Steroid withdrawal in pediatric and adult renal transplant recipients

Limited sampling strategy to predict mycophenolic acid area under the curve in pediatric patients with nephrotic syndrome: a retrospective cohort study

PURPOSE

Limited sampling strategy (LSS) is a precise and relatively convenient therapeutic drug monitoring method. We evaluated LSSs for mycophenolic acid (MPA) in children with nephrotic syndrome treated with mycophenolic mofetil (MMF) and validated the LSSs using two different approaches.

METHODS

We measured MPA plasma concentrations in 31 children using HPLC-UV method and received 37 MPA pharmacokinetic profiles (0-12 h). For six children, MPA profiles were estimated twice after two MMF doses. LSSs were developed using multilinear regression with STATISTICA and R software and validated using validation group and bootstrap method, respectively.

RESULTS

The best three time point equations included C₁, C₃, C₆ (good guess 83%, bias - 2.78%; 95% confidence interval (CI) - 9.85-0.46); C₁, C₂, C₆ (good guess 72%, bias 0.72%; 95% CI - 5.33-7.69); and C₁, C₂, C₄ (good guess 72%, bias 2.05%; 95% CI - 4.92-13.01) for STATISTICA software. For R software, the best equations consisted of C₁, C₃, C₆ (good guess 92%, bias - 2.69%; 95% CI - 27.18-33.75); C₀, C₁, C₃ (good guess 84%, bias - 2.11%; 95% CI - 24.19-22.29); and C₀, C₁, C₂ (good guess 84%, bias - 0.48%; 95% CI - 30.77-54.07). During validation, better results were obtained for R evaluations, i.e., bootstrap method.

CONCLUSIONS

The most useful equations included C₀, C₁, C₃ and C₀, C₁, C₂ time points; however, the most precise included C₁, C₃, C₆ time points because of MPA enterohepatic recirculation. Better results were obtained for bootstrap validation due to greater number of patients. Validated LSS should be used only in the population for which it was developed. As there is growing evidence that underexposure of MPA is associated with insufficient treatment response, we recommend the introduction of therapeutic drug monitoring for MPA in children with nephrotic syndrome.

Steroid withdrawal improves blood pressure control and nocturnal dipping in pediatric renal transplant recipients: analysis of a prospective, randomized, controlled trial

BACKGROUND

Variable effects of steroid minimization strategies on blood pressure in pediatric renal transplant recipients have been reported, but data on the effect of steroid withdrawal on ambulatory blood pressure and circadian blood pressure rhythm have not been published so far.

METHODS

In a prospective, randomized, multicenter study on steroid withdrawal in pediatric renal transplant recipients (n = 42) on cyclosporine, mycophenolate mofetil, and methylprednisolone, we performed a substudy in 28 patients, aged 11.2 ± 3.8 years, for whom ambulatory blood pressure monitoring (ABPM) data were available.

RESULTS

In the steroid-withdrawal group, the percentage of patients with arterial hypertension, defined as systolic and/or diastolic blood pressure values recorded by ABPM > 1.64 SDS and/or antihypertensive medication, at month 15 was significantly lower (35.7%, p = 0.002) than in controls (92.9%). The need of antihypertensive medication dropped significantly by 61.2% (p < 0.000 vs. control), while in controls, it even rose by 69.3%. One year after steroid withdrawal, no patient exhibited hypertensive blood pressure values above the 95th percentile, compared to 35.7% at baseline (p = 0.014) and to 14.3% of control (p = 0.142). The beneficial impact of steroid withdrawal was especially pronounced for nocturnal blood pressure, leading to a recovered circadian rhythm in 71.4% of patients vs. 14.3% at baseline (p = 0.002), while the percentage of controls with an abnormal circadian rhythm (35.7%) did not change.

CONCLUSIONS

Steroid withdrawal in pediatric renal transplant recipients with well-preserved allograft function is associated with less arterial hypertension recorded by ABPM and recovery of circadian blood pressure rhythm by restoration of nocturnal blood pressure dipping.

