A peripheral blood diagnostic test for acute rejection in renal transplantation.

Monitoring of renal graft status through peripheral blood (PB) rather than invasive biopsy is important as it will lessen the risk of infection and other stresses, while reducing the costs of rejection diagnosis. Blood gene biomarker panels were discovered by microarrays at a single center and subsequently validated and cross-validated by QPCR in the NIH SNSO1 randomized study from 12 US pediatric transplant programs. A total of 367 unique human PB samples, each paired with a graft biopsy for centralized, blinded phenotype classification, were analyzed (115 acute rejection (AR), 180 stable and 72 other causes of graft injury). Of the differentially expressed genes by microarray, Q-PCR analysis of a five gene-set (DUSP1, PBEF1, PSEN1, MAPK9 and NKTR) classified AR with high accuracy. A logistic regression model was built on independent training-set (n = 47) and validated on independent test-set (n = 198)samples, discriminating AR from STA with 91% sensitivity and 94% specificity and AR from all other non-AR phenotypes with 91% sensitivity and 90% specificity. The 5-gene set can diagnose AR potentially avoiding the need for invasive renal biopsy. These data support the conduct of a prospective study to validate the clinical predictive utility of this diagnostic tool.

Subclinical inflammation and chronic renal allograft injury in a randomized trial on steroid avoidance in pediatric kidney transplantation.

Steroid avoidance is safe and effective in children receiving kidney transplants in terms of graft function and survival, but the effects on allograft histology are unknown. In this multicenter trial, 130 pediatric renal transplant recipients were randomized to steroid-free (SF; n = 60) or steroid-based (SB; n = 70) immunosuppression, and underwent renal allograft biopsies at the time of graft dysfunction and per protocol at implantation and 6, 12 and 24 months after transplantation. Clinical follow-up was 3 years posttransplant. Subclinical acute rejection was present in 10.6% SF versus 11.3% SB biopsies at 6 months (p = 0.91), 0% SF versus 4.3% SB biopsies at 1 year (p = 0.21) and 0% versus 4.8% at 2 years (p = 0.20). Clinical acute rejection was present in 13.3% SF and 11.4% SB patients by 1 year (p = 0.74) and in 16.7% SF and 17.1% SB patients by 3 years (p = 0.94) after transplantation. The cumulative incidence of antibody-mediated rejection was 6.7% in SF and 2.9% in SB by 3 years after transplantation (p = 0.30). There was a significant increase in chronic histological damage over time (p < 0.001), without difference between SF and SB patients. Smaller recipient size and higher donor age were the main risk factors for chronic histological injury in posttransplant biopsies.

Complete steroid avoidance is effective and safe in children with renal transplants: a multicenter randomized trial with three-year follow-up.

To determine whether steroid avoidance in pediatric kidney transplantation is safe and efficacious, a randomized, multicenter trial was performed in 12 pediatric kidney transplant centers. One hundred thirty children receiving primary kidney transplants were randomized to steroid-free (SF) or steroid-based (SB) immunosuppression, with concomitant tacrolimus, mycophenolate and standard dose daclizumab (SB group) or extended dose daclizumab (SF group). Follow-up was 3 years posttransplant. Standardized height Z-score change after 3 years follow-up was -0.99 ± 2.20 in SF versus -0.93 ± 1.11 in SB; p = 0.825. In subgroup analysis, recipients under 5 years of age showed improved linear growth with SF compared to SB treatment (change in standardized height Z-score at 3 years -0.43 ± 1.15 vs. -1.07 ± 1.14; p = 0.019). There were no differences in the rates of biopsy-proven acute rejection at 3 years after transplantation (16.7% in SF vs. 17.1% in SB; p = 0.94). Patient survival was 100% in both arms; graft survival was 95% in the SF and 90% in the SB arms (p = 0.30) at 3 years follow-up. Over the 3 year follow-up period, the SF group showed lower systolic BP (p = 0.017) and lower cholesterol levels (p = 0.034). In conclusion, complete steroid avoidance is safe and effective in unsensitized children receiving primary kidney transplants.

Pharmacokinetics of oral valganciclovir solution and intravenous ganciclovir in pediatric renal and liver transplant recipients.

