Complete avoidance of calcineurin inhibitors in renal transplantation: a randomized trial comparing sirolimus and tacrolimus

Recent developments in kidney transplantation--a critical assessment

Rapid advances have been made in decreasing acute rejection rates and improving short-term graft survival in kidney transplant recipients. Whether these advances ultimately will lead to a commensurate improvement in long-term survival is not yet known. In recent years, greater attention has been placed on defining the precise etiology of graft loss, determining how far and with what agents we can minimize immunosuppression, and delineating the nature of both T-cell-mediated as well as antibody-mediated rejection. In addition, with the growing disparity of available organs and patients in need of a transplant, greater attention has been placed on optimizing allocation. In this minireview, we will focus on developments over the last couple of years, paying particular attention to insights, studies and observations that may attempt to elucidate some of these open questions.

Sirolimus in kidney transplantation indications and practical guidelines: de novo sirolimus-based therapy without calcineurin inhibitors

A de novo calcineurin inhibitor avoidance regimen based on sirolimus has been successfully used worldwide; demonstrating improved renal function from 1 to 5 years. This includes use of an induction antibody followed by sirolimus, mycophenolate mofetil, and steroids. This combination has a somewhat different side effect profile and wider experience has revealed that the use of de novo sirolimus requires careful therapeutic drug level monitoring, especially the first 6 months posttransplant. Experience has also demonstrated that delaying the introduction of sirolimus in patients considered at high risk for early mammalian target of rapamycin associated complications will optimize these results. For such recipients, the initial use of a calcineurin inhibitor drug for 2 to 4 months is preferred, followed by conversion to sirolimus. The late withdrawal of steroids may be possible, but awaits further evaluation in randomized controlled trials.

Mycophenolic acid formulations in adult renal transplantation - update on efficacy and tolerability

The description more than 30 years ago of the role of de novo purine synthesis in T and B lymphocytes clonal proliferation opened the possibility for selective immunosuppression by targeting specific enzymatic pathways. Mycophenolic acid (MPA) blocks the key enzyme inosine monophosphate dehydrogenase and the production of guanosine nucleotides required for DNA synthesis. Two MPA formulations are currently used in clinical transplantation as part of the maintenance immunosuppressive regimen. Mycophenolate mofetil (MMF) was the first MPA agent to be approved for the prevention of acute rejection following renal transplantation, in combination with cyclosporine and steroids. Enteric-coated mycophenolate sodium (EC-MPS) is an alternative MPA formulation available in clinical transplantation. In this review, we will discuss the clinical trials that have evaluated the efficacy and safety of MPA in adult kidney transplantation for the prevention of acute rejection and their use in new combination regimens aiming at minimizing calcineurin inhibitor toxicity and chronic allograft nephropathy. We will also discuss MPA pharmacokinetics and the rationale for therapeutic drug monitoring in optimizing the balance between efficacy and safety in individual patients.

Efficacy on renal function of early conversion from cyclosporine to sirolimus 3 months after renal transplantation: concept study

Sirolimus (SRL) allows to minimize the use of cyclosporine (CsA), but de novo administration after transplantation is associated with various complications. We report a prospective, open-label, multicenter randomized study to evaluate conversion from a CsA-based regimen to a SRL-based regimen 3 months after transplantation. One hundred ninety-two of a total of 237 patients were eligible at 3 months to be converted to SRL (n = 95) or to continue CsA (n = 97). All patients were also given mycophenolate mofetil (MMF) and oral steroids, planned to be discontinued at month 8. The primary endpoint, the clearance estimated according to Cockcroft and Gault at week 52, was significantly better in the SRL group (68.9 vs. 64.4 mL/min, p = 0.017). Patient and graft survival were not statistically different. The incidence of acute rejection episodes, mainly occurring after withdrawal of steroids, was numerically but not statistically higher in the SRL group (17% vs. 8%, p = 0.071). Sixteen patients discontinued SRL, mainly for adverse events (n = 11), and seven patients discontinued CsA for renal failure or acute rejection. Significantly, more patients in the SRL group reported aphthous, diarrhea, acne and high triglyceride levels. Conversion CsA to SRL 3 months after transplantation combined with MMF is associated with improvement in renal function.

Mycophenolate mofetil: safety and efficacy in the prophylaxis of acute kidney transplantation rejection

Mycophenolate mofetil (MMF), a prodrug of mycophenolic acid (MPA), is an inhibitor of inosine monophosphate dehydrogenase (IMPDH). It preferentially inhibits denovo pathway of guanosine nucleotide synthesis in T and B-lymphocytes and prevents their proliferation, thereby suppresses both cell mediated and humoral immune responses. Clinical trials in kidney transplant recipients have shown the efficacy of MMF in reducing the incidence and severity of acute rejection episodes. It also improves long term graft function as well as graft and patient survival in kidney transplant recipients. MMF is useful as a component of toxicity sparing regimens to reduce or avoid exposure of steroids or calcineurin inhibitor (CNI). Enteric-coated mycophenolate sodium (EC-MPS) can be used as an alternative immunosuppressive agent in kidney transplant recipients with efficacy and safety profile similar to MMF.

A systematic approach to minimizing wound problems for de novo sirolimus-treated kidney transplant recipients

BACKGROUND

Wound healing problems and lymphoceles have been reported with greater frequency in kidney recipients given de novo sirolimus. This problem has led to increased patient morbidity and cost; and has been an impediment to the completion of randomized controlled trials in which wound problems have necessitated premature discontinuation of mammalian target of rapamycin inhibitors.

