What is the calcineurin inhibitor of choice for pediatric renal transplantation?

Novel and Promising Strategies for Therapy of Post-Transplant Chronic GVHD

Despite the achievements that have increased viability after the transplantation of allogeneic hematopoietic stem cells (aHSCT), chronic graft-versus-host disease (cGVHD) remains the main cause of late complications and post-transplant deaths. At the moment, therapy alternatives demonstrate limited effectiveness in steroid-refractory illness; in addition, we have no reliable data on the mechanism of this condition. The lack of drugs of choice for the treatment of GVHD underscores the significance of the design of new therapies. Improved understanding of the mechanism of chronic GVHD has secured new therapy goals, and organized diagnostic recommendations and the development of medical tests have ensured a general language and routes for studies in this field. These factors, combined with the rapid development of pharmacology, have helped speed up the search of medicines and medical studies regarding chronic GVHD. At present, we can hope for success in curing this formidable complication. This review summarizes the latest clinical developments in new treatments for chronic GVHD.

Adverse Events under Tacrolimus and Cyclosporine in the First 3 Years Post-Renal Transplantation in Children

BACKGROUND

Progress in immunosuppression has reduced acute rejection, graft loss and mortality after renal transplantation. Adverse drug reactions are well described in adults but few data are available in children. Our objectives were to analyse the adverse events reported in the first 3 years post-transplantation in children receiving tacrolimus or cyclosporine-based immunosuppression and compare them with the information of the Summary of Product Characteristics.

METHODS

This retrospective study included all children who underwent a renal transplant at Hospital Robert Debré between 2002 and 2015. Initial immunosuppression was based on induction, calcineurin inhibitor, mycophenolate mofetil and corticosteroids. Adverse events were collected from medical records and coded using the Medical Dictionary for Regulatory Activities and the implications of tacrolimus and cyclosporine analysed. Statistical analyses were performed using SAS 9.4.

RESULTS

One hundred and twenty-five children were included. During the observation period [2.7 years (0.6-4.3)], 105 patients received tacrolimus and 39 received cyclosporine. The incidence rate for gastrointestinal disorders was 0.128 and 0.056 by patient-years of exposure (p < 0.05), under tacrolimus and cyclosporine schedules. For neutropenia, it was 0.064 and 0.014 (p < 0.05). The frequencies of toxic nephropathy and gastrointestinal pain were higher than those in the Summary of Product Characteristics of tacrolimus (> 20%) and cyclosporine (> 10%). Cosmetic events for cyclosporine and neutropenia for tacrolimus were frequently observed (18 and 14.3%, respectively), although uncommon in the Summary of Product Characteristics.

CONCLUSIONS

The exposure-adjusted incidence rate of gastrointestinal disorders and neutropenia was higher in children under the tacrolimus schedule. Our findings contribute to the evaluation of the benefit-risk balance of immunosuppressive therapy following paediatric renal transplantation.

Long-term outcome of deceased donor renal transplantation in pediatric recipients: a single-center experience from a developing country

RTx is best treatment for children with ESRD. Data scarcity on DDRTx outcome in children prompted us to review our experience. This study was undertaken to evaluate patient/graft survival, function vis-a-vis SCr, rejection episodes, and mortality in DDRTx performed in 37 children between 1998 and 2011. The most common recipient diseases leading to ESRD were congenital anomalies of kidney and urinary tract (48.6%) and chronic glomerulonephritis (18.9%). Mean recipient age was 13.8 ± 3.1 yr; 67.5% (n = 25) were men. Mean donor age was 38.8 ± 18.6 yr; 48.5% (n = 18) were men. Mean dialysis duration pre-transplantation was 15.5 ± 3.5 months. All recipients received r-ATG, and triple immunosuppression. Over a mean follow-up of 3.93 ± 3.5 yr, patient and graft survival rates were 72.9% (n = 27) and 83.7% (n = 31), respectively, with a mean SCr of 1.1 mg/dL; 21.6% (n = 8) of patients had acute rejection episodes; 24.3% (n = 9) of patients had DGF. A total of 27% (n = 10) patients died, mainly owing to infections (n = 6) and cardiovascular disease (n = 3). DDRTx is a viable option for children and achieves acceptable graft function with patient/graft survival over long-term follow-up, encouraging use of this approach.