In an open-label, prospective, pharmacokinetic assessment, we evaluated total drug exposure (area under the curve [AUC]) of intravenous (IV) ganciclovir (GCV) and oral (p.o.) valganciclovir when normalized for body surface area (BSA) in pediatric liver (n=20) and renal (n=26) transplant patients Reference doses for IV GCV (200 mg/m(2)) and p.o. valganciclovir (520 mg/m(2)) were based on adult doses, and adjusted for BSA initially, and BSA and renal function (estimated via creatinine clearance [CrCL]) thereafter. Renal transplant patients received GCV on days 1-2, valganciclovir 260 mg/m(2) on day 3, and valganciclovir 520 mg/m(2) on day 4. Liver transplant patients received twice daily GCV from enrollment to day 12, and then valganciclovir twice daily on days 13-14. GCV pharmacokinetics were described using a population pharmacokinetic approach. Type of solid organ transplant (kidney or liver) had no effect on GCV pharmacokinetics. Median GCV exposure following valganciclovir 520 mg/m(2) was similar to that with IV GCV, and to that reported in adults. Patients <5 years of age had AUC values approximately 50% of those compared with older age ranges; dosing based on both BSA and CrCL increased drug exposure in younger patients. A dosing algorithm based on BSA and CrCL should be tested in future studies.

Should pediatric patients wait for HLA-DR-matched renal transplants?

Graft survival rates from deceased donors aged 35 years or less among all primary pediatric kidney transplant recipients in the United States between 1996 and 2004 were retrospectively examined to determine the effect of HLA-DR mismatches on graft survival. Zero HLA-DR-mismatched kidneys had statistically comparable 5-year graft survival (71%), to 1-DR-mismatched kidneys (69%) and 2-DR-mismatched kidneys (71%). When compared to donors less than 35 years of age, the relative rate of allograft failure was 1.32 (p = 0.0326) for donor age greater than or equal to age 35. There was no statistical increase in the odds of developing a panel-reactive antibody (PRA) greater than 30% at the time of second waitlisting, based upon the degree of HLA-A, -B or -DR mismatch of the first transplant, nor was there a 'dose effect' when more HLA antigens were mismatched between the donor and recipient. Therefore, pediatric transplant programs should utilize the recently implemented Organ Procurement and Transplantation Network's (OPTN)allocation policy, which prioritizes pediatric recipients to receive kidneys from deceased donors less than 35 years of age, and should not turn down such kidney offers to wait for a better HLA-DR-matched kidney.

Medication non-adherence in the adolescent renal transplant recipient: a clinician's viewpoint.

Recent advancements in immunosuppression and surgical techniques have significantly improved the outcome of kidney transplantation in the pediatric population. Adolescents enjoy the best 1-year graft survival of any age group. However, the long-term transplant outcome in adolescents is disappointing. Non-adherence with immunosuppressive medications is one of the most important contributing factors for graft rejection and loss in teenagers. The impact of non-adherence is perceived to be far more powerful in adolescent transplant recipients than in the transplant population as a whole. To better understand adolescent non-adherence, the process of transplantation must be placed in the context of adolescent development. Adolescents try to establish their identity and autonomy separately from the parents; however at the same time, adolescents with chronic illness require help, support and guidance from adults, including parents and medical personnel. Adolescents have limited ability to anticipate abstractly the long-term consequences of their immediate actions. This inconsistency can create frustration in both adolescents and in the supporting systems around them. Despite the significant consequences of adolescent non-adherence, research in this area is scarce. There are still no established definitions, standardized diagnostic methods and effective interventions to treat and prevent this problem. We propose the recommendations to approach the problems of adolescent transplant non-adherence from the transplant clinician's viewpoint. With early identification and appropriate interventions, significant improvement in adolescent graft survival is possible.

Safety and efficacy of TOR inhibitors in pediatric renal transplant recipients.

