Efficacy and safety of thymoglobulin induction as an alternative approach for steroid-free maintenance immunosuppression in pediatric renal transplantation. Transplantation. 2010;90:1516-1520. [PMID: 20935596 DOI: 10.1097/tp.0b013e3181fc8937]

Outcomes based on induction regimens in pediatric kidney transplantation: a NAPRTCS and PHIS collaborative study

BACKGROUND

Induction agent used at the time of kidney transplant is often based upon center practice and recipient characteristics. We evaluated outcomes across induction therapies among children enrolled in the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) transplant registry with data in the Pediatric Health Information System (PHIS).

METHODS

This is a retrospective study of merged data from NAPRTCS and PHIS. Participants were grouped by induction agent: interleukin-2 receptor blocker (IL-2 RB), anti-thymocyte/anti-lymphocyte globulin (ATG/ALG), and alemtuzumab. Outcomes assessed included 1-, 3-, and 5-year allograft function and survival, rejection, viral infections, malignancy, and death.

RESULTS

A total of 830 children transplanted between 2010 and 2019. At 1 year post-transplant, the alemtuzumab group had higher median eGFR (86 ml/min/1.73 m2) compared to IL-2 RB and ATG/ALG (79 and 75 ml/min/1.73 m2, respectively; P < 0.001); at 3 and 5 years, there was no difference. Adjusted eGFR over time was similar across all induction agents. Rejection rates were lower among the alemtuzumab group vs. IL-2RB and ATG (13.9% vs. 27.3% and 24.6%, respectively; P = 0.006). Adjusted ATG/ALG and alemtuzumab had higher hazard ratio for time to graft failure compared to IL-2 RB (HR 2.48 and HR 2.11, respectively; P < 0.05). Incidence of malignancy, mortality, and time to first viral infection was similar.

CONCLUSION

Although rejection and allograft loss rates were distinct, the incidences of viral infection and malignancy were comparable across induction agents. By 3 years post-transplant, there was no difference in eGFR. A higher resolution version of the Graphical abstract is available as Supplementary information.

Low dose rabbit antithymocyte globulin is non-inferior to higher dose in low-risk pediatric kidney transplant recipients

BACKGROUND

Currently, there is no consensus among pediatric kidney transplant centers regarding the use and regimen for immunosuppressive induction therapy.

METHODS

In this single center, retrospective cohort study, pediatric kidney transplant recipients transplanted between 1 May 2013 and 1 May 2018 with rabbit antithymocyte globulin (rATG) induction were included. We stratified patients based on immunological risk, with high risk defined as those with repeat transplant, preformed donor specific antibody, current panel-reactive antibodies > 20%, 0 antigen match and/or African-American heritage. Outcome of interest was the incidence of biopsy proven acute rejection by 1 year.

RESULTS

A total of 166 patients met inclusion criteria. Age of patients was 12 years (11 mo-21 y), (median, range), 21.5% received a living donor transplant and 50.6% were female. Low-immunologic-risk patients were divided into 2 groups, those who received the lower cumulative rATG dose of ≤ 3.5 mg/kg (n = 52) versus the higher cumulative dose of > 3.5 mg/kg (n = 47). The median total dose in the lower dose group was 3.1 (IQR 0.3) and 4.4 (IQR 0.8) in the higher dose group, P < 0.001. Rejection rate did not differ significantly between the 2 treatment groups (7/52 vs. 6/47). None in the lower dose group developed BK nephropathy versus 3 in the higher dose group. Graft loss due to BK nephropathy occurred in 1 patient in the higher dose group. Graft loss in the whole cohort at 12 months was a rare event (n = 1) with 99.5% graft survival and 100% patient survival.

