Everolimus and reduced calcineurin inhibitor therapy in pediatric liver transplant recipients: Results from a multicenter, prospective study

Role of mTOR Inhibitors in Pediatric Liver Transplant Recipients: A Systematic Review

BACKGROUND

Immunosuppressive medications play a crucial role in determining both organ and patient survival following liver transplantation (LT). Typically, immunosuppressive protocols for pediatric LT patients rely on calcineurin inhibitors (CNIs). While inhibitors of mammalian target of rapamycin (mTOR) have demonstrated beneficial outcomes in adult recipients of liver allografts, such as improved renal function post-LT, their application in pediatric liver transplant recipients is a subject of debate due to uncertain efficacy and potential adverse effects.

OBJECTIVES

This review evaluates the potential roles of mTOR inhibitors in the context of pediatric LT patients.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol for conduct and reporting. Databases until 31 August 2023 were searched using specific terms and keywords. All clinical studies focusing on mTOR inhibitors in pediatric LT were included.

RESULTS

Out of 888 identified articles, 30 studies, involving 386 children who had undergone liver transplantation and received mTOR-inhibitor-based immunosuppressive regimens, met the inclusion criteria. The beneficial impacts of switching from a CNI to an mTOR inhibitor or adding an mTOR inhibitor to CNI-reduced immunosuppression in LT pediatric patients with impaired kidney function are controversial, and high-powered clinical studies are need. It appears that enhancing immunosuppression by adding an mTOR inhibitor to CNI is helpful for pediatric LT recipients who are experiencing refractory acute rejection or chronic rejection. mTOR-inhibitor-containing regimens failed to reduce the occurrence of post-transplant lymphoproliferative disorders (PTLD) among children with LT that may be due to concomitant high CNI concentration among studied patients. The effectiveness of mTOR inhibitors in treating PTLD remains uncertain; however, in patients with PTLD who are at high risk of rejection, mTOR inhibitors may be administered. Conversion to or the addition of mTOR inhibitors to maintenance immunosuppression seems to be suitable for pediatric patients who received a transplant due to hepatic malignancies such as hepatoblastoma or hepatocellular carcinoma or for those with post-transplant primary or recurrent malignancies. Switching to an mTOR inhibitor may improve some CNI-related adverse effects such as gingival hyperplasia, neurotoxicity, nephropathy, hypertrophic cardiomyopathy, or thrombotic microangiopathy.

CONCLUSION

Although the exact role of mTOR inhibitors among pediatric patients who have received a liver transplant needs further study, two algorithms are presented in this review to guide conversion from CNIs to mTOR inhibitors or the addition of mTOR inhibitor to a CNI-minimization immunosuppressive regimen for pediatric patients who may benefit from this class of drugs. This review mainly consisted of retrospective studies with inadequate sample sizes and lacked a control group, which represents the main limitation of this study.

The IPTA Nashville consensus conference on post-transplant lymphoproliferative disorders after solid organ transplantation in children: IV-consensus guidelines for the management of post-transplant lymphoproliferative disorders in children and adolescents

The International Pediatric Transplant Association convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorders (PTLD) after pediatric solid organ transplantation. This report addresses the outcomes of deliberations by the PTLD Management Working Group. A strong recommendation was made for reduction in immunosuppression as the first step in management. Similarly, strong recommendations were made for the use of the anti-CD20 monoclonal antibody (rituximab) as was the case for chemotherapy in selected scenarios. In some scenarios, there is uncoupling of the strength of the recommendations from the available evidence in situations where such evidence is lacking but collective clinical experiences drive decision-making. Of note, there are no large, randomized phase III trials of any treatment for PTLD in the pediatric age group. Current gaps and future research priorities are highlighted.

Sirolimus to treat chronic and steroid-resistant allograft rejection-related fibrosis in pediatric liver transplantation

This study aimed to report our experience with the use of sirolimus in pediatric liver transplant patients with chronic rejection or steroid-resistant rejection with hepatic fibrosis, focusing on their histological evolution. All pediatric liver transplant recipients who received off-label treatment with sirolimus for chronic ductopenic rejection or cortico-resistant rejection between July 2003 and July 2022 were included in the study. All nine patients included in the study showed improvement in liver enzymes and cholestasis parameters as soon as 1-month after postsirolimus introduction. A decrease in fibrosis stage was observed in 7/9 (77.7%) patients at 36 months. All but one patient experienced an improvement in the Rejection Activity Index and ductopenia at 12 months. A single patient had to discontinue sirolimus treatment owing to nephrotic proteinuria. In conclusion, sirolimus may be a safe and effective treatment for chronic and steroid-resistant rejection and may improve allograft rejection-related fibrosis and ductal damage.

