Renal function in children with heart transplantation after switching to CNI-free immunosuppression with everolimus

Long-term experience using CNI-free immunosuppression in selected paediatric heart transplant recipients

BACKGROUND

CNI-free immunosuppression with conversion to mTORi-based immunosuppression has been demonstrated to reduce CNI-toxicity and to exhibit anti-proliferative properties. However, the experience of CNI-free immunosuppression in paediatric heart transplantation is limited.

METHODS

A retrospective analysis was conducted of 129 paediatric heart transplants performed between 1997 and 2015. Fifteen patients with clinically indicated conversion from CNI-based to CNI-free immunosuppression were identified. Survival data, rejection episodes, renal function, post-transplantation lymphoproliferative disorder and CAV, including examination with OCT were analysed.

RESULTS

Immunosuppression conversion was successful in all patients. Fourteen of 15 patients (93%) are currently living with good graft function. Median post-transplant survival was 15 years (range, 5-23 years), and median follow-up since conversion was 6 years (range, 1-11 years). Mild (grade 1R) ACR was present in three patients after discontinuation of CNIs. The recovery of renal function with a significant increase in eGFR was observed at 1 and 3 years after conversion. No patient had angiographic signs of macroscopic CAV according to the current ISHLT classification; however, OCT showed the signs of angiographically silent CAV in all patients. CAV did not progress in any patient, implying CAV was stabilised by mTORi-based CNI-free immunosuppression.

CONCLUSIONS

CNI-free immunosuppression based on mTORis is a safe and appropriate strategy for maintenance therapy in selected paediatric patients, significantly improves renal function and stabilises CAV. OCT revealed early development of angiographically silent CAV.

Immunosuppression in the pediatric transplant recipient

The field of pediatric solid-organ transplantation has significantly evolved since its beginnings in the early 20^th century. As advancements have led to the development of innovative surgical techniques and novel medication regimens, transplantation has now become a routine practice leading to an increase in the rates of organ recipients worldwide. The care of pediatric solid-organ transplant recipients differs from adults in several areas not only due to technically challenging surgeries, but mostly due to the complexity of their immunosuppression management. Although there is large variation of pediatric immunosuppression regimens worldwide, the use of calcineurin inhibitors, either tacrolimus or cyclosporine, still forms the backbone of immunosuppression regimens after solid-organ transplantation. Both medications are relatively well tolerated but are known to have long-term side effects, especially nephrotoxicity and neurotoxicity. The goal of care in long-term pediatric survivors of solid-organ transplant now aims to safely minimize exposure to immunosuppression and to achieve long-term graft tolerance.

Calcineurin inhibitor- and corticosteroid-free immunosuppression in pediatric heart transplant patients

Pediatric heart transplant patients at our institution are immunosuppressed with a CNI and another immune-modulating agent without utilizing corticosteroids. Patients whose renal function worsened and who did not respond to CNI minimization had their CNI discontinued. The clinical history of 35 pediatric heart transplant patients with significant renal insufficiency whose CNI was discontinued was retrospectively analyzed. Data including serum creatinine and weight were collected before, at time of, and every 3-6 months after CNI discontinuation. This was used to calculate an eGFR. Cardiac allograft rejection and mortality data were also collected. CNI discontinuation occurred 39 times in 35 patients. The median eGFR significantly increased by 14 mL/min 3 months after CNI discontinuation and the increase continued to be significant (P≤.05) at 5 years. Freedom from rejection analysis showed no difference between graft rejection 2 years before versus after CNI discontinuation (P=.437). No mortality was associated with CNI discontinuation. Immunosuppression free of CNIs and corticosteroids appears to be a safe alternative in pediatric heart transplant patients with significant renal insufficiency. Furthermore, this strategy can significantly reverse renal insufficiency, even late after transplantation.

Use of sirolimus in pediatric heart transplant patients: A multi-institutional study from the Pediatric Heart Transplant Study Group

BACKGROUND

Proliferation signal inhibitors, such as sirolimus, are increasingly used in solid-organ transplantation. However, limited data exist on sirolimus-treated pediatric patients. We aimed to describe sirolimus use in pediatric heart transplant patients and test the hypothesis that sirolimus use is associated with improved outcomes.

METHODS

A retrospective review and propensity-matched analysis of the Pediatric Heart Transplant Study database was performed on patients undergoing primary heart transplantation from 2004 to 2013 with at least 1 year of follow-up comparing patients treated vs not treated with sirolimus at 1 year after transplant. The primary outcome of interest was patient survival, with secondary outcomes including cardiac allograft vasculopathy, rejection, malignancy, and renal insufficiency.