CONCLUSIONS

Reduced rATG dosing (≤ 3.5 mg/kg) when compared to higher dosing (> 3.5 mg/kg) is safe and effective in low-risk pediatric kidney transplant recipients without increasing risk of rejection. A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinical Relevance of Corticosteroid Withdrawal on Graft Histological Lesions in Low-Immunological-Risk Kidney Transplant Patients

The impact of corticosteroid withdrawal on medium-term graft histological changes in kidney transplant (KT) recipients under standard immunosuppression is uncertain. As part of an open-label, multicenter, prospective, phase IV, 24-month clinical trial (ClinicalTrials.gov, NCT02284464) in low-immunological-risk KT recipients, 105 patients were randomized, after a protocol-biopsy at 3 months, to corticosteroid continuation (CSC, n = 52) or corticosteroid withdrawal (CSW, n = 53). Both groups received tacrolimus and MMF and had another protocol-biopsy at 24 months. The acute rejection rate, including subclinical inflammation (SCI), was comparable between groups (21.2 vs. 24.5%). No patients developed dnDSA. Inflammatory and chronicity scores increased from 3 to 24 months in patients with, at baseline, no inflammation (NI) or SCI, regardless of treatment. CSW patients with SCI at 3 months had a significantly increased chronicity score at 24 months. HbA1c levels were lower in CSW patients (6.4 ± 1.2 vs. 5.7 ± 0.6%; p = 0.013) at 24 months, as was systolic blood pressure (134.2 ± 14.9 vs. 125.7 ± 15.3 mmHg; p = 0.016). Allograft function was comparable between groups and no patients died or lost their graft. An increase in chronicity scores at 2-years post-transplantation was observed in low-immunological-risk KT recipients with initial NI or SCI, but CSW may accelerate chronicity changes, especially in patients with early SCI. This strategy did, however, improve the cardiovascular profiles of patients.

Donor-specific antibodies development in renal living-donor receptors: Effect of a single cohort

Minimization in immunosuppression could contribute to the appearance the donor-specific HLA antibodies (DSA) and graft failure. The objective was to compare the incidence of DSA in renal transplantation (RT) in recipients with immunosuppression with and without steroids. A prospective cohort from March 1st, 2013 to March 1st, 2014 and follow-up (1 year), ended in March 2015, was performed in living donor renal transplant (LDRT) recipients with immunosuppression and early steroid withdrawal (ESW) and compared with a control cohort (CC) of patients with steroid-sustained immunosuppression. All patients were negative cross-matched and for DSA pre-transplant. The regression model was used to associate the development of DSA antibodies and acute rejection (AR) in subjects with immunosuppressive regimens with and without steroids. Seventy-seven patients were included (30 ESW and 47 CC). The positivity of DSA class I (13% vs 2%; P < 0.05) and class II (17% vs 4%, P = 0.06) antibodies were higher in ESW versus CC. The ESW tended to predict DSA class II (RR 5.7; CI (0.93–34.5, P = 0.06). T-cell mediated rejection presented in 80% of patients with DSA class I (P = 0.07), and 86% with DSA II (P = 0.03), and was associated with DSA class II, (RR 7.23; CI (1.2–44), P = 0.03). ESW could favor the positivity of DSA. A most strictly monitoring the DSA is necessary for the early stages of the transplant to clarify the relationship between T-cell mediated rejection and DSA.

Early outcomes comparing induction with antithymocyte globulin vs alemtuzumab in two steroid-avoidance protocols in pediatric renal transplantation

