The use of cyclosporine in renal transplantation

Immunosuppression trends in solid organ transplantation: The future of individualization, monitoring, and management

Immunosuppression regimens used in solid organ transplant have evolved significantly over the past 70 years in the United States. Early immunosuppression and targets for allograft success were measured by incidence and severity of allograft rejection and 1-year patient survival. The limited number of agents, infancy of human leukocyte antigen (HLA) matching techniques and lack of understanding of immunoreactivity limited the early development of effective regimens. The 1980s and 1990s saw incredible advancements in these areas, with acute rejection rates halving in a short span of time. However, the constant struggle to achieve the optimal balance between under- and overimmunosuppression is weaved throughout the history of transplant immunosuppression. The aim of this paper is to discuss the different eras of immunosuppression and highlight the important milestones that were achieved while also discussing this in the context of rational agent selection and regimen design. This discussion sets the stage for how we can achieve optimal long-term outcomes during the next era of immunosuppression, which will move from universal protocols to patient-specific optimization.

Early isolated optic neuropathy caused by cyclosporine

PURPOSE

To examine, for the first time, whether cyclosporine intake has an early isolated effect on the optic nerve.

MATERIALS AND METHODS

This observational case series consisted of 192 eyes of 98 patients treated with cyclosporine. Patient age and duration and dosage of cyclosporine were recorded, and visual acuity, optic nerve function, visual fields, and visual evoked potential (VEP) were tested. Fundus examination was also performed. Patients with glaucoma, vascular retinopathies, and deep amblyopia were excluded.

RESULTS

Mean patient age was 46 years, average duration of treatment was 6 years, and median dosage of cyclosporine was 200 mg daily. VEP was tested in 73 patients (142 eyes) and yielded a delayed P100 wave in 9 (12.32%) (14 eyes). Among these 9 patients, abnormal findings were also noted on the Ishihara colour test in 42.86% of the eyes, and on the visual field test in 64.3% of the eyes. Abnormal VEP showed a significant correlation (p < 0.05) with older age (> 46 years) and a non-significant correlation with longer duration of treatment. Higher abnormal VEP potential was not correlated with higher cyclosporine dose, and there was no correlation between abnormal VEP and blood level of cyclosporine.

CONCLUSION

Optic neuropathy was significantly associated with older age in cyclosporine-treated patients. A correlation between optic neuropathy with longer duration of cyclosporine treatment was noted but was not statistically significant. We suggest that tests of optic nerve function, including VEP, be a part of the follow-up of patients receiving cyclosporine.

The Effect of ABCB1 C3435T Polymorphism on Cyclosporine Dose Requirements in Kidney Transplant Recipients: A Meta-Analysis

Cyclosporine A (CsA) is a substrate of the multi-drug efflux pump P-glycoprotein (P-gp) encoded by ABCB1. Among the various single nucleotide polymorphisms (SNPs) of ABCB1, C3435T has been extensively investigated to determine the relationship with the pharmacokinetics of CsA. However, the results are controversial. This meta-analysis was designed to evaluate the influence of C3435T SNP on the dose-adjusted trough (C0 /D) and peak (Cmax /D) concentrations of CsA. Based on a literature search of four authoritative databases, 13 studies since 2001 concerning 1293 kidney transplant recipients were included. The results indicated a significant difference of C0 /D and Cmax /D between 3435CC and 3435TT genotype carriers (weighted mean difference (WMD) of C0 /D: 4.18 (ng ml(-1))/(mg kg(-1)), 95% CIs: 1.00-7.37, p = 0.01; WMD of Cmax /D: 20.85 (ng ml(-1))/(mg kg(-1)), 95% CIs: 2.25-39.46, p = 0.03). Subgroup analysis by ethnicity demonstrated that C0 /D was lower in Asian CC versus TT genotype carriers (WMD = 10.32 (ng ml(-1))/(mg kg(-1)), 95% CIs: 4.78-15.85, p = 0.0003) but did not vary by genotype for Caucasian recipients. Moreover, significant variation of C0 /D was found at 1 week and 1-3 months after transplantation between CC and TT genotype carriers. Therefore, this meta-analysis showed a correlation between ABCB1 C3435T polymorphism and the dose-adjusted concentration of CsA. Patients with 3435CC genotype will require a higher dose of CsA to achieve target therapeutic concentrations when compared with 3435TT carriers after kidney transplantation, especially in the Asian population and especially during the early and middle time periods after transplantation.

