Cyclosporine sparing with mycophenolate mofetil, daclizumab and corticosteroids in renal allograft recipients: the CAESAR Study

Calcineurin-inhibitor-free immunosuppression based on the JAK inhibitor CP-690,550: a pilot study in de novo kidney allograft recipients

This randomized, pilot study compared the Janus kinase inhibitor CP-690,550 (15 mg BID [CP15] and 30 mg BID [CP30], n = 20 each) with tacrolimus (n = 21) in de novo kidney allograft recipients. Patients received an IL-2 receptor antagonist, concomitant mycophenolate mofetil (MMF) and corticosteroids. CP-690,550 doses were reduced after 6 months. Due to a high incidence of BK virus nephropathy (BKN) in CP30, MMF was discontinued in this group. The 6-month biopsy-proven acute rejection rates were 1 of 20, 4 of 20 and 1 of 21 for CP15, CP30 and tacrolimus groups, respectively. BKN developed in 4 of 20 patients in CP30 group. The 6-month rates of cytomegalovirus disease were 2 of 20, 4 of 20 and none of 21 for CP15, CP30 and tacrolimus groups, respectively. Estimated glomerular filtration rate was >70 mL/min at 6 and 12 months (all groups). NK cells were reduced by </=77% in CP-690,550-treated patients. In the CP-690,550 arms, there were modest lipid elevations and a trend toward more frequent anemia and neutropenia during the first 6 months. These data suggest that coadministration of CP-690,550 30 mg BID with MMF is associated with overimmunosuppression. At 15 mg BID, the efficacy/safety profile was comparable to the tacrolimus control group, excepting a higher rate of viral infection. Further dose-ranging evaluation of CP-690,550 is warranted.

Anti-interleukin-2 receptor antibodies-basiliximab and daclizumab-for the prevention of acute rejection in renal transplantation

The use of antibody induction after kidney transplantation has increased from 25% to 63% in the past decade and roughly one half of the induction agent used is anti-interleukin-2 receptor antibody (IL-2RA, ie, basiliximab or daclizumab). When combined with calcineurin inhibitor (CNI)-based immunosuppression, IL-2RAs have been shown to reduce the incidence of acute rejection, one of the predictors of poor graft survival, without increasing risks of infections and malignancies in kidney transplantation. For low-immunological-risk patients, IL-2RAs, as compared with lymphocyte-depleting antibodies, are equally efficacious and have better safety profiles. For high-risk patients, however, IL-2RAs may be inferior to lymphocyte-depleting antibodies for the prophylaxis of acute rejection. In an effort to reduce toxicities of other immunosuppressive medications without increasing the risk of acute rejection and chronic graft loss, IL-2RAs have often been combined with steroid- and CNI-sparing immunosuppression protocols. More data support the benefits of early steroid withdrawal with IL-2RA in low-risk patients, but preferred induction therapy for high-risk patients has yet to be determined. Although CNI-sparing protocols with IL-2RA may preserve renal function and improve long-term survival in selected patients, further studies are needed to identify those who benefit most from this strategy.

Can protocol biopsy better inform our choices in renal transplantation?

The use of protocol biopsies has provided insights into the pathogenesis of many renal allograft diseases. It is now widely accepted that acute and chronic immune injury, as well as other pathologies associated with eventual graft loss, may occur initially in the absence of graft dysfunction. Indeed, renal transplant biopsies performed at the time of graft dysfunction may disclose advanced stages of renal injury that may not be amenable to treatment. However, protocol biopsies have several limitations that include their morbidity, cost, and potential for sampling error. Furthermore, the prevalence of early subclinical rejection is decreasing in the modern era of immunosuppression, which argues against their use in patients of low immunological risk. Conversely, the transplantation community has, perhaps unadvisedly, embarked upon protocols of immunosuppressive drug minimization. The consequences of these practices may result in late inflammation in the graft that could prove deleterious to its function in the long term. It is hoped that in the future "systems biology" techniques (eg, genomics, proteomics, and metabolomics) may guide clinicians regarding the safety of drug minimization protocols, inform them as to when a renal transplant biopsy should be procured, and perhaps one day replace the renal transplant biopsy altogether. Until such time, however, the renal biopsy remains an indispensable tool in the management of renal transplant recipients.