Information about the pharmacokinetics, safety, and efficacy of target of rapamycin (TOR) inhibitors, such as sirolimus and everolimus, in pediatric renal transplant recipients is limited. In an ascending single-dose pharmacokinetic study of sirolimus in pediatric dialysis patients, no clinically significant association was observed between patient age and absorption of sirolimus from the gastrointestinal tract. However, young pediatric patients (5 to 11 years of age) exhibited significantly greater apparent oral clearances, suggesting that pediatric patients require slightly higher doses than do adults when adjusted for body weight or surface area. Similarly, in studies performed in pediatric renal transplant recipients, the half-life of sirolimus was shorter and the clearance was greater in younger patients. On the other hand, in single-dose pharmacokinetic studies of everolimus, the apparent clearance was reduced in pediatric renal transplant recipients compared with clearance in adults. This reduced clearance was attributed to a smaller apparent volume of distribution in pediatric patients, rather than to a difference in terminal half-life. This suggested that, although the adult 12-hour dosing interval was appropriate for pediatric patients, they would require reduced dosing based on body size compared with adults. In a large trial (N = 719) of sirolimus versus azathioprine in combination with cyclosporine microemulsion and prednisone, 6 pediatric patients (13 to 18 years of age) received sirolimus at 2 mg/d, 3 received sirolimus at 5 mg/d, and 3 received azathioprine. Seven of the nine patients who received sirolimus experienced no rejection episodes. Six infectious episodes occurred in the 6 patients receiving sirolimus at 2 mg/d, 10 episodes occurred in the 3 patients receiving sirolimus at 5 mg/d, and 8 episodes occurred in the 3 patients receiving azathioprine. At 6 months after transplantation, renal function was similar in all 3 groups, although there was a statistically nonsignificant increase in the group receiving sirolimus at 5 mg/d. The mean cholesterol and triglyceride levels were generally comparable in all 3 groups. TOR inhibitors are promising agents for the prevention of graft rejection in pediatric renal transplant recipients, but more pharmacokinetic data are required to assess the optimal dosing regimens in this population. In addition, further data are needed on the efficacy and safety of TOR inhibitors in combination with other agents in pediatric transplantation recipients to best assess the role of TOR inhibition in corticosteroid and/or calcineurin inhibitor-sparing regimens.

Immediate post-transplant nephrosis in a patient with congenital nephrotic syndrome.

A 19-month-old girl with congenital nephrotic syndrome of the Finnish type underwent a living-related renal transplant; 24 h after transplantation she became massively nephrotic. She did not respond to steroids, plasmapheresis, and high-dose cyclosporine. A month later, a renal biopsy showed only glomerular foot process effacement. She was treated with high-dose methylprednisolone pulses and oral cyclophosphamide. She rapidly went into complete remission with no further relapses. Graft function has been stable 2 years after transplantation.

Bone disease in children and adolescents undergoing successful renal transplantation.

Little is known about the extent and severity of bone disease in children undergoing successful renal transplantation. To address this issue, 47 patients with stable renal function 3.2 +/- 1.7 years after transplantation (Tx) underwent iliac crest bone biopsy. The mean age of patients was 12 +/- 2.0 years; 36 had received cadaveric renal grafts, whereas 11 had undergone living-related Tx. Immunosuppressive drugs included cyclosporine 0.17 +/- 0.4 mg/kg/day, prednisone 7.5 +/- 2.1 mg/kg/day, and either azathioprine 1.6 +/- 0.9 mg/kg/day or mycophenolate mofetil 30 +/- 3 mg/kg/day. In addition to quantitative bone histomorphometry, the bone mineral content (BMC) of the lumbar spine was measured by dual energy X-ray absorptiometry (DXA) in 24/47 patients. Thirty-one transplant recipients had normal bone formation (N-Bfr), 11 had mild hyperparathyroidism (HPT) and 5 had adynamic skeletal lesions (AD). The interval since Tx, duration of dialysis before Tx and cumulative prednisone dose did not differ among groups. Trabecular bone area was highest in subjects with HPT. Unexpectedly, eroded bone perimeter exceeded normal reference values both in patients with AD and in those with N-Bfr; the osteoid area and osteoid perimeter were also elevated in these two groups. Hyperparathyroidism improved or resolved after Tx in all 14 subjects with this skeletal lesion prior to Tx, but one patient developed AD after Tx. Bone histology did not change after Tx in those with N-Bfr during regular dialysis, but bone formation increased after Tx in two of three patients with AD during regular dialysis. Z-scores for height in pre-pubertal patients after Tx were below age-appropriate values in each histologic subgroup, but values did not differ among groups. Z-scores for bone mineral content at the lumbar spine were also less than age-predicted values, -0.67 +/- 1.2. After adjusting for the degree of growth retardation, height-adjusted z-scores for lumbar spine BMC after Tx were above normal in all three histologic groups (0.68 +/- 1.0). The results suggest that reductions in bone mass and post-transplant osteoporosis are not prominent findings in pediatric renal transplant recipients when the influence of growth retardation on bone mass measurements by DXA is carefully considered.

Subcutaneous recombinant human erythropoietin in chronic renal allograft dysfunction.

