Pediatric kidney transplantation using a novel protocol of rapid (6-day) discontinuation of prednisone: 2-year results

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.

Steroid avoidance/withdrawal and maintenance immunosuppression in pediatric kidney transplantation

BACKGROUND

Corticosteroids have been an integral part of maintenance immunosuppression for pediatric kidney transplantation. However, prolonged steroid therapy is associated with significant toxicities resulting in several SW/avoidance strategies in recent years.

METHOD/OBJECTIVE

This comprehensive review aims to discuss steroid-related toxicities and the safety, efficacy, and benefit of steroid avoidance/withdrawal immunosuppression in pediatric kidney transplant recipients.

RESULTS

Initial studies of SW/avoidance conducted in the setting of CSA and AZA showed an increased incidence of AR but no increase in graft loss or mortality with SW/avoidance maintenance immunosuppression. Studies performed under modern immunosuppression (induction therapy, Tac, and MMF) show no significant increase in AR or graft loss with SW/avoidance immunosuppression. Furthermore, SW/avoidance immunosuppression is associated with significant improvement in growth, BMI, BP control, and lipid profile in pediatric kidney transplant recipients. Despite these data, SW/avoidance remains controversial, and only 40% of pediatric kidney transplant recipients in the United States are currently on SW/avoidance maintenance immunosuppression.

CONCLUSION

SW/avoidance maintenance immunosuppression is safe and associated with fewer side effects compared with steroid-inclusive maintenance immunosuppression in pediatric kidney transplant recipients.

Primary pediatric live-donor-kidney transplant-recipients' outcomes by immunosuppression induction received in the United States

OBJECTIVE

We examined the association between induction type and outcomes of live-donor pediatric kidney recipients on tacrolimus and mycophenolate maintenance.

MATERIAL AND METHODS

We analyzed the SRTR standard analysis file to evaluate primary live-donor pediatric kidney recipients between 2000 and 2018. Recipients were grouped by induction type into three groups: alemtuzumab n = 289, anti-thymocyte n = 1197, and IL-2RA n = 1625. Kaplan-Meier curves were generated for recipient and death-censored graft survival. Predictors of recipient and allograft survival were examined using Cox proportional hazards models. Models were adjusted for age, sex, ethnicity, renal failure etiology, HLA-mismatches, transplant year, steroid maintenance, preemptive transplantation, payor type, and donor factors such as age, sex, and donor-recipient relationship. The transplant center was included as a random effect to account for inter-center variability.

RESULTS

Rejection rates at 6 months (Alemtuzumab 9.5% vs. r-ATG 5.7% vs. IL2-RA 5.3%; P: .023) and 12 months (Alemtuzumab 14.5% vs. r-ATG 10.8% vs. IL2-RA 9%; P: .028) were significantly higher in the alemtuzumab group. PTLD rate (Alemtuzumab 0.8% vs. r-ATG 2.2% vs. IL2-RA 1%; P: .028) was significantly higher in the anti-thymocyte group. In the multivariable models, induction type did not influence patient or death-censored graft survival within ten years post-transplant.

CONCLUSION

In this large cohort of standard immunological risk primary pediatric live-donor kidney recipients, as compared to IL-2RA, neither alemtuzumab nor anti-thymocyte globulin was associated with improved long-term graft or recipient survival. In the first year post-transplant, recipients of alemtuzumab induction had a higher rejection rate, while PTLD was more frequently observed in the anti-thymocyte recipients.

Considerations and controversies of pharmacologic management of the pediatric kidney transplant recipient

Pediatric kidney transplantation has experienced considerable growth and improvement in patient and allograft outcomes over the past 20 years, in part due to advancements in immunosuppressive regimens and management. Despite this progress, care for this unique population can be challenging due to limited pediatric transplant data and trials, intricacies related to differences in children and adolescents compared with their adult counterparts, and limitations to long-term survival facing all solid organ transplant populations. Immunosuppression and infection prevention practices vary from one pediatric transplant center to another and clinical controversies exist surrounding treatment and dosing. This review aims to summarize key aspects of pharmacologic management in this population and present pertinent data that describe the influence of practice to serve as a resource for practitioners caring for this unique specialty patient population. Additionally, this review highlights select controversies that exist within pediatric kidney transplantation.