Steroid avoidance in pediatric kidney transplants was found effective with extended daclizumab induction. Upon discontinuation of daclizumab, lymphocyte-depleting agents became used, with little comparative data. We assessed outcomes in children undergoing low immunologic-risk deceased donor (DD) kidney transplants using induction with antithymocyte globulin (ATG) compared to alemtuzumab. We reviewed consecutive DD kidney transplants from January 2015 to September 2017 at two pediatric centers that used different lymphocyte-depleting agents in steroid-avoidance protocols: ATG (Center A) and alemtuzumab (Center B), with tacrolimus and MMF as maintenance immunosuppression. Anti-infective prophylaxis was based on center protocol. Over the first year post-tx, there were similar rates of infections. EBV and BK viremia were comparable though Center A manifested more low-grade CMV viremia (A 46% vs B 0%; P = .0009) at median onset 1.8 months, followed by early seroconversion. Reduction of immunosuppression did not differ between groups. DSA at 1 year was similar (A 8% vs 13%) with low rates of BPAR. Need for steroid-based conversion was low. There were no graft losses and no differences in median eGFR at 30, 90, 180, and 365 days. (a) 1-year graft outcomes are excellent in steroid-avoidance regimens using ATG or alemtuzumab induction; (b) conversion to steroid-based therapy is low; (c) alemtuzumab/high-dose MMF is associated with lower WBC and more GCSF use; (d) alemtuzumab/higher dose MMF results in more diarrhea and azathioprine conversion than ATG/lower dose MMF; (e) CMV viremia is seen more often with ATG use with infection prophylaxis reduction; however, seroconversion occurs promptly.

A Review of Induction with Rabbit Antithymocyte Globulin in Pediatric Heart Transplant Recipients

Pediatric heart transplantation (pHTx) represents only a small proportion of cardiac transplants. Due to these low numbers, clinical data relating to induction therapy in this special population are far less extensive than for adults. Induction is used more widely in pHTx than in adults, mainly because of early steroid withdrawal or complete steroid avoidance. Antithymocyte globulin (ATG) is the most frequent choice for induction in pHTx, and rabbit antithymocyte globulin (rATG, Thymoglobulin^®) (Sanofi Genzyme) is the most widely-used ATG preparation. In the absence of large, prospective, blinded trials, we aimed to review the current literature and databases for evidence regarding the use, complications, and dosages of rATG. Analyses from registry databases suggest that, overall, ATG preparations are associated with improved graft survival compared to interleukin-2 receptor antagonists. Advantages for the use of rATG have been shown in low-risk patients given tacrolimus and mycophenolate mofetil in a steroid-free regimen, in sensitized patients with pre-formed alloantibodies and/or a positive donor-specific crossmatch, and in ABO-incompatible pHTx. Registry and clinical data have indicated no increased risk of infection or post-transplant lymphoproliferative disorder in children given rATG after pHTx. A total rATG dose in the range 3.5–7.5 mg/kg is advisable.

Graft survival of pediatric kidney transplant recipients selected for de novo steroid avoidance-a propensity score-matched study

Background

Steroid-avoidance protocols have gained popularity in pediatric kidney transplant recipients at low immunologic risk. The long-term safety of steroid avoidance in children with immunologic risk factors remains unknown.

Methods

Pediatric kidney transplant recipients from 2004 to 2014 in the Organ Procurement and Transplantation Network database who received tacrolimus and mycophenolate immunosuppression were investigated. Propensity score matching was used to compare graft survival in 1624 children who received steroid avoidance with 1624 children who received steroid-based immunosuppression. The effect of steroid avoidance on graft failure among immunologic risk strata was estimated using Cox proportional hazards regression in this propensity score-matched cohort.

Results

It was observed that 5-year graft survival was mildly improved in children receiving steroid avoidance (84.8% versus 81.2%, P = 0.03). This improvement in graft survival occurred in the first 2 years following transplant, when the hazard ratio (HR) for allograft failure in children receiving steroid avoidance was 0.62 [95% confidence interval (CI) 0.45-0.86]. In contrast, steroid avoidance was not associated with improved allograft survival during Years 2-10 following transplant (HR = 0.93; 95% CI 0.75-1.15). During this time period, HRs (95% CIs) for allograft failure within immunologic risk strata were not significantly different from the null value of 1: repeat kidney transplants, 1.84 (0.84-4.05); African-Americans, 1.02 (0.67-1.56); sensitized recipients, 1.24 (0.63-2.43); recipients of deceased donor kidneys, 1.02 (0.79-1.32); recipients of completely human leukocyte antigen-mismatched kidneys, 0.80 (0.47-1.37); and recipients with pretransplant glomerular disease, 0.94 (0.71-1.23).

