The use of an anti-CD25 monoclonal antibody and mycophenolate mofetil enables the use of a low-dose tacrolimus and early withdrawal of steroids in renal transplant recipients

Outcomes of Interleukin-2 Receptor Antagonist Induction Therapy in Standard-Risk Renal Transplant Recipients Maintained on Tacrolimus: A Systematic Review and Meta-Analysis

INTRODUCTION

The additive benefit of interleukin-2 receptor antagonist (IL2-RA) induction in standard-risk kidney transplant recipients, while maintained on tacrolimus-based immunosuppressive therapy, is uncertain.

METHODS

We divided the studies included in this meta-analysis into 2 groups: group A (included studies that used same dose of tacrolimus in both arms of each study) and group B (included studies that compared patients who received induction therapy and low-dose tacrolimus vs. those who received no-induction therapy and high dose of tacrolimus).

RESULTS

In group A, 11 studies were included (n = 2,886). IL2-RA induction therapy was not associated with significant differences in comparison to no-induction therapy in terms of acute rejection rates at 6 months post-transplant (risk ratio = 1.12 and 95% confidence interval [CI] range: 0.94-1.35) or graft survival at 1 year post-transplant (risk ratio = 0.78 and 95% CI range: 0.45-1.36). In group B, 2 studies were included (n = 669). There was no difference between both arms in terms of acute rejection rates (risk ratio = 0.62, with 95% CI range: 0.33-1.14) or graft survival (risk ratio = 1 and 95% CI range: 0.57-1.74).

CONCLUSION

IL2-RA induction therapy does not improve outcomes in patients maintained on tacrolimus-based immunotherapy in standard-risk population.

Avoiding Tacrolimus Underexposure and Overexposure with a Dosing Algorithm for Renal Transplant Recipients: A Single Arm Prospective Intervention Trial

Bodyweight‐based tacrolimus dosing followed by therapeutic drug monitoring is standard clinical care after renal transplantation. However, after transplantation, a meager 38% of patients are on target at first steady‐state and it can take up to 3 weeks to reach the target tacrolimus predose concentration (C₀). Tacrolimus underexposure and overexposure is associated with an increased risk of rejection and drug‐related toxicity, respectively. To minimize subtherapeutic and supratherapeutic tacrolimus exposure in the immediate post‐transplant phase, a previously developed dosing algorithm to predict an individual’s tacrolimus starting dose was tested prospectively. In this single‐arm, prospective, therapeutic intervention trial, 60 de novo kidney transplant recipients received a tacrolimus starting dose based on a dosing algorithm instead of a standard, bodyweight‐based dose. The algorithm included cytochrome P450 (CYP)3A4 and CYP3A5 genotype, body surface area, and age as covariates. The target tacrolimus C₀, measured for the first time at day 3, was 7.5–12.5 ng/mL. Between February 23, 2019, and July 7, 2020, 60 patients were included. One patient was excluded because of a protocol violation. On day 3 post‐transplantation, 34 of 59 patients (58%, 90% CI 47–68%) had a tacrolimus C₀ within the therapeutic range. Markedly subtherapeutic (< 5.0 ng/mL) and supratherapeutic (> 20 ng/mL) tacrolimus concentrations were observed in 7% and 3% of the patients, respectively. Biopsy‐proven acute rejection occurred in three patients (5%). In conclusion, algorithm‐based tacrolimus dosing leads to the achievement of the tacrolimus target C₀ in as many as 58% of the patients on day 3 after kidney transplantation.

Immunological risk stratification and tailored minimisation of immunosuppression in renal transplant recipients

Background

The efficacy and safety of minimisation of immunosuppression including early steroid withdrawal in kidney transplant recipients treated with Basiliximab induction remains unclear.

Methods

This retrospective cohort study reports the outcomes from 298 consecutive renal transplants performed since 1st July 2010–June 2013 treated with Basiliximab induction and early steroid withdrawal in low immunological risk patients using a simple immunological risk stratification and 3-month protocol biopsy to optimise therapy. The cohort comprised 225 low-risk patients (first transplant or HLA antibody calculated reaction frequency (CRF ≤50% with no donor specific HLA antibodies) who underwent basiliximab induction, steroid withdrawal on day 7 and maintenance with tacrolimus and mycophenolate mofetil (MMF), and 73 high-risk patients who received tacrolimus, MMF and prednisolone for the first 3 months followed by long term maintenance immunosuppression with tacrolimus and prednisolone. High-risk patients not undergoing 3-month protocol biopsy were continued on triple immunosuppression.

Results

Steroid withdrawal could be safely achieved in low immunological risk recipients with IL2 receptor antibody induction. The incidence of biopsy-proven acute rejection was 15.1% in the low-risk and 13.9% in the high-risk group (including sub-clinical rejection detected at protocol biopsy). One- year graft survival was 93.3% and patient survival 98.5% in the low-risk group, and 97.3 and 100% respectively in the high-risk group. Graft function was similar in each group at 1 year (mean eGFR 61.2 ± 23.4 mL/min low-risk and 64.6 ± 19.2 mL/min high-risk).

Conclusions

Immunosuppression regimen comprising basiliximab induction, tacrolimus, MMF and prednisolone with early steroid withdrawal in low risk patients and MMF withdrawal in high risk patients following a normal 3-month protocol biopsy is effective in limiting acute rejection episodes and produces excellent rates of patient survival, graft function and complications.

Early Steroid Withdrawal in Recipients of a Kidney Transplant From a Living Donor: Experience of a Single Mexican Center

BACKGROUND

Early steroid withdrawal (ESW) can improve lipid and hemodynamic profiles without severe acute rejection (AR) events in renal transplant patients. Our objective was to evaluate the effects of ESW on the frequency and severity of AR.

METHODS

A randomized, open-label, controlled clinical trial was performed on renal transplant recipients with a follow-up of 12 months. In the ESW group, patients were selected for corticosteroid treatment withdrawal on the fifth day post transplantation. In the Control group, patients continued with steroid treatment. All patients were over 18 years of age with panel reactive antibody (PRA) class I and II HLA <20%.

RESULTS

In total, 71 patients, 37 in the ESW group (52.1%) and 34 in the Control group (47.9%), had comparable AR incidences at the end of the follow-up (16% vs 15%) (NS) (RR = 1.20, 95% CI = 0.32-3.33). Although renal graft survival was similar between the ESW and Control groups (87% vs 94%), renal function was superior in the ESW group (85 vs 75 mL/min). Additionally, hypertension was less frequent in the ESW group (3% vs 35%), requiring the use of fewer antihypertensives (8% vs 50%).

CONCLUSIONS

ESW was also associated with better blood pressure control and similar AR risk. The ESW group exhibited stable renal function.