Pharmacogenetics in immunosuppressants: impact on dose requirement of calcineurin inhibitors in renal and liver pediatric transplant recipients

PURPOSE OF REVIEW

Calcineurin inhibitors (CNI) are the mainstay immunosuppressive therapy in pediatric solid organ transplantation. These drugs have narrow therapeutic window, and continuous therapeutic drug monitoring is required to keep blood levels within the therapeutic range. Personalization of immunosuppressive therapy according to the genetic profile may provide a way to optimize drug dosing from the first day of transplantation. In this review, we will highlight the recent pharmacogenetic studies of CNIs in pediatric renal and liver transplantation.

RECENT FINDINGS

CNIs are metabolized by CYP3A4 and CYP3A5. In the intestine, the absorption of these drugs is limited by the P-glycoprotein efflux transporter. Most of the pediatric studies showed an association between CYP3A5 genetic variation and CNI dosing. Carriers of the wild-type allele (CYP3A5*1) required higher doses of CNIs as compared with individuals homozygous to the variant CYP3A5*3 allele. CYP3A4 and ABCB1 (encoding P-glycoprotein) genetic variations did not show an association with CNI dosing.

SUMMARY

The pharmacogenetics of CNIs has been widely investigated in adults, little is known about this field in the pediatric groups. Prospective studies are needed to elucidate the effect of genetic variations on CNI drug dosing and to investigate their impact on short and long-term clinical outcome.

Association of immunosuppressant-induced protein changes in the rat kidney with changes in urine metabolite patterns: a proteo-metabonomic study

The basic mechanisms underlying calcineurin inhibitor (CI) nephrotoxicity and its enhancement by sirolimus are still largely unknown. We investigated the effects of CIs alone and in combination with sirolimus on the renal proteome and correlated these effects with urine metabolite pattern changes. Thirty-six male Wistar rats were assigned to six treatment groups (n = 4/group for proteome analysis and n = 6/group for urine (1)H NMR metabolite pattern analysis): vehicle controls, sirolimus 1 mg/kg/day, cyclosporine 10 mg/kg/day, cyclosporine 10 mg/kg/day + sirolimus 1 mg/kg/day, tacrolimus 1 mg/kg/day, tacrolimus 1 mg/kg/day + sirolimus 1 mg/kg/day. After 28 days, 24 h-urine was collected for (1)H NMR-based metabolic analysis and kidneys were harvested for 2D-gel electrophoresis and histology. Cyclosporine affected the following groups of proteins: calcium homeostasis (regucalcin, calbindin), cytoskeleton (vimentin, caldesmon), response to hypoxia and mitochondrial function (prolyl 4-hydroxylase, proteasome, NADH dehydrogenase), and cell metabolism (kidney aminoacylase, pyruvate dehydrogenase, fructose-1,6-bis phosphate). Several of the changes in protein expression, confirmed by Western blot, were associated with and explained changes in metabolite concentrations in urine. Representative examples are an increase in kidney aminoacylase expression (decrease of hippurate concentrations in urine), up regulation of pyruvate dehydrogenase and fructose-1,6-bisphosphatase, (increased glucose metabolism), and down regulation of arginine/glycine-amidino transferase (most likely due to an increase in creatinine concentrations). Protein changes explained and qualified immunosuppressant-induced metabolite pattern changes in urine.

Strategies to modulate immune responses: a new frontier for gene therapy

The success of gene therapy strategies to cure disease relies on the control of unwanted immune responses to transgene products, genetically modified cells and/or to the vector. Effective treatment of an established immune response is much harder to achieve than prevention of a response before it has had a chance to develop. However, preventive strategies are not always effective in avoiding immune responses, thus the use of drugs to induce immunosuppression (IS) is required. The growing discovery of novel drugs provides a conceptual shift from using generalized, moderately intensive immunosuppressive regimens towards a refined approach to attain the optimal balance of naive cells, effector cells, memory cells, and regulatory cells, harnessing the natural tolerance mechanisms of the body. We review several strategies based on transient IS coupled with gene therapy for sustained immune tolerance induction to the therapeutic transgene.