Experience with the mTOR Inhibitor Everolimus in Pediatric Liver Graft Recipients

INTRODUCTION

Immunosuppression after pediatric liver transplantation remains a major challenge. MTOR inhibitors provide a promising therapeutic approach in combination with reduced CNI after transplantation. However, there are still few data regarding their use in children.

PATIENTS

We analyzed 37 patients with a median age of 10 years, who received Everolimus for one or more of the following indications: I = chronic graft dysfunction (n = 22); II = progressive renal impairment (n = 5); III = non-tolerable side effects with previous immunosuppressive medication (n = 6); and IV = malignancies (n = 10). The median follow-up time was 36 months.

RESULTS

Patient survival was 97%, and graft survival 84%, respectively. Stabilization of graft function was observed in 59% in subgroup 1, with 18.2% ultimately requiring retransplantation. No patient in subgroup IV developed recurrence of his primary tumor or PTLD by the endpoint of the study. Side effects were observed in 67.5% of the study patients, with infections being the most frequent (n = 20; 54.1%). There were no relevant effects on growth and development.

CONCLUSION

Everolimus seems to be a treatment option in selected pediatric liver graft recipients for whom other regimens are not suitable. Overall, the efficacy was good and the side effect profile appeared to be acceptable.

Everolimus is Safe as a Second-/Third-Line Therapy in Pediatric Autoimmune Hepatitis

Autoimmune hepatitis (AIH) can lead to progressive fibrosis in patients refractory to conventional therapy with prednisolone and azathioprine. The use of mammalian target of rapamycin (mTOR) inhibitors has recently emerged in refractory AIH, but no data have been published about everolimus in pediatric AIH to date. Our aim was to share our experience about everolimus as a second-/third-line therapy in pediatric AIH.

Methods

Pretransplant AIH patients aged 0-18 years who received everolimus therapy from 2014 to 2021 were retrospectively identified. All patients underwent regular plasma monitoring of everolimus trough levels to avoid toxicity and assess adherence. Special attention was paid to the clinical and biochemical occurrence of everolimus-related adverse events.

Results

We report six difficult-to-treat AIH patients who received everolimus therapy for 8-46 months (median 28 months). No side effects were reported when everolimus plasma trough levels were in the therapeutic range. Liver transaminases improved in 5 of 6 patients at everolimus introduction and significantly decreased at the last follow-up (FU) in our cohort (P < 0.05). None of our patients achieved complete biochemical remission at the last FU and 3 of 6 admitted to have suboptimal adherence to therapy.

Conclusions

Our data bring preliminary safety for the use of everolimus as a second-/third-line therapy in pediatric AIH. Although liver transaminases improved in our cohort, prospective studies are needed to determine if everolimus can induce long-term remission.

Exposure-response modeling for extrapolation from adult to pediatric patients who differ with respect to prognostic factors: Application to everolimus

Pediatric extrapolation is essential for bringing treatments to the pediatric population, especially for indications where the recruitment of pediatric patients into clinical trials is difficult and where fully powered trials are impossible. Often a similar exposure-response relationship between adult and pediatric patients can be assumed, but just matching exposures can be misleading when some prognostic factors for efficacy differ between those two patient populations. We present an example in liver transplantation where different study designs led to different (time-dependent) hazards between populations. Only after accounting for this difference an apparent mismatch between the extrapolation from adults and the pediatric study could be resolved. This article also exemplifies a clear scientific, methodological approach of pediatric extrapolation, including model building in adults, extrapolation to pediatrics, qualification of the extrapolation, and derivation of the actual pediatric efficacy.