Salidroside inhibits steroid-induced avascular necrosis of the femoral head via the PI3K/Akt signaling pathway: In vitro and in vivo studies

Dexamethasone (Dex) and other glucocorticoids are widely used to treat serious infections and immunological diseases, however they may cause steroid-induced avascular necrosis of the femoral head (SANFH). Salidroside (Sal) has demonstrated an anti-apoptotic effect on neurocytes by activating the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. In the present study, primary osteoblasts were used in vitro and in rats in vivo to determine the anti-apoptotic effect of Sal on SANFH. The result of the present study demonstrated that pretreatment with Sal increased the cell survival rate while decreasing the cell apoptosis and lactate dehydrogenase release rate. Additionally, Sal also caused the reduction of TUNEL positive cells in TUNEL staining assay. Sal decreased the expression of cleaved caspase-3, cleaved caspase-9, apoptosis regulator BAX and cytochrome C, while it increased the expression of B cell lymphoma-2 and phosphorylated-Akt in Dex-induced osteoblasts. In vivo Sal protected against SANFH in rats by decreasing the percentage of empty lacunae. The present study demonstrated that Sal alleviated Dex-induced osteoblast apoptosis by activating the PI3K/Akt signaling pathway and downregulating caspase-3 expression in osteoblasts. Sal also protected against SANFH in a rat model of SANFH by decreasing the percentage of empty lacunae. The inhibition of the mitochondrial apoptosis pathway was also involved. Further research is required to determine the full underlying mechanisms by which Sal has an effect.

Inhibitory effects of vitamin E on osteocyte apoptosis and DNA oxidative damage in bone marrow hemopoietic cells at early stage of steroid-induced femoral head necrosis

Apoptosis and DNA oxidative damage serve significant roles in the pathogenesis of steroid-induced femoral head necrosis. Vitamin E demonstrates anti-apoptotic and anti-oxidant properties. Therefore, the present study investigated the effects of vitamin E on osteocyte apoptosis and DNA oxidative damage in bone marrow hemopoietic cells at an early stage of steroid-induced femoral head osteonecrosis. Japanese white rabbits were randomly divided into three groups (steroid, vitamin E-treated, and control groups), each comprising 12 rabbits. Those in the steroid group (group S) were initially injected twice with an intravenous dose of 100 µg/kg Escherichia coli endotoxin, with a 24 h interval between the two injections, and then with an intramuscular dose of 20 mg/kg methylprednisolone, three times at intervals of 24 h in order to establish a rabbit model of osteonecrosis. The vitamin E treated group (group E) received the same treatment as group S, and were administered 0.6 g/kg/d vitamin E daily from the beginning of modeling. The control group (group C) was injected with normal saline at the equivalent dosage and times as the aforementioned two groups. Two time points, weeks 4 and 6 following the completion of modeling, were selected. Osteonecrosis was verified by histopathology with hematoxylin-eosin staining. The apoptosis rate of osteonecrosis was analyzed by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The apoptosis expression levels of caspase-3 and B-cell lymphoma 2 (Bcl-2), and DNA oxidative damage of bone marrow hematopoietic cells were analyzed by immunohistochemistry. At weeks 4 and 6 following the completion of modeling, the vacant bone lacunae rates of group E were 15.87±1.97 and 25.09±2.67%, respectively, lower than the results of 20.02±2.21 and 27.79±1.39% for group S; and the osteocyte apoptosis indexes of group E were 20.99±2.95 and 33.93±1.62%, respectively, lower than the results of 26.46±3.37 and 39.90±3.74% from group S. In addition, the Bcl-2 expression at week 4 in the femoral head tissues of group E was higher compared with group S; and the proportion of Bcl-2-positive cells of group E was 9.81±1.01%, higher compared with group S at 8.26±1.13%. The caspase-3 staining data at week 4 in femoral head tissues demonstrated that in the 12 femoral heads of group S, four were negative (32%) and eight were positive (68%); in group E, five were negative (45%) and seven were positive (55%); and in group C, 11 were negative (95%) and one was positive (5%). In addition, the DNA oxidative damage rate at week 4 in the bone marrow hemopoietic cells of group E was (7.24±1.44%), lower compared with group S (11.80±1.26%), and higher compared with group C (5.75±1.47%). Vitamin E is effective in intervening in apoptosis through decreasing caspase-3 expression and upregulating Bcl-2 expression, and by alleviating DNA oxidative damage in bone marrow hemopoietic cells at the early stage of steroid-induced femoral head necrosis in rabbit models.