RESULTS

Between 2004 and 2013, 2,531 patients underwent transplantation. At least 1 year of follow-up was available for 2,080 patients, of whom 144 (7%) were on sirolimus at 1 year post-transplant. Sirolimus-treated and non-treated patients had similar survival in the overall cohorts and in the propensity-matched analysis. The secondary outcomes measures were also similar, including a composite end point of all outcome measures. There was a trend toward increased time to cardiac allograft vasculopathy (p = 0.09) and decreased time to infection (p = 0.05) among sirolimus-treated patients in the overall cohort (p = 0.19) but not in the propensity-matched cohort (p = 0.17).

CONCLUSIONS

Sirolimus was used in less than 10% of patients at 1 year post-transplant. Overall outcomes of sirolimus treated and non-treated patients were similar with respect to survival and major transplant adverse events. Further study of sirolimus in pediatric heart transplant patients is needed.

Pediatric Cardiac Intensive Care Society 2014 Consensus Statement: Pharmacotherapies in Cardiac Critical Care Immune Therapy

OBJECTIVE

In this Consensus Statement, we review the etiology and pathophysiology of inflammatory processes seen in critically ill children with cardiac disease. Immunomodulatory therapies aimed at improving outcomes in patients with myocarditis, heart failure, and transplantation are extensively reviewed.

DATA SOURCES

The author team experience and along with an extensive review of the medical literature were used as data sources.

DATA SYNTHESIS

The authors synthesized the data in the literature to present current immumodulatory therapies. For each drug, the physiologic rationale, mechanism of action, and pharmacokinetics are synthesized, and the evidence in the literature to support the therapy is discussed.

CONCLUSIONS

Immunomodulation has a crucial role in the treatment of certain pediatric cardiac diseases. Immunomodulatory treatments that have been used to treat myocarditis include corticosteroids, IV immunoglobulin, cyclosporine, and azathioprine. Contemporary outcomes of pediatric transplant recipients have improved over the past few decades, partly related to improvements in immunomodulatory therapy to prevent rejection of the donor heart. Immunosuppression therapy is commonly divided into induction, maintenance, and acute rejection therapy. Common induction medications include antithymocyte globulin, muromonab-CD3, and basiliximab. Maintenance therapy includes chronic medications that are used daily to prevent rejection episodes. Examples of maintenance medications are corticosteroids, cyclosporine, tacrolimus, sirolimus, everolimus, azathioprine, and mycophenolate mofetil. Rejection of the donor heart is diagnosed either by clinically or by biopsy and is treated with intensification of immunosuppression.

Renal function assessment in child and adolescent heart transplant recipients during routine cardiac catheterization

CKD identification after pediatric heart transplantation (PHT) is limited by inaccuracies in estimates of GFR. We hypothesized that GFR can be measured by a modified iohexol clearance protocol in PHT recipients and that the CKiD formula provides a better estimate of GFR than other estimating equations. A cross-sectional study of PHT recipients, ages 2-18 yr, undergoing coronary angiography was undertaken. The angiography dose of iohexol was divided by the area under the curve from three iohexol levels post-infusion to calculate GFR. Agreement between iGFR and multiple estimating equations (eGFR) was assessed. In 31 subjects, median age was 15.0 yr (IQR 7.6, 16.6). Mean iGFR was 93.8 (s.d. 22.5) mL/min/1.73 m(2) ; 16 (52%) had an iGFR <90 mL/min/1.73 m(2) . The full CKiD formula (mean eGFR 88.9, s.d. 14.9) had low bias (-5.0), narrowest 95% limits of agreement (-42.0, 32.1), highest 30% (94%) and 10% (52%) accuracy, and highest correlation coefficient (0.576) relative to iGFR. We describe a novel modified iohexol clearance method to assess GFR after PHT. Over half of the cohort had an iGFR <90, suggesting CKD. The full CKiD formula performs best with respect to bias, accuracy, and correlation.

New immunosuppressive agents in pediatric transplantation

Immunosuppressive therapy in pediatrics continues to evolve. Over the past decade, newer immunosuppressive agents have been introduced into adult and pediatric transplant patients with the goal of improving patient and allograft survival. Unfortunately, large-scale randomized clinical trials are not commonly performed in children. The purpose of this review is to discuss the newer immunosuppressive agents available for induction therapy, maintenance immunosuppression, and the treatment of rejection.

Everolimus in heart transplantation: an update

The evidence base relating to the use of everolimus in heart transplantation has expanded considerably in recent years, providing clinically relevant information regarding its use in clinical practice. Unless there are special considerations to take into account, all de novo heart transplant patients can be regarded as potential candidates for immunosuppression with everolimus and reduced-exposure calcineurin inhibitor therapy. Caution about the use of everolimus immediately after transplantation should be exercised in certain patients with the risk of severe proteinuria, with poor wound healing, or with uncontrolled severe hyperlipidemia. Initiation of everolimus in the early phase aftertransplant is not advisable in patients with severe pretransplant end-organ dysfunction or in patients on a left ventricular assist device beforetransplant who are at high risk of infection or of wound healing complications. The most frequent reason for introducing everolimus in maintenance heart transplant patients is to support minimization or withdrawal of calcineurin inhibitor therapy, for example, due to impaired renal function or malignancy. Due to its potential to inhibit the progression of cardiac allograft vasculopathy and to reduce cytomegalovirus infection, everolimus should be initiated as soon as possible after heart transplantation. Immediate and adequate reduction of CNI exposure is mandatory from the start of everolimus therapy.