Conclusions

In pediatric kidney transplant recipients receiving tacrolimus- and mycophenolate-based immunosuppression, steroid avoidance can be safely practiced in children with immunologic risk factors.

The Influence of Immunosuppressive Agents on the Risk of De Novo Donor-Specific HLA Antibody Production in Solid Organ Transplant Recipients

Production of de novo donor-specific antibodies (dnDSA) is a major risk factor for acute and chronic antibody-mediated rejection and graft loss after all solid organ transplantation. In this article, we review the data available on the risk of individual immunosuppressive agents and their ability to prevent dnDSA production. Induction therapy with rabbit antithymocyte globulin may achieve a short-term decrease in dnDSA production in moderately sensitized patients. Rituximab induction may be beneficial in sensitized patients, and in abrogating rebound antibody response in patients undergoing desensitization or treatment for antibody-mediated rejection. Use of bortezomib for induction therapy in at-risk patients is of interest, but the benefits are unproven. In maintenance regimens, nonadherent and previously sensitized patients are not suitable for aggressive weaning protocols, particularly early calcineurin inhibitor withdrawal without lymphocyte-depleting induction. Early conversion to mammalian target of rapamycin inhibitor monotherapy has been reported to increase the risk of dnDSA formation, but a combination of mammalian target of rapamycin inhibitor and reduced-exposure calcineurin inhibitor does not appear to alter the risk. Early steroid therapy withdrawal in standard-risk patients after induction has no known dnDSA penalty. The available data do not demonstrate a consistent effect of mycophenolic acid on dnDSA production. Risk minimization for dnDSA requires monitoring of adherence, appropriate risk stratification, risk-based immunosuppression intensity, and prospective DSA surveillance.

Corticosteroid-free Kidney Transplantation Improves Growth: 2-Year Follow-up of the TWIST Randomized Controlled Trial

BACKGROUND

Corticosteroid withdrawal (CW) after pediatric kidney transplantation potentially improves growth while avoiding metabolic and other adverse events. We have recently reported the results of a 196 subject randomized controlled trial comparing early CW (tacrolimus, mycophenolate mofetil (MMF), daclizumab, and corticosteroids until day 4) with tacrolimus, MMF, and corticosteroid continuation (CC). At 6 months, CW subjects showed better growth with no adverse impact on acute rejection or graft survival (Am J Transplant 2010; 10: 828-836). This 2-year investigator-driven follow-up study aimed to determine whether improved growth persisted in the longer term.

METHODS

Data regarding growth, graft outcomes and adverse events were collected at 1 year (113 patients) and 2 years (106 patients) after transplantation. The primary endpoint, longitudinal growth calculated as delta height standard deviation score, was analyzed using a mixed model repeated measures model.

RESULTS

Corticosteroid withdrawal subjects grew better at 1 year (difference in adjusted mean change, 0.25; 95% confidence interval, 0.10, 0.40; P = 0.001). At 2 years, growth remained numerically better in CW subjects (0.20 (-0.01, 0.41); P = 0.06), and significantly better in prepubertal subjects (0.50 (0.16, 0.84); P = 0.004). Bacterial and viral infection was significantly more common in CW subjects at 1 year only. Corticosteroid withdrawal and CC subjects received similar exposure to both tacrolimus and MMF at 1 and 2 years. No significant difference in patient or graft survival, rejection, estimated glomerular filtration rate, or other adverse events was detected.

CONCLUSION

Early CW effectively and safely improves growth up to 2 years after transplantation, particularly in prepubertal children.