Monitoring of mycophenolate mofetil metabolites in children with nephrotic syndrome and the proposed novel target values of pharmacokinetic parameters

The aim of the study was to estimate target values of mycophenolate mofetil (MMF) pharmacokinetic parameters in children with proteinuric glomerulopathies by calculating the pharmacokinetic parameters of MMF metabolites (mycophenolic acid [MPA], free MPA [fMPA] and MPA glucuronide [MPAG]) and assessing their relation to proteinuria recurrence. One hundred and sixty-eight blood samples were collected from children, aged 3-18 years, diagnosed with nephrotic syndrome or lupus nephritis. MMF metabolites concentrations were examined before drug administration (Ctrough) and up to 12h afterward employing high-performance liquid chromatography. Dose-normalized MPA Ctrough and area under the concentration-time curve from 0 to 12h (AUC12) were within 0.29-6.47 μg/mL/600 mg/m(2) and 9.97-105.52 μg h/mL/600 mg/m(2), respectively. MPA Ctrough was twofold lower (p=0.024) in children with proteinuria recurrence. MPA, fMPA and MPAG concentrations correlated positively to respective AUC12. It may be suggested MMF metabolites monitoring in children with proteinuric glomerulopathies is justified by MPA Ctrough<2 μg/mL in patients at risk of the proteinuria recurrence. Such a recurrence is most probably caused by not sufficient MPA concentration during proteinuric glomerulopathies treatment. MPA Ctrough>3 μg/mL may be considered as an efficient one to avoid proteinuria recurrence. Finally, MPA target AUC12 should exceed 60 μg h/mL to ensure the safe and effective treatment in children with nephrotic syndrome, however, the upper limit is still to be established.

Gene expression profile of steroid-induced necrosis of femoral head of rats

The key to treating steroid-induced necrosis of femoral heads (SINFH) is early diagnosis. Dramatic improvements in diagnosis could be made if the pathogenesis of SINFH was more fully understood; however, the underlying mechanism of this disease is currently unknown. To explore the potential mechanism of SINFH, we performed gene array analysis on a rat model of the disease and compare the expression profile with that of normal rats. A quantitative RT-PCR and immunohistochemistry (IHC) assays were used to confirm the microarray results. Compared to the control group, 190 genes in the experimental group were differentially expressed, with 52 up-regulated and 138 down-regulated. Of these genes, 102 are known (deposited in GenBank), while 88 of them are unknown. The known genes can be divided into several families according to their biological functions, such as oxidative stress, apoptosis, signal transduction, angiogenesis, extracellular matrix, lipid metabolism, and transcription related genes. The results of quantitative RT-PCR and IHC were consistent with gene chip results. Our findings indicate that many genes involved in diverse signaling pathways were differentially expressed between SINFH rats and normal rats. Furthermore, our findings suggest that the development of SINFH is a complicated and dynamic process affected by multiple factors and signaling pathways and regulated by various genes.

Metabolic syndrome in pediatric renal transplant recipients: comparing early discontinuation of steroids vs. steroid group

Steroids have played a valuable role in transplantation as a treatment option. The purpose of this study is to assess the prevalence of MS in pediatric RT patients receiving SG or early SWG; SG discontinued five days after transplantation. We retrospectively reviewed 58 pediatric RT patients between 2000 and 2007. MS criterion was defined as the presence of any three of five criteria: (i) BMI >97th percentile, (ii) hypertension (SBP/DBP > 95th percentile or on medications); (iii) triglycerides > 95thpercentile, (iv) HDL cholesterol < 5th percentile, (v) fasting glucose > 100 mg/dL. Twenty-five patients (43%) received SG and 33 patients (57%) received SWG. The prevalence of MS in SG was 68% compared to 15% in SWG. At six months and one yr after transplantation, mean serum glucose, total cholesterol, and triglycerides were significantly lower in the SWG. The prevalence of hypertension was significantly lower in the SWG, and patients in the SWG received significantly less lipid-lowering and anti-hypertensive medications than SG. Mean BMI percentile was significantly higher in SG one yr after transplantation but not after six months, although always significantly higher in patients with MS (p < 0.05). From this study, we conclude that for pediatric RT patients, cardiovascular risk factors are significantly lower in SG withdrawal groups.