Recovery of tacrolimus-associated brachial neuritis after conversion to everolimus in a pediatric renal transplant recipient--case report and review of the literature

TAC has been shown to be a potent immunosuppressive agent for solid organ transplantation in pediatrics. Neurotoxicity is a potentially serious toxic effect. It is characterized by encephalopathy, headaches, seizures, or neurological deficits. Here, we describe an eight-and-a-half-yr-old male renal transplant recipient with right BN. MRI demonstrated hyperintense T2 signals in the cervical cord and right brachial plexus roots indicative of both myelitis and right brachial plexitis. Symptoms persisted for three months despite TAC dose reduction, administration of IVIG and four doses of methylprednisolone pulse therapy. Improvement and eventually full recovery only occurred after TAC was completely discontinued and successfully replaced by everolimus.

Induction of synapse associated protein 102 expression in cyclosporin A-stimulated hair growth

Cyclosporin A (CsA) has been used as a potent immunosuppressive agent for inhibiting the graft rejection after organ transplantation. However, CsA provokes lots of side effects including hirsutism, the phenomenon of abnormal hair growth in the body. In the present study, we investigated the hair growth stimulating effect of CsA using in vivo and in vitro test models. When topically applied on the back skin of mice, CsA induced fast telogen to anagen transition. In contrast, CsA had no effect on the growth of human hair follicle tissues cultured in vitro, indicating that it might not have the mitogenic effect on hair follicles. To identify the genes related with CsA-induced hair growth, we performed differential display RT-PCR. Among the genes obtained, the expression of synapse associated protein 102 (SAP102) was verified using competitive RT-PCR. The result showed that the expression of SAP102 was significantly induced by CsA treatment in the back skin of C57BL/6 mice. However, the increase of SAP102 mRNA was also seen in spontaneous anagen mice, suggesting that induction of SAP102 is one event of the anagen hair growth response regardless of how the growth state was induced. SAP102 was not expressed in cultured human hair outer root sheath and dermal papilla cells. Immunohistochemistry analysis showed that CsA induced the expression of SAP102 in perifollicular region of mouse anagen hair. Together, these results suggest that SAP102 is one of hair-cycle-dependent genes, whose expression is related with the anagen progression.

Calcineurin inhibitors in pediatric renal transplant recipients

The calcineurin inhibitors, cyclosporine (ciclosporin) [microemulsion] and tacrolimus, are the principal immunosuppressants prescribed for adult and pediatric renal transplantation. For pediatric patients, both drugs should be dosed per body surface area, and pharmacokinetic monitoring is mandatory. While monitoring of the trough levels may suffice for tacrolimus, cyclosporine therapy that utilizes the microemulsion formulation requires additional monitoring (e.g. determination of 2-hour post-dose levels). In a well designed randomized study in children, as in studies in adults, there was no difference in short-term patient and graft survival with cyclosporine microemulsion and tacrolimus. However, tacrolimus was significantly more effective than cyclosporine microemulsion in preventing acute rejection after renal transplantation when used in conjunction with azathioprine and corticosteroids. With regard to long-term outcome, the difference in acute rejection episodes resulted in a better glomerular filtration rate at 1 year after transplantation and eventually in better graft survival 4 years after renal transplantation. Whether this difference persists when calcineurin inhibitors are used in combination with mycophenolate mofetil has not been determined. The prevalence of hypomagnesemia was higher in the tacrolimus group whereas hypertrichosis and gingival hyperplasia occurred more frequently in the cyclosporine group. In contrast with adults, the incidence of post-transplantation diabetes mellitus was not significantly different between tacrolimus- and cyclosporine-treated patients. There was also no difference with regard to post-transplantation lymphoproliferative disorder. Medication costs were similar, but in view of the lower rejection episodes and better long-term graft survival as well as the more favorable cosmetic side effect profile, tacrolimus may be preferable. The recommendation drawn from the available data is that both cyclosporine and tacrolimus can be used safely and effectively in children. We recommend that cyclosporine should be chosen when patients experience tacrolimus-related adverse events.