METHODS

We developed a systematic program to reduce these problems based on patient selection (body mass index [BMI] <32 kg/m2), the use of closed suction drains, modifications of surgical technique, and avoidance of a loading dose of sirolimus. Consecutive series of adult kidney-only recipients given antibody induction followed by de novo sirolimus, mycophenolate mofetil, and steroids were compared; group 1: 204 patients transplanted with few restrictions and group 2: 103 patients transplanted using the above program.

RESULTS

This approach resulted in a significant reduction (group 2 vs. group 1) in cumulative wound complications (7.8% vs. 19.6%, P=0.007), and nonoperative wound complications (2.9% vs. 14.2%, P=0.001). In addition, the incidence of lymphoceles detected (22.3% vs. 47.1%, P<0.0001), treated (4.8% vs. 24.5%, P<0.0001), or needing surgical intervention (1.9% vs. 14.2%, P=0.001) was significantly reduced. Multivariate analysis demonstrated that a BMI more than 30 to 32 kg/m2 was the most significant variable related to delayed wound healing (odds ratio [OR] 3.01, 0.02) or surgical repair (OR 8.05, P=0.0001), whereas BMI (OR 1.54, P=0.038) and acute rejections (OR 1.34, P=0.03) were most associated with lymphocele treatment.

CONCLUSIONS

A systematic program of wound care using de novo sirolimus can produce wound healing complications comparable with that reported with other agents.

Late spontaneous kidney graft decapsulation after administration of sirolimus in a recipient with chronic hepatitis B and C infection: a case report

Late spontaneous kidney graft decapsulation with fluid collection is a rare condition with only a few cases reported in the literature. Common causes of renal allograft rupture include acute rejection, acute tubular necrosis, renal vein thrombosis, and trauma. Sirolimus related late spontaneous decapsulation has not been reported in the past. Interestingly, sirolimus may promote lymphocele formation in renal transplant recipients, including those presenting with chronic hepatitis B or C. Herein, we report a case of late spontaneous decapsulation with subcapsular hematoma formation developing 12 years after receipt of a cadaveric allograft. The patient was infected with both hepatitis B and C viruses. Cyclosporine was replaced by sirolimus for maintenance therapy because of chronic rejection and acute deterioration of renal function. He presented to the hospital at 9 months after sirolimus inception because of a sudden onset of pain and swelling over the kidney graft. Magnetic resonance imaging found the capsule to be stripped from the kidney by a collection of liquefied hematomas. A laparoscopic fenestration was performed by creation of a peritoneal window adjacent to the renal allograft. When patients have chronic hepatitis, tacrolimus might be a better choice than sirolimus.

Tacrolimus withdrawal and conversion to sirolimus at three months post-pediatric renal transplantation

Nephrotoxicity caused by CNI may adversely affect long-term graft outcomes. For this reason, we have adopted a protocol for withdrawing TAC and converting to SRL at three months post-renal transplantation. All recipients received basiliximab induction and TAC, MMF, and prednisone. Patients without acute rejection by surveillance biopsy at three months were eligible for SRL conversion.

RESULTS

From August 2004 to September 2006, TAC was withdrawn and replaced by SRL in 30 first transplant recipients, who were followed for six to 39 months (mean 18 +/- 8). Renal function did not improve significantly after SRL conversion (p = 0.25). Acute rejection occurred in three patients (10%) at five to 12 months after CNI withdrawal. There were no occurrences of wound healing problems, pneumonitis or post-transplant lymphoproliferative disease. Thrombocytopenia and diabetes each occurred in one patient. Four patients received treatment for hypercholesterolemia. CNI withdrawal and replacement with SRL was an effective regimen in children who did not display biopsy evidence of acute rejection at three months post-transplant. While these early results are promising, the ultimate benefit of this protocol to enhance the long-term renal function and graft survival requires ongoing follow-up.

Pathogenesis and management of chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is a common cause of late kidney transplant failure, characterized by progressive histological damage in the allograft. Although functional biomarkers such as creatinine are typically used to predict CAN, recent evidence suggests that composite, quantitative histological indices may be better predictors of long-term graft outcomes. Calcineurin inhibitors (CNIs) have been associated with major improvements in early rejection outcomes, but appear to cause both acute and chronic nephrotoxicity. The acute phase is associated with functional nephrotoxicity and is reversible with a reduction in CNI dosage, whereas the chronic phase is characterized by persistent histological lesions that are typically irreversible. Results from recent clinical trials suggest that converting from a CNI to sirolimus, withdrawing a CNI from a sirolimus-based regimen or using a CNI-free strategy may improve long-term outcomes by reducing CNI-related nephrotoxicity. However, in the de novo transplant setting, triple therapy with sirolimus, mycophenolate mofetil and corticosteroids is not recommended in combination with basiliximab induction. A treatment algorithm, based on the patient's histological score obtained on an allograft biopsy taken at approximately 6-12 months post-transplant, has been developed by our group and is described here.

Minimization of calcineurin inhibitors to improve long-term outcomes in kidney transplantation

Long-term outcomes after kidney transplantation remain suboptimal, despite the great achievements observed in recent years with the use of modern immunosuppressive drugs. Currently, the calcineurin inhibitors (CNI) cyclosporine and tacrolimus remain the cornerstones of immunosuppressive regimens in many centers worldwide, regardless of their well described side-effects, including nephrotoxicity. In this article, we review recent CNI-minimization strategies in kidney transplantation, while emphasizing on the importance of long-term follow-up and patient monitoring. Finally, accumulating data indicate that low-dose CNI-based regimens would provide an interesting balance between efficacy and toxicity.