Clinical Practice of Steroid Avoidance in Pediatric Kidney Transplantation

Steroid-avoidance protocols have recently gained popularity in pediatric kidney transplantation. We investigated the clinical practice of steroid avoidance among 9494 kidney transplant recipients at 124 transplant centers between 2000 and 2012 in the Organ Procurement and Transplantation Network database. The practice of steroid avoidance increased during the study period and demonstrated significant variability among transplant centers. From 2008 to 2012, 39% of transplant centers used steroid avoidance in <10% of all discharged transplant recipients. Twenty-one percent of transplant centers practiced steroid avoidance in 10-40% of transplant recipients, and 40% of transplant centers used steroid avoidance in >40% of discharged patients. Children receiving steroid avoidance more frequently received induction with lymphocyte-depleting agents. Repeat kidney transplants were the least likely to receive steroid avoidance. Children who received a deceased donor kidney, underwent pretransplant dialysis, were highly sensitized, or had glomerular kidney disease or delayed graft function were also less likely to receive steroid avoidance. The variation in practice between centers remained highly significant (p < 0.0001) after adjustment for all patient- and center-level factors in multivariate analysis. We conclude that significant differences in the practice of steroid avoidance among transplant centers remain unexplained and may reflect uncertainty about the safety and efficacy of steroid-avoidance protocols.

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.

Perturbations in the urinary exosome in transplant rejection

Background: Urine exosomes are small vesicles exocytosed into the urine by all renal epithelial cell types under normal physiologic and disease states. Urine exosomal proteins may mirror disease specific proteome perturbations in kidney injury. Analysis methodologies for the exosomal fraction of the urinary proteome were developed for comparing the urinary exosomal fraction versus unfractionated proteome for biomarker discovery.

Methods: Urine exosomes were isolated by centrifugal filtration of urine samples collected from kidney transplant patients with and without acute rejection (AR), which were biopsy matched. The proteomes of unfractionated whole urine (Uw) and urine exosomes (Ue) underwent mass spectroscopy-based quantitative proteomics analysis. The proteome data were analyzed for significant differential protein abundances in AR.

Results: A total of 1018 proteins were identified in Uw and 349 proteins in Ue. Two hundred seventy-nine overlapped between the two urinary compartments and 70 proteins were unique to the Ue compartment. Of 349 exosomal proteins identified from transplant patients, 220 had not been previously identified in the normal Ue fraction. Eleven Ue proteins, functionally involved in an inflammatory and stress response, were more abundant in urine samples from patients with AR, three of which are exclusive to the Ue fraction. Ue AR-specific biomarkers (1) were also detected in Uw, but since they were observed at significantly lower abundances in Uw, they were not significant for AR in Uw.

Conclusion: A rapid urinary exosome isolation method and quantitative measurement of enriched Ue proteins was applied. Perturbed proteins in the exosomal compartment of urine collected from kidney transplant patients were specific to inflammatory responses, and were not observed in the Ue fraction from normal healthy subjects. Ue-specific protein alterations in renal disease provide potential mechanistic insights and offer a unique panel of sensitive biomarkers for monitoring AR.

Biologics in renal transplantation

The biologics used in transplantation clinical practice include several monoclonal and polyclonal antibodies aimed at specific cellular receptors. The effect of their mechanisms of action includes depleting or blocking specific cell subpopulations, complement system, or removing circulating preformed antibodies and blocking their production. They are used in induction, desensitization ABO-incompatible renal transplantation, rescue therapy of steroid-resistant acute rejection, treatment of posttransplant recurrence of primary disease such as nephrotic syndrome or atypical hemolytic-uremic syndrome, and in late humoral rejection. There are various indications for the use of biologic agents before and early or late after renal transplantation in both high- and low-risk recipients. In the latter situation, the biologics-based induction is used to further minimize immunosuppression maintenance. The targets of several biologic agents are present across a variety of cells, and manipulation of the immune system with biologics may be associated with significant risk of acute and late-onset adverse events; therefore, clinical risk-versus-benefit ratio must be carefully balanced in every case. Several trials on novel biologics are reported in adults but not in the pediatric population.