Two doses of humanized anti-CD25 antibody in renal transplantation: a preliminary comparative study

HuCD25mAb is a humanized anti-CD25 antibody which has the same amino acid sequence as daclizumab (Zenapax, Roche). HuCD25mAb is expressed in Chinese hamster ovary (CHO) cells while daclizumab is expressed in the NSO myeloma cell line. A comparative study was performed to evaluate the pharmacokinetics and pharmacodynamics between huCD25mAb and daclizumab in a two-dose regimen incorporating triple immunosuppressant treatment regimens (MMF, CsA and steroids). Fifteen patients were enrolled and randomized to receive intravenous infusion of either huCD25mAb (n = 10) or daclizumab (n = 5) at a dosage of 1 mg.kg(-1) on operation day 0 and post-operation day 14. Serum concentrations of huCD25mAb and daclizumab were measured by a validated competitive ELISA. Subgroups of CD3(+), CD25(+), CD4(+) and CD8(+) lymphocytes were monitored periodically by flow cytometry. The concentration-time curves of huCD25mAb and daclizumab were found to fit well to a one-compartment model. A significant decline of proportion (%) of CD3-CD25(+) and CD3(+)CD25(+) lymphocytes was observed 30 min after first infusion on day 0 (3.40 +/- 1.83 to 0.03 +/- 0.07, 3.35 +/- 2.02 to 0.37 +/- 0.49), and these levels remained low for at least 70 days (0.03 +/- 0.05, 0.31 +/- 0.47). All pharmacokinetic parameters of huCD25mAb seemed similar to those of daclizumab. The two-dose huCD25mAb regimen was as effective as daclizumab in rapidly achieving high therapeutic concentration in the treated patients, and a significant decrease of CD3(-)CD25(+) and CD3(+)CD25(+) lymphocytes was demonstrated. This suggests that two-dose regimen is feasible in maintaining host immunosuppression and may provide an effective and economical strategy for reducing incidence of acute graft rejection.

Impact of daclizumab, low-dose cyclosporine, mycophenolate mofetil and steroids on renal function after kidney transplantation

BACKGROUND

Early and long-term use of cyclosporine A (CsA) leads to increased risks of renal toxicity. We hypothesized that administration of daclizumab in combination with mycophenolate mofetil (MMF) allows a relevant reduction in the dose of CsA.

METHODS

We carried out a 3-year, prospective, randomized, controlled clinical multi-centre trial in 156 patients. The patients were randomized to standard treatment (CsA, MMF, steroids) or to high-dose daclizumab (first dose: 2 mg/kg), in combination with low-dose CsA, MMF and steroids. We maintained the mean CsA levels of daclizumab patients at 57% of standard patients (132 versus 216 ng/ml) on Day 7 post-transplant, and 84% by 6 months.

RESULTS

Primary outcome, creatinine clearance (with imputation of informative dropouts) at 12 months, was significantly better in daclizumab-treated (34 +/- 17) than standard patients (29 +/- 17; P = 0.028, two sided). Only 5 cases of BPAR were recorded in the daclizumab compared to 22 in the standard group (P = 0.0016). Daclizumab patients had 91% event-free survival after 1 year compared to 66% in standard patients (P = 0.00017).

CONCLUSION

We demonstrate here that high-dose daclizumab in combination with lower CsA levels in adult renal transplant recipients is as or more effective than standard regimen (CsA, MMF, steroids) and may result in better outcomes at 12 months post-transplant with no increase in adverse reactions.

Evolving trends in induction therapy

A decade of spectacular innovation in maintenance immunosuppressive drugs has resulted in dramatic reductions in acute rejection and improvement in short- and long-term outcomes after renal transplantation. However, the new drugs continue to lack specificity, many require frequent therapeutic drug monitoring, and all of them are associated with acute and chronic toxicities. The new biologic agents, monoclonal antibodies, and receptor-fusion proteins lack immunogenicity, have long half-life and prolonged biologic effects, require intermittent administration, and have minimal toxicity. The specificity and selectively of the targets of the new biologic agents render them less toxic than the oral maintenance drugs and thus could possibly replace those drugs most frequently associated with long-term toxicity such as the corticosteroids and the calcineurin inhibitors.

Opportunities to optimize tacrolimus therapy in solid organ transplantation: report of the European consensus conference

In 2007, a consortium of European experts on tacrolimus (TAC) met to discuss the most recent advances in the drug/dose optimization of TAC taking into account specific clinical situations and the analytical methods currently available and drew some recommendations and guidelines to help clinicians with the practical use of the drug. Pharmacokinetic, pharmacodynamic, and more recently pharmacogenetic approaches aid physicians to individualize long-term therapies as TAC demonstrates a high degree of both between- and within-individual variability, which may result in an increased risk of therapeutic failure if all patients are administered a uniform dose. TAC has undoubtedly benefited from therapeutic drug monitoring, but interpretation of the blood concentration is confounded by the relative differences between the assays. Single time points, limited sampling strategies, and area under concentration-time curve have all been considered to determine the most appropriate sampling procedure that correlates with efficacy. Therapeutic trough TAC concentration ranges have changed since the initial introduction of the drug, while still maintaining adequate immunosuppression and avoiding drug-related adverse effects. Pharmacodynamic markers have also been considered advantageous to the clinician, which may better reflect efficacy and safety, taking into account the between-individual variability rather than whole blood concentrations. The choice of method, differences between methods, and potential pitfalls of the method should all be considered when determining TAC concentrations. The recommendations of this consensus meeting regarding the analytical methods include the following: encourage the development and promote the use of analytical methods displaying a lower limit of quantification (1 ng/mL), perform careful validation when implementing a new analytical assay, participate in external proficiency testing programs, promote the use of certified material as calibrators in high-performance liquid chromatography with mass spectrometric detection methods, and take account of the assay and intermethod bias when comparing clinical trial outcomes. It is also important to consider that TAC concentrations may also be influenced by other factors such as specific pharmacokinetic characteristics associated with the population, drug interactions, pharmacogenetics, adverse events that may alter TAC concentrations, and any change in the oral formulation that may result in pharmacokinetic changes. This meeting emphasized the importance of obtaining multicenter prospective trials to assess the efficacy of alternative strategies to TAC trough concentrations whether it is other single time points or area under the concentration-time curve Bayesian estimation using limited sampling strategies and to select, standardize, and validate routine biomarkers of TAC pharmacodynamics.

Steroid avoidance or withdrawal for kidney transplant recipients

BACKGROUND

Steroid-sparing strategies have been attempted during the last two decades in order to avoid morbidity in kidney transplant recipients. Previous systematic reviews of steroid withdrawal after kidney transplantation have shown significant increases in acute rejection and an increase in graft failure rates. Steroid avoidance in kidney transplantation is increasingly attempted and the possible benefits or harms have never been a subject of a systematic review.

OBJECTIVES

To assess the safety and efficacy of steroid withdrawal or avoidance in patients receiving a kidney transplant.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE and EMBASE, references lists and abstracts from international transplantation society scientific meetings.