The new CYP3A4 intron 6 C>T polymorphism (CYP3A4*22) is associated with an increased risk of delayed graft function and worse renal function in cyclosporine-treated kidney transplant patients

OBJECTIVE

Cyclosporine A (CsA) is a substrate of cytochrome P450 3A4 (CYP3A4). Recently, a newly discovered intron 6 single-nucleotide polymorphism in CYP3A4 (rs35599367 C>T), defining the CYP3A4*22 allele, has been linked to reduced hepatic expression and activity of CYP3A4. In the present study, the clinical impact of this single-nucleotide polymorphism was investigated in a cohort of patients receiving a CsA-based immunosuppressive regimen.

MATERIALS AND METHODS

A total of 172 de-novo kidney transplant recipients, receiving CsA/mycophenolate mofetil as immunosuppressive therapy and participating in the Fixed-Dose Concentration Controlled study, were genotyped for the new CYP3A4*22 allele. CsA C(0) and/or C(2) levels were measured on days 3 and 10 and in months 1, 3, 6, and 12 after transplantation. Plasma creatinine concentrations, delayed graft function (DGF), and biopsy-proven acute rejection were recorded.

RESULTS

The CYP3A4*22 allele was significantly associated with a higher risk of DGF compared with the CYP3A4*1/*1 patients after adjustment for known risk factors [odds ratio (OR)=6.34, confidence interval (CI(95%): 1.38-29.3), P=0.015]. Mixed-model analysis demonstrated that the overall creatinine clearance was 20% lower in CYP3A4*22 allele carriers compared with CYP3A4*1/*1 patients [CI(95%) (-33.1 to -7.2%), P=0.002]. For ABCB1 3435C>T, T-variant carriers had a decreased risk of developing DGF compared with CC patients [CT: OR=0.30, CI(95%) (0.11-0.77), P=0.011; TT: OR=0.18, CI(95%) (0.05-0.67), P=0.011].

CONCLUSION

CYP3A4*22 constitutes a risk factor for DGF and worse creatinine clearance in patients receiving CsA-based immunosuppressive therapy. Therefore, pretransplant genotyping for the CYP3A4*22 allele might help clinicians to identify patients at risk of DGF and poor renal function when treated with CsA.

Cyclosporine-A as a neuroprotective agent against stroke: its translation from laboratory research to clinical application

Stoke remains a leading cause of death and disability with limited treatment options. Extensive research has been aimed at studying cell death events that accompany stroke and how to use these same cell death pathways as potential therapeutic targets for treating the disease. The mitochondrial permeability transition pore (MPTP) has been implicated as a major factor associated with stroke-induced neuronal cell death. MPTP activation and increased permeability has been shown to contribute to the events that lead to cell death. Cyclosporine A (CsA), a widely used immunosuppressant in transplantation and rheumatic medicine, has been recently shown to possess neuroprotective properties through its ability to block the MPTP, which in turn inhibits neuronal damage. This newfound CsA-mediated neuroprotection pathway prompted research on its use to prevent cell death in stroke and other neurological conditions. Preclinical studies are being conducted in hopes of establishing the safety and efficacy guidelines for CsA use in human trials as a potential neuroprotective agent against stroke. In this review, we provide an overview of the current laboratory and clinical status of CsA neuroprotection.

Polymorphisms in CYP3A5, CYP3A4, and ABCB1 are not associated with cyclosporine pharmacokinetics nor with cyclosporine clinical end points after renal transplantation

BACKGROUND

The association of CYP3A5, CYP3A4, and ABCB1 single nucleotide polymorphisms (SNPs) with cyclosporine (CsA) pharmacokinetics is controversial. The authors studied the influence of these SNPs on CsA pharmacokinetics as well as on the incidence of biopsy-proven acute rejection (BPAR) and renal function after kidney transplantation.

