Random effects models were used to assess the incidence of AR, steroid-resistant rejection, graft loss, patient death, and adverse drug reaction, with or without IL-2RA. Six studies (two randomized and four non-randomized) met the eligibility criteria. Acute rejection at six months or later favored the use of IL-2RA significantly (RR 0.38; 95% CI 0.22-0.66, p = 0.0005). Although not statistically significant, IL-2RA showed a substantial reduction of the risk of steroid-resistant rejection (RR 0.32; CI 0.19-1.03, p = 0.0594). Graft loss and patient death showed a reductive tendency through the use of IL-2RA. The use of IL-2RA is safe and is associated with a statistically significantly lower incidence of AR after transplantation and substantial reduction of steroid-resistant rejection, graft loss, and patient death.

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.

Induction immunosuppression in liver transplantation: a review

Antibody therapy for induction is seldom used in liver transplantation in the United States, but continues to be used in approximately 10% of patients. The most commonly used antibody at the current time is basiliximab (Simulect, Novartis) and is used in adults with renal dysfunction at the time of liver transplantation with the intention of delaying introduction of calcineurin-inhibitors. In children, the same antibody is commonly used in order to reduce rates of acute rejection. Most patients, adult and pediatric, are treated with initially higher levels of tacrolimus rather than antibody induction.

The kidney in pediatric liver transplantation: an updated perspective

CKD continues to detract from the success of improved survival in pediatric liver transplantation, and its presence is likely under recognized. Here we review the literature regarding the prevalence, etiology, and management of renal dysfunction in pediatric liver transplant recipients. Long-term studies suggest the prevalence of CKD to be 25-38% by 5-10 yr post-transplant. While important, sole use of serum creatinine overestimates renal function in this population. Screening for and treatment of persistent proteinuria and hypertension as well as minimization of nephrotoxic insults are the mainstays to delay or prevent CKD progression. Office-based blood pressure measures are less sensitive than ABPM, which is specifically recommended by the American Heart Association for its ability to diagnose masked hypertension in pediatric liver transplant recipients. Long-term risk of CKD is predominantly secondary to CNI toxicity. CNI minimization protocols have shown promise in slowing progression of CKD while maintaining graft function, but large-scale randomized control trials with long-term follow-up are needed.

Impact of immunosuppression on the development of Epstein-Barr virus (EBV) viremia after pediatric liver transplantation

OBJECTIVES

Pediatric liver transplant (OLT) patients are at risk of posttransplant lymphoproliferative disease (PTLD) from Epstein-Barr virus (EBV). This study examined the impact of induction and immunosuppression on EBV viremia.

METHODS

A retrospective chart review was performed on 197 pediatric patients and induction regimen, immunosuppression levels, and EBV viremia were documented for 1 year post-OLT. Logistic regression models determined associations between induction, immunosuppression, and EBV.

RESULTS

Fifty six percent of patients developed EBV viremia. Incidence of EBV viremia was 73% with antithymocyte globulin (ATG), 63% with daclizumab, and 39% for neither, though the trend was not significant [ATG: odds ratio (OR) 0.19; 95% confidence interval (CI) 0.024-1.58; P = .125; daclizumab OR; 1.07; 95% CI 0.270-4.23; P = .925]. Tacrolimus immunosuppression levels were supratherapeutic 28.7% of the time; however, only supratherapeutic tacrolimus levels between 0 and 2 weeks increased EBV viremia at 2 to 4 weeks post-OLT (OR 1.80; 95% CI 1.10-2.94; P = .02). Three patients developed PTLD.

CONCLUSIONS

The use of ATG and daclizumab induction likely does not play a role in the development of EBV viremia. Supratherapeutic tacrolimus levels 0 to 2 weeks post-OLT impact the development of EBV viremia at 2 to 4 weeks. The incidence of PTLD was low, suggesting better EBV and immunosuppression monitoring plays an important role in reducing PTLD.

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.