Long-term outcomes of pediatric kidney transplant recipients with a pretransplant malignancy

A childhood malignancy can rarely progress to ESRD requiring a KT. To date, few reports describe long-term outcomes of pediatric KT recipients with a pretransplant malignancy. Between 1963 and 2015, 884 pediatric (age: 0-17 years old) recipients received 1055 KTs at our institution. KT outcomes were analyzed in children with a pretransplant malignancy. We identified 14 patients who had a pretransplant malignancy prior to KT; the majority were <10 years old at the time of KT. Ten (71%) patients received their grafts from living donors, the majority of which were related to the recipient. Wilms' tumor was the dominant type of pretransplant malignancy, seen in 50% of patients. The other pretransplant malignancy types were EBV-positive lymphoproliferative disorders, non-EBV-positive lymphoma, leukemia, neuroblastoma, soft-tissue sarcoma, and ovarian cancer. Ten of the 14 patients received chemotherapy as part of their pretransplant malignancy treatment. Graft survival at 1, 3, and 5 years was 93%, 83%, and 72%, respectively. Patient survival at 1, 5, and 10 years was 100%, 91%, and 83%, respectively. Six (40%) patients suffered AR following KT; half of them had their first episode of AR within 1 month of KT. Our single-center experience demonstrates that pediatric KT recipients with a previously treated pretransplant malignancy did not exhibit worse outcomes than other pediatric KT patients.

Outcomes of kidney transplants in pediatric patients with the vertebral defects, anal atresia, cardiac defects, tracheoesophageal fistula, renal anomalies, limb abnormalities association

In this single-center retrospective study, we analyzed kidney transplant outcomes in nine pediatric patients with VACTERL [vertebral defects, anal atresia, cardiac defects, tracheoesophageal fistula, renal anomalies, limb abnormalities] association-making this the largest study of its kind. Of 743 pediatric kidney transplant recipients at our center (1980-2017), nine had documented diagnoses of VACTERL association. All nine had congenital anorectal malformations and renal anomalies, five had vertebral defects, and one had a bifid thumb and tracheoesophageal fistula. Renal anomalies included dysplasia (n = 6), aplasia (n = 3), and horseshoe kidney (n = 2). Congenital lower urinary tract anomalies included neurogenic bladder (n = 6), obstructive uropathy (n = 4), anovesicular fistula (n = 1), rectourethral fistula (n = 1), and posterior urethral valves (n = 1). Age at transplant ranged from 1.2 to 15 years (mean, 7.3; standard deviation [SD], 5.5); 6 (67%) were male, and 3 (33%) were female; 6 (67%) had a living related donor, and 3 (33%) had a deceased donor. The overall graft survival rate was 78% (range, 1.5 to 25.2 years; mean, 10.5; SD, 8.9). One month post-transplant, one recipient died with a functioning graft. At 3.7 years post-transplant, one graft failed because of recurrent pyelonephritis. Post-transplant urologic complications included pyelonephritis (n = 6), vesicoureteral reflux (n = 5), and graft hydronephrosis (n = 4). We conclude that pediatric patients with VACTERL association can be safely transplanted-careful patient selection with vigilance and intervention for pre- and post-transplant urologic complications is essential.

Immunosuppressants in Organ Transplantation

The goal of immunosuppressive therapy post-transplantation in pediatric renal transplant recipients is to prevent acute and chronic rejection while minimizing drug side effects. Most therapies alter immune response mechanisms but are not immunologically specific, and a careful balance is required to find the dose that prevents rejection of the graft while minimizing the risks of overimmunosuppression leading to infection and cancer. While this chapter because of space constraints focuses on immunosuppressive therapy in pediatric renal transplant recipients, many aspects can be applied on pediatric recipients of other solid organ transplants such as the liver and heart. The major maintenance immunosuppressive agents currently used in various combination regimens are tacrolimus, cyclosporine, mycophenolate mofetil, azathioprine, everolimus, sirolimus, and glucocorticoids (steroids). Although data from adult renal transplantation trials are used to help guide management decisions in pediatric patients, immunosuppressive therapy in pediatric renal transplant recipients often must be modified because of the unique dosage requirements and clinical effects of these agents in children, including their impact on growth and development. The optimal immunosuppressive therapy post-transplant is not established. The goal remains to find the best combination of immunosuppressive agents that optimizes allograft survival by preventing acute rejection while limiting drug toxicities.