Challenges in pediatric renal transplantation

Transplantation in children is the best option to treat renal failure. Over the last 25 years the improvements in therapy have dramatically reduced the risk of early acute rejection and graft loss, however the long term results in terms of graft survival and morbidity still require search for new immunosuppressive regimens. Tolerance of the graft and minimization of side effects are the challenges for improving the outcome of children with a grafted kidney. Notwithstanding the difficulties in settling in children large multicenter trials to derive statistically useful data, many important contributions in the last years brought important modifications in the immunosuppressive therapy, including minimization protocols of steroids and calcineurin inhibitors and new induction drugs. New methods for diagnosis of anti HLA antibodies and some new protocols to improve both chance and outcome of transplantation in immunized subjects represent area of ongoing research of extreme interest for children.

A Three-Gene Assay for Monitoring Immune Quiescence in Kidney Transplantation

Organ transplant recipients face life-long immunosuppression and consequently are at high risk of comorbidities. Occasionally, kidney transplant recipients develop a state of targeted immune quiescence (operational tolerance) against an HLA-mismatched graft, allowing them to withdraw all immunosuppression and retain stable graft function while resuming immune responses to third-party antigens. Methods to better understand and monitor this state of alloimmune quiescence by transcriptional profiling may reveal a gene signature that identifies patients for whom immunosuppression could be titrated to reduce patient and graft morbidities. Therefore, we investigated 571 unique peripheral blood samples from 348 HLA-mismatched renal transplant recipients and 101 nontransplant controls in a four-stage study including microarray, quantitative PCR, and flow cytometry analyses. We report a refined and highly validated (area under the curve, 0.95; 95% confidence interval, 0.92 to 0.97) peripheral blood three-gene assay (KLF6, BNC2, CYP1B1) to detect the state of operational tolerance by quantitative PCR. The frequency of predicted alloimmune quiescence in stable renal transplant patients receiving long-term immunosuppression (n=150) was 7.3% by the three-gene assay. Targeted cell sorting of peripheral blood from operationally tolerant patients showed a significant shift in the ratio of circulating monocyte-derived dendritic cells with significantly different expression of the genes constituting the three-gene assay. Our results suggest that incorporation of patient screening by specific cellular and gene expression assays may support the safety of drug minimization trials and protocols.

The identification of novel potential injury mechanisms and candidate biomarkers in renal allograft rejection by quantitative proteomics

Early transplant dysfunction and failure because of immunological and nonimmunological factors still presents a significant clinical problem for transplant recipients. A critical unmet need is the noninvasive detection and prediction of immune injury such that acute injury can be reversed by proactive immunosuppression titration. In this study, we used iTRAQ -based proteomic discovery and targeted ELISA validation to discover and validate candidate urine protein biomarkers from 262 renal allograft recipients with biopsy-confirmed allograft injury. Urine samples were randomly split into a training set of 108 patients and an independent validation set of 154 patients, which comprised the clinical biopsy-confirmed phenotypes of acute rejection (AR) (n = 74), stable graft (STA) (n = 74), chronic allograft injury (CAI) (n = 58), BK virus nephritis (BKVN) (n = 38), nephrotic syndrome (NS) (n = 8), and healthy, normal control (HC) (n = 10). A total of 389 proteins were measured that displayed differential abundances across urine specimens of the injury types (p < 0.05) with a significant finding that SUMO2 (small ubiquitin-related modifier 2) was identified as a "hub" protein for graft injury irrespective of causation. Sixty-nine urine proteins had differences in abundance (p < 0.01) in AR compared with stable graft, of which 12 proteins were up-regulated in AR with a mean fold increase of 2.8. Nine urine proteins were highly specific for AR because of their significant differences (p < 0.01; fold increase >1.5) from all other transplant categories (HLA class II protein HLA-DRB1, KRT14, HIST1H4B, FGG, ACTB, FGB, FGA, KRT7, DPP4). Increased levels of three of these proteins, fibrinogen beta (FGB; p = 0.04), fibrinogen gamma (FGG; p = 0.03), and HLA DRB1 (p = 0.003) were validated by ELISA in AR using an independent sample set. The fibrinogen proteins further segregated AR from BK virus nephritis (FGB p = 0.03, FGG p = 0.02), a finding that supports the utility of monitoring these urinary proteins for the specific and sensitive noninvasive diagnosis of acute renal allograft rejection.