Antibody immunosuppressive therapy in solid-organ transplant: Part I

Currently, a wide variety of both polyclonal and monoclonal antibodies are being routinely utilized to prevent and treat solid organ rejection. More commonly, these agents are also administered in order to delay introduction of calcineurin inhibitors, especially in patients with already compromised renal function. While these antibody therapies dramatically reduced the incidence of acute rejection episodes and improved both short and long-term graft survival, they are also associated with an increased incidence of opportunistic infections and neoplastic complications. Therefore, effective patient management must necessarily balance these risks against the potential benefits of the therapy.

Calcineurin inhibitor minimization in pediatric liver allograft recipients

The use of CNI in pediatric LTx has dramatically improved the outcome for children with end-stage liver disease by significantly reducing the rate of acute and chronic rejection. Long-term concerns about CNI-induced nephrotoxicity and other adverse effects remain an issue, particularly as the emphasis moves from short-term survival to long-term quality of life. This review summarizes lessons learnt from pediatric and adult solid organ transplantation in minimizing CNI use in immunosuppression protocols in children following LTx. There are three models for CNI minimization: dose reduction, withdrawal or avoidance, supplemented by the use of IL-2 receptor blocking antibodies in the peri-transplant period, and early transition to alternate drugs such as MMF or SRL. Prospective studies evaluating reduction or withdrawal protocols in adult and pediatric LTx indicate that rejection rates are comparable with traditional CNI-based immunosuppression and that two and five yr patient and graft survival are similar, with recovery in renal function. There are few studies evaluating complete avoidance of CNI, apart from that in renal transplantation, although the benefits of long-term reduction in cardiovascular, metabolic, and possibly neoplastic side effects may justify this approach. It is not clear yet how CNI minimization will affect the development of tolerance but experimental and preliminary clinical studies indicate that CNI and steroid avoidance or minimization in the peri-operative period may favor the development of long-term graft tolerance. In summary, CNI minimization may be safe and effective in the short term but large-scale pediatric randomized studies are required to evaluate the long-term efficacy of these regimes in the development of chronic rejection, PTLD, and graft tolerance.

Pediatric liver transplantation

In previous decades, pediatric liver transplantation has become a state-of-the-art operation with excellent success and limited mortality. Graft and patient survival have continued to improve as a result of improvements in medical, surgical and anesthetic management, organ availability, immunosuppression, and identification and treatment of postoperative complications. The utilization of split-liver grafts and living-related donors has provided more organs for pediatric patients. Newer immunosuppression regimens, including induction therapy, have had a significant impact on graft and patient survival. Future developments of pediatric liver transplantation will deal with long-term follow-up, with prevention of immunosuppression-related complications and promotion of as normal growth as possible. This review describes the state-of-the-art in pediatric liver transplantation.

Calcineurin inhibitor sparing in paediatric solid organ transplantation : managing the efficacy/toxicity conundrum

Despite their efficacy, the calcineurin inhibitors (CNIs) ciclosporin and tacrolimus carry a risk of debilitating adverse effects, especially nephrotoxicity, that affect the long-term outcome and survival of children who are given organ transplants. Simple reduction in dosage of CNI has little or no long-term benefit on their adverse effects, and complete withdrawal without threatening graft outcome may only be possible after liver transplantation. Until the last decade, the only option was to increase corticosteroid and/or azathioprine doses, which imposed additional long-term hazards. Considered here are the emerging generation of new agents offering an opportunity for improving long-term graft survival, minimizing CNI-related adverse events and ensuring patient well-being.A holistic, multifaceted strategy may need to be considered - initial selection and optimized use and monitoring of immunosuppressant regimens, early recognition of indicators of patient and graft dysfunction, and, where applicable, early introduction of CNI-sparing regimens facilitating CNI withdrawal. The evidence reviewed here supports these approaches but remains far from definitive in paediatric solid organ transplantation. Because de novo immunosuppression uses CNI in more than 93% of patients, reduction of CNI-related adverse effects has focused on CNI sparing or withdrawal.A recurring theme where sirolimus and mycophenolate mofetil have been used for this purpose is the importance of their early introduction to limit CNI damage and provide long-term benefit: for example, long-term renal function critically reflects that at 1 year post-transplant. While mycophenolic acid shows advantages over sirolimus in preserving renal function because the latter is associated with proteinuria, sirolimus appears the more potent immunosuppressant but also impairs early wound healing. The use of CNI-free immunosuppressant regimens with depleting or non-depleting antibodies plus sirolimus and mycophenolic acid needs much wider investigation to achieve acceptable rejection rates and conserve renal function. The adverse effects of the alternative immunosuppressants, particularly the dyslipidaemia associated with sirolimus, needs to be minimized to avoid replacing one set of adverse effects (from CNIs) with another. While we can only conjecture that judicious combinations with the second generation of novel immunosuppressants currently in development will provide these solutions, a rationale of low-dose therapy with multiple immunosuppressants acting by complementary mechanisms seems to hold the promise for efficacy with minimal toxicity until the vision of tolerance achieves reality.