METHOD

One hundred seventy-one patients participating in an international, randomized controlled trial were genotyped for CYP3A5*3, CYP3A4*1B and the ABCB1 1236 C>T, 2677 G>T/A, and 3435 C>T SNPs. The patients were treated with CsA, mycophenolate mofetil, and glucocorticoids. CsA was dosed to reach predose concentrations (C0) or two hours postdose concentrations (C2). Pharmacokinetic parameters were measured on Days 3 and 10 and Months 1, 3, 6, and 12 after transplantation. Renal function was assessed by measuring serum creatinine and calculating the creatinine clearance. The incidence of BPAR and delayed-graft function was recorded.

RESULTS

CYP3A5, CYP3A4, and ABCB1 genotype were not associated with dose-adjusted CsA C0 or C2. The incidence of BPAR in this cohort was 16% and was comparable between the different ABCB1 genotype groups. No significant difference in the incidence of BPAR was found between CYP3A5 expressers (10%) and nonexpressers (18%) (P = 0.24) nor was there a difference in the incidence of BPAR between CYP3A4*1 homozygotes (5%) versus CYP3A4*1B carriers (18%) (P = 0.13). There were no differences with regard to creatinine clearance between the different CYP3A and ABCB1 genotype groups.

CONCLUSION

According to the results, determination of CYP3A and ABCB1 SNPs pretransplantation is not helpful in determining the CsA starting dose and does not aid in predicting the risk of BPAR or worse renal function in an individual patient.

Bioavailability of Sandimmun® versus Sandimmun Neoral®: a meta-analysis of published studies

For the past 25 years, cyclosporine A (CyA) has played a pivotal role in transplant immunosuppressant therapy. From the availability of the 2 primary marketed formulations (Sandimmun® and Sandimmun Neoral®, Novartis), confusion has existed with regard to whether these two formulations are bioequivalent. Due to the underlying clinical relevance of this information, we therefore conducted a meta-analysis of all available comparative pharmacokinetic studies to assess whether the two different CyA formulations, Sandimmun® and Sandimmun Neoral®, can be considered bioequivalent. All clinical studies that compared the bioavailability of the 2 formulations in organ transplant recipients were considered for analysis. We searched computerised databases (Embase/Excerpta Medica and Medline/PubMed) from their inception to May 2010. Only studies with AUC values determined at 12 hours were considered for analysis. Relative bioavailability was calculated with 90 percent confidence intervals (CI) for Sandimmun® (test substance) versus Sandimmun Neoral® (reference substance) according to Schuirmann?s Two One-Sided Tests Procedure and the Classical Shortest CI. Homogeneity of data was tested using the Χ(2) test. Fifteen studies were considered for meta-analysis and none of these studies reported AUC values in the 80-125 percent range required for the bioequivalence of two formulations. The overall bioavailability for Sandimmun® versus the microemulsion formulation Sandimmun Neoral® was 76 percent, with upper CI limits lower than 80 percent in some cases. Mean AUC values for Sandimmun® were significantly lower than those for Sandimmun Neoral® (p<0.01). This study demonstrates that the 2 main cyclosporine formulations, Sandimmun® and Sandimmun Neoral®, cannot be considered bioequivalent.

Effects of the CYP3A5*3 variant on cyclosporine exposure and acute rejection rate in renal transplant patients: a meta-analysis

BACKGROUND

Whether the loss-of-function allele CYP3A5*3 variant is associated with significantly impaired metabolism of cyclosporine A (CsA) in transplant patients is still controversial because of the lack of prospective, large-scale clinical studies performed among diversely ethnic populations.

OBJECTIVES

This meta-analysis was designed to determine whether the CYP3A5*3 variant could affect CsA blood concentrations and the rate of acute rejection in renal transplant recipients.