Incidence and magnitude of post-transplant cardiovascular disease after pediatric kidney transplantation: Risk factor analysis of 1058 pediatric kidney transplants at the university of Minnesota

BACKGROUND

KT recipients have increased the risk of CVD. The incidence of post-transplant CVEs among pediatric recipients has not been well-characterized.

PATIENTS AND METHODS

Between 1963 and 2015, 884 pediatric (age: 0-17 years old) recipients received 1058 KTs at our institution. The cumulative incidence of CVEs was analyzed. Statistical models were used to estimate risk factors for developing post-transplant CVEs.

RESULTS

Overall median patient survival was 33 years (IQR: 18.7-47). A total of 362 CVEs occurred in 161 (18.3%) patients at a median age of 20.5 years. Arrhythmias (18%) were most common. Cumulative risk of post-transplant CVEs was 9% at 10 years, 17% at 20 years, 25% at 30 years, and 36% at 40 years. Development of post-transplant CVEs was associated with increased mortality (HR 2.25 [95% CI 1.61-3.14]); of those who developed a CVE and died, 22/51 (43.1%) died of CVD. Multivariable risk factors for post-transplant CVEs included a history of pretransplant CVD (aHR 1.92 [1.18-3.13] and graft failure (4.57 [3.13-6.67]).

DISCUSSION

A pretransplant history of CVD and a failed graft are significant risk factors for the development of post-transplant CVE. CVD increases the risk of post-transplant death or graft loss.

Estimating heterogeneous treatment effects for latent subgroups in observational studies

Individuals may vary in their responses to treatment, and identification of subgroups differentially affected by a treatment is an important issue in medical research. The risk of misleading subgroup analyses has become well known, and some exploratory analyses can be helpful in clarifying how covariates potentially interact with the treatment. Motivated by a real data study of pediatric kidney transplant, we consider a semiparametric Bayesian latent model and examine its utility for an exploratory subgroup effect analysis using secondary data. The proposed method is concerned with a clinical setting where the number of subgroups is much smaller than that of potential predictors and subgroups are only latently associated with observed covariates. The semiparametric model is flexible in capturing the latent structure driven by data rather than dictated by parametric modeling assumptions. Since it is difficult to correctly specify the conditional relationship between the response and a large number of confounders in modeling, we use propensity score matching to improve the model robustness by balancing the covariates distribution. Simulation studies show that the proposed analysis can find the latent subgrouping structure and, with propensity score matching adjustment, yield robust estimates even when the outcome model is misspecified. In the real data analysis, the proposed analysis reports significant subgroup effects on steroid avoidance in kidney transplant patients, whereas standard proportional hazards regression analysis does not.

The effect of peri-transplant plasmapheresis in the prevention of recurrent FSGS

Many pediatric centers utilize a variety of protocols including preemptive plasmapheresis to prevent the recurrence of FSGS post-transplant. But the effectiveness of this expensive, time-consuming process of plasmapheresis in the prevention of FSGS recurrence is still unclear. We retrospectively reviewed all pediatric cases of FSGS in our center that received a kidney transplant and compared the transplant and patient outcomes of those transplanted after 2006 who received pretransplant plasmapheresis to those prior to 2006 who did not. Of the 57 children with FSGS, 31 and 26 were transplanted before and after 2006, respectively. The cohorts differed significantly in keeping with the center immunosuppression protocol changes, and prior to 2006, the recipients were significantly younger. All children with FSGS transplanted after 2006 underwent three and one sessions of 1.0 plasma volume/exchange plasmapheresis with fresh frozen plasma replacement prior to the transplant in living and deceased donors, respectively, in addition to five sessions of every other day post-transplant pheresis. The incidence (27% vs 26%, P = 1.0) and time to recurrence of FSGS in the kidney allograft (P = .22) were not significantly different in patients that did and did not undergo prophylactic plasmapheresis. We need to re-evaluate the role of preemptive plasmapheresis in the prevention of FSGS recurrence in a prospective multicenter study.