Safety and pharmacokinetics of daclizumab in pediatric renal transplant recipients

This study examined the safety and pharmacokinetics/pharmacodynamics of daclizumab in combination with mycophenolate mofetil (or azathioprine), corticosteroids, and cyclosporine or tacrolimus, in 61 pediatric renal allograft recipients in three age groups: less than or equal to five yr (n = 18), 6-12 yr (n = 18), and 13-17 yr (n = 25). The dosing regimen was daclizumab 1.0 mg/kg before transplantation, followed by four biweekly doses. The pharmacokinetics of daclizumab were described using NONMEM software. Median (range) estimated trough daclizumab levels achieved on day 56 (before dose 5) were 3.88 microg/mL (2.48-8.78), 4.54 microg/mL (1.79-18.7), and 4.94 microg/mL (0.05-10.6) in the less than or equal to five yr (n = 15), 6-12 yr (n = 17), and 13-17 yr (n = 22) age groups, respectively. Steady-state median (range) daclizumab exposures were 2040 mg x h/mL (1585-3778), 2757 mg x h/mL (1873-3494) and 3297 mg x h/mL (1705-6453), respectively. Saturation of the IL-2R occurred rapidly and was maintained for greater than or equal to three months after transplantation. Daclizumab was generally well-tolerated with no acute allergic or anaphylactic reactions, deaths or malignancies during the study. The proportion of patients who developed acute rejection at six and 12 months was 8.5% and 16.7%, respectively. This study shows that adding daclizumab at 1 mg/kg to standard immunosuppressive therapy provides safe and effective IL-2R blockade.

Risk factors for rejection and infection in pediatric liver transplantation

Rejection and infection are important adverse events after pediatric liver transplantation, not previously subject to concurrent risk analysis. Of 2291 children (<18 years), rejection occurred at least once in 46%, serious bacterial/fungal or viral infections in 52%. Infection caused more deaths than rejection (5.5% vs. 0.6% of patients, p < 0.001). Early rejection (<6 month) did not contribute to mortality or graft failure. Recurrent/chronic rejection was a risk in graft failure, but led to retransplant in only 1.6% of first grafts. Multivariate predictors of bacterial/fungal infection included recipient age (highest in infants), race, donor organ variants, bilirubin, anhepatic time, cyclosporin (vs. tacrolimus) and era of transplant (before 2002 vs. after 2002); serious viral infection predictors included donor organ variants, rejection, Epstein-Barr Virus (EBV) naivety and era; for rejection, predictors included age (lowest in infants), primary diagnosis, donor-recipient blood type mismatch, the use of cyclosporin (vs. tacrolimus), no induction and era. In pediatric liver transplantation, infection risk far exceeds that of rejection, which causes limited harm to the patient or graft, particularly in infants. Aggressive infection control, attention to modifiable factors such as pretransplant nutrition and donor organ options and rigorous age-specific review of the risk/benefit of choice and intensity of immunosuppressive regimes is warranted.