Comparison of four different immunosuppression protocols without long-term steroid therapy in kidney recipients monitored by surveillance biopsy: five-year outcomes

Induction and maintenance immunosuppression protocols with or without long-term steroid therapy in kidney transplant recipients are variable and are transplant center-specific. The aim of this prospective randomized pilot study was to compare 5-year outcomes in kidney recipients maintained on 4 different calcineurin inhibitor (CNI)-based immunosuppression protocols without long-term steroid therapy. Two hundred consenting patients who received kidney transplants between June 2000 and October 2004 were enrolled in 4 immunosuppression protocol groups, with 50 patients in each group: cyclosporine (CSA)/mycophenolate mofetil (MMF), CSA/sirolimus (SRL), tacrolimus (TAC)/MMF, and TAC/SRL. Induction therapy was done with basiliximab and methylprednisolone. Steroids were withdrawn on post-transplant day 2, and long-term steroid therapy was not used. Demographic characteristics among the four groups were comparable; approximately 50% of the recipients were African American and > or =80% of the kidneys transplanted were from deceased donors. Clinical acute rejection (CAR) was confirmed by biopsy and treated with intravenous pulse steroid therapy. Steroid-unresponsive CAR was treated with Thymoglobulin. Surveillance biopsies were performed at 1, 6, 12, 24, 36, 48, and 60 months to evaluate subclinical acute rejection (SCAR), chronic allograft injury (CAI), and other pathological changes per the Banff 2005 schema. The primary end point was CAR, and secondary end points were 5-year patient and graft survival rates, renal function, SCAR, CAI, and adverse events. In the first year post-transplant, the incidence of CAR was 18% in the CSA/MMF group, 8% in the CSA/SRL group, 14% in the TAC/MMF group, and 4% in the TAC/SRL group (CSA/MMF vs. TAC/SRL; p=0.05). The incidence of SCAR was 22% in the CSA/MMF group, 8% in the CSA/SRL group, 16% in the TAC/MMF group, and 6% in the TAC/SRL group (CSA/MMF vs. CSA/SRL and TAC/SRL; p=0.05). After the first year, the incidences of CAR and SCAR decreased and were comparable in all 4 groups. At 5 years post-transplant, cumulative CAI due to interstitial fibrosis/tubular atrophy (IF/TA), hypertension (HTN), and chronic calcineurin inhibitor (CNI) toxicity was observed in 54%, 48%, and 8% of the CSA/MMF group vs. 16%, 36%, and 12% of the CSA/SRL group vs. 38%, 24% and 6% of the TAC/MMF group vs. 14%, 25% and 12% of the TAC/SLR group (IF/TA: CSA/MMF vs. CSA/SRL and TAC/SRL; p=0.04, HTN: CSA/MMF vs. TAC/MMF and TAC/SRL; p=0.05, CNI toxicity: TAC/SRL and CSA/SRL vs. TAC/MMF; p=0.05). Five-year patient and graft survival rates were 82% and 60% in the CSA/MMF group, 82% and 60% in the CSA/SRL group, 84% and 62% in the TAC/MMF group, and 82% and 64% in the TAC/SRL group (p=0.9). Serum creatinine levels and creatinine clearances at 5 years were comparable among the groups. Our data show that the rates of CAR and SCAR in the first year post-transplant were significantly lower in the CSA/SRL and TAC/SRL groups and that cumulative CAI rates due to IF/TA and HTN at 5 years were significantly lower in the TAC/MMF, TAC/SRL, and CSA/SRL groups than in the CSA/MMF group. Despite significant differences in the incidences of CAR and SCAR and prevalence of different types of CAI at 5 years, renal function and patient and graft survival rates at 5 years were comparable among kidney recipients maintained on 4 different immunosuppression protocols without long-term steroid therapy.

Design and analysis of clinical trials in transplantation: principles and pitfalls

The contributions of prospective randomized controlled trials (RCTs) to the advancement of solid organ transplantation are well appreciated. However, some misconception exists that results deriving from RCTs uniformly provide clinically relevant, definitive and generalized evidence. While there is little doubt that RCTs are the gold standard to test cause-and-effect relationships, the quality and subsequent utility of trials carried out in this field vary substantially. As with all other disciplines, our ability to interpret and implement the findings of RCTs into practice is strongly dependent on the study design and statistical rigor of the analysis. Failure to conduct trials with appropriate standards or interpret trials with the appropriate limitations may place patients at risk or waste valuable healthcare resources. The purpose of this review is to delineate important principles of study design and analysis of RCTs that are commonly overlooked. This review will discuss possible limitations of trials with specific applications in the field of transplantation. Progress in the field of transplantation is highly dependent on critical examination of existing clinical trials and vigilance regarding the optimal development of future trials.

Immunosuppression without calcineurin inhibition: optimization of renal function in expanded criteria donor renal transplantation

INTRODUCTION

To assess the efficacy of calcineurin inhibitor (CNI)-free immunosuppression vs. calcineurin-based immunosuppression in patients receiving expanded criteria donor (ECD) kidneys.

PATIENT AND METHODS

Thirteen recipients of ECD kidneys were enrolled in this pilot study and treated with induction therapy and maintained on sirolimus, mycophenolate mofetil (MMF) and prednisone. A contemporaneous control group was randomly selected comprised of 13 recipients of ECD kidneys who had been maintained on CNI plus MMF and prednisone.

RESULTS

For the study group vs. the control group, two-yr graft survival was 92.3% vs. 84.6% (p = NS), two-yr patient survival was 100% vs. 92.3% (p = NS) and the acute rejection rates were 23% vs. 31% (p = NS), respectively. Renal function was significantly better in the study group compared with control up to the six-month mark, after which, it remained numerically but not statistically significant. Complications were more common in the study group, but serious adverse events requiring discontinuation were rare.