SELECTION CRITERIA

Randomised controlled studies (RCTs) of steroid avoidance or withdrawal were included providing that one treatment arm consisted in steroid avoidance or withdrawal and intention-to-treat rates of acute rejection and graft failure were clearly established after steroid avoidance or use or withdrawal or continuation. Observational studies were tabulated.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and results expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We included 30 RCTs (5949 participants). Steroid-sparing strategies showed no effect on mortality or graft loss including death. Patients on any steroid-sparing strategy showed a higher risk of graft loss excluding death than those with conventional steroid use (RR 1.23, 95% CI 1.00 to 1.52), especially in those not receiving MMF/Myf or everolimus (RR 1.70, 95% CI 1.00 to 2.90). Acute rejection was more frequent with a steroid-sparing strategy (RR 1.27, 95% CI 1.14 to 1.40) and more frequent after steroid withdrawal or avoidance when compared with standard steroid treatment when cyclosporin (CsA) was used. Steroid-sparing and withdrawal strategies showed benefits in reducing antihypertensive drug need, serum cholesterol, antihyperlipidaemic drug need, new-onset diabetes after transplantation (NODAT) requiring any treatment and cataracts. Steroid avoidance did not alter serum cholesterol, but was associated with less frequent NODAT requiring any treatment. Cardiovascular events were reduced with steroid avoidance. Reduced antihypertensive drug need and serum cholesterol were similar with CsA or tacrolimus (TAC). Reduced antihyperlipidaemic drug need was only evident with TAC, whereas the reduction in NODAT requiring any treatment was only evident with CsA. Infection was lower in steroid-sparing patients using CsA (RR 0.88, 95% CI 0.78 to 1.00). NODAT requiring any treatment was less frequent with steroid avoidance than with steroid withdrawal.

AUTHORS' CONCLUSIONS

This review confirms that steroid avoidance and steroid withdrawal strategies in kidney transplantation are not associated with increased mortality or graft loss despite an increase in acute rejection. These immunosuppression strategies may allow safe steroid avoidance or elimination a few days after kidney transplantation if antibody induction treatment is prescribed or after three to six months if such induction is not used.

Prevention of diabetes: effect of mycophenolate mofetil and anti-CD25 on onset of diabetes in the DRBB rat

BACKGROUND

Anti-CD25 and mycophenolate mofetil (MMF) treatment of patients with new-onset diabetes is currently being tested as one of the trials in TrialNet. We tested the effectiveness of MMF and anti-CD25 in preventing autoimmune diabetes in the diabetes-resistant biobreeding (DRBB) rat.

METHODS

Autoimmune diabetes in the DRBB rat was induced with a Treg cell depletion regimen starting at 24-26 d of age. Treatment was started on the first day of the depletion regimen in the following groups: (i) control (vehicle); (ii) MMF 25 mg/kg/d intramuscularly daily for 8 wk; (iii) anti-CD25 0.8 mg/kg/d intraperitoneally 5 d/wk for 3 wk; and (iv) combination of MMF and anti-CD25. In a second set of experiments, treatments were started on day 5 of the depletion regimen (delayed treatment) with groups 1, 3, and 4. Rats that had diabetes-free survival for at least 30 d after the treatment was stopped underwent a second Treg depletion (redepletion).

RESULTS

In each of the three treatment groups (n = 10/group), onset of diabetes was delayed or prevented in 20, 40 and 80% in groups 2, 3, and 4, respectively. After redepletion, diabetes-free survival was unchanged in group 2 and decreased to 10 and 30% in groups 3 and 4, respectively. With delayed treatment, groups 3 and 4 had 33 and 50% diabetes-free survival that decreased to 0 and 33% after redepletion.

SUMMARY

MMF and anti-CD25 alone or in combination are effective in delaying and preventing diabetes in the DRBB rat especially if treatment is started before stimulation and expansion of the autoreactive T cells.

Daclizumab

Daclizumab is a humanized monoclonal antibody which binds to the IL-2 receptor on activated lymphocytes and blocks the production of IL-2. Its use is well established in solid organ transplantation as induction therapy, especially in high-risk patients where reduction or delayed dose of standard immunosuppression would be beneficial. It has been used effectively in both 2-dose and 5-dose regimens in conjunction with other standard immunosuppressive agents. The incidence of acute rejection appears reduced without increasing the rates of infection or post-transplant lympho-proliferative disorders. The agent is generally well tolerated in adults and children and there is no need for additional monitoring. Daclizumab has also been used outside the transplant arena in a variety of immune-mediated diseases with limited success.

Corticosteroid withdrawal in kidney transplantation: the present status

Corticosteroids (CS) have played a vital role in organ transplantation, both for prevention and treatment of allograft rejection. However, the use of CS is associated with a wide range of adverse effects. With advances in immunosuppressive drug therapy, attempts have been made to minimize the use of CS to avoid or alleviate their side effects. Withdrawal of CS months after transplantation has transitioned to days. In low to intermediate risk renal allograft recipients, use of induction therapy and modern maintenance drug combinations allows safe withdrawal of CS within the first week of transplantation. In other groups, existing potent maintenance agents permit tapering of CS to low doses over the first few months. Withdrawal of these small doses may not add to the benefits.

Basiliximab Improves Graft Survival in Renal Transplant Recipients With Delayed Graft Function

The aim of this study was to evaluate the use of basiliximab in first renal transplant recipients with delayed graft function, defined by the need for dialysis in the first week posttransplantation. Among 148 patients in the study, 90 received basiliximab (60.8%) with 58 comprising the control group. There were no significant differences between the 2 groups related to the evaluated variables, except that the control group received more blood transfusions pretransplantation. There was a lower incidence of steroid-resistant rejection (6% vs 20.9%; P = .017) and humoral rejections (0% vs 7%; P = .038) in the basiliximab group. Also, graft survival was significantly higher in basiliximab group compared with the control one (92.8% vs 80.4%; P = .028). There were no significant differences in the other outcomes. In conclusion, this study confirmed the beneficial effects of addition of basiliximab to the immunosuppressive schema of patients with delayed graft function.

Therapeutic monitoring of calcineurin inhibitors for the nephrologist

The calcineurin inhibitors (CNI) cyclosporine and tacrolimus remain the backbone of immunosuppression for most kidney transplant recipients. Despite many years of experience, protocols that optimize efficacy with minimal toxicity remain a subject of debate. Nevertheless, studies of the pharmacokinetic properties of the CNI, particularly cyclosporine, have led to improved dosing strategies. The purpose of this article is to review the current understanding of CNI pharmacokinetics and its relevance to proper dosing and monitoring of these medications. This article also reviews the trials that have helped to define the optimal dosages and discusses the effect of adjunctive immunosuppressive agents on CNI pharmacokinetics and dosing.

Immunosuppressive preconditioning or induction regimens : evidence to date

The success of solid organ transplantation has been directly related to the development of immunosuppressive drug therapies. Preconditioning or induction therapy was developed to reduce early immunological and nonimmunological renal injury, with the goal of increasing long-term graft survival. However, the routine induction of immunological tolerance to solid organ allograft is currently not achievable because of the morbidity and mortality related to the immunosuppressive regimens themselves. The different therapeutic preconditioning or induction agents and their associated effects on cellular rejection, graft survival outcomes and the need for multiagent post-transplant maintenance therapy are reviewed.