Kidney transplantation: the ideal immunosuppression regimen

Kidney transplantation today has excellent short-term outcomes, but long-term graft survival has not improved in a parallel fashion. The goal of immunosuppressive therapy is to balance the beneficial effects of reducing acute rejection while minimizing adverse effects from oversuppression including the development of infections, malignancy, and cardiovascular risk factors. In general, current immunosuppressive protocols use combinations of immunosuppressive agents with different mechanisms of action to maximize efficacy and minimize the toxicity of each drug. During the past decade, there has been a growing interest in identifying regimens that permit the minimization of calcineurin inhibitors or corticosteroids in an attempt to decrease nephrotoxicity and metabolic side effects. The emergence of new immunosuppressive agents and tolerance protocols appear promising as a means to deliver immunosuppression without long-term toxicity. Ultimately, the goal of prescribing immunosuppression is to transition from empiric therapy to one of individualized therapy.

Mycophenolate blood level monitoring: recent progress

The concentration-effect relationship for mycophenolic acid (MPA), and the high variability in MPA concentrations in patients on standard dose mycophenolate mofetil (MMF) therapy, for some centers has provided enough evidence to implement therapeutic drug monitoring (TDM) for MMF in daily practice. Two randomized trials Adaption de Posologie du MMF en Greffe Renale (APOMYGRE) and fixed-dose versus concentration controlled (FDCC) investigated the added benefit of TDM for MMF in renal transplant recipients. The APOMYGRE study showed a significant reduction in the incidence of acute rejection in concentration-controlled patients, while the FDCC study had a negative outcome, despite a similar study design. Although it was expected that these prospective trials would give the final answer to the question of whether or not TDM for MMF would be of benefit, it seems that the studies have not had much impact on patient management. Several trials have shown the importance of early adequate exposure to MPA in the first week after transplantation. As it will be hard to improve MPA exposure with TDM, this early, ongoing study now investigates the use of an increased starting dose. The increased starting dose will avoid underexposure to MPA in higher proportions of patients shortly after transplantation but may result in more toxicity in patients with MPA exposures exceeding the upper threshold of the therapeutic window.

Calcineurin inhibitor nephrotoxicity

The use of the calcineurin inhibitors cyclosporine and tacrolimus led to major advances in the field of transplantation, with excellent short-term outcome. However, the chronic nephrotoxicity of these drugs is the Achilles' heel of current immunosuppressive regimens. In this review, the authors summarize the clinical features and histologic appearance of both acute and chronic calcineurin inhibitor nephrotoxicity in renal and nonrenal transplantation, together with the pitfalls in its diagnosis. The authors also review the available literature on the physiologic and molecular mechanisms underlying acute and chronic calcineurin inhibitor nephrotoxicity, and demonstrate that its development is related to both reversible alterations and irreversible damage to all compartments of the kidneys, including glomeruli, arterioles, and tubulo-interstitium. The main question--whether nephrotoxicity is secondary to the actions of cyclosporine and tacrolimus on the calcineurin-NFAT pathway--remains largely unanswered. The authors critically review the current evidence relating systemic blood levels of cyclosporine and tacrolimus to calcineurin inhibitor nephrotoxicity, and summarize the data suggesting that local exposure to cyclosporine or tacrolimus could be more important than systemic exposure. Finally, other local susceptibility factors for calcineurin inhibitor nephrotoxicity are reviewed, including variability in P-glycoprotein and CYP3A4/5 expression or activity, older kidney age, salt depletion, the use of nonsteroidal anti-inflammatory drugs, and genetic polymorphisms in genes like TGF-beta and ACE. Better insight into the mechanisms underlying calcineurin inhibitor nephrotoxicity might pave the way toward more targeted therapy or prevention of calcineurin inhibitor nephrotoxicity.

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.

Calcineurin inhibitor sparing with mycophenolate in kidney transplantation: a systematic review and meta-analysis

BACKGROUND

Limiting the exposure of kidney transplant recipients to calcineurin inhibitors (CNIs) has potential merit, but there is no clear consensus on the utility of current strategies. In an attempt to aid clarification, we conducted a systematic review and meta-analysis of randomized trials that assessed CNI sparing (minimization or elimination) with mycophenolate as sole adjunctive immunosuppression.