We investigated the efficacy and safety of subcutaneous recombinant human erythropoietin (rHuEpo) in 25 children with chronic renal allograft dysfunction (13 girls, 12 boys, mean age 15.8 +/- 4.2 years) for a treatment period of 9-162 (median 43) weeks. rHuEpo was started once weekly at a dose of 105 +/- 25 U/kg per week in 16 children, twice weekly at a dose of 175 +/- 70 U/kg per week in 6 children, and three times weekly at a dose of 270 +/- 28 U/kg per week in 3 children. The hematocrit increased in 21 children from 23.2% +/- 3.1% to 33% +/- 3.1% within 7.2 +/- 4.9 weeks at a mean rate of 1.98%/week. The hematocrit increase and rHuEpo starting dose were linearly related (delta hematocrit/week = 0.8+0.08 U/kg per week, r = 0.44, P < 0.05). The maintenance dose was 74 +/- 23 (43-114) U/kg per week. Four children failed to reach the target hematocrit, most likely due to noncompliance. Seventeen recurrences of anemia ("anemic episodes") during rHuEpo therapy were identified in 12 children, mostly associated with acute or insidious deteriorations in graft function. There was no acceleration of progression of graft dysfunction with rHuEpo treatment. We conclude that subcutaneous rHuEpo at a single weekly dose of 100 IU/kg per week is highly effective in children with chronic graft dysfunction. Children who appear to be rHuEpo resistant or experience rHuEpo-resistant episodes should be assessed for noncompliance, changes in graft function since the last dosage adjustment, and blood loss, such as seen in dysfunctional uterine bleeding in adolescent girls.

Oral metronidazole does not improve cyclosporine A-induced gingival hyperplasia.

Recently, resolution of cyclosporine A (CSA)-induced gingival hyperplasia was reported with antibiotic treatment. We therefore assessed the oral status of 45 children on CSA after renal transplantation and evaluated the effects of metronidazole treatment in children with high-grade gingival hyperplasia. Gingival hyperplasia was absent in 19 (42%), mild in 5 (11%), moderate in 13 (29%), and severe in 8 (18%) children. There was no significantly different incidence in high-grade gingival hyperplasia (moderate and severe) between children with (16 of 30) or without (5 of 15) concomitant treatment with calcium channel blockers. The mean trough level of CSA was not different between children with varying severities of gingival hyperplasia. We treated 13 children with high-grade CSA-induced gingival hyperplasia (9 boys, 4 girls, mean age 14.2 +/- 3.4 years) with 750 mg metronidazole in three divided doses (10-25 mg/kg) for a total of 7 days. All 13 children were concomitantly treated with calcium channel blockers for hypertension; their mean monoclonal CSA trough level was 246 +/- 34 ng/ml. Oral examination and photographic documentation were performed by the same examiner on all patients before and 1 and 3 months after metronidazole treatment. We found no changes in gingival hyperplasia; gingival inflammation improved in 5 children (P = ns). We conclude that synergistic effects of calcium channel blockers and high concentrations of CSA in our population may outweigh beneficial effects of metronidazole treatment of CSA-induced gingival hyperplasia after renal transplantation.

Growth rates in pediatric dialysis patients and renal transplant recipients.

We compared growth rates by modality over a 6- to 14-month period in 1,302 US pediatric end-stage renal disese (ESRD) patients treated during 1990. Modality comparisons were adjusted for age, sex, race, ethnicity, and ESRD duration using linear regression models by age group (0.5 to 4 years, 5 to 9 years, 10 to 14 years, and 15 to 18 years). Growth rates were higher in young children receiving a transplant compared with those receiving dialysis (ages 0.5 to 4 years, delta = 3.1 cm/yr v continuous cycling peritoneal dialysis [CCPD], P < 0.01; ages 5 to 9 years, delta = 2.0 to 2.6 cm/yr v CCPD, chronic ambulatory peritoneal dialysis (CAPD), and hemodialysis, P < 0.01). In contrast, growth rates in older children were not statistically different when comparing transplantation with each dialysis modality. For most age groups of transplant recipients, we observed faster growth with alternate-day versus daily steroids that was not fully explained by differences in allograft function. Younger patients (<15 years) grew at comparable rates with each dialysis modality, while older CAPD patients grew faster compared with hemodialysis or CCPD patients (P < 0.02). There was no substantial pubertal growth spurt in transplant or dialysis patients. This national US study of pediatric growth rates with dialysis and transplantation shows differences in growth by modality that vary by age group.

Principles of renal replacement therapy in children.

Much has changed in pediatric renal replacement therapy during the past decade. Even the smallest critically ill patients can be temporarily supported, and chronic peritoneal and hemodialysis in young children has become routine. Although improved technical capabilities often may raise difficult ethical dilemmas, the health care team must know that such therapeutic modalities are available for the pediatric patient.