Safety and efficacy of a calcineurin inhibitor avoidance regimen in pediatric renal transplantation

Thirty-four children were entered into a pilot trial of calcineurin inhibitor avoidance after living-donor kidney transplantation, the CN-01 study. Patients were treated with anti-CD25 mAb, prednisone, mycophenolate mofetil, and sirolimus. Twenty patients were maintained on the protocol for up to 3 yr of follow-up. One enrolled patient did not receive the transplant because of a donor problem, eight terminated because of one or more rejection episodes, four terminated because of adverse events, and one was lost to follow-up. Two grafts were lost, one as a result of chronic rejection and the other as a result of posttransplantation lymphoproliferative disorder. There were no deaths. The 6- and 12-mo acute rejection rates were 21.8 and 31.5%, respectively. GFR were stable throughout the course of the study, with a slight downward trend by 6 mo after transplantation followed by a slight upward trend to a mean of 70 ml/min thereafter. Early surveillance graft biopsies frequently showed focal interstitial mononuclear cellular infiltrates without overt vasculitis or tubulitis, but these infiltrates disappeared without treatment. Anti-HLA class I and II antibodies were detected in three patients before transplantation, and all three had acute rejections, including the two patients who lost their grafts. De novo anti-HLA Ab production occurred in only one patient after transplantation. There were two episodes of Epstein Barr virus-related posttransplantation lymphoproliferative disorder, one of which developed after the patient had been terminated from the study. It is concluded that calcineurin inhibitor-free immunosuppression can be safe and effective in pediatric living-donor renal transplantation. However, further modifications that are designed to lessen early rejection rates and decrease complications should be tested before this approach is used routinely.

Effects of Calcineurin Inhibitors on Pharmacokinetics of Mycophenolic Acid and Its Glucuronide Metabolite during the Maintenance Period Following Renal Transplantation

Mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF) has been introduced into renal transplant immunosuppressant protocols in combination with calcineurin inhibitors (CNIs) and steroids. This study compared the pharmacokinetic profiles of MPA and its major metabolite MPA glucuronide (MPAG) in combination with tacrolimus (TAC) or cyclosporine (CyA) during the maintenance period (>6 months) following renal transplantation. There was no difference between TAC and CyA-treated groups in MPA plasma concentration before drug administration (C(0)). MPA C(0) in TAC and CyA-treated patients did not differ from that in patients who were not treated with a CNI. In patients treated with a CNI, MPAG C(0) was significantly greater in those treated with CyA compared with TAC. The MPAG/MPA ratio in CyA-treated patients was significantly greater than that in the TAC-treated group. We observed that C(0) of MPA was negatively correlated with that of TAC and CyA. Positive correlation between MPA C(0), MPAG C(0) and serum creatinine was stronger in patients treated with CyA compared with TAC. Our study suggests that CyA, but not TAC, inhibits enterohepatic circulation of MPAG as a secondary excretion pathway, and that renal function makes a major contribution to elimination of MPA and MPAG. We indicate that it may be necessary to estimate biliary excretion of MPAG to avoid the risk of intestinal injury in patients receiving combination therapy with TAC during the maintenance period.

Mycophenolate Mofetil in Pediatric Renal Transplantation

Mycophenolate mofetil (MMF) has become a popular immunosuppressive agent in pediatric renal transplantation and has helped to address the unique challenges of transplantation in this population. This paper reviews the early studies that proved MMF's efficacy in reducing the risk of acute renal rejection, as well as its safety and tolerability in comparison to azathioprine. Key conclusions about the pharmacokinetics of MMF from studies of MMF alone and in combination with other immunosuppressive therapies are outlined. The importance of therapeutic drug monitoring (TDM) in this population is also explored in this review. Finally, recent studies showing that newer agents used in combination with MMF can further increase efficacy and reduce the risk of adverse events such as posttransplant lymphoproliferative disease are discussed.