Improvements in Disease-Specific Health-Related Quality of Life of Pediatric Liver Transplant Recipients During Immunosuppression Withdrawal

Long-term immunosuppression (IS) leads to systemic complications affecting health-related quality of life (HRQOL) in pediatric liver transplantation (LT) recipients. We serially assessed HRQOL using the PedsQL Generic and Multidimensional Fatigue Scales and Family Impact and Transplant Modules as part of a multicenter prospective immunosuppression withdrawal (ISW) trial between 2012 and 2018. Participants received a primary LT ≥4 years before the study and were on stable IS with normal liver tests and without rejection in the prior 2 years. IS was withdrawn in 7 steps over 36 to 48 weeks. HRQOL was assessed at regular intervals. The primary endpoint was change in disease-specific HRQOL measured by the PedsQL Transplant Module. Generic HRQOL was measured by the PedsQL Generic Scale and was compared with an age-matched and sex-matched multicenter cohort. Of the 88 participants, 39 were boys, median age was 11 years (range, 8-13), and time since transplant was 9 years (range, 6-11). For 36 months, disease-specific HRQOL improved for all participants, whereas generic HRQOL was unchanged. Neither generic nor disease-specific HRQOL changed for the 35 participants who developed acute rejection during ISW. In the first use of patient-reported outcome measures during an ISW trial, we found improvements in disease-specific HRQOL in all participants and no lasting detrimental effects in those who experienced rejection.

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.

Three-year outcomes from the CRADLE study in de novo pediatric kidney transplant recipients receiving everolimus with reduced tacrolimus and early steroid withdrawal

CRADLE was a 36-month multicenter study in pediatric (≥1 to <18 years) kidney transplant recipients randomized at 4 to 6 weeks posttransplant to receive everolimus + reduced-exposure tacrolimus (EVR + rTAC; n = 52) with corticosteroid withdrawal at 6-month posttransplant or continue mycophenolate mofetil + standard-exposure TAC (MMF + sTAC; n = 54) with corticosteroids. The incidence of composite efficacy failure (biopsy-proven acute rejection [BPAR], graft loss, or death) at month 36 was 9.8% vs 9.6% (difference: 0.2%; 80% confidence interval: -7.3 to 7.7) for EVR + rTAC and MMF + sTAC, respectively, which was driven by BPARs. Graft loss was low (2.1% vs 3.8%) with no deaths. Mean estimated glomerular filtration rate at month 36 was comparable between groups (68.1 vs 67.3 mL/min/1.73 m² ). Mean changes (z-score) in height (0.72 vs 0.39; P = .158) and weight (0.61 vs 0.82; P = .453) from randomization to month 36 were comparable, whereas growth in prepubertal patients on EVR + rTAC was better (P = .050) vs MMF + sTAC. The overall incidence of adverse events (AEs) and serious AEs was comparable between groups. Rejection was the leading AE for study drug discontinuation in the EVR + rTAC group. In conclusion, though AE-related study drug discontinuation was higher, an EVR + rTAC regimen represents an alternative treatment option that enables withdrawal of steroids as well as reduction of CNIs for pediatric kidney transplant recipients. ClinicalTrials.gov: NCT01544491.

Acute and chronic kidney disease after pediatric liver transplantation: An underestimated problem

Acute and chronic kidney injuries represent critical issues after liver transplantation (LTx), but whereas renal dysfunction in adult transplant patients is well documented, little is known about its prevalence in childhood. It is a challenge to accurately evaluate renal function in patients with liver disease, due to several confounding factors. Creatinine-based equations estimating glomerular filtration rate, validated in nephropathic patients without hepatic issues, are frequently inaccurate in end-stage liver disease, underestimating the real impact of renal disease. Moreover, whereas renal issues observed within 1 year from LTx were often related to acute injuries, kidney damage observed after 5-7 years from LTx, is due to chronic, irreversible mechanisms. Most immunosuppression protocols are based on calcineurin inhibitors (CNIs) and corticosteroids, but mycophenolate mofetil or sirolimus could play significant roles, also in children. Early diagnosis and personalized treatment represent the bases of kidney disease management, in order to minimize its close relation with increased mortality. This review analyzed acute and chronic kidney damage after pediatric LTx, also discussing the impact of pre-existent renal disease. The main immunosuppressant strategies have been reviewed, highlighting their impact on kidney function. Different methods assessing renal function were reported, with the potential application of new renal biomarkers.

Post Transplant Lymphoproliferative Disorder risk factors in children: Analysis of a 23-year single-institutional experience

INTRODUCTION

PTLD is the most frequent malignancy following SOT in children and the second most common SOT complication in adults. However, factors determining outcomes in children are poorly understood due to its relative rarity.