Infection rates in tacrolimus versus cyclosporine-treated pediatric kidney transplant recipients on a rapid discontinuation of prednisone protocol: 1-year analysis

AR is lower in pKTx recipients on Tac vs CsA. Data comparing infection outcomes for children treated with these agents are limited. We retrospectively studied infection outcomes in 96 pKTx recipients on a RDP. PS, DCGS, AR, and infection-free survival were assessed using Kaplan-Meier/log-rank tests and proportional hazards models. There were no differences in 1-year PS, DCGS, or AR between Tac and CsA recipients. After adjusting for AR, the hazard of CMV viremia was 4.0 times higher (95%CI: 1.04, 15.5; P = .044) and that of BK viremia was 3.8 times higher (95%CI: 1.5, 10.2; P = .007) in Tac recipients. The incidence of EBV viremia was similar between the groups (P = .56). PostTx lymphoproliferative disease was only observed in Tac recipients (3%). There was no difference in the incidence of pneumonia, urinary tract, or Clostridium difficile infections between Tac and CsA recipients. Among KTx recipients on RDP, the hazards of CMV and BK viremia within 1 year post-KTx were significantly higher in Tac recipients compared to CsA. Regular assessment for infections and lower Tac trough levels may be warranted in Tac recipients.

Corticosteroid Use and Growth After Pediatric Solid Organ Transplantation: A Systematic Review and Meta-Analysis

BACKGROUND

A number of corticosteroid minimization and avoidance protocols for post-solid organ transplant have been developed. The study objective was to examine the effect of corticosteroid withdrawal/avoidance on growth and safety parameters in pediatric solid organ transplant recipients.

METHODS

A systematic review using Medline and Embase was performed. All randomized controlled trials (RCT) and observational studies comparing corticosteroid withdrawal/avoidance to controls receiving corticosteroids in pediatric transplant recipients which reported growth as change in height or final height were included. Two reviewers independently abstracted study data and assessed quality.

RESULTS

The search yielded 930 records, 14 separate studies involving 1146 patients. Renal RCTs (n = 5) showed that corticosteroid withdrawal/avoidance was associated with a significant increase in growth (mean difference in height standard deviation score [SDS], 0.18; 95% confidence interval [95% CI], 0.07-0.29; P = 0.001) compared with those remaining on steroids. In liver RCTs (n = 2), mean difference in height SDS was -0.20 (95% CI, -1.08 to 0.68; P = 0.66). Results for renal observational studies (n = 5) was 0.34 (95% CI, 0.03-0.65; P = 0.03). The most pronounced effect was seen in prepubertal children with SDS of 0.28 (95% CI, 0.14-0.41; P < 0.0001). In pubertal participants this was not observed (SDS, 0.06; 95% CI, -0.04 to 0.15; P = 0.24). Corticosteroid withdrawal/avoidance was not associated with acute rejection (odds ratio [OR], 0.87; P = 0.63), graft failure (OR, 0.45; P = 0.08), or death (OR, 0.34; P = 0.16) in renal trials.

CONCLUSIONS

Corticosteroid withdrawal/avoidance in pediatric renal transplantation is associated with a significant improvement in height. Prepubertal patients appeared to have the greatest benefit. Importantly, the improvement in growth was not accompanied by increased rejection or worsening patient/allograft survival in the short term.