Improved growth and cardiovascular risk after late steroid withdrawal: 2-year results of a prospective, randomised trial in paediatric renal transplantation

BACKGROUND

Long-term corticosteroid treatment impairs growth and increases cardiovascular risk factors. Hence, steroid withdrawal constitutes a major topic in paediatric renal transplantation and maintenance immunosuppression.

METHODS

The lack of data from randomised controlled trials caused us to conduct the first prospective, randomised, multicentre study on late steroid withdrawal among paediatric kidney allograft recipients treated with standard-dose cyclosporine microemulsion (CsA) and mycophenolate mofetil (MMF) for 2 years. Forty-two low- or regular-immunologic risk patients were randomly assigned, >or=1 year post-transplant, to continue taking or to withdraw steroids over 3 months.

RESULTS

Two years after steroid withdrawal, they showed a longitudinal growth superior to controls [mean height standard deviation score (SDS) gain, 0.6 +/- 0.1 SDS versus -0.2 +/- 0.1 SDS (P < 0.001)]. The prevalence of the metabolic syndrome declined significantly (P < 0.05), 2 years after steroid withdrawal, from 39% (9/23) to 6% (1/16). Steroid-free patients had less frequent arterial hypertension (50% versus 93% (P < 0.05)) and required fewer antihypertensive drugs [0.6 +/- 0.2 versus 1.5 +/- 0.3 (P < 0.05 versus control)]. Additionally, they had a significantly improved carbohydrate and lipid metabolism with fewer hypercholesterolaemia and hypertriglyceridaemia (P < 0.05 versus control). Patient and graft survival amounted to 100%. Allograft function remained stable 2 years after steroid withdrawal. The incidence of acute rejections was similar in the steroid-withdrawal group (1/23, 4%) and controls (2/19, 11%).

CONCLUSION

Late steroid withdrawal in selected CsA- and MMF-treated paediatric kidney transplant recipients improves growth, mitigates cardiovascular risk factors and reduces the prevalence of the metabolic syndrome, at no increased risk of acute rejection or unstable graft function.

Steroid-free immunosuppression in pediatric renal transplantation: rationale for and [corrected] outcomes following conversion to steroid based therapy

BACKGROUND

Short-term outcomes using steroid-free immunosuppression after renal transplantation have been promising. No studies have examined the incidence of and reasons for steroid-avoidance protocol failures.

METHODS

We present a single-center analysis of steroid-free immunosuppression failures among 129 pediatric renal transplant recipients with mean follow-up of 5 years. We analyzed causes for failure and examined reasons for conversion to steroid-based therapy. We compared actual patient and allograft survival and allograft function in the cohort of patients who required conversion to steroid-based immunosuppression with that of the cohort maintaining steroid-free immunosuppression.

RESULTS

A total of 13.2% (17/129) of patients failed steroid-free immunosuppression. Actual patient survival was equivalent in the two cohorts, 96.4% for the cohort maintaining steroid-free immunosuppression and 94.1% for those requiring conversion. Actual allograft survival was lower in patients requiring conversion to a steroid-based protocol, 76.5% vs. 95.5% (P=0.004). Estimated glomerular filtration rates 12-months and 24-months posttransplant were greater in patients maintaining steroid-free immunosuppression (P=0.003). Most patients (52.9%, 9/17) who broke the steroid-free protocol did so because of refractory acute rejection. The second most common reason was recurrence of glomerulonephritis (GN; 35.3%, 6/17).

CONCLUSION

The failure rate of steroid-free immunosuppression among selective pediatric patients undergoing renal transplantation is low. Patients maintaining steroid-free immunosuppression have better allograft survival and function than those requiring conversion to steroid-based therapy. The most common reasons for failure of steroid-free immunosuppression are recalcitrant or recurrent allograft rejection and recurrent GN; the role of conversion to steroid-based immunosuppression after episodes of acute rejection and recurrent GN requires additional analysis.