CONCLUSION

This pilot study demonstrates that CNI-free regimens can be safely implemented in patients receiving ECD kidneys with excellent two-yr patient and graft survival and good renal allograft function. Longer follow-up in larger randomized controlled trials are necessary to establish these findings.

Randomized trial of single-dose versus divided-dose rabbit anti-thymocyte globulin induction in renal transplantation: an interim report

BACKGROUND

The optimal dosing protocol for rabbit anti-thymocyte globulin (rATG) induction in renal transplantation has not been determined, but evidence exists that rATG infusion before renal allograft reperfusion improves early graft function. Infusing a large rATG dose over a short interval has not previously been evaluated for its effect on renal function and allograft nephropathy in a prospective, randomized comparison against conventional rATG induction.

METHODS

Between April 20, 2004 and December 26, 2007 we enrolled renal transplant patients into a prospective, randomized, nonblinded trial of two rATG dosing protocols (single dose, 6 mg/kg vs. divided doses, 1.5 mg/kg every other day x 4; target enrollment=160) followed after 6 months by calcineurin-inhibitor withdrawal. Primary endpoints are renal function by calculated glomerular filtration rate (GFR) and chronic allograft nephropathy at protocol biopsy. We now present the early GFR data of all 160 patients and safety and efficacy data of the first 142 patients with 6 months follow up and before calcineurin inhibitor withdrawal (average follow up=23.3+/-11.6 months).

RESULTS

There were no differences between groups in rATG-related adverse events, patient and graft survival, acute rejection, or chronic allograft nephropathy rate at 6 months. Calculated DeltaGFR (POD 1-4) was significantly better in the single-dose group (P=0.02), with a trend toward improved renal function from months 2 to 6 in recipients of deceased donor kidneys (P=0.08).

CONCLUSIONS

This study demonstrates that administering 6 mg/kg of rATG over 24 hr is safe and is associated with improved early renal function compared with administering rATG in alternate-day doses.

Mammalian target of rapamycin inhibitor dyslipidemia in kidney transplant recipients

The incidence, pathogenesis, consequences and treatment of mammalian target of rapamycin (mTOR) inhibitor dyslipidemia are not well described. We conducted a systematic review of randomized controlled trials reporting cholesterol and triglycerides in mTOR versus non-mTOR inhibitor immunosuppressive treatment regimens in kidney transplant recipients. All but one of 17 trials reported higher levels of cholesterol and triglycerides, or an increased prevalence of treatment with lipid-lowering agents. Approximately 60% of mTOR inhibitor-treated patients received lipid-lowering agents (2-fold higher than controls). There appeared to be little difference between dyslipidemias caused by sirolimus (14 trials) versus everolimus (3 trials). It was difficult to determine the extent to which declines in lipids over time posttransplant were due to lipid-lowering therapy, changes in doses and/or discontinuations of mTOR inhibitors. From the four trials that measured lipoproteins, it appeared that at least some of the increase in total cholesterol with mTOR inhibitors was due to increased low-density lipoprotein cholesterol. What direct or indirect effects mTOR inhibitors have on atherosclerotic cardiovascular disease in kidney transplant patients are unknown. However, in the absence of the necessary clinical trials, dyslipidemia should be managed, as it would be in nontransplant patients at high risk for cardiovascular disease.

Lifetime cost-effectiveness of calcineurin inhibitor withdrawal after de novo renal transplantation

After renal transplantation, immunosuppressive regimens associated with high short-term survival rates are not necessarily associated with high long-term survival rates, suggesting that regimens may need to be optimized over time. Calcineurin inhibitor (CNI) withdrawal from a sirolimus-based immunosuppressive regimen may maximize the likelihood of long-term graft and patient survival by minimizing CNI-associated nephrotoxicity. In this study, a lifetime Markov model was created to compare the cost-effectiveness of a sirolimus-based CNI withdrawal regimen (sirolimus plus steroids) with other common CNI-containing regimens in adult de novo renal transplantation patients. Long-term graft survival was estimated by renal function and data from published studies and the US transplant registry, including short- and long-term outcomes, utility weights, and health-state costs were incorporated. Drug costs were based on average daily consumption and wholesale acquisition costs. The model suggests that treatment with sirolimus plus steroids is more efficacious and less costly than regimens consisting of a CNI, mycophenolate mofetil, and steroids; therefore, CNI withdrawal not only shows potential for long-term clinical benefits but also is expected to be cost-saving over a patient's life compared with the most commonly prescribed CNI-containing regimens.

The pharmacodynamic effect of sirolimus: individual variation of cytokine mRNA expression profiles in human whole blood samples

Sirolimus (SRL) has become an important alternative to calcineurin inhibitors due to its unique mechanism of action. Since rejection and poor graft outcome are still frequent problems despite therapeutic-range blood concentrations, pharmacodynamic measurements of its immunosuppressive effects would be of great clinical value to optimize treatment in individual patients. We performed a human whole blood assay using real time cytokine RT-PCR for the pharmacodynamic assessment of SRL. IL-2, IL-4 and IL-6 mRNA levels were quantitatively determined upon T-cell-specific stimulation in healthy individuals (n=11; in vitro) and in kidney-transplant patients (n=3; ex vivo). Furthermore, IL-2 protein secretion and T-cell proliferation was measured. After 24h incubation we observed a stronger suppression of IL-2 and IL-4 mRNA expression upon SRL addition (p<0.005; p<0.005) versus 4h (p<0.05; p<0.05). SRL effects displayed a remarkable interindividual variation, which proved to be independent of the concentration applied. Notably, 3/11 and 2/11 individuals had unaffected IL-2 and IL-4 mRNA expression after 4h incubation with SRL, respectively. In contrast, a general suppression of IL-2 protein secretion and T-cell proliferation was induced. Analysis of kidney-transplant patients verified interindividual variation and proved comparability of in vitro and ex vivo effects. We describe an individual degree of SRL-sensitivity that may correlate with clinical efficacy. Rather than analysis of one single peak, we suggest determination of two absolute cytokine mRNA peak levels for the pharmacodynamic assessment of SRL. However, prospective clinical studies are necessary to determine whether individual degrees of SRL-sensitivity correlate with clinical outcome.