Post-transplant blood transfusions and pediatric renal allograft outcomes

The association of blood transfusions with GS after pediatric KTx is unclear. We retrospectively analyzed blood transfusions post-KTx and subsequent outcomes. Between 1984 and 2013, 482 children (<18 years of age) underwent KTx at our center. Recipient demographics, outcomes and transfusion data were collected. Cox regression with post-KTx blood transfusion as a time-dependent covariate was performed to model the impact of blood transfusion on outcomes. Of the 208 (44%) that were transfused, 39% had transfusion <1 month post-KTx; 48% >12 months. Transfused and non-transfused recipients were not significantly different. In univariate and multivariate analyses, there was no difference between transfused and non-transfused recipient patient survival, antibody-mediated and ACR, and DSA free survival. Transfusions <1 month post-KTx did not impact DCGS (P=NS). Patients transfused >12 months post-KTx had significantly lower 12 month eGFR (compared to non-transfused) and worse subsequent DCGS. Post-KTx blood transfusions have increased in pediatric KTx over time but have no negative association with rejection or DSA production. DCGS is unaffected by transfusion within first month. Transfusions after the first year occur in patients with more advanced chronic kidney disease and are associated with significantly worse DCGS.

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.

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.

Single-center experience in pediatric renal transplantation using thymoglobulin induction and steroid minimization

Our center has offered thymoglobulin induction with steroid minimization to our pediatric renal transplant patients for the last 10 yr. Steroid minimization or avoidance has shown favorable results in survival, kidney function, and growth in previous studies of pediatric patients. We report our experience with this protocol over the past 10 yr with respect to patient/graft survival, acute rejection episodes, renal function, linear growth, bone density, cardiovascular risk factors, and opportunistic infections. A retrospective chart review was performed for pediatric renal transplant patients on the steroid-minimized protocol between January 2002 and December 2011 on an intention to treat basis. Patient demographics, height, weight, serum creatinine, iGFR, biopsies, and survival data were collected. Height and weight z-scores were calculated with EpiInfo 7, using the CDC 2000 growth charts. Survival was calculated using Kaplan-Meier analysis. eGFR was calculated using the original and modified Schwartz equations. Forty-four pediatric patients were identified, aged 13 months to 19 yr. Five-yr survival was 95.5% for males and 94.4% for females. Only five patients had biopsy-proven ACR, two of which were at more than 12 months post-transplantation. Height delta z-scores from transplant to one, three, and five yr were 0.34, 0.38, and 0.79, respectively. Weight delta z-scores from transplant to one, three, and five yr were 0.87, 0.79, and 0.84, respectively. Mean original Schwartz eGFR was 84.3 ± 15.8 mL/min/1.73 m(2) , modified Schwartz eGFR was 59.3 ± 11.5 mL/min/1.73 m(2) , and iGFR was 64.2 ± 8.5 mL/min/1.73 m(2) at three yr. Of 18 subjects who had a bone density exam, none had a z-score less than -2 on DEXA exam at one-yr post-transplantation. Fifty-one percent of patients were on antihypertensives at the time of transplant compared with 43% at one-yr post-transplantation. Three yr post-transplantation, the average LDL was <100 mg/dL, and average total cholesterol was <200 mg/dL. There were no clinical episodes of EBV or CMV infection. A steroid-minimized protocol with thymoglobulin induction is safe and provides favorable improvement in linear growth, stable graft function, stable or improved cardiovascular risk factors, and normal bone density in pediatric renal transplant patients.

Recent developments in kidney transplantation in children

PURPOSE OF REVIEW

Renal transplantation in childhood is a well established procedure with excellent short-term outcomes. However, waiting times for transplantation are still relatively long if living donation cannot be performed, and long-term outcomes after transplantation have not significantly improved during the last decade.

RECENT FINDINGS

This review describes alternative modalities to improve donation rates such as en bloc kidney transplantation from young donors, ABO-incompatible transplantation and kidney paired donation. This review also deals with long-term post-transplant morbidities, such as follows: first, medication side-effects (metabolic syndrome, cardiovascular disease) and with the benefits of steroid and calcineurin inhibitor drug minimization; second, the deleterious impact of viral infections and their management and third, chronic antibody-mediated rejection, its therapeutic and prevention possibilities.

SUMMARY

Donor shortage and long-term morbidities, after transplantation, are still relevant issues in paediatric renal transplantation medicine. Significant research and efforts have been made to advance the field and create novel approaches for improvement of transplantation rates and post-transplant graft or patient survival. These modalities are to be established in the routine setting.

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.