METHODS AND RESULTS

All relevant publications were retrieved online from 1966 to March 2010, in which 14 studies were chosen, and 1821 renal transplant patients were enrolled. The results showed that there were significant differences in the CsA dose-adjusted trough concentration (C0) between the CYP3A5*3/*3 and CYP3A5*1/*1 carriers [weighted mean difference (WMD): 10.06 mug/l per mg/kg, 95% confidence interval (CI): 3.12-17.00, P=0.004] and between the non-CYP3A5*1 allele carriers and the CYP3A5*1 allele carriers (WMD: 8.32 mug/l per mg/kg, 95% CI: 3.16-13.49, P=0.002). In addition, a subgroup analysis stratified by ethnicity indicated that a significant difference in CsA dose-adjusted C0 was observed between the non-CYP3A5*1 allele carriers and the CYP3A5*1 allele carriers in Asian patients, but not in Caucasian patients. Moreover, a significant difference in the mean daily dose was observed between the non-CYP3A5*1 allele carriers and the CYP3A5*1 allele carriers (WMD: -0.19 mg/kg, 95% CI: -0.31 to -0.07, P=0.002). However, the meta-analysis suggested that there was little or no association of the CYP3A5*3 variant with the acute rejection rate in renal transplant patients treated with CsA [odds ratio=0.94, 95% CI: 0.57-1.54, P=0.80].

CONCLUSION

We concluded that the CYP3A5*3 variant could be associated, to a certain extent, with increased CsA dose-adjusted C0 in blood and reduced mean daily doses, but that this genetic variant allele seemed to have little effect on the acute rejection rate in renal transplant patients taking CsA.

Second cadaveric kidney transplantations in the pediatric population

OBJECTIVE

To evaluate the functional outcomes and complications among a series of second in comparison to first kidney transplantations in pediatric patients.

MATERIALS AND METHODS

We reviewed 163 consecutive kidney transplants in pediatric recipients performed from 1978 to present: 120 cases (69.3%) were first transplants (group A) and 43 (24.8%), second transplant (group B). We analyzed the incidences of delayed graft function (DGF), medical and surgical complications, as well as medium- and long-term graft survivals.

RESULTS

We observed DGF among 51 group A patients (43%) versus 32.5% of group B. Ten patients suffered vascular complications in group A (8.3%) versus one in group B (2.3%) (P < .05). The 15-year graft survivals were 54.2% for group A and 45% for group B. The 15-year patient survivals were 84.9% in group A versus 93.6% in group B.

CONCLUSIONS

Second kidney transplantations for children are a satisfactory option that achieves good functional results as well as acceptable graft and patient survivals.

Cyclosporin-A induced toxicity in rat renal collecting duct cells: interference with enhanced hypertonicity induced apoptosis

BACKGROUND/AIMS

Rat renal inner medullary collecting duct (IMCD) cells are physiologically exposed to a wide range of ambient tonicity. To maintain their function upon changes in osmolality, IMCD cells induce expression of osmoprotective and antiapoptotic genes, mainly mediated by the transcription factor Tonicity Enhancer Binding Protein (TonEBP). Some drugs like Cyclosporin-A (CsA) are discussed to interfere with the activity of TonEBP and thereby mediate their nephrotoxic effects. The aim of our study was to further understand CsA toxicity during elevation of ambient osmolality.

METHODS

First we examined cytotoxicity of CsA in IMCD exposed to elevated tonicity. Employing microarray analysis of gene expression, real-time PCR and immunoassays, we scrutinized pathways contributing to this effect.

RESULTS

We show that in IMCD cells CsA but not FK506 increases apoptosis upon an increase in tonicity. This effect is independent of cellular TonEBP localization or activity and reactive oxygen species. Microarray studies revealed marked quantitative differences in gene expression. Functional analysis showed overrepresentation of genes associated with cell death in presence of CsA. This correlated with increased mRNA expression of genes associated with the death receptor pathway and detection of TNFα in culture medium of cells treated with CsA.

CONCLUSION

Our results show that CsA cytotoxicity is induced under elevated ambient osmolality and that death receptor signaling probably contributes to CsA cytotoxicity.

Renal transplantation in the elderly

Elderly patients are increasingly being considered for kidney transplantation due to a global explosion of the aging population with end-stage renal disease (ESRD). However, mounting scarcity of available organs for transplant has led to a wider disparity between organ supply and demand. Consequently, the criteria for accepting kidneys for transplantation have been extended in an attempt to allow the use of organs from elderly donors or those with significant co-morbidities, so-called "expanded criteria donor" (ECD) kidneys. Excellent outcomes have been achieved from ECD kidneys with appropriate donor and recipient profiling and selection. With increasing recovery efforts directed at older donors, the concept of age-matching is becoming more accepted as a method of optimizing utilization of organs in elderly donors and recipients. Utilization of pulsatile perfusion has further improved ECD outcomes and helped the decision-making process for the UNOS (United Network for Organ Sharing) offer. However, age-related immune dysfunction and associated co-morbidities make the elderly transplant recipients ever more susceptible to complications associated with immunosuppressive agents. Consequently, the elderly population is at a higher risk to develop infections and malignancy in the post-transplant period notwithstanding improved transplant outcomes. Appropriate immunosuppressive agents and dosages should be selected to minimize adverse events while reducing the risk of acute rejections and maximizing patient and renal allograft survival.