Long-term efficacy and safety of a calcineurin inhibitor-free regimen in live-donor renal transplant recipients

Calcineurin inhibitor (CNI) nephrotoxicity is a major concern after renal transplantation. To investigate the safety and efficacy of a CNI-free immunosuppressive regimen, 132 live-donor renal transplant recipients were included in a prospective, randomized controlled trial. All patients received induction therapy with basiliximab and steroids. The patients were randomized to a maintenance immunosuppression regimen that included steroids, sirolimus, and either low-dose tacrolimus or mycophenolate mofetil (MMF). Over a mean follow-up period of approximately 5 yr, patient and graft survival did not significantly differ between the two maintenance regimens. Patient survival was 93.8% and 98.5% in the tacrolimus/sirolimus and MMF/sirolimus groups, respectively, and graft survival was 83% and 88%, respectively. However, the MMF/sirolimus group had significantly better renal function, calculated by Cockcroft-Gault, from the second year post-transplant until the last follow-up. In addition, this group was less likely to require a change in their primary immunosuppression regimen than the tacrolimus/sirolimus group (20.8% versus 53.8%, P = 0.001). The safety profile was similar between groups. In summary, after long-term follow-up, a CNI-free maintenance regimen consisting of sirolimus, MMF, and steroids was both safe and efficacious among low to moderate immunologic risk renal transplant recipients.

Kidney transplant histology after one year of continuous therapy with sirolimus compared with tacrolimus

Analysis of 1-year surveillance biopsies was carried out for kidney transplant recipients participating in a randomized trial comparing tacrolimus- and sirolimus-based immunosuppression. The analysis was restricted to recipients remaining on assigned regimen throughout the first posttransplant year. Biopsies from 57 of 84 (68%) tacrolimus-randomized recipients were compared with 38 of 81 (47%) of sirolimus-randomized recipients, the discrepancy being explained by a higher rate of sirolimus discontinuation for non-graft-related complications. Included recipients from the two groups did not differ for baseline characteristics or 1-year iothalamate clearance. Histologic analysis indicated no differences between the groups for glomerular, arterial/arteriolar, or acute interstitial abnormalities. There were, however, significantly higher mean scores in the tacrolimus group for interstitial fibrosis and tubular atrophy with a trend toward higher estimated percent interstitial fibrosis. The results indicate that sirolimus may be associated with reduced early graft fibrosis compared with tacrolimus. This potential benefit is offset by lower success rate in maintaining the regimen and was not accompanied by superior glomerular filtration rate at 1 year.

Sirolimus-based triple immunosupression with antithymocyte globulin induction in expanded criteria donor kidney transplantation

BACKGROUND

Target of rapamycin inhibitors have presented similar graft and patient outcomes with no evidence of drug-induced nephrotoxicity when compared with calcineurin inhibitors. The principal aim of this study is to demonstrate the efficacy of sirolimus-based triple immunosuppression with antithymocyte globulin induction in expanded donor kidney transplantation.

METHODS

Twenty-seven primary expanded criteria donor kidney transplant recipients were recruited. The severity of kidney damage was qualified by zero-hour biopsies. Protocol biopsies were performed at 1 year to assess the chronic allograft damage. Death, graft function, proteinuria and adverse events were systematically analysed during the study period.

RESULTS

The mean follow up was 20.2 months. Patient and graft survival was 100% with a mean glomerular filtration rate (GFR) of 53.1+/-4.9 mL/min at last follow up. The cumulative incidence of acute rejection was 11% at the last follow up. At 1 year, mean creatinine, GFR and proteinuria were 1.84 mg/dL, 52.3 mL/min, 651.5 mg/day, respectively. Four patients required surgical intervention due to urinary complications and recovered successfully. Two patients developed acute graft dysfunction due to acute tubular necrosis which was presumably drug related. Ten patients developed relapsing urinary tract infections and three patients had pneumonia. No infectious death occurred throughout the study period. Baseline renal structure was preserved in 13 biopsies at 1 year post transplant. Five patients demonstrated progressive but mild tubular atrophy or interstitial fibrosis in their protocol biopsies. The mean chronic allograft damage index scores at baseline and at 1 year from biopsy were 2.57+/-0.23 and 2.83+/-0.23, respectively (P=0.046).

CONCLUSIONS

Low-dose sirolimus-based triple immunosuppression with antibody induction offered a safe clinical outcome in expanded criteria donor kidneys with the achievement of stable renal function and favourable recipient outcomes throughout the short term. However, mild progression of histological damage and increased risk of bacterial infection are a major concern. Additionally, the benefit (if any) of the low acute rejection rate on long-term graft outcome is still undetermined.