Corticosteroid-sparing strategies in renal transplantation: are we still balancing rejection risk with improved tolerability?

Chronic allograft nephropathy and death with a functioning graft (mainly due to cardiovascular causes) are the most common causes of graft loss after the first year of renal transplantation. Immunosuppressants, and corticosteroids among them, contribute to an increase in cardiovascular risk because of their significant adverse effects, including hypertension, hyperlipidaemia and hyperglycaemia. Thus, corticosteroid discontinuation or avoidance has become a priority among the transplant community in order to enhance long-term graft and patient survival. Nevertheless, corticosteroid-sparing strategies may increase the risk of acute and chronic rejection and, thus, worsen the prognosis of transplant recipients. Initial attempts during the azathioprine epoch did not provide satisfactory results, as they were associated with high acute rejection rates, emphasising the risk of under-immunosuppression. The advent of new immunosuppressants, such as mycophenolate mofetil, mTOR inhibitors and anti-interleukin-2 receptor antibodies, have renewed the interest in corticosteroid-sparing protocols, and the results of new trials suggest that these corticosteroid-sparing strategies, even at an early stage after transplantation, are safe enough in view of the stable renal function and low rates of acute rejection reported. However, immunological risk factors, such as African American ethnicity, the presence of panel-reactive anti-HLA antibodies (even at low rates), and a history of previous acute rejection episodes should be taken into account and corticosteroid withdrawal strategies should be undertaken with caution. Long-term follow-up studies must be performed to confirm the encouraging short-term data.

Effect of Basiliximab on Renal Allograft Rejection Within 1 Year After Transplantation

Basiliximab is widely used in clinical practice for initial immunosuppressive treatment of renal transplant recipients, seeking to reduce the incidence of acute rejection episodes without adverse events. This retrospective study included 123 renal allograft recipients transplanted at a single center. All were followed for longer than 1 year after transplantation and treated with calcineurin inhibitor and steroid (methylprednisolone) for prophylactic immunosuppression, but basiliximab and mycophenolate mofetil were optional. We compared the outcomes of renal transplant recipients who were versus treated were not with basiliximab as initial immunosuppressive therapy. Basiliximab was used for initial immunosuppression in 42 patients. Their maintenance immunosuppressive treatment included triple (n = 44) or double (n = 79) regimens, including a calcineurin inhibitor (cyclosporine [n = 87] or tacrolimus [n = 36]), methylprednisolone with or without mycophenolate mofetil. Twenty-six (21.1%) patients had a rejection episode within 1 year after transplantation and 22 (17.9%) had infections. Within the first year after transplantation the patients who were treated with basiliximab showed fewer rejection episodes (n = 6, 14.3%) than the patients without this therapy (n = 20, 24.7%), which was not statistically significant (P = .245). However, basiliximab significantly affected the occurrence of rejection episodes among the double immunosuppressive regimen group (P = .006), but not the triple regimen group (P = .098) without an impact on infection episodes (P value of double, triple = .291, .414) within 1 year after transplantation. We concluded that basiliximab was more useful for the recipients treated with double immunosuppression with a calcineurin inhibitor and steroid than for those on a triple regimen including mycophenolate mofetil.

Treatment strategies in pediatric solid organ transplant recipients with calcineurin inhibitor-induced nephrotoxicity

Although short-term kidney allograft survival has improved significantly since the introduction of the calcineurin inhibitors (CNI) cyclosporine A (CsA) and tacrolimus, long-term transplant survival remains a major concern, chronic allograft nephropathy (CAN) being the principal reason for graft loss after the first post-transplant year. This is particularly major for pediatric renal transplant recipients because of their higher life expectancy compared with adults. The mechanisms leading to CAN are multiple, including acute and chronic alloimmune responses and nephrotoxicity of CNIs. CNI-induced nephrotoxicity is also a long-term concern in other pediatric solid organ transplant recipients, such as liver and heart. Prevention of allograft nephropathy requires a balance of maintaining adequate immunosuppression, while avoiding the toxic effects of CNIs. Regimens that are based on mycophenolate mofetil (MMF) alone or in combination with newer agents may allow for reduced reliance on CNIs and thus may represent an effective treatment paradigm for long-term maintenance of a renal allograft. From the available data it appears that the currently safest treatment strategy in pediatric renal and heart transplant recipients with CNI toxicity is an MMF-based therapy with low-dose CNIs +/- low-dose steroids, while in pediatric liver transplant recipients, CNI-free MMF-based immunosuppressive therapy with or without steroids appears feasible in a significant subset of patients. In renal transplant recipients, the benefit of a CNI-free MMF/steroid therapy on renal function is gained at the cost of increased rejection in a subset of patients, although the relative importance of rejection vs. overall renal function requires further clinical investigation. The introduction of mammalian target of rapamycin (mTOR) inhibitors provides an opportunity for unique CNI-sparing regimens that combine two antiproliferative agents (MMF and TOR inhibitors). It is possible that a sirolimus-based CNI-free immunosuppressive regimen in terms of renal transplant survival is superior to CNI minimization, where the detrimental effects of CNIs on allograft function and structure are still operative, albeit to a lesser degree. Substitution of CNIs by mTOR inhibitors is therefore promising, but requires validation in long-term studies in large cohorts.

Is Microparticle Enzyme-Linked Immunoassay (MEIA) Reliable for Use in Tacrolimus TDM? Comparison of MEIA to Liquid Chromatography With Mass Spectrometric Detection Using Longitudinal Trough Samples From Transplant Recipients

In the larger transplant centers where technical expertise is available, liquid chromatography with mass spectrometric detection (LC-MS) for tacrolimus therapeutic drug monitoring is replacing the popular microparticle enzyme-linked immunoassay (MEIA) as a cost-effective alternative technology. As more labs convert to LC-MS, the accuracy, precision, selectivity, and sensitivity of the tacrolimus MEIA are being challenged, using data from large populations of clinical samples. However, little attention has been paid to how the results of particular procedures may differ within and among individual patients and to how such differences may relate to patients' characteristics or to relevant biochemical parameters. So, after validation of an LC/MS procedure and verification of an LC/MS/MS procedure, the author analyzed 552 serial trough blood tacrolimus samples, collected from 38 patients over a 3-month period, by controlled MEIA and LC-MS procedures. Corresponding hematocrit and serum albumin level data were obtained. In an attempt to investigate whether the observations of others who studied population-based data could be illustrated for individuals, longitudinal data from several patients were plotted to visually elucidate any relations between the tacrolimus concentration and biochemical data. Finally tacrolimus concentration, hematocrit, and serum albumin data were compared using data stratified by transplant type, in-/outpatient status, male/female gender, or period elapsed since transplant surgery. The validated/verified LC-MS procedures were shown to be much better controlled than the MEIA during the 3-month parallel comparison study period. The longitudinal data of several individuals who experienced wide changes in the biochemical parameters clearly illustrated the relation between the difference in tacrolimus concentrations determined by MEIA and LC-MS and hematocrit (and sometimes albumin). Differences between the MEIA- and LC-MS-determined tacrolimus concentration data were strongly correlated to transplant type, in-/outpatient status, gender, time elapsed since liver transplant surgery, hematocrit, and weakly to serum albumin levels. In summary, the LC-MS methods provide highly reliable and reproducible estimates of tacrolimus concentrations, whereas the performance of MEIA technology did not provide reliable long-term performance for longitudinal therapeutic drug monitoring of tacrolimus because it was effected by several inherent demographic factors and by factors that can change over time in transplant recipients.