METHODS

The search strategy identified trials where CNI sparing was accompanied by the continuation of, or conversion to, mycophenolate and compared with standard or higher dose CNI therapy. Two investigators independently examined each trial for eligibility, quality, and outcome measures. Additional subgroup analyses were assessed: (1) de novo CNI sparing; (2) elective CNI sparing beyond 2 months posttransplantation; and (3) CNI sparing for transplant dysfunction.

RESULTS

Nineteen randomized controlled trials met the inclusion criteria permitting analysis of 3312 renal transplant recipients with median follow-up of 12 months. CNI sparing significantly improved glomerular filtration rate (weighted mean difference 4.4 mL/min, 95% confidence interval [CI] 2.9-5.9, P<0.001); with some evidence, albeit weak, of improved graft survival (odds ratio 0.72, 95% CI 0.52-1.01, P=0.06). Acute rejection rates were only increased after elective CNI elimination (odds ratio 2.23, 95% CI 1.57-3.17, P<0.001). There were no significant differences in mortality, malignancy or incidence of infections.

CONCLUSIONS

CNI sparing strategies with adjunctive mycophenolate may play an important role in kidney transplant recipients. Improvements in short-term graft function, and possibly graft survival, are achievable. Longer term studies are needed to substantiate the short-term benefits, and refining elective CNI elimination protocols may help to reduce the risk of rejection.

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.

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.

Rationale and criteria of eligibility for calcineurin inhibitor interruption following kidney transplantation

PURPOSE OF REVIEW

To summarize predictive low-risk parameters of renal allograft recipients for purposes of improving the initiation of calcineurin inhibitor withdrawal protocols.

RECENT FINDINGS

Clinical trials have demonstrated the potential global benefit of calcineurin inhibitor interruption protocols on graft survival despite being associated with an increased rate of acute rejection episodes, thus underlying a number of risk factors. Recent identification or confirmation of variables updating the list of parameters and molecular markers that can be used to predict graft outcome are described.

SUMMARY

The effect of calcineurin inhibitor withdrawal on long-term graft and recipient survival patterns is assessed in relation to the large number of calcineurin inhibitor-related side-effects. However, current protocols are based on empirical observations and there is a clear requirement for reliable parameters to define patient eligibility for calcineurin inhibitor weaning procedures. Here, we review biological, clinical and genetic parameters that can be used as predictive markers of long-term graft outcome and could serve as criteria for patient selection in calcineurin inhibitor weaning protocols.

Recovery of tacrolimus-associated brachial neuritis after conversion to everolimus in a pediatric renal transplant recipient--case report and review of the literature

TAC has been shown to be a potent immunosuppressive agent for solid organ transplantation in pediatrics. Neurotoxicity is a potentially serious toxic effect. It is characterized by encephalopathy, headaches, seizures, or neurological deficits. Here, we describe an eight-and-a-half-yr-old male renal transplant recipient with right BN. MRI demonstrated hyperintense T2 signals in the cervical cord and right brachial plexus roots indicative of both myelitis and right brachial plexitis. Symptoms persisted for three months despite TAC dose reduction, administration of IVIG and four doses of methylprednisolone pulse therapy. Improvement and eventually full recovery only occurred after TAC was completely discontinued and successfully replaced by everolimus.

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.