Late kidney allograft loss: what we know about it, and what we can do about it

Despite dramatic improvements in immunosuppression, late graft loss after kidney transplantation remains a common and difficult problem. Histologic evaluation may reveal changes related to BK polyomavirus infection, hypertension, or calcineurin inhibitor toxicity, which can help to guide therapy. The designation chronic allograft nephropathy should thus be reserved for biopsies with tubular atrophy and interstitial fibrosis without an apparent cause. Although the cause clearly includes both antigen-dependent and antigen-independent events, the approach remains largely to exclude immune mechanisms. Although this review discusses the potential contribution of antibody to chronic injury, it focuses on the basic elements of kidney injury, the role of parenchymal cells in promoting injury, and the proliferative and inflammatory responses that accompanying injury. Strategies to manage these recipients include close attention to accompanying hypertension, diabetes, and hyperlipidemia, as well as consideration for altering immunosuppression; however, therapies that limit epithelial-to-mesenchymal transition or directly block fibrosis pathways may reduce chronic allograft fibrosis and may prove to be useful. Understanding the basic pathogenesis sufficiently to allow early intervention may finally benefit patients who are at high risk for tubular atrophy and interstitial fibrosis and promote their long-term graft function.

Minimizing immunosuppression, an alternative approach to reducing side effects: objectives and interim result

Exceptionally low acute rejection rates and excellent graft survival can be achieved with cyclosporine and tacrolimus (CNI)-based immunosuppressive protocols that incorporate antiproliferative immunosuppressants and corticosteroids. However, despite short-term success, long-term attrition of graft function and side effects of immunosuppressive agents continue to be significant problems, leaving clinicians looking for possible interventions. CNI nephrotoxicity is but one of numerous factors that may contribute to long-term damage in transplant kidneys. Metabolic, cosmetic, and neuropsychiatric complications of steroids affect quality of life after transplantation. Newer immunosuppressive agents such as mycophenolate mofetil and sirolimus (Rapa) have raised the possibility of withdrawing or avoiding CNIs or steroids altogether. In this report we review studies that address either CNI or steroid minimization strategies and discuss their risks versus benefits. Given the accumulated experience to date, in our opinion the use of CNIs and steroids as part of immunosuppressive regimens remains the proven standard of care for renal transplant patients. The long-term safety and efficacy of CNI and steroid minimization strategies needs to be further validated in controlled clinical trials with adequate long-term follow-up.

Calcineurin inhibitor-sparing regimens in solid organ transplantation: focus on improving renal function and nephrotoxicity

BACKGROUND

The calcineurin inhibitors (CNIs), cyclosporine and tacrolimus, have had a revolutionary effect on the overall success of renal transplantation through reduction in early immunologic injury and acute rejection rates. However, the CNIs have a significant adverse impact on renal function and cardiovascular disease, and extended long-term graft survival has not been achieved. The recognition of these effects sparked interest in CNI-sparing strategies. Strategies to limit CNI exposure include CNI minimization, avoidance, and withdrawal. We sought to review the impact of CNI-sparing strategies in kidney, liver, and heart transplantation.

MATERIALS AND METHODS

A PubMed search 1966 to August 2006 was conducted to identify relevant research articles, and the references of these articles as well as the authors' personal files were reviewed.

RESULTS

Calcineurin inhibitor minimization using mycophenolate mofetil or sirolimus may be associated with a modest increase in creatinine clearance (CrCl) and a decrease in serum creatinine (SCr) in the short term. Despite improvement in CrCl or SCr, CNI nephrotoxicity and chronic allograft nephrotoxicity are progressive over time when CNI exposure is maintained. In kidney transplantation, the tubulo-interstitial and glomerular damage are irreversible. Mycophenolate mofetil may improve renal outcomes during CNI minimization more than sirolimus, and antibody induction may be effective to limit CNI exposure, but longer-term follow-up data are required. Use of sirolimus with mycophenolate mofetil or azathioprine to avoid CNI exposure de novo has improved glomerular filtration rate for at least two yr in most studies in kidney transplantation; however, experience is limited in liver and heart transplantation, and reports of delayed graft function and wound healing with sirolimus may have dampened enthusiasm for de novo use. Late CNI withdrawal has achieved variable results, possibly because withdrawal was attempted after the kidney damage was too extensive. Early CNI withdrawal, prior to significant graft damage, has generally improved CrCl and markers of fibrosis and decreased chronic allograft lesions, a finding also observed with sirolimus in most CNI avoidance studies. Successful withdrawal appears to be more effective than CNI minimization.

CONCLUSIONS

Calcineurin inhibitors are associated with significant nephrotoxicity and chronic kidney damage. Minimization is associated with a modest increase in renal function, but persistent damage is observed on biopsies as long as the CNIs are continued. Avoidance is hampered by lack of experience and possible sirolimus-induced side effects. CNI withdrawal may be the best option by delivering CNIs during the early period of immunologic graft injury and then converting them to less nephrotoxic agents before significant renal damage occurs.

Sirolimus reduces polycystic liver volume in ADPKD patients

The immunosuppressive agent sirolimus exerts an antiproliferative effect by inhibiting mammalian target of rapamycin (mTOR). Because excessive proliferation of the biliary epithelium is a prominent feature of the polycystic liver that accompanies autosomal dominant polycystic kidney disease (ADPKD), we hypothesized that sirolimus may benefit patients with this disorder. We retrospectively measured the volumes of polycystic livers and kidneys in ADPKD patients who had received kidney transplants and had participated in a prospective randomized trial that compared a sirolimus-containing immunosuppression regimen to a tacrolimus-containing regimen. Sixteen subjects (seven with sirolimus, nine with tacrolimus) had received abdominal imaging studies within 11 mo before and at least 7 mo after transplantation, making them suitable for our analysis. Treatment with the sirolimus regimen for an average of 19.4 mo was associated with an 11.9 +/- 0.03% reduction in polycystic liver volume, whereas treatment with tacrolimus for a comparable duration was associated with a 14.1 +/- 0.09% increase. A trend toward a greater reduction in native kidney volume was also noted in the sirolimus group compared with the nonsirolimus group. Regarding mechanism, the epithelium that lines hepatic cysts exhibited markedly higher levels of phospho-AKT, phospho-ERK, phospho-mTOR, and the downstream effector phospho-S6rp compared with control biliary epithelium. In summary, treatment with sirolimus was associated with decreased polycystic liver volume, perhaps by preventing aberrant activation of mTOR in epithelial cells lining the cysts.