A novel three-dose regimen of daclizumab in liver transplant recipients with hepatitis C: a pharmacokinetic and pharmacodynamic study

This study evaluated the pharmacokinetics and pharmacodynamics of a novel 3-dose regimen of daclizumab in de novo hepatitis C liver transplant recipients. In 30 of 156 recipients receiving daclizumab, mycophenolate mofetil, tacrolimus, and no steroids (Arm 3 of Hep C 3 Liver Study), daclizumab (2, 2, and 1 mg/kg, respectively) was given on days 1, 3, and 8 posttransplant, respectively, with trough, peak (C(max)), and CD25 saturation (CD(sat)) measured sequentially. Mean daclizumab C(max) was 50.3 microg/mL on day 1, and mean trough levels were 21.8, 25.7, and 9.9 microg/mL on days 3, 8, and 30, respectively. A significant decline in CD(sat) (mean, 15.7% to 4.7%) was observed on day 1 and was sustained throughout the study (2.8% on day 30). Daclizumab concentration > or = 5 microg/mL was the level where most of the effect on CD(sat) was noticed. Elevated baseline CD(sat) was observed in African Americans, patients weighing < or = 75 kg, and patients <60 years of age. After 365 days, 2 patients had experienced 3 rejections, 10 patients had recurrent hepatitis C, 4 patients died, and 2 grafts were lost. In conclusion, this novel 3-dose regimen is effective in rapidly achieving high therapeutic concentration of daclizumab and a significant decline in CD(sat) lasting over 30 days.

Use of IL-2 receptor antagonists to reduce delayed graft function following renal transplantation: a review

Delayed graft function (DGF) occurs in approximately 30% of renal transplant patients, and significantly increases risk of long-term graft loss. This article reviews the potential for use of interleukin-2 receptor (IL-2R) antagonists to reduce the burden of DGF. IL-2R antagonists decrease incidence of acute rejection without increasing risk of cytomegalovirus infection or malignancy, and show equivalent efficacy to lymphocyte-depleting antibody agents in standard risk patients with immediate graft function. The nephrotoxicity associated with calcineurin inhibitors (CNIs) has led to use of delayed or low-dose CNI regimens with induction therapy in patients with DGF. In this setting, use of an IL-2R antagonist with mycophenolate mofetil and steroids with delayed cyclosporine appears to be associated with a low incidence of biopsy-proven rejection and comparable renal function to patients with immediate function. Additionally, there is intriguing evidence to suggests that IL-2R antagonists may reduce risk of DGF occurring. A number of large-scale and smaller studies have reported a trend to reduced incidence of DGF or improved early renal function using IL-2R antagonists compared with placebo, although data are not entirely consistent. In conclusion, the ability of IL-2R antagonists to reduce acute rejection with no additional safety concerns makes them an attractive option for patients with DGF.

Two corticosteroid-free regimens-tacrolimus monotherapy after basiliximab administration and tacrolimus/mycophenolate mofetil-in comparison with a standard triple regimen in renal transplantation: results of the Atlas study

BACKGROUND

The side effects associated with corticosteroids have led to efforts to minimize their use in renal transplant patients. In this study we compared two corticosteroid-free tacrolimus-based regimens with a standard triple therapy.

METHODS

This was a 6-month, phase III, open-label, parallel-group, multicenter study. The total analysis set comprised 451 patients, randomized (1:1:1) to receive tacrolimus (Tac) monotherapy following basiliximab (Bas) administration (n=153), Tac/mycophenolate mofetil (MMF) (n=151), or, Tac/MMF/corticosteroids triple therapy as a control (n=147).

RESULTS

The study was completed by 91.2% (triple therapy), 94.7% (Tac/MMF), and 82.4% (Bas/Tac) of patients. Patient baseline characteristics were similar in all groups. The incidences of biopsy-proven acute rejection were 8.2% (triple therapy), 30.5% (Tac/MMF), and 26.1% (Bas/Tac), p<0.001 (multiple test for comparison with triple therapy); Bas/Tac vs. Tac/MMF, p=ns. The incidences of corticosteroid-resistant acute rejection were 2.0%, 4.0%, and 5.2%, p=ns. Graft survival (95.9%, 96.7%, and 94.7%, p=ns) and patient survival (100%, 99.3%, and 99.3%, p=ns) were similar in all groups. Median serum creatinine at month 6 was 123.0 micromol/L (triple therapy), 134.7 micromol/L (Tac/MMF) and 135.8 micromol/L (Bas/Tac). The overall safety profiles were similar; differences (p<0.05) were reported for anaemia (24.5% vs. 12.6% vs. 14.5%), diarrhoea (12.9% vs. 17.9% vs. 5.9%), and leukopenia (7.5% vs. 18.5% vs. 5.9%) for the triple therapy, Tac/MMF, and Bas/Tac group, respectively. The incidences of new-onset diabetes mellitus were 4.6%, 7.1%, and 1.4%, respectively.

CONCLUSION

Corticosteroid-free immunosuppression was feasible with the Bas/Tac and the Tac/MMF regimens. Both corticosteroid-free regimens were equally effective in preventing acute rejection, with the Bas/Tac therapy offering some safety benefits.

Efficacy of Alemtuzumab in Organ Transplantation

An overview of the past 5 years of clinical renal transplantation would include progress in (i) the development of protocols with new induction agents (non-depleting versus depleting monoclonal and polyclonal antibodies) designed to reduce the incidence and severity of acute rejection, (ii) the attempt to reduce calcineurin inhibitor short- and long-term nephrotoxicity, and (iii) the attempt to reduce immunosuppression overall if an immunoregulatory state ('tolerance') against donor alloantigens could be achieved. One such induction agent is the humanized anti-CD52 monoclonal antibody alemtuzumab (Campath-1H), which depletes T cells (most potently), as well as B cells and other lymphoid subsets, and may decrease the dosage or need for concurrent maintenance immunosuppressive agents.