Meta-analysis of the effect of MDR1 C3435T polymorphism on cyclosporine pharmacokinetics

The published data revealed conflicting results of the polymorphism of MDR1 exon 26 SNP C3435T on the pharmacokinetics of cyclosporine; thus, the aim was to conduct a meta-analysis of significant magnitude to investigate the influence of SNP C3435T on the pharmacokinetics of cyclosporine. A literature search was conducted to locate the relevant papers by using the PubMed electronic source from 1997 and onwards. The pharmacokinetic parameters, including AUC(0-4), AUC(0-12), AUC(0-inf), C(max), CL/F and trough concentration (C(0)), were extracted and a meta-analysis was performed by using Stata version 9.1. A total of 14 papers concerning 1036 individuals were included in the meta-analysis. The overall results showed no major influence of SNP C3435T on the pharmacokinetic parameters, including AUC(0-4), AUC(0-inf), CL/F, C(max) and C(0), although AUC(0-12) was lower in subjects with CC genotype. A subanalysis by ethnic population showed that C(0) was lower in Caucasian individuals harbouring CC genotype. In conclusion, our meta-analysis of available studies has thus far failed to demonstrate a definitive correlation between the SNP C3435T in MDR1 gene and alterations in P-glycoprotein function that can result in altered pharmacokinetics of cyclosporine, although it was indicated in this meta-analysis that the carrier of CC genotype of the SNP C3435T of MDR1 had lower cyclosporine exposure presented as AUC(0-12) than those with at least one T allele. There seems to be ethnic differences in the relationship between the SNP C3435T of MDR1 and cyclosporine pharmacokinetics.

A drug transporter for all ages? ABCB1 and the developmental pharmacogenetics of cyclosporine

Evaluation of: Fanta S, Niemi M, Jönsson S et al.: Pharmacogenetics of cyclosporine in children suggests an age-dependent influence of ABCB1polymorphisms. Pharmacogenet. Genomics 18(2), 77-90 (2008). The clinical use of the immunosuppressive agent cyclosporine is complicated by its toxicity, narrow therapeutic window and highly variable pharmacokinetics between individuals. In adults, genetic polymorphisms in the genes encoding the cyclosporine-metabolizing enzymes CYP3A4 and CYP3A5, as well as the ABCB1 gene, which encodes the efflux-pump P-glycoprotein, seem to have a limited effect, if any, on cyclosporine pharmacokinetics. However, the authors have now reported for the first time an association between cyclosporine oral bioavailability and the ABCB1 c.1236C>T and c.2677G>T polymorphisms, as well as the related haplotype c.1199G-c.1236C-c.2677G-c.3435C, in children with end-stage renal disease older than 8 years of age. Carriers of the variant alleles had a cyclosporine oral bioavailability that was around 1.5-times higher compared with noncarriers. This association was not observed in children younger than 8 years of age. In addition, no relation between cyclosporine disposition and genetic variation in the CYP3A4, CYP3A5, ABCC2, SLCO1B1 and NR1I2 genes was observed. These data suggest that the effect of ABCB1 polymorphisms on cyclosporine pharmacokinetics is related to age, and thus developmental stage. Although further study is necessary to establish the predictive value of ABCB1 genotyping for individualization of cyclosporine therapy in children older than 8 years, an important step towards further personalized immunosuppressive drug therapy has been made.

Association of MDR1, CYP3A4*18B, and CYP3A5*3 polymorphisms with cyclosporine pharmacokinetics in Chinese renal transplant recipients

OBJECTIVE

The objective of this study was to retrospectively evaluate the effects of MDR1, CYP3A4*18B, and CYP3A5*3 genetic polymorphisms on cyclosporine A (CsA) pharmacokinetics in Chinese renal transplant patients during the first month after transplantation.