Impact of tacrolimus and mycophenolate mofetil combination on cardiovascular risk profile after kidney transplantation

Cardiovascular risk factors after kidney transplantation are enhanced as a result of the chronic use of immunosuppressants. Tacrolimus with mycophenolate mofetil has become the most commonly used combination after kidney transplantation. Cardiovascular risk factors that are related to the use of this combined therapy have been analyzed in various clinical trials in comparison with other immunosuppressive therapies. This review summarizes the main results of these studies regarding arterial hypertension, lipid profile, posttransplantation diabetes, renal function, and even acute rejection rate. The aim is to characterize the cardiovascular risk profile of tacrolimus and mycophenolate mofetil association when compared with older and newer immunosuppressive associations.

Proteinuria after kidney transplantation, relationship to allograft histology and survival

Proteinuria is associated with reduced kidney allograft survival. Herein we assessed the association between proteinuria, graft histology and survival. The cohort included 613 kidney allograft recipients who had proteinuria (measured) and surveillance biopsies at 1-year posttransplant. Proteinuria >150 mg/day was detected in 276 patients (45%) and in 182 of these, proteinuria was below 500. In >84% of patients even low levels of proteinuria were associated with albuminuria. Proteinuria was associated with the presence of graft glomerular pathology and the use of sirolimus. Eighty percent of patients with proteinuria >1500 mg/day had glomerular pathology on biopsy. However, lower levels of proteinuria were not associated with specific pathologies at 1 year. Compared to no sirolimus, sirolimus use was associated with higher prevalence of proteinuria (40% vs. 76%, p < 0.0001) and higher protein excretion (378 + 997 vs. 955 + 1986 mg/day, p < 0.0001). Proteinuria was associated with reduced graft survival (HR = 1.40, p = 0.001) independent of other risk factors including, glomerular pathology, graft function, recipient age and acute rejection. The predominant pathology in lost allografts (n = 57) was glomerular, particularly in patients with 1-year proteinuria >500. Thus, proteinuria, usually at low levels (<500 mg/day), is present in 45% of recipients at 1 year. However, and even low levels of proteinuria relate to poor graft survival. Proteinuria and glomerular pathology relate independently to survival.

Sirolimus versus cyclosporine in kidney recipients receiving thymoglobulin, mycophenolate mofetil and a 6-month course of steroids

To evaluate the efficacy and tolerance of a calcineurin inhibitor (CNI)-free regimen, 145 renal recipients were prospectively randomized to receive either sirolimus (n = 71) or cyclosporine (CsA; n = 74). All patients received polyclonal antilymphocyte antibodies, mycophenolate mofetil (MMF) and steroids (6 months). The primary endpoint, estimated glomerular filtration rate (eGFR) was not significantly different at 12 months comparing sirolimus- and CsA-treated patients (60 +/- 27 vs. 57 +/- 21 mL/min). At 12 months, patient and graft survival, incidence of biopsy-proven rejection and rates of steroid withdrawal were not statistically different (97% vs. 97%; 90% vs. 93%; 14.3% vs. 8.6% and 82.8% vs. 84.1%, respectively). Delayed and slow graft function (SGF) was not significantly different (18.6% vs. 12.3% and 11.4% vs. 13.7%, respectively). In patients who remained on treatment according to protocol at 12 months, eGFR was significantly higher with sirolimus (69 +/- 19 vs. 60 +/- 14 mL/min, p = 0.01). Overall study drug discontinuation rates were 28.2% with sirolimus and 14.9% with CsA. Adverse events (wound complications, mouth ulcers, diarrhea, hypokalemia, bronchopneumonia) and proteinuria >0.5 g/24h (38.8% vs. 5.6%, p < 0.001) were significantly more frequent in sirolimus-treated patients. Cytomegalovirus (CMV) infections were significantly less frequent with sirolimus (6% vs. 23%, p < 0.01). A CNI-free regimen using sirolimus-MMF can achieve excellent renal function, but patients on sirolimus experienced a high rate of adverse events and study drug discontinuation.

Immunosuppressive strategies to improve outcomes of kidney transplantation

The introduction of several immunosuppressive agents over the past decade has reduced the rate of acute rejection significantly and has improved short-term renal allograft survival. However, their impact on long-term outcomes remains unclear. Current immunosuppressive strategies are focused on improving long-term graft and patient survival along with maintaining allograft function. The approval of the new immunosuppressive agents: rabbit antithymocyte globulin, basiliximab, daclizumab, tacrolimus, mycophenolate, and sirolimus, also has facilitated the development of steroid- and calcineurin inhibitor-sparing regimens in kidney transplantation. We discuss the impact of various immunosuppressive regimens on the outcome measures of kidney transplantation: acute rejection episodes, allograft survival, and renal function.

Kidney transplantation with sirolimus and mycophenolate mofetil-based immunosuppression: 5-year results of a randomized prospective trial compared to calcineurin inhibitor drugs

BACKGROUND

We report the 5-year outcomes from a randomized prospective trial in primary adult renal allograft recipients, designed to evaluate calcineurin inhibitor (CNI)-free immunosuppression on kidney transplant function.

METHODS

Sixty-one patients were randomized to either sirolimus (n=31) or cyclosporine (n=30) after basiliximab induction and mycophenolate mofetil (MMF) with steroids. Sirolimus was concentration controlled at 10-12 ng/mL for at least 6 months.