METHODS

This study was performed at the University of Florida. Univariate and multivariate analyses were used to identify prognostic factors in pediatric patients diagnosed with PTLD.

RESULTS

We reviewed records of 54 pediatric (younger than 18 years old at diagnosis) patients diagnosed with PTLD from 1994 to 2017. The median follow-up was 28.8 months. The estimated 5-year survival rate was 87.6% (95% CI 74.3-94.2%). Univariate analysis showed that organ transplanted (specifically heart transplant), poor response to initial treatment, allograft rejection, and low Karnofsky score were statistically significant for negative prognostic factors in determining survival. Multivariate analysis determined progression in response to initial treatment and presence of allograft rejection as statistically significant prognostic factors affecting overall survival. We found no statistically significant impact of EBV serological status on PTLD prognosis.

CONCLUSIONS

Disease progression and allograft rejection were strong negative prognostic indicators in our study cohort. Close attention to graft status and development of therapies that protect the graft from rejection while bolstering anti-EBV immunity will be essential to further improving PTLD outcomes in children.

Safety and Efficacy of Everolimus Rescue Treatment After Pediatric Living Donor Liver Transplantation

PURPOSE

Everolimus (EVR) is a derivative of sirolimus with a similar mechanism of action. The safety and efficacy of EVR after pediatric living donor liver transplantation (LDLT) are currently unknown. The purpose of this study was to examine the safety and efficacy of EVR as rescue therapy after pediatric LDLT.

METHODS

This study included patients younger than 19 years of age who received EVR after LDLT at our institution. EVR was administered as rescue treatment in addition to tacrolimus. In 21 patients, EVR dose, trough level, outcomes, and adverse effects were assessed.

RESULTS

Original diseases of patients consisted of biliary atresia (n = 11), Alagille syndrome (n = 3), fulminant hepatitis (n = 3), hepatoblastoma (n = 2), and other (n = 2). Mean age at transplant was 2.0 years (range 0.6-6.2 years). Mean age at initial EVR administration was 8.0 years (range 0.9-18.9 years). Indications for EVR use were graft fibrosis (n = 8), refractory acute cellular rejection (n = 5), renal sparing (n = 4), hepatoblastoma (n = 2), and chronic rejection (CR) (n = 2). Mean duration of administration was 17.1 months (range 2.1-60.4 months). Mean dose was 0.5 mg/m² twice daily. Mean EVR trough level was 2.5 ng/mL (range 1.5-5.0 ng/mL). Liver function improved and fibrosis did not progress in all patients with CR. However, 14 patients (67%) experienced adverse effects that required EVR dose reduction or discontinuation.

CONCLUSION

EVR is tolerable for pediatric patients after LDLT with dose adjustment. EVR had a certain effect to relieve progression on CR. Further follow-up is required.

Effect of everolimus rescue therapy for acute cellular rejection following pediatric living donor liver transplantation: Report of one case

Acute cellular rejection (ACR) after pediatric living donor liver transplantation (LDLT) is often curable with steroid pulse therapy, but a few pediatric patients show steroid-resistant ACR, which is difficult to control. We report the effect of everolimus as a rescue therapy for ACR in a case of pediatric LDLT. The patient was a 11-year-old girl who was admitted due to subacute liver failure of unknown cause. LDLT operation using a modified right liver graft from her mother was performed. The graft-recipient weight ratio was 1.30. The explant liver showed massive hepatic necrosis. The patient recovered uneventfully with immunosuppression using tacrolimus and low-dose steroid. However, at postoperative day (POD) 20, the liver enzyme levels began to increase. The first liver biopsy taken at POD 25 showed moderate ACR with rejection activity index (RAI) score of 7. At that time, steroid pulse therapy was performed, but the patient did not respond and the liver enzyme levels increased further. The second liver biopsy taken at POD 40 showed moderate ACR with RAI score of 7. At this time, everolimus was administered, and soon after that, liver enzyme levels had gradually improved. Currently, the patient is doing well for 44 months to date without any abnormal findings. The maintenance target trough concentrations were tacrolimus 5 ng/ml and everolimus 3 ng/ml. Our case demonstrated the effect of rescue therapy using everolimus for ACR following pediatric LDLT. Further studies are needed to assess the role of everolimus in pediatric liver transplant recipients suffering from ACR.

mTOR inhibitors in pediatric liver transplant recipients

BACKGROUND

During the past decade, mTOR inhibitors (mTORi), everolimus and sirolimus, have been increasingly used after adult liver transplantation (LT). The aim of the present study was to describe the use of mTORi in pediatric LT recipients.