METHODS

A total of 103 renal transplant recipients receiving CsA were genotyped for MDR1 (C1236T, G2677T/A, and C3435T), CYP3A4*18B, and CYP3A5*3. The predose and 2-h postdose concentrations of CsA (C(0) and C(2), respectively) were determined by fluorescence polarization immunoassay, and their relationships with corresponding genotypes and haplotypes were investigated.

RESULTS

Patients with a CYP3A4*1/*1 genotype were found to have a higher dose-adjusted concentration compared with those with CYP3A4*18B/*18B, as follows: for C(2), 19.3% (P = 0.008) during days 8-15, 35.2% (P = 0.008) during days 16-30, and for C(0), 39.7% (P = 0.012) during days 16-30. The dose-adjusted C(0) was higher in patients with MDR1 1236CC compared with those with 1236TT in the first month postoperation. The dose-adjusted C(0) in patients with the CYP3A5*3/*3 genotype was 25.5% and 30.7% higher than those with the wild-type genotype during days 8-15 (P = 0.011) and days 16-30 (P = 0.015), respectively. Haplotype analysis revealed that the dose-adjusted C(0) was higher in the first month following surgery in carriers of haplotype MDR1 CAC than in noncarriers. Polymorphisms of MDR1 and CYP3A5*3 did not affect dose-adjusted C(2.)

CONCLUSION

The data suggests that the CYP3A4*18B genotype affects CsA pharmacokinetics during the first month following surgery in Chinese renal transplant recipients. Patients with CYP3A4*18B alleles may require higher doses of CsA to reach the target levels. Large prospective studies may be needed to further explore the impact of MDR1 and CYP3A5*3 polymorphisms on CsA pharmacokinetics in renal transplant recipients.

Association of MDR1, CYP3A4*18B, and CYP3A5*3 polymorphisms with cyclosporine pharmacokinetics in Chinese renal transplant recipients

OBJECTIVE

The objective of this study was to retrospectively evaluate the effects of MDR1, CYP3A4*18B, and CYP3A5*3 genetic polymorphisms on cyclosporine A (CsA) pharmacokinetics in Chinese renal transplant patients during the first month after transplantation.

METHODS

A total of 103 renal transplant recipients receiving CsA were genotyped for MDR1 (C1236T, G2677T/A, and C3435T), CYP3A4*18B, and CYP3A5*3. The predose and 2-h postdose concentrations of CsA (C(0) and C(2), respectively) were determined by fluorescence polarization immunoassay, and their relationships with corresponding genotypes and haplotypes were investigated.

RESULTS

Patients with a CYP3A4*1/*1 genotype were found to have a higher dose-adjusted concentration compared with those with CYP3A4*18B/*18B, as follows: for C(2), 19.3% (P = 0.008) during days 8-15, 35.2% (P = 0.008) during days 16-30, and for C(0), 39.7% (P = 0.012) during days 16-30. The dose-adjusted C(0) was higher in patients with MDR1 1236CC compared with those with 1236TT in the first month postoperation. The dose-adjusted C(0) in patients with the CYP3A5*3/*3 genotype was 25.5% and 30.7% higher than those with the wild-type genotype during days 8-15 (P = 0.011) and days 16-30 (P = 0.015), respectively. Haplotype analysis revealed that the dose-adjusted C(0) was higher in the first month following surgery in carriers of haplotype MDR1 CAC than in noncarriers. Polymorphisms of MDR1 and CYP3A5*3 did not affect dose-adjusted C(2.)

CONCLUSION

The data suggests that the CYP3A4*18B genotype affects CsA pharmacokinetics during the first month following surgery in Chinese renal transplant recipients. Patients with CYP3A4*18B alleles may require higher doses of CsA to reach the target levels. Large prospective studies may be needed to further explore the impact of MDR1 and CYP3A5*3 polymorphisms on CsA pharmacokinetics in renal transplant recipients.