Antihypertensive pharmacotherapy and long-term outcomes in pediatric kidney transplantation

Hypertension (HTN) is common in pediatric recipients following kidney transplantation (KT). We retrospectively assessed the impact of HTN on long-term (>10-yr) outcomes in pediatric KT recipients (aged < 18 yr) at our center. Two hundred and ninety-three pediatric KT recipients (83% living donor [LD]) with graft survival (GS) for ≥5 yr were studied. HTN was defined by antihypertensive medication use at five yr post-KT. One hundred and sixty (55%) recipients did not have HTN, and 133 (45%) had HTN at five yr post-KT. There were no differences in actuarial patient survival between cohorts. Actuarial GS at 15 and 20 yr was 68% and 53% for recipients without HTN, and 53% and 33% for recipients with HTN (p = 0.006). Among LD recipients using one antihypertensive, GS at 15 yr was 100% for those using an angiotensin-converting enzyme inhibitor (ACEI) and 44% for those not using an ACEI (p = 0.04). Among these recipients, HTN treated with no ACEI was a significant risk factor for graft failure at >5 yr (hazard ratio [HR] = 2.5, p = 0.02), but HTN treated with an ACEI was not (HR = 0.6, p = 0.7). HTN at five yr post-KT is associated with poorer long-term GS in pediatric recipients, but ACEI therapy may enable better outcomes and should be studied further.

Paediatric use of mycophenolate mofetil

A number of medications do not have a licence, or label, for use in the paediatric age group nor for the specific indication for which they are being used in children. Over recent years, mycophenolate mofetil has increasingly been used off-label (i.e. off-licence) in adults for a number of indications, including autoimmune conditions; progressively, this wider use has been extended to children. This review summarizes current use of mycophenolate mofetil (MMF) in children, looking at how MMF works, the pharmacokinetics, the clinical conditions for which it is used, the advantages it has when compared with other immunosuppressants and the unresolved issues remaining with use in children. The review aims to focus on off-label use in children so as to identify areas that require further research and investigation. The overall commercial value of MMF is limited because it has now come off patent in adults. Given the increasing knowledge of the pharmacodynamics, pharmacokinetics and pharmacogenomics demonstrating the clinical benefits of MMF, new, formal, investigator-led studies, including trials focusing on the use of MMF in children, would be of immense value.

Outcomes of steroid-avoidance protocols in pediatric kidney transplant recipients

Advances in immunosuppression have facilitated increased use of steroid-avoidance protocols in pediatric kidney transplantation. To evaluate such steroid avoidance, a retrospective cohort analysis of pediatric kidney transplant recipients between 2002 and 2009 in the United Network for Organ Sharing database was performed. Outcomes (acute rejection and graft loss) in steroid-based and steroid-avoidance protocols were assessed in 4627 children who received tacrolimus and mycophenolate immunosuppression and did not have multiorgan transplants. Compared to steroid-based protocols, steroid avoidance was associated with decreased risk of acute rejection at 6 months posttransplant (8.3% vs. 10.9%, p = 0.02) and improved 5-year graft survival (84% vs. 78%, p < 0.001). However, patients not receiving steroids experienced less delayed graft function (p = 0.01) and pretransplant dialysis, were less likely to be African-American and more frequently received a first transplant from a living donor (all p < 0.001). In multivariate analysis, steroid avoidance trended toward decreased acute rejection at 6 months, but this no longer reached statistical significance, and there was no association of steroid avoidance with graft loss. We conclude that, in clinical practice, steroid avoidance appears safe with regard to graft rejection and loss in pediatric kidney transplant recipients at lower immunologic risk.