Steroid-free immunosuppression since 1999: 129 pediatric renal transplants with sustained graft and patient benefits

Despite early promising patient and graft outcomes with steroid-free (SF) immunosuppression in pediatric kidney transplant recipients, data on long-term safety and efficacy results are lacking. We present our single-center experience with 129 consecutive pediatric kidney transplant recipients on SF immunosuppression, with a mean follow-up of 5 years. Outcomes are compared against a matched cohort of 57 concurrent recipients treated with steroid-based (SB) immunosuppression. In the SF group, 87% of kidney recipients with functioning grafts remain corticosteroid-free. Actual intent-to-treat SF (ITT-SF) and still-on-protocol SF patient survivals are 96% and 96%, respectively, actual graft survivals for both groups are 93% and 96%, respectively and actual death-censored graft survivals for both groups are 97% and 99%, respectively. Unprecedented catch-up growth is observed in SF recipients below 12 years of age. Continued low rates of acute rejection, posttransplant diabetes mellitus (PTDM), hypertension and hyperlipidemia are seen in SF patients, with sustained benefits for graft function. In conclusion, extended enrollment and longer experience with SF immunosuppression for renal transplantation in low-risk children confirms protocol safety, continued benefits for growth and graft function, low acute rejection rates and reduced cardiovascular morbidity.

Prospective, randomized trial on late steroid withdrawal in pediatric renal transplant recipients under cyclosporine microemulsion and mycophenolate mofetil

BACKGROUND

: Many transplant centers practice late steroid withdrawal after pediatric renal transplantation, but evidence-based data on the overall risk-to-benefit ratio in this patient population are lacking.

METHODS

: We therefore conducted the first prospective, randomized, open-label multicenter study to validate this strategy: 42 low-immunologic risk pediatric kidney allograft recipients, aged 10.3+/-4.3 years, on cyclosporine microemulsion, mycophenolate mofetil, and corticosteroids were randomly assigned, more than or equal to 1-year posttransplant, to continue steroids or to withdraw over 3 months. This report contains the 1-year results.

RESULTS

: In response to steroid withdrawal, patients experienced a significant catch-up growth with a mean standardized height gain of 0.3+/-0.1 standard deviation score (SDS) per year (P<0.05 vs. control), whereas mean height SDS in the control group did not change (0.0+/-0.1 SDS). Standardized body mass index declined significantly by 0.68+/-0.23 SDS after steroid withdrawal, but rose significantly by 0.26+/-0.34 SDS in the control group. Patients off steroids had less frequent arterial hypertension (50% vs. 87.5% (P<0.05) and significantly lower serum cholesterol (by 21%) and triglyceride values (by 36%) than control patients. Patient and graft survival were 100%. The incidence of acute rejection episodes in the steroid-withdrawal group was 1 of 23 (4%) compared with 1 of 19 (5%) in controls. Transplant function remained stable in both groups.

CONCLUSION

: Late steroid withdrawal in low-immunologic risk European pediatric kidney transplant recipients on cyclosporine microemulsion and mycophenolate mofetil is not associated with an increased rate of acute rejection episodes, enables catch-up growth and ameliorates cardiovascular risk factors.

Early steroid withdrawal in pediatric renal transplant on newer immunosuppressive drugs

Steroids have been a cornerstone in renal transplant immunosuppression. New immunosuppressive drugs have led to protocols using early steroid withdrawal or complete avoidance. A prospective protocol in 23 pediatric renal transplant (ages 2-14 yr) who received decreasing steroid doses stopping at day 7 post-Tx, FK, and MMF were compared with a CsA, AZT, historically matched steroid-based control group. Basiliximab was used in two doses. Anthropometric, biochemical variables, AR rates, and CMV infection were evaluated and compared using Student's t-test and regression analysis. A better growth pattern was seen in steroid withdrawal group. GFR rate and serum glucose were similar in both groups. Total serum cholesterol levels were significantly lower in steroid withdrawal group. The incidence of AR at 12 months was 4.3% in steroid withdrawal group vs. 8.6% in steroid-based group (p = ns). No difference in CMV infection was observed. Hemoglobin levels were low during the first months in both groups; reached normal values after six months. SBP became higher at 12 months in steroid-based group. Patient and graft survival was 98% in both groups at one-yr post-transplant. Early steroid withdrawal was efficacious, safe, and did not increase risk of rejection, preserving optimal growth, renal function, and reducing cardiovascular risk factors.