Individualizing Therapy in Patients With Chronic Kidney Disease

Patients with chronic kidney diseases have multiple clinical abnormalities that may affect disposition of drugs, including alterations in glomerular filtration rate, excretion of plasma proteins, reductions in serum albumin, and reductions in drug metabolizing enzyme activity. Inflammation may also influence the previous factors. Concomitant drug therapies can lead to drug— drug interactions that may affect the pharmacokinetics of administered drugs. Pharmacogenomics has begun to be evaluated for effects of genotype and haplotype of drug metabolizing enzymes and transporters on drug disposition. Because of the multiple potential etiologies for alterations in drug disposition in patients with chronic kidney diseases, they require appropriate evaluation for implementation of individualized strategies in therapies to enhance efficacy and reduce toxicities. This review will highlight the disease- and patient-specific variables that are targets for patient-centered approaches to therapeutic interventions. The field of pharmacogenomics will be reviewed with reference to common therapies for transplantation and glomerular diseases.

Retrospective analysis of renal transplantation outcomes in children admitted to a paediatric intensive care unit in Brazil

Renal transplantation has been described as the main treatment for children with end-stage renal disease. Traditionally, infants and small children represented a high-risk group with poor allograft survival. However, studies conducted mainly in developed countries have been demonstrated improvements in allograft survival rates. The aim of this study was to identify demographic characteristics of recipients and kidney donors and to analyse the outcomes of children who received postoperative care following renal transplantation in one Paediatric Intensive Care Unit (PICU). This retrospective study was carried out in a university hospital in Brazil. The data were collected through reviewing the follow up of medical records of recipients and kidney donors between 1988 and 2002. Chi-square or Fisher exact tests were used to analyse differences in outcome between living and donor transplants, whereas Mann-Whitney and Kruskal-Wallis tests were used to compare differences in outcome by age groups and by the number of complications affecting recipients. A total of 44 children were admitted for renal transplantation. Within this group, the median age was 10.1(+/-3.2) years, 63.6% were men and 38% were non-Caucasians. In contrast, the donor group had a median age of 17.5(+/-12.5) years, of which 51.3% were male, 56.8% were Caucasian and 70.5% were cadaver donors. The average length of PICU stay was 31.4 h, with complications being identified in the majority of the transplanted children. The occurrence of four or more complications was significantly associated with acute rejection (p= 0.009). In conclusion, the main outcomes of this study were similar to those observed in developed countries, in terms of acute rejections (52.3%), dialysis resumption (31.8%), graft loss (29.5%), chronic rejections (9.1%) and death (4.5%). Complications during PICU stay were significantly linked to the occurrence of acute rejection.

Rosiglitazone Suppresses Cyclosporin-Induced Chronic Transplant Dysfunction and Prolongs Survival of Rat Cardiac Allografts

BACKGROUND

The lack of effective treatment for chronic transplant dysfunction restricts the long-term survival of solid organ allografts. Peroxisome proliferator-activated receptor ligands can suppress vascular inflammation. The aim of this study was to analyze the effects of rosiglitazone on chronic transplant dysfunction in a rat cardiac transplant model.

METHODS

Inbred male Fisher 344 (F344, RT1lvl) and Lewis (LEW, RT1(1)) rats were subjected to heterotopic abdominal heart transplantation according to standard procedures. Cyclosporine A was administered intraperitoneally to cover acute rejection, and rosiglitazone was administered orally by gavage daily from 3 days before the operation to the end of experiments.

RESULTS

Rosiglitazone significantly prolonged the survival of cardiac allografts in rats (F344 to LEW) that had received a 10-day course of cyclosporin A compared to treatment with immunosuppressant alone. Analysis of allografts at 120 days posttransplantation showed that rosiglitazone reduced the inflammatory cell infiltrate in both the vessels and graft parenchyma as were neointimal formation, vascular occlusion, and fibrosis. Expression of transforming growth factor-beta and related proteins was less abundant after cyclosporin A/rosiglitazone treatment.

CONCLUSIONS

The findings reported here demonstrate that rosiglitazone given under the cover of short-term treatment with cyclosporin A prolongs cardiac allograft survival and reduces the severity of chronic transplant dysfunction. This may be mediated in part through the downregulation of transforming growth factor-beta and related proteins. The combined effects of rosiglitazone and immunosuppressive drugs are potentially beneficial to patients receiving organ transplants.