RESULTS

After 5 years, sirolimus-MMF-steroids compared to cyclosporine-MMF-steroids provides similar patient survival (87.1 vs. 90%, P=0.681), acute rejection rates (12.9 vs. 23.3%, P=0.22), total cholesterol (209.1 vs. 204.3 mg/dL, P=0.973), urine protein/creatinine ratios (0.398 vs. 0.478 mg/dL, P=0.72), and overall medical and surgical morbidity (P=NS). Although unadjusted patient survival was similar, sirolimus based CNI-free patients had longer death censored graft survival (96.4 vs. 76.7%, P=0.0265), higher glomerular filtration rate (GFR) by the abbreviated Modified Diet in Renal Disease (66.7 vs. 50.7 cc/min, P=0.0075), and fewer graft losses from chronic allograft nephropathy. The Banff chronic scores at two years were strong predictors of 5-year GFR. At 5 years, there were six de novo (three solid organ, three skin) cancers in the CNI group and only two de novo (one skin, one leukemia, no solid organ) cancers in the sirolimus group (P=NS).

CONCLUSIONS

This study of low to moderate risk patients demonstrates that excellent 5-year kidney transplant outcomes can be achieved without CNI drugs, when therapeutic drug monitoring of sirolimus is employed. The application of CNI drug avoidance protocols to high-risk recipients (retransplants, highly sensitized, etc.), extrarenal allograft recipients, or alternative drug regimens such as steroid or MMF elimination should be subjected to controlled trials.

Molecular evidence of injury and inflammation in normal and fibrotic renal allografts one year posttransplant

INTRODUCTION

Factors contributing to kidney transplant fibrosis remain incompletely understood, particularly in the absence of acute complications.

METHODS

Baseline and 1-year surveillance biopsies from 15 uncomplicated living donor kidney transplants were subjected to microarray and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analyses to examine changes in gene expression patterns over time. Biopsy pairs were purposefully selected from allografts with no history of acute complications and were divided into those that were histologically normal (n=7) and those that had developed subclinical interstitial fibrosis (n=8) at 1 year.

RESULTS

Compared with the paired baseline specimens, expression levels of 3578 probesets were found altered in all the 1-year biopsies studied. A large proportion of the up-regulated genes in this transplant-associated profile were functionally linked with inflammation, immunity, or response to injury. These included components of inflammation-related signaling pathways (integrin, interferon, and Toll-like receptor) as well as individual mediators of inflammatory and immune responses. An additional 2884 probesets demonstrated altered expression in fibrotic grafts only at 1 year. The gene products in this fibrosis-associated profile also were predominantly linked with inflammation and immune function, suggesting exaggerated inflammatory activity within the fibrotic grafts. qRT-PCR analyses confirmed the predicted expression patterns for selected transcripts from the microarray profiles.

CONCLUSIONS

Transcriptional profiles of histologically normal living donor renal allografts indicate that there is ongoing injury response and inflammation at 1 year compared to the immediate posttransplant period. Subclinical development of interstitial fibrosis during the first posttransplant year is associated with additional up-regulation of inflammation-related genes.

Calcineurin inhibitor-free immunosuppression in kidney transplantation

The introduction of calcineurin inhibitors (CNI) revolutionized kidney transplantation (KTx). Exceptionally low acute rejection rates and excellent graft survival could be achieved with CNI-based (cyclosporine and tacrolimus) immunosuppressive protocols. However, despite short-term success, long-term graft attrition continues to be a significant problem, thus leaving clinicians looking for possible interventions. CNI nephrotoxicity is but one of numerous factors that may be contributing to long-term damage in transplant kidneys. Therefore, newer immunosuppressive agents such as mycophenolate mofetil and sirolimus (Rapa) have raised the possibility of withdrawing or avoiding CNIs altogether. Protocols exploring these options have gained greater attention over the last few years. Herein, we review studies addressing either CNI withdrawal or CNI avoidance strategies as well as discuss the risks versus benefits of these protocols. Given the accumulated experience to date, in our opinion, the use of CNIs as a part of immunosuppressive regimens remains the proven standard of care for renal transplant patients. The long-term safety and efficacy of CNI withdrawal and avoidance strategies need to be further validated in controlled clinical trials.

Conversion from a calcineurin inhibitor-based immunosuppressive regimen to everolimus in renal transplant recipients: effect on renal function and proteinuria

New immunosuppressive agents are being actively researched to avoid complications of chronic allograft nephropathy (CAN), calcineurin inhibitor (CNI) nephrotoxicity, and posttransplantation cancer. The family of mTOR inhibitors offers a unique immunosuppressive opportunity to avoid CNI toxicity and reduce the incidence of malignancy. Nevertheless, increasing data have demonstrated that sirolimus (SRL), the first mTOR introduced in the treatment of solid organ transplant recipients, induces proteinuria, an adverse event that could produce deterioration of long-term renal function. In this short-term study of patients followed for 1 to 16 months, we examined changes in renal function and proteinuria among renal transplant recipients converted from a CNI-based regimen to an everolimus (EVL)-based one, a recently introduced mTOR inhibitor. Our data showed that renal function can be optimized after conversion to EVL by up to 42% in recipients showing CAN grade 1 or 2, or CNI nephrotoxicity. Importantly, patients who improved their creatinine clearance did not show increased proteinuria measured in a voided specimen as the ratio of urinary protein and creatinine concentration (P/C). These results, if confirmed with long-term follow-up and a larger number of patients, would allow us to consider EVL as a promising agent for maintenance immunosuppressive regimens in kidney transplantation.