Graft loss due to recurrent disease in pediatric kidney transplant recipients on a rapid prednisone discontinuation protocol

Recurrent disease is the fourth most common cause of graft loss (GL) in pediatric KTx recipients. We studied the incidence of recurrent disease and GL due to recurrent disease in pediatric KTx recipients on a RDP protocol. Between 2002 and 2010, we performed 74 KTxs in patients aged 5-18 yr using an RDP protocol, 25 (34%) were at risk of recurrence of primary disease. Outcomes were compared to 69 historical controls (18 [26%] at risk of recurrence), KTx between 1996 and 2000. Follow-up period was 39 ± 25 months in RDP and 124 ± 38 months in controls. The incidence of recurrent disease at three yr post-KTx was 16% in RDP and 28% in controls (p = NS). Mean time to recurrent disease was 22 ± 26 months in RDP and 46 ± 48 months in controls (p = 0.54). Nine (12%) grafts were lost in the RDP group (1-recurrence) and 32 (46%) in the control group (4-recurrence). Time to GL was 85 months in the RDP recipient and 46 ± 21 months in controls. An RDP protocol in pediatric KTx recipients may not be associated with increased risk of graft loss due to recurrent disease.

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.

Ten-year outcome after rapid discontinuation of prednisone in adult primary kidney transplantation

BACKGROUND AND OBJECTIVES

Rapid discontinuation of prednisone after kidney transplantation potentially allows for minimization of steroid-related side effects. Although intermediate-term data with rapid discontinuation of prednisone have been promising, concern still exists regarding long-term outcomes. The 10-year experience is reported herein.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Between October 1, 1999 and December 31, 2010, 1241 adult primary kidney transplants (791 living donor and 450 deceased donor) were performed using a protocol in which prednisone is discontinued after postoperative day 5. The 10-year actuarial recipient and graft survival rates and prednisone-related side effects were studied.

RESULTS

Ten-year actuarial patient survival was 71% for living donor transplants and 62% for deceased donor transplants; 10-year graft survival was 61% for living donor transplants and 51% for deceased donor transplants, and was comparable to 10-year Scientific Registry of Transplant Recipients national data. Ten-year death-censored graft survival was 79% for living donor transplants and 80% for deceased donor transplants. Ten-year acute rejection rates were 25% for deceased donor transplants and 31% for living donor transplants; 10-year chronic rejection (interstitial fibrosis/tubular atrophy) rates were 39% for deceased donor transplants and 47% for living donor transplants. For nondiabetic recipients of living donor or deceased donor allografts, the incidence of new-onset diabetes was significantly lower than in historical controls on prednisone (P<0.001). We also found significantly reduced rates of cataracts, avascular necrosis, and cytomegalovirus infection in some subgroups.

CONCLUSIONS

Prednisone-related side effects can be minimized in a protocol incorporating rapid discontinuation of prednisone for maintenance immunosuppression. Ten-year patient and graft outcomes remain acceptable.

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.

Steroid minimization in pediatric renal transplantation: Early withdrawal or avoidance?

  Clinically important adverse events associated with the use of corticosteroids post-transplantation include hypertension, dyslipidemia, impaired glucose metabolism (including diabetes mellitus), growth retardation, bone fractures, and cosmetic problems. Over recent years, a number of studies have investigated the effect of minimizing exposure to corticosteroids in post-transplant immunosuppression protocols in both adults and children. In pediatric patients, several different approaches have been evaluated, including late steroid withdrawal, early steroid withdrawal, and complete steroid avoidance with or without poly- or monoclonal antibody induction and a variety of maintenance immunosuppressants. This manuscript reviews the key studies and documents the specific clinical benefits associated with steroid minimization. The development of PTLD and bone marrow suppression has been a major safety concern in some of these studies. These studies and other adverse effects are discussed.

Pediatric renal transplantation: an overview and update

PURPOSE OF REVIEW

Transplantation is the preferred method of treatment for end-stage renal disease in children. The rate of pediatric kidney transplantation has been steadily rising over the past decade. The use of increasingly potent immunosuppressive drugs has lessened the risk for acute rejection substantially and improved short-term outcomes; however, the long-term outcomes have remained inadequate.

RECENT FINDINGS

The follow-up of pediatric cohorts and the encouraging results from data registries prompt us to revisit our practices in transplantation so as to devise additional strategies to improve long-term outcomes.

SUMMARY

This review presents a comprehensive discussion of the major issues in pediatric renal transplantation, the newer immunosuppression approaches to limit toxicities of therapies in children and some critical issues that remain to be addressed, specific to the care of the transplanted child. The ultimate goal of designing optimum conditions for equating graft survival to patient survival still remains a major goal for pediatric organ transplantation.