METHODS

All pediatric LT recipients who received mTORi before December 2017 from 4 European pediatric LT centers were included and analyzed.

RESULTS

The present retrospective study included 30 patients; 21 were male (70%), median age was 9.3 years (range: 1.2-17.1 years) at mTORi introduction. Main indications for mTORi introduction were pre-existing liver malignancy (43.3%), calcineurin inhibitor (CNI) nephrotoxicity (26.7%), or rejection (23.4%). At last follow-up, mTORi CNIs were withdrawn in 10 patients (10/29, 34.5%). The median dose of mTORi was 1.8 mg/day (range: 0.3-5.0) or 0.058 mg/kg/day (range: 0.01-0.26), and the median trough level was 5.1 μg/L (range: 1.0-15.5). After a median follow-up of 2.8 years (range: 0.2-10.0), 50.0% of the patients presented with at least one adverse event. The main adverse events included hyperlipidemia, proteinuria, dermatitis, and mucitis. Overall mTORi discontinuation rate was 23.3% (10.0% because of adverse event). Introduction of mTORi had no significant impact on renal function.

CONCLUSION

Our results suggest that mTORi can be used in pediatric LT recipients in different clinical situations, both to reinforce immunosuppressive therapy, and to reduce CNI and related toxicity.

Center variation in screening for and management of metabolic syndrome in pediatric liver transplant recipients: A survey of SPLIT centers

INTRODUCTION

PTMS-a clustering of hypertension, dyslipidemia, glucose intolerance/diabetes, and obesity-is increasingly recognized as a contributor to long-term morbidity after transplant. We sought to describe pediatric liver transplant center protocols and provider practices in screening for and managing these conditions.

METHODS

Cross-sectional survey of pediatric liver transplant providers from centers that participate in Studies of Liver Transplantation (SPLIT).

RESULTS

Of 49 survey respondents from 39 centers, 64% were hepatologists or surgeons, 18% nurses/NPs/PAs, 12% coordinators, and 4% other. All providers felt that pediatric liver transplant recipients should be routinely screened for PTMS components. For each condition, at least 70% felt that the liver transplant team should be primarily responsible for routine screening. For each condition, at least 30% of providers reported that their center had no standardized protocol for screening. For diagnostic evaluation and initial management, >60% of providers reported that their center had no standardized protocol for glucose intolerance/diabetes, dyslipidemia, or obesity. Almost 40% had no standardized workup or initial management protocol for hypertension or chronic kidney disease. Of centers that did have screening or workup protocols, most were based on existing center practice, provider consensus, or informal review of published evidence. Screening tools, treatment steps, and thresholds for referral to another specialist varied widely.

CONCLUSIONS

Transplant providers intend to screen for and initiate management of PTMS components in these children, but protocols and practices vary substantially. This highlights opportunities for multi-center collaboration on protocols or interventions to improve screening and management.

Combined and sequential liver-kidney transplantation in children

Combined and sequential liver-kidney transplantation (CLKT and SLKT) is a definitive treatment in children with end-stage organ failure. There are two major indications: - terminal insufficiency of both organs, or - need for transplanting new liver as a source of lacking enzyme or specific regulator of the immune system in a patient with renal failure. A third (uncommon) option is secondary end-stage renal failure in liver transplant recipients. These three clinical settings use distinct qualification algorithms. The most common indications include primary hyperoxaluria type 1 (PH1) and autosomal recessive polycystic kidney disease (ARPKD), followed by liver diseases associated with occasional kidney failure. Availability of anti-C5a antibody (eculizumab) has limited the validity of CLKT in genetic atypical hemolytic uremic syndrome (aHUS). The liver coming from the same donor as renal graft (in CLKT) is immunologically protective for the kidney and this provides long-term rejection-free follow-up. No such protection is observed in SLKT, when both organs come from different donors, except uncommon cases of living donation of both organs. Overall long-term outcome in CLKT in terms of graft survival is good and not different from isolated liver or kidney transplantation, however patient survival is inferior due to complexity of this procedure.