Steroid withdrawal in renal transplantation

Over the last decade, steroid minimization became one of the major goals in pediatric renal transplantation. Different protocols have been used by individual centers and multicenter study groups, including early and late steroid withdrawal or even complete avoidance. The timing of steroid withdrawal determines if antibodies are used, as avoidance and early withdrawal require antibody induction, while late withdrawal typically does not. A monoclonal antibody was used in most protocols during an early steroid withdrawal together with tacrolimus and mycophenolate mofetil in low immunological risk patients. Polyclonal induction was reported as effective in high-risk patients. Cyclosporine A and mycophenolate mofetil were used in late steroid withdrawal with no induction. All described protocols were effective in terms of preventing acute rejection and preserving renal graft function. There was no superiority of any specific protocol in terms of clinical benefits of steroid withdrawal. Pre-puberty determined growth benefit while other clinical advantages, including better control of glycemia, lipids, and blood pressure, were age independent. It is not clear whether the steroid withdrawal increases the risk of recurrence of primary glomerular diseases post-transplant, however it cannot be excluded. There is no evidence to date for a higher risk of anti-HLA production in steroid-free children after renal transplantation. Key summary points--Current strategies to minimize the steroid-related adverse effects in pediatric renal graft recipients include steroid withdrawal, early or late after transplantation, or complete steroid avoidance--Early steroid withdrawal or avoidance is generally used following the induction therapy with mono- or polyclonal antibodies, while in late steroid withdrawal induction therapy was generally not used- Elimination of steroids (early or late) does not increase the risk of acute rejection and does not deteriorate long-term renal graft function- Early steroid withdrawal is possible in patients at high immunological risk using a combination of polyclonal antibody induction, tacrolimus, and mycophenolate mofetil- All protocols of steroid minimization showed relevant clinical benefits, however the growth-related benefit was limited to pre-pubertal patients in all but one of the studies- Adverse events of steroid withdrawal occurred in a higher incidence of post-transplant bone marrow suppression Key research points - There is no clear evidence of the impact of steroid withdrawal on the risk of recurrence of primary glomerulonephritis after renal transplantation in children, therefore further evaluation of this important issue should be performed in prospective trials- There is limited pediatric data on the risk of anti-HLA/donor-specific antibody production in steroid-free patients after renal transplantation. It is not clear whether the selection of the type of induction antibody (lymphocyte depleting versus short, two-dose administration of anti-IL2R inhibitor) is important in this term. The production of anti-HLA antibodies should then be monitored on a regular basis and analyzed in prospective trials.

Efficacy and safety of thymoglobulin and basiliximab in kidney transplant patients at high risk for acute rejection and delayed graft function

OBJECTIVES

To compare the efficacy and safety of thymoglobulin compared with basiliximab in patients who had kidney transplants and are at high risk for acute rejection and delayed graft function.

MATERIALS AND METHODS

A retrospective review of patients who had 1 or more risk factors for acute rejection and delayed graft function and who were given either thymoglobulin or basiliximab for induction therapy. Incidences of acute rejection, antibody-treated acute rejection, delayed graft function, chronic rejection, cancer, infection, leucopenia, and thrombocytopenia were compared between thymoglobulin and basiliximab groups. Serum creatinine levels within 1 year and long-term graft and patient survival also were compared.