Avoiding steroids in pediatric renal transplantation: long-term experience from a single centre

We report our experience in pediatric renal transplantation avoiding steroids whenever possible. Immunosuppression consisted of an initial induction with antithymocyte globulin followed by maintenance therapy with a calcineurin inhibitor and MMF. Steroids were only given to selected patients because of the primary disease, recurrence, rejection, or PTLD. Thirty-four transplants grafted into 32 recipients between 1995 and 2005 were followed for a median of 3.5 yr (range 1-9.8). All patients survived. Graft rejection occurred in 10 cases during the first year post-transplantation and graft survival at one, five, and seven yr was 97, 88 and 88%, respectively. Steroids were given to half of the patients (n = 16); in nine cases due to rejection. Only four patients (13%) were continuously on steroids. Calculated GFR at one to five yr post-transplant were 73, 74, 68, 64, and 70 mL/min/1.73 m(2). Unfortunately PTLD occurred in three patients, but all survived with functioning grafts. Accordingly, our findings indicate that steroid avoidance in pediatric renal transplantation is possible with good results with respect to acute graft rejection as well as long-term graft survival.

Rapid steroid discontinuation for pediatric renal transplantation: a single center experience

To determine the outcomes of pediatric renal transplant recipients who received immunosuppression consisting of early withdrawal of corticosteroids at a single Northern California center. Protocols using minimal steroid exposure have been recently reported in adult transplant recipients with successful results. We examined the outcomes of pediatric renal transplant recipients who were managed at our center using a protocol with very early discontinuation of steroids after renal transplantation. We retrospectively studied the medical records of all renal transplant recipients followed at the Children's Hospital at the University of California, Davis Medical Center from 01/2004 to 12/2005. All patients were less than 18 yr of age at the time of transplantation. The immunosuppressive protocol included three tapering daily doses of methylprednisolone, together with five doses of thymoglobulin followed by maintenance therapy with tacrolimus and MMF. Eight patients with equal numbers of males and females were transplanted during this time period. There were equal numbers of Caucasians, African-Americans, Hispanics, and Asians. A total of 37.5% (3/8) of the subjects received preemptive transplantation, 25% (2/8) received peritoneal, and 37.5% (3/8) received hemodialysis before transplantation. The median (range) age at transplantation was 12.3 (3.1-16.0) year with a follow-up of 1.7 (0.9-2.8) year. At one yr post-transplantation, 57% (4/7) of patients still required anti-hypertensives. Three children required erythropoietin supplementation after transplantation. The mean delta height standard deviation score at 12 months was 0.20 +/- 0.56. There were no episodes of clinical acute rejection. One patient switched from tacrolimus to sirolimus due to biopsy-proven CAN. No patient became diabetic or required hypoglycemic agents. Surveillance biopsies showed no subclinical acute rejection in any patient. Steroid-free immunosuppression is safe in children after renal transplantation. Larger number of patients and longer follow-up are required to further confirm the effectiveness and safety of immunosuppression with rapid steroid discontinuation.

The immunology of composite tissue transplantation

Composite tissue allotransplantation holds great potential for reconstructive surgery. That these procedures can be successful has been clearly demonstrated by the success of hand, face, and larynx transplants around the world. Although the immunology of composite tissue allotransplantation mirrors that of any allogeneic organ transplant, there are several unique aspects to these grafts. This article reviews the immunology of transplantation, histocompatibility testing for composite tissue allotransplantation, graft rejection, immunosuppression, and specific immunologic considerations of composite tissue allotransplantation.