Empiric switch from calcineurin inhibitor to sirolimus-based immunosuppression in pediatric heart transplantation recipients

Sirolimus is used in heart transplant patients with CAV and CNI-induced nephropathy. However, little is known regarding the tolerability, rejection rate, and effect on renal function when used empirically in children. We describe our experience with the empiric use of a sirolimus-based immunosuppressive regimen in pediatric heart transplantation recipients. We reviewed records of patients in whom conversion was attempted to a CNI-free sirolimus-based regimen. Rejection episodes and measures of renal function were recorded. We attempted to convert 20 patients, of which 16 were successful. In total, six of 20 patients (30%) experienced adverse effects. Of the 16 converted, four patients converted to sirolimus due to CNI-induced disease (three nephropathy, one CAV), while 12 patients (mean age 5.5 yr, range 0.1-21 yr; 33% female; 33% with a history of congenital heart disease) were empirically switched to sirolimus at a mean of 2.3 yr after transplant. Follow-up was available for a mean of 2.5 yr after conversion (range 0.5-8.3 yr). The rate of rejection while taking CNIs was 0.18 rejection episodes per patient-year (total of five episodes), compared with 0.03 rejection episodes per patient-year (total of one episode) while on sirolimus. Renal function, in terms of GFR, significantly improved after sirolimus conversion at latest follow-up (from 86 ± 37 mL/min to 130 ± 49 mL/min, p = 0.02). Here, we demonstrate the potential benefit of empiric use of sirolimus in pediatric heart transplant patients in a CNI-free regimen. Larger and longer studies are needed to further clarify risks of rejection and adverse effect profiles.

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.

De novo therapy with everolimus and reduced-exposure cyclosporine following pediatric kidney transplantation: a prospective, multicenter, 12-month study

Prospective data regarding the de novo use of everolimus following kidney transplantation in children are sparse. In a prospective, 12-month, single-arm, open-label study, pediatric kidney transplant patients received everolimus (target trough concentration ≥3 ng/mL) with reduced-exposure CsA and corticosteroids, with or without basiliximab induction. Sixteen of the 18 patients completed the study on-treatment. Age range was 2-16 yr (mean 10.9 yr); eight patients received a living donor graft. Mean (s.d.) everolimus level was 7.4 (3.1) ng/mL during the first 12 months post-transplant. There were no cases of BPAR, graft loss, or death during the study. Protocol biopsies were performed at month 12 in seven patients, with subclinical (untreated) acute rejection diagnosed in one case. Mean (s.d.) estimated GFR (Schwartz formula) was 98 (34) mL/min/1.73 m(2) at month 12. Three patients experienced one or more serious adverse events with a suspected relation to study medication. One patient discontinued study medication due to post-transplant lymphoproliferative disease (5.6%). Everolimus with reduced-dose CsA and corticosteroids achieved good efficacy and renal function and was well tolerated in this small cohort of pediatric kidney transplant patients. Controlled trials are required to answer remaining questions about the optimal use of everolimus in this setting.

Conversion to sirolimus in pediatric renal transplant patients: a single-center experience

We studied efficacy and safety of conversion from CNI- to SRL-based immunosuppression in 92 kidney TX recipients, mainly due to CAN (69%). Median time of conversion was 31 months (r: 0.3-165); median time of follow-up: 36 months (r: 2-102). In the whole group mean eGFR increased from 53 ± 22 to 67 ± 26mL/min/1.73 m(2) at three months (p = 0.02) and did not change subsequently. Patients with grade I CAN had higher eGFR than those with grade II CAN. Patient and graft survival was 96% and 70% 10 yr after conversion. Patients with grade I CAN had better graft survival than those with grade II CAN: 89% vs. 65% at six yr (p = 0.02) post conversion. There were two episodes of BPAR. Baseline proteinuria >20 mg/kg/day (HR: 10) and baseline eGFR <50 mL/min/1.73 m(2) (HR: 8) were independent predictors of graft loss. Sixty-seven of 92 subjects had ≥1 AEs: diarrhea (n = 52), urinary tract infections (n = 35), and lower respiratory tract infections (n = 12) were the most frequent. Patients with >2 AEs had SRL blood levels >9 ng/mL at month 3 (p = 0.01). In conclusion, patients converted from CNI to SRL had good graft survival and tolerable but frequent AEs. Independent predictors of graft loss were baseline proteinuria and eGFR.