Toxicity-sparing protocols using mycophenolate mofetil in renal transplantation

The introduction of triple-therapy regimens that include a calcineurin inhibitor (CNI), steroids, and azathioprine greatly reduced the risk of acute rejection in renal transplantation. However, the long-term use of both CNIs and steroids is associated with serious toxicities that ultimately can impact patient/graft survival. Mycophenolate mofetil (MMF), a highly effective immunosuppressant with no known nephrotoxicity, has been shown to provide benefits in preserving long-term renal allograft function relative to azathioprine. For these reasons, MMF has become an integral component of toxicity-sparing maintenance regimens that seek to minimize patient exposure to CNIs and steroids. This paper provides an overview of current strategies for reducing the toxicities associated with these agents, which include both withdrawal and avoidance regimens with or without induction therapy. Data are accumulating that toxicity-sparing regimens involving MMF are safe and decrease the risk of side effects that accompany the use of CNIs and steroids. Future studies will determine how to best implement these regimens in the renal transplant population.

Immunosuppressive agents in solid organ transplantation: Mechanisms of action and therapeutic efficacy

Effective immunosuppression is an essential pre-requisite for successful organ transplantation and improvements in outcome after transplantation have to a large extent been dependent on developments in immunosuppressive therapy. Here we provide an overview of the different immunosuppressive agents currently used in solid organ transplantation. A historical perspective on the development of immunosuppression for organ transplantation is followed by a review of the individual agents, with a focus on their mechanism of action and efficacy. Steroids, anti-proliferative agents (azathioprine and mycophenolate), calcineurin inhibitors (cyclosporine and tacrolimus) and TOR inhibitors (sirolimus and everolimus) are discussed along with both polyclonal and monoclonal antibody preparations. Many of the key clinical trials that underpin current clinical usage of these agents are described and side-effects of the different agents are highlighted. Finally, a number of newer agents still in various stages of clinical development are briefly considered.

Updated Metaanalysis of Steroid Withdrawal in Renal Transplant Patients on Calcineurin Inhibitor and Mycophenolate Mofetil

During the 1990s two metaanalysis of randomized clinical trials of steroid withdrawal after renal transplantation showed significant increases in acute rejection episodes and graft failure rates. A recently published metaanalysis of steroid withdrawal in patients on a calcineurin inhibitor and MMF included randomized clinical trials. We have updated this study, searching more publications during the last 2 years. Finally, the same six trials were included, four in patients receiving cyclosporine and two tacrolimus. Risk ratio (RR) for acute rejection was 2.28 [95%CI 1.65-3.16, P < .00001], and pooled risk difference (RD) was 0.08 [0.05-0.11, P < .001], indicating that the proportion of patients with acute rejection episodes after prednisone withdrawal was significantly higher compared with controls. RR for graft failure was 0.73 [0.42-1.28, P = .27], and RD was -0.01 [-0.03-0.01, P = .28], indicating that the proportion of patients with graft failure after withdrawal was not significantly different from that of controls. Total cholesterol was significantly lower after steroid withdrawal (weighted mean difference -0.53 mumol/L [-0.70--0.36, P < .0001]). Renal allograft recipients on triple therapy with a calcineurin inhibitor, MMF, and steroids are at low but significant risk of acute rejection after steroid withdrawal, but do not suffer an increased risk of early graft failure. It is necessary to extend controlled follow-up to confirm graft function stabilization.

Review of Major Clinical Trials with Mycophenolate Mofetil in Renal Transplantation

Mycophenolate mofetil (MMF) was approved for the prevention of acute rejection following renal transplantation based on the results of three groundbreaking, large, clinical trials that demonstrated a significantly reduced risk of acute rejection in patients receiving MMF when compared with those receiving placebo or azathioprine. These three multicenter, prospective, double-blind trials performed at 55 transplant centers on three continents were the largest immunosuppressive drug trials ever attempted and the first prospective, randomized, double-blind trials ever performed in transplantation. These pivotal trials established a foundation for widespread acceptance of MMF in combination with cyclosporine and steroids as a maintenance regimen for renal transplant patients. The findings of these initial trials that led to the approval of MMF for renal transplantation, including long-term follow-up data, will be reviewed in this paper. The expanding scope of major trials of MMF, including trials in pediatric patients, combination regimens with novel induction therapies or other maintenance agents, and trials in special patient populations such as those at high immunological risk or with deteriorating kidney function, will also be discussed.

Corticosteroid-free immunosuppression with tacrolimus, mycophenolate mofetil, and daclizumab induction in renal transplantation

BACKGROUND

Corticosteroid-free maintenance immunosuppression after organ transplantation eliminates the well-known corticosteroid-related side effects and may help to improve long-term outcome. We investigated whether a corticosteroid-free tacrolimus (Tac)/mycophenolate mofetil (MMF) regimen, in combination with daclizumab (Dac) induction therapy, provides adequate immunosuppression after renal transplantation.

METHODS

This 6-month, open-label, multicenter, parallel-group study involved 538 renal patients randomized (1:1) to a Dac/Tac/MMF regimen (n = 260) or a Tac/MMF/corticosteroids regimen (n = 278) as a control group.

RESULTS

Of the patients who completed the study, 88.8% in the Dac/Tac/MMF group were free from corticosteroid therapy at month 6. The incidence of biopsy-proven acute rejection was 16.5% in both treatment groups; the incidence of biopsy-proven corticosteroid-resistant acute rejection was 4.3% and 5.0% with Tac/MMF/corticosteroids and Dac/Tac/MMF, respectively (P = NS for both comparisons). Renal function was also similar in both groups: median serum creatinine at month 6 was 125.0 micromol/L (Tac/MMF/corticosteroids) and 131.0 microml/L (Dac/Tac/MMF), P = 0.277. The overall safety profile was similar with both regimens. However, compared with the Tac/MMF/steroid regimen, a significantly reduced incidence of new-onset insulin-dependent diabetes mellitus (5.4% vs. 0.4%, P = 0.003) was found with steroid-free immunosuppression. Moreover, mean total cholesterol concentrations increased from baseline in the Tac/MMF/corticosteroids group by 0.19 mmol/L, whereas in the Dac/Tac/MMF group, levels decreased by 0.19 mmol/L, P = 0.005.

CONCLUSIONS

Corticosteroid-free immunosuppression with a Dac/Tac/MMF regimen is as effective at preventing acute rejection after renal transplantation as a standard triple regimen of Tac/MMF/corticosteroids. Furthermore, the safety benefits reported with Dac/Tac/MMF treatment may help improve the long-term outcome for renal-transplant patients.