RESULTS

A total of 327 patients were included. Incidences of acute rejection, antibody-treated acute rejection, delayed graft function, and chronic rejection were significantly lower in the thymoglobulin group than in the basiliximab group (P < .05). Serum creatinine levels were lower in the thymoglobulin group on postoperative days 7, 14, and 30 (P < .05). There were no statistically significant differences regarding long-term graft and patient survival, cancer, or total infection rate between the groups. Incidences of Cytomegalovirus infection, leucopenia, and thrombocytopenia were significantly higher in the thymoglobulin group (P < .05).

CONCLUSIONS

Thymoglobulin may improve short-term outcomes, compared with basiliximab, in patients who had kidney transplants and are at high risk for acute rejection and delayed graft function. However, long-term outcomes are similar with thymoglobulin and basiliximab.

Acute humoral rejection in pediatric renal transplant recipients receiving steroid minimization immunosuppression

SM protocols have increasingly gained acceptance owing to their favorable side effect profile with comparable cellular rejection rates. After encountering SM patients with AHR, we performed a case-control study to identify predictors associated with AHR in this cohort. Patients with (n = 4) and without (n = 19) biopsy proven AHR on a SM regimen were compared using the Student's t-tests. The median age at transplant was 13.8 yr. Compared to controls, the AHR cohort was older (15.9 vs. 12.1 yr, p = 0.01). Children with AHR had a lower mean tacrolimus trough level and were more likely to have a sub-therapeutic trough at six months (3.5 vs. 5.5 ng/mL, p = 0.05); mean MMF doses were lower at all times points except three months in the AHR group (not statistically significant). This occurred in spite of higher MPA trough levels at all study points in the AHR group (significant at 3 [p = 0.019] and 6 [p = 0.03] months). Children receiving a SM regimen have a lower safety net and may benefit from more intensive monitoring of tacrolimus exposure. MMF dose modifications based on MPA trough determinations should be resisted in the setting of SM.

Steroid avoidance in renal transplantation

PURPOSE OF REVIEW

The recent surge in the use of steroid-avoidance protocols for pediatric renal transplant recipients has been fueled by the numerous adverse side effects of steroids and development of alternatives for successful immunosuppression. Steroid-avoidance protocols were first attempted in the adult population, and with positive outcomes, pediatrics soon followed. As more pediatric patients are placed on steroid-avoidance protocols, we must begin answering several important questions such as patient and graft outcome, safety profiles of various steroid-avoidance induction protocols, viral complications and incidence of transplant lymphoproliferative disease (PTLD), metabolic benefits, and the affect of steroid minimization on growth.

RECENT FINDINGS

Initial results from steroid-avoidance protocols show these protocols are safe and effective with improved graft survival, metabolic profiles, and linear growth without an increase in viremia or PTLD.

SUMMARY

Although initial results are promising, there is still a lack of long-term data from large, prospective randomized trials, and there is not enough data to determine the optimal steroid-avoidance protocol for pediatric renal transplant recipients.

[Immunosuppressive treatment]

Immunosuppressive treatment following renal transplantation includes induction therapy during the initial period when the risk of rejection is higher. Depleting anti-lymphocyte antibodies are indicated mostly in patients who developped anti-HLA antibodies and following a second graft. Anti-IL2 receptor antibodies may be used in non-responders. After the first month, maintenance therapy mostly consists in the association of several immunosuppressants, mainly corticosteroids, an antimetabolic agent (azathioprine or mycophenolate mofetil) and a calcineurin inhibitor (cyclosporine or tacrolimus). Side effects associated with these treatments led to the development of new immunosuppressive protocols, with the reduction or withdrawal of corticosteroids treatment due to its deleterious effects on statural growth, and decreased doses of anti-calcineurin agents to reduce their nephrotoxic effect. These therapeutic options are possible in patients at low immunological risk.