Growth in Pediatric Renal Transplant Recipients

One of the fundamental challenges in managing pediatric renal transplant recipient is to ensure normal growth and development. The goal of renal transplant is not just to prolong life but to optimize quality of life. Short stature during childhood may be associated with academic underachievement and development of comorbidities such as attention deficit hyperactivity disorder, learning disability, and mood disorders. The most important factors affecting growth are use of corticosteroids, allograft function, and age and height deficit at the time of transplant. Aggressive conservative management of chronic renal failure and early use of growth hormone therapy will help in optimizing height at time of transplant. Early transplant, steroid minimization or withdrawal, and growth hormone therapy will help in achieving normal adult height in a majority of renal post transplant population. Steroid avoidance to achieve good growth still needs to be validated.

Mycophenolate Mofetil (Cellcept) in Pediatric Renal Transplantation

Mycophenolate mofetil (MMF) was introduced in pediatric renal transplantation almost 10 years ago. In several pediatric studies, MMF has been associated with improved graft survival and improved renal function with standard immunosuppression of steroids and calcineurin inhibitors (CNI). Both drugs are associated with significant negative effects including influence on growth, blood pressure, glucose metabolism, and also cosmetic side effects. Reduction of CNI was possible with MMF without increased rejection, improving blood pressure and renal function. Information is accumulating that steroid-sparing protocols including CNI are also associated with clinical improvement. Recent reports are positive in the pediatric population using the combination of induction with interleukin-2-receptor antagonists and mTOR inhibitors to spare steroids and CNI. Therefore MMF remains a mainstay of immunosuppressive protocols in the pediatric renal transplantation.

Pharmacogenetic differences and drug-drug interactions in immunosuppressive therapy

With the advent of new immunosuppressants and formulations, the elucidation of molecular targets and the evolution of therapeutic drug monitoring, the field of organ transplantation has witnessed significant reductions in acute rejection rates, prolonged graft survival and improved patient outcome. Nonetheless, challenges persist in the use of immunosuppressive medications. Marked interindividual variability remains in drug concentrations and drug response. As medications with narrow therapeutic indices, variations in immunosuppressant concentrations can result in acute toxicity or transplant rejection. Recent studies have begun to identify factors that contribute to this variability with the promise of tailoring immunosuppressive regimens to the individual patient. These advances have uncovered differences in genetic composition in drug-metabolising enzymes, drug transporters and drug targets. This review focuses on commonly used maintenance immunosuppressants (including cyclosporin, mycophenolate mofetil, tacrolimus, sirolimus, everolimus, azathioprine and corticosteroids), examines current studies on pharmacogenetic differences in drug-metabolising enzymes, drug transporters and drug targets and addresses common drug-drug interactions with immunosuppressant therapies. The potential role of drug-metabolising enzymes in contributing to these drug-drug interactions is briefly considered.

Longitudinal growth in children following kidney transplantation: from conservative to pharmacological strategies

Impairment of longitudinal growth in children with chronic renal failure (CRF) is multifactorial. It is mainly due to disturbances in the growth hormone (GH)/insulin-like growth factor (IGF)/IGF-binding protein axis. Growth failure can be managed by optimizing nutrition and fluid/electrolyte homeostasis, and overcoming the growth-inhibiting effects of uremia by high-dose recombinant human (rh) GH treatment. A sufficient catch-up growth is one of the determining issues for the overall success of pediatric kidney transplantation (Tx). However, despite satisfactory renal function, spontaneous catch-up growth is often insufficient as glucocorticoid treatment is the main inhibiting factor for longitudinal growth after Tx. In addition, longitudinal growth may be jeopardized by low glomerular filtration rate (GFR) and African American or Hispanic background. Supraphysiological doses of GH and/or IGF-I in vitro and in vivo can partially overcome the growth-inhibiting effects of glucocorticoid treatment. GH-associated increase of leukocyte proliferation and cytotoxicity with stimulated interferon synthesis have been demonstrated. However, it is not clear whether such stimulatory effects on leukocyte function are a transitory or a constant risk factor after organ Tx. Clinical trials of GH in children after renal Tx have suggested a rather moderate or transient effect of rhGH on the immune system, and corticosteroids induce a hyporesponsiveness to the action of GH. As long as corticosteroids are believed to be essential after renal Tx, rhGH should be considered to optimize longitudinal growth in children.