Use of different immunosuppressive strategies in recipients of kidneys from nonheart-beating donors

In nonheart-beating donor (NHBD) kidney transplants, immunosuppressive management is difficult mainly because of the high incidence of acute tubular necrosis. This has meant that since the start of our NHBD transplant program, several immunosuppression regimes have been used. The aim of this retrospective study was to evaluate the results obtained over 7 years using different treatment protocols. A total of 172 consecutive NHBD transplants performed between April 1996 and December 2002 were treated as follows: G-I (n = 21), cyclosporine (8 mg/kg/day) plus azathioprine plus steroids; G-II (n = 65), low-dose cyclosporine (5 mg/kg/day) plus mycophenolate plus steroids; G-III (n =17), low-dose tacrolimus (0.1 mg/kg/day) plus mycophenolate plus steroids; and G-IV (n = 69), daclizumab plus low-dose tacrolimus plus mycophenolate plus steroids. Delayed graft function rates were 76.2%, 72.3%, 76.5%, and 42%, respectively, for the four groups (P = 0.000). Rejection-free patient rates were 76.2%, 46.2%, 35.3%, and 71% (P < 0.001). Vascular rejection rates were 19%, 30.8%, 52.9%, and 18.8%, (P = 0.025). Two-year graft survival was 71.4% in group I, 95.4% in group II, 94.1 in group III, and 93.8% in group IV (P =0.004). Patient survival was worse in group I (75.2% in group I, 100% in group II, 100% in group III, and 96.7% in group IV at 2 years; P < 0.001). The use of daclizumab and low-dose tacrolimus could be effective at lowering the incidence of delayed graft function in NHBDT, with no negative repercussions on acute rejection.

Immunosuppressive drug monitoring - what to use in clinical practice today to improve renal graft outcome

Therapeutic drug monitoring (TDM) of immunosuppressive therapy is becoming an increasingly complex matter as the number of compounds and their respective combinations are continuously expanding. Unfortunately, in clinical practice, monitoring predose trough blood concentrations is often not sufficient for guiding optimal long-term dosing of these drugs. The excellent short-term results obtained nowadays in renal transplantation confer a misleading feeling of safety despite the fact that long-term results have not substantially improved, definitely not to a point where longer graft survival could counteract the increasing need for transplant organs and less toxicity and side-effects could ameliorate patient survival. It is therefore a challenging task to try to tailor immunosuppressive drug therapy to the individual patient profile and this in a time-dependent manner. For the majority of currently used immunosuppressive drugs, measurement of total drug exposure by determination of the dose-interval area under the concentration curve (AUC) seems to provide more useful information for clinicians in terms of concentration-exposure and exposure-response as well as reproducibility. To simplify this laborious way of measuring drug exposure, several validated abbreviated AUC profiles, accurately predicting the dose-interval AUC, have been put forward. Together with an increasing knowledge of the time-related pharmacokinetic behaviour of immunosuppressive drug and their metabolites, studies are focusing on how to apply abbreviated AUC sampling methods in clinical transplantation, taking into account the numerous factors affecting drug pharmacokinetics. Eventually, TDM using abbreviated AUC profiles has to be prospectively tested against classic methods of drug monitoring in terms of cost-effectiveness, feasibility and clinical relevance with the ultimate goal of improving patient and graft survival.

A multicenter pilot study of early (4-day) steroid cessation in renal transplant recipients under simulect, tacrolimus and sirolimus

This study presents the first prospective multicenter study assessing sirolimus-based immunosuppression with early (4-day) corticosteroid withdrawal (CSWD) in renal transplantation. Immunosuppression included: anti-IL-2 receptor antibody and tacrolimus/sirolimus. Inclusion criteria included adult primary recipients. Exclusion criteria included: (i) African Americans, (ii) current PRA >50%, (iii) multiple organ transplants, (iv) WBC < 3000 cells/microL and (v) fasting hypercholesterolemia/hypertriglyceridemia. The primary endpoints were acute rejection and the proportion of patients off corticosteroids. Seventy-seven patients were enrolled: mean age of 49.7 +/- 12 years. Transplants included: cadaveric (26%) and living donor (74%). Patient and graft survival were 100%. Biopsy proven acute rejection occurred in 13%; presumptive rejection in 10.5%. Banff grades included: IA (seven patients), IB (one patient), IIA (one patient) and IIB (one patient). Renal function at 1 year: serum creatinine (1.18 +/- 0.06 mg/dL). Mean weight gain was minimal at 1 year: 3 +/- 2 kg/patient. Mild increases in total, LDL and HDL cholesterol were observed and new antilipid agent use occurred in 26 patients. In conclusion, early CSWD under tacrolimus/sirolimus-based immunosuppression in selected, low-risk renal transplant recipients provides: (i) excellent patient and graft survival, (ii) good renal function, (iii) reduced hyperlipidemia and antilipid agent use and (iv) low acute rejection rates.

Steroid sparing with tacrolimus and mycophenolate mofetil in renal transplantation

Evidence suggests that steroid sparing in renal transplantation is associated with good outcomes, although there are limited data regarding steroid sparing in Tacrolimus and Mycophenolate Mofetil (MMF)-based regimes. In this study we describe the use of these agents in 101 consecutive patients undergoing renal transplantation using only a 7-day course of prednisolone. Median follow-up was 33 months (range 18-44). Patient and graft survival at 1 year were 100% and 98%, respectively. The acute rejection rate at both 6 and 12 months was 19%, with two episodes beyond 12 months. Anti-CD25 monoclonal antibody (anti-CD25 mAb) was administered to 25 patients at high immunological risk: a trend toward a lower rejection rate was seen in these patients compared with those at lower risk but not receiving induction therapy (8% vs. 22%; p = 0.11). Two patients experienced recurrent rejection. Of the twenty-three rejection episodes in total, 26% showed vascular involvement. Allograft function was preserved at 12 months with a mean creatinine of 144 micromol/L and mean estimated glomerular filtration rate (GFR) of 55 mL/min. At 12 months, the incidence of post-transplant diabetes mellitus was 3.5%. This steroid-sparing regime is associated with excellent patient and graft outcomes, and a low incidence of side effects.

Interleukin-2 receptor antagonists and aggressive steroid minimization strategies for kidney transplant patients

Steroid withdrawal during the first week after transplantation surgery, or complete avoidance of steroids, offers potential benefits. The interleukin-2 (IL-2) receptor antibodies, basiliximab and daclizumab, can enable aggressive steroid minimization protocols that are efficacious while reducing toxicity. A multicenter, randomized trial of kidney transplant recipients has shown the incidence of biopsy-proven acute rejection with basiliximab, cyclosporine and mycophenolate mofetil with steroids withdrawn at day 5 to be similar to a conventional triple-therapy regimen. A single perioperative dose of corticosteroids with an IL-2 receptor antagonist also seems as efficacious as standard steroid therapy. Corticosteroid-minimization with IL-2 receptor antagonists has also been investigated with sirolimus-containing regimens and has shown excellent outcomes. Experience with complete steroid avoidance, using an IL-2 receptor antagonist, is limited, but initial results are promising, particularly in pediatric patients. Administration of an IL-2 receptor antagonist with aggressive steroid minimization in selected, well-monitored patients seems reasonable, but further trials are required to define optimal protocols.

