Steroid avoidance using sirolimus and cyclosporine in pediatric renal transplantation: one year analysis

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.

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.

mTOR inhibitors in pediatric kidney transplantation

The mammalian target of the rapamycin (mTOR) inhibitors sirolimus and everolimus are increasingly being used in pediatric kidney transplantation in different combinations and doses. Several studies have shown beneficial effects of using mTOR inhibitors in children after pediatric renal transplantation. A switch to a low-dose calcineurin inhibitor (CNI) and mTOR inhibitor has been proven to stabilize the glomerular filtration rate. Additionally, de novo studies using a low-dose CNI and an mTOR inhibitor have shown good graft survival and a low number of rejections. Side effects of mTOR inhibitors, such as hyperlipidemia, wound healing problems, and proteinuria, mainly occur if high doses are given and if treatment is not combined with a CNI. Lower doses of mTOR inhibitors do not result in growth impairment or reduced testosterone levels. Treatment with mTOR inhibitors is also associated with a lower number of viral infections, especially cytomegalovirus. Due to their antiproliferative effect, mTOR inhibitors could theoretically reduce the risk of post-transplant lymphoproliferative disease. mTOR inhibitors, especially in combination with low-dose CNIs, can safely be used in children after kidney transplantation as de novo therapy or for conversion from CNI- and mycophenolate mofetil-based regimens.

Early protocol biopsies in pediatric renal transplantation: interest for the adaptation of immunosuppression

GPB are often performed in PRT to detect subclinical acute rejection or IF/TA. Reducing immunosuppression side effects without increasing rejection is a major concern in PRT. We report the results of GPB in children transplanted with a steroid-sparing protocol adapted to immunological risk. Children under 18 yr who received a renal transplantation between April 1, 2009 and May 31, 2012 were included. Immunosuppression consisted of an antibody induction therapy, tacrolimus, and MMF for all recipients. CSs were administered to children under five yr old, or receiving a second allograft. Twenty-eight children were included, 50% were CSs free. GPB were performed between three and six months. IF/TA was documented in seven biopsies; four of these seven children were CS free. One child, with CSs, presented a borderline rejection, and another child, steroid free, with significant inflammatory interstitial infiltrate, considered as a subclinical rejection, was treated with CSs pulses. The median eGFR was stable (74, 67.5, and 82 mL/min/1.73 m² at, respectively, seven days, three months, and one yr). Patient and graft survival were 100%. These results have to be confirmed in a larger cohort, with long-term follow-up.

Growing experience with mTOR inhibitors in pediatric solid organ transplantation

Controlled trials of mTOR inhibitors in children following solid organ transplantation are scarce, although evidence from prospective single-arm studies is growing. Everolimus with reduced CNI therapy has been shown to be efficacious and safe in de novo pediatric kidney transplant patients in prospective trials. Prospective and retrospective data in children converted from CNI therapy to mTOR inhibition following kidney, liver, or heart transplantation suggest preservation of immunosuppressive efficacy. Good renal function has been maintained when mTOR inhibitors are used de novo in children following kidney transplantation or after conversion to mTOR inhibition with CNI minimization. mTOR inhibition with reduced CNI exposure is associated with a low risk for developing infection in children. Growth and development do not appear to be impaired during low-dose mTOR inhibition, but more studies are required. No firm conclusions can be drawn as to whether mTOR inhibitors should be discontinued in children requiring surgical intervention or whether mTOR inhibition delays progression of hepatic fibrosis after pediatric liver transplantation. In conclusion, current evidence suggests that use of mTOR inhibitors in children undergoing solid organ transplantation is efficacious and safe, but a number of issues remain unresolved and further studies are required.

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.

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.

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.

Sirolimus in pediatric renal transplantation

SRL, an mTOR inhibitor that inhibits cell cycle progression, represents an important alternative to CNIs, which are still the cornerstones of pediatric solid organ tx. Because there are still limited data on SRL use among pediatric solid organ recipients, further studies are needed to verify the efficacy and safety of SRL. It has unique pharmacokinetic characteristics concerning dosing intervals and reduction of the dose in combination with other immunosuppressants. SRL also has antineoplastic, antiviral, and antiatherogenic advantages over other immunosuppressive agents. The adverse effects of SRL including thrombocytopenia, hyperlipidemia, proteinuria, impaired wound healing, mouth ulcers, edema, male hypogonadism, TMA, and interstitial pneumonitis must be considered carefully in pediatric population. This article reviews the most recent data on SRL application in the field of pediatric renal tx.

The role and future challenges for recombinant growth hormone therapy to promote growth in children after renal transplantation

Chronic kidney disease can severely impair linear growth in children. For many children, growth improves after renal transplantation, but for some, growth velocity remains low and for others, catch-up growth is insufficient to compensate for the deficit imparted by renal disease in the preceding years. Inadequate final adult height after renal transplant is multifactorial and can adversely affect the quality of life (QOL), psychosocial development and long term prospects for these children as they grow into adulthood. Growth failure after renal transplant requires thorough evaluation and its management in renal transplant recipients can involve improved nutritional intake, correction of metabolic acidosis, treatment of secondary hyperparathyroidism, steroid-sparing immunosuppression and/or use of recombinant human growth hormone (rGH). Treatment with rGH after renal transplant has been evaluated by a limited number of clinical trials suggesting efficacy and safety for this treatment strategy. Several important clinical questions regarding rGH use in children post-renal transplant remain unanswered.

Anthropometric growth and utilization of enteral feeding support in pediatric heart transplant recipients

We sought to outline trends in anthropometric growth before and after cardiac transplantation and to document our experience with the use of EFS in this population. A total of 130 patients (59% male) were enrolled and followed for a median of 4.4 yr after transplantation. Negative changes over time in weight z-score (EST: -0.256 [0.160] z/yr, p = 0.01), height z-score (EST: -0.214 [0.096] z/yr, p = 0.03), and BMI z-score (EST: -0.287 [0.161] z/yr, p = 0.07) were observed prior to transplantation. Significant increases in weight z-score (EST: +0.342 [0.143] z/yr, p < 0.001) and BMI z-score (EST: +0.396 [0.140] z/yr, p = 0.005) were seen in the first 18 months following transplantation. No further increases in height, weight, or BMI z-score were seen beyond this. Forty-two (32%) patients received EFS. Prior to transplantation, it was not found to be associated with change in anthropomorphic growth. Post-transplantation exposure to EFS was associated with a faster increase in weight z-score (EST: +0.480 [0.231] z/yr, p = 0.04) and height z-score over time (EST: +0.366 [0.141] z/yr, p = 0.01). Normalization of weight and height z-scores was not achieved during the study follow-up period. This study suggests that further investigation into the role of EFS is warranted to identify strategies to improve growth in pediatric heart transplant recipients.