Population Pharmacokinetics of Cyclosporine in Chinese Cardiac Transplant Recipients

STUDY OBJECTIVE

To characterize the population pharmacokinetics of cyclosporine in Chinese patients undergoing cardiac transplantation and to identify the demographic and clinical covariates affecting cyclosporine clearance.

DESIGN

Population pharmacokinetic analysis using data from a retrospective chart review.

SETTING

Specialty hospital in Hong Kong for treatment of cardiac and pulmonary diseases.

PATIENTS

Thirty-eight Chinese adult patients (mean age 46 yrs) who had undergone routine cyclosporine therapeutic drug monitoring after cardiac transplantation between January 1, 1991, and December 31, 2003.

MEASUREMENTS AND MAIN RESULTS

Data regarding dosing, demographics, clinical laboratory values, and concurrent drugs were collected retrospectively. Data were included if patients had blood cyclosporine concentrations determined for at least 12 weeks after transplantation; an average of 18 blood samples/patient were collected. Population modeling was performed using a one-compartment linear model with first-order absorption and elimination. Various demographic and clinical covariates were tested for their significant effects on the apparent oral clearance (Cl/F) of cyclosporine. The stability of the final population model was evaluated by using the bootstrap resampling method. Statistically significant associations were observed between Cl/F and each of the following covariates: body weight (BW), use of diltiazem (DIL), and hematocrit value (HCT). The final model was Cl/F=5.00*(1-DIL)+365/HCT+(0.144*BW). The interindividual variabilities of Cl/F and apparent volume of distribution were 14.5% and 40.2%, respectively. The mean parameter estimates obtained from bootstrap analyses were highly consistent with those obtained with the original data set.

CONCLUSION

The estimated Cl/F values of cyclosporine in our Chinese cardiac transplant recipients appeared to be similar to those reported for Caucasian cardiac transplant recipients. Thus, our data provide support that a cyclosporine dosage regimen similar to that in Caucasian patients may be needed in Chinese cardiac transplant recipients. However, further studies are required to determine the optimum cyclosporine dosage regimen in the Chinese population.

Population pharmacokinetics of cyclosporine in clinical renal transplant patients

Population pharmacokinetics of cyclosporine (CsA) in clinical renal transplant patients has been reported in the present study. A total of 2,548 retrospective drug monitoring data points were collected from 120 renal transplant patients receiving CsA. Population modeling was performed using the NONMEM (nonlinear mixed-effect modeling) program, using a one-compartment model with first-order absorption and elimination. The final regression model for CsA clearance (CL/F) with the influence of six significant covariates, comprising postoperative days (POD), total bilirubin level (TBIL, micromolar concentration), current body weight (CBW, kilograms), age (years), concurrent metabolic inhibitors of cyclosporine (INHI), and hematocrit (HCT, percentage), has been established and expressed as CL/F=28.5 -- 1.24 . POD -- 0.252 . (TBIL -- 11)+0.188 . (CBW -- 58) --0.191 . (Age -- 42) -- 2.45 . INHI -- 0.212 . (HCT-- 28) (liters per hour). The values in parentheses represent the median level for each of the corresponding covariates. The population estimates for CL/F (28.5 l/h), V/F (volume of distribution, 133 l), and interpatient variability (CV%=19.7%) for CL/F were achieved, respectively. The population model was further validated by internal and external approaches, and was demonstrated to be effective and stable. Moreover, simulation was conducted to facilitate the individualized treatment based on patient information and the final model.

Age and immune response in organ transplantation

The immune system undergoes a complex and continuous remodeling as the result of aging. These changes have a major impact on allorecognition and alloresponse. In addition, immunosuppression in the elderly is challenging as a consequence of an increased incidence of associated comorbidities and altered pharmacokinetics. Both advanced donor and recipient age should be considered independent risk factors for poor patient and graft survival rates, albeit acting in a synergistic manner. Consequently, modifications of the immune system because of aging may request an age-adapted allocation and immunosuppression in parallel with close patient monitoring. Interventions to selectively target changes associated with the senescence process seem to be promising therapeutic strategies to improve transplantation outcome. Here, we are going to review the immunologic changes associated with the aging process relevant for transplantation and their impact on immunosuppressive protocols, organ allocation policies, and transplantation outcome.