Interleukin-2 receptor antagonists and aggressive steroid minimization strategies for kidney transplant patients

Steroid withdrawal during the first week after transplantation surgery, or complete avoidance of steroids, offers potential benefits. The interleukin-2 (IL-2) receptor antibodies, basiliximab and daclizumab, can enable aggressive steroid minimization protocols that are efficacious while reducing toxicity. A multicenter, randomized trial of kidney transplant recipients has shown the incidence of biopsy-proven acute rejection with basiliximab, cyclosporine and mycophenolate mofetil with steroids withdrawn at day 5 to be similar to a conventional triple-therapy regimen. A single perioperative dose of corticosteroids with an IL-2 receptor antagonist also seems as efficacious as standard steroid therapy. Corticosteroid-minimization with IL-2 receptor antagonists has also been investigated with sirolimus-containing regimens and has shown excellent outcomes. Experience with complete steroid avoidance, using an IL-2 receptor antagonist, is limited, but initial results are promising, particularly in pediatric patients. Administration of an IL-2 receptor antagonist with aggressive steroid minimization in selected, well-monitored patients seems reasonable, but further trials are required to define optimal protocols.

The Use of Campath-1H as Induction Therapy in Renal Transplantation: Preliminary Results

BACKGROUND

In an attempt to reduce both initial and long-term (nephrotoxic) calcineurin inhibitor maintenance dosage and totally eliminate maintenance corticosteroids, alemtuzumab (Campath-1H) was used as induction therapy in first cadaver and non-HLA-identical living donor renal transplantation.

METHODS

Forty-four de novo renal allograft recipients were treated with Campath-1H (0.3 mg/kg) on days 0 and 4 postoperatively, preceded by methylprednisolone boluses. Maintenance target 12-hr tacrolimus trough levels of 5 to 7 ng/mL were operational from the outset as well as (reduced) mycophenolate mofetil dosage of 500 mg twice daily. No corticosteroids were planned to be given after the first week postoperatively.

RESULTS

With a median follow-up of 9 (range, 1-19) months, patient and graft survival rates are each at 100%. Biopsy-proven acute rejection was diagnosed in four patients. Infections requiring hospitalization developed in four patients. Thirty-eight recipients remain without the need for long-term corticosteroid therapy.

CONCLUSIONS

In an early assessment, the combination of Campath-1H, low dosing of tacrolimus and mycophenolate mofetil, and avoidance of maintenance corticosteroid use seems to be safe and effective for kidney transplant recipients. Long-term outcomes will be reported in the future.

Mycophenolate mofetil in solid-organ transplantation

This review focuses on the use of mycophenolate mofetil (MMF) as an immunosuppressive agent in solid-organ transplantation. MMF, a non-competitive inhibitor of inosine monophosphate dehydrogenase, blocks de novo purine synthesis in T and B lymphocytes, resulting in the selective inhibition of proliferation of these cells in response to antigenic stimuli. MMF may also promote apoptosis of these cells. The immunosuppressive ability of MMF is thought to derive mainly from the inhibition of inosine monophosphate dehydrogenase. The other effects of MMF include suppression of antibody synthesis by B lymphocytes, inhibition of proliferation of smooth muscle cells in culture and impaired glycosylation of adhesion molecules. MMF may exhibit anti-inflammatory effects resulting from decreased activity of the inducible form of nitric oxide synthase, a consequence of depletion of tetrahydrobiopterin, which leads to decreased generation of peroxynitrite, a pro-inflammatory molecule. The pharmacokinetics, pharmacodynamics and principles underlying therapeutic drug monitoring of MMF are reviewed. The results of the pivotal clinical trials of MMF in kidney and heart transplantation are discussed and a summary of the major studies demonstrating a positive effect of MMF on renal transplantation outcomes is presented. The use of MMF in the context of ABO-incompatible renal transplantation, renal transplantation in highly sensitised and cross-match positive recipients, humoral rejection of renal allografts, chronic allograft nephropathy and steroid/calcineurin inhibitor minimisation in renal transplantation are also discussed.

Immunosuppression for Long-Term Maintenance of Renal Allograft Function

The incidence and severity of acute rejection episodes was markedly reduced by the introduction of new immunosuppressive drug regimens for renal transplantation, resulting in improved graft survival at 1 year. However, only modest improvement has been shown in long-term graft function rates. This overview evaluates the efficacy of currently used immunosuppressive drugs and drug combinations for long-term maintenance therapy. Prospective controlled trials rarely extend beyond 5 years; therefore, registry data and retrospective reports have also been employed. From currently available data it may be concluded that the initial beneficial effect of ciclosporin (cyclosporin) is lost 10 years after transplantation. Tacrolimus is an alternative to ciclosporin with a different profile of adverse effects and a higher efficacy in acute rejection treatment. For long-term maintenance, projected half-lives of kidney graft function are in favour of tacrolimus. Mycophenolate mofetil (MMF) has been shown to significantly reduce the incidence of early rejections. However, the improved long-term graft survival reported in retrospective studies has still to be confirmed in controlled trials. There is no convincing evidence for superiority of triple therapy including prednisone (or prednisolone), calcineurin inhibitors and azathioprine/MMF over dual therapy without azathioprine/MMF with respect to long-term outcome. Withdrawal of corticosteroids or calcineurin inhibitors clearly reduces adverse drug effects but carries the risk of acute rejection episodes. Avoidance of corticosteroids by using new immunosuppressive drug combinations may be an option to minimise toxic adverse effects in the future. At present, it seems unjustified to convert renal transplant recipients with stable graft function and tolerable adverse effects from one drug to another solely in expectation of future benefits. Acute early or late rejection episodes and intolerable adverse effects are good reasons for conversions between calcineurin inhibitors or cytotoxic agents. Chronic allograft nephropathy with slowly deteriorating graft function remains an unresolved problem.

Two Doses of Daclizumab in Conjunction with Low-Dose Cyclosporine, Mycophenolate Mofetil and Steroids Resulted in a Low Incidence of Acute Rejection after Renal Transplantation

Five doses of daclizumab, given initially after kidney transplantation, reduce the rate of acute rejection (AR). Without cyclosporin A (CsA), a protocol, including daclizumab, mycophenolate mofetil (MMF) and corticosteroids (CSs), has recently shown efficacy in terms of graft function and survival. The rate of AR was relatively high, however. In this single-centre study, a CsA low-dose regimen was combined with two doses of daclizumab (1 mg/kg day 0 and 14), plus MMF (2 g) and CS. Forty-three cadaver donor renal recipients were included. Following the onset of graft function, target trough levels of CsA were 150-200 ng/ml for 90 days, then 100-150 ng/ml. One year AR rate was 23% (n = 10) and events occurred at a median of 2.9 months (range from 9 days to 9.6 months). Delayed graft function (DGF) (absent spontaneous reduction of serum creatinine day 1) was 51%. Graft survival was 95% and patient survival 98% after 1 year. With respect to our previous experience, we used CsA, azathioprine and CSs (n = 223) from 1988 to 1995, and the rate of AR was 57%. From 1996 to 1998, standard CsA doses, MMF and CS (n = 67) resulted in 31% AR. Median time to AR was 0.8 and 1.0 month, and the rate of DGF was 20 and 22%, respectively. This CsA low-dose protocol, including two doses of daclizumab, MMF and CS, resulted in a reduction and delay of AR episodes and excellent graft function, graft survival and patient survival, despite an increase in DGF.