Calcineurin inhibitor sparing in renal transplantation

Although calcineurin inhibitors (CNIs) are effective at preventing acute rejection, their long-term use is associated with nephrotoxicity that may compromise long-term renal allograft survival. Consequently, there is considerable interest in identifying immunosuppressive regimens that permit reduced exposure to CNIs while maintaining adequate immunosuppression. Introducing such strategies early after transplantation may mean that the development of CNI-associated nephrotoxicity could be minimized or prevented. Several CNI-sparing regimens have shown at least comparable efficacy with standard-dose CNI regimens. In particular, a regimen of mycophenolate mofetil (MMF), corticosteroids, interleukin-2 receptor antagonist induction, and low-dose tacrolimus from the time of transplantation provided superior renal function and a lower acute rejection rate than the same regimen but with low-dose cyclosporine or low-dose sirolimus, or standard-dose cyclosporine, MMF, and corticosteroids. The use of low-dose cyclosporine does not seem to eliminate nephrotoxicity in de novo renal transplant recipients. The early withdrawal of CNIs from MMF-based regimens generally improves renal function but has been associated with an increased risk of acute rejection, in particular when the levels of mycophenolic acid were not adjusted to maintain the same total level of immunosuppression. Research aiming to achieve the "best" balance of efficacy and toxicity of available immunosuppressive regimens continues.

[Immunosuppressive strategies and chronic graft dysfunction in kidney transplantation]

Chronic graft dysfunction is a major cause of return to dialysis. In the majority of cases, it is correlated with histological signs of cellular and/or humoral rejection, the nephrotoxicity of anticalcineurins, or nonspecific lesions of interstitial fibrosis and tubular atrophy. Although the incidence of acute rejection has considerably decreased, renal toxicity of the calcineurin inhibitors remains problematic. In cases of established nephrotoxicity, the use of non-nephrotoxic immunosuppressors such as mycophenolic acid or the proliferation signal inhibitors makes it possible to reduce or even stop the anticalcineurins. In prevention of anticalcineurin nephrotoxicity, many attempts to minimize or wean patients from them have shown that improvement in renal function is only obtained at the cost of an increase in the incidence of acute rejection. This makes it necessary to select patients who may benefit from anticalcineurin-sparing treatment, based on clinical, histological, and biological markers. Finally, long-term follow-up is also fundamental in order to validate the positive impact on renal function of this strategy in terms of graft survival.

Aggressive immunosuppression minimization reduces graft loss following diagnosis of BK virus-associated nephropathy: a comparison of two reduction strategies

BACKGROUND AND OBJECTIVES

BK virus-associated nephropathy (BKVAN) has emerged as a leading cause of kidney graft loss, with no known predictors for graft loss and no consensus regarding treatment other than reduction of immunosuppression.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

A single-center retrospective analysis was performed of all cases of BKVAN from 1999 to 2005 for clinical predictors of graft loss, with evaluation of the impact of immunosuppression withdrawal (3-drug to 2-drug immunosuppression) within the first month versus reduction of immunosuppression.

RESULTS

Of 910 kidney transplants, 35 (3.8%) cases of BKVAN were diagnosed at a median of 15 months after transplant (range, 5.5 to 90 months after transplant), 16 (46%) of which progressed to graft failure at a median of 11 months (range, 2 to 36 months) after diagnosis. Depleting antibody induction was a significant risk factor for graft loss on univariate analysis, whereas early drug withdrawal (<1 mo following diagnosis) protected against graft loss. On multivariate analysis, these findings were independent predictors of graft outcomes. Additionally, when patients were comanaged by referring nephrologists and the transplant center before the diagnosis of BKVAN, the risk of graft loss was 11-fold higher (P = 0.03) than if patients were managed solely by the transplant center.

CONCLUSIONS

Increased awareness and early diagnosis of BKVAN, with aggressive tapering of immunosuppression once established, is critical to preserve kidney graft function. Early drug withdrawal to low-dose two-drug therapy maintenance may be preferable to a general reduction of agents.

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.

Calcineurin inhibitor minimization, withdrawal and avoidance protocols after kidney transplantation

A nonquantitative summary of the current evidence suggests that calcineurin inhibitor (CNI) minimization and also CNI-free protocols are safe and efficient when used after the initial 3 months post-transplantation. In fact, the largest study so far showed that low-dose CNI in combination with mycophenolate mofetil (MMF) and steroids performed better than standard dose cyclosporine A (CsA). If CsA is used in combination with a mammalian target of rapamycin-Inhibitor (mTOR-I) considerable dose reduction of both drugs is required. A better choice than using both drug groups in lower doses together may be the withdrawal of CsA from this combination after 3-12 months. Later withdrawals or conversions to an mTOR-I failed to show additional benefit in terms of graft function or survival but caused less post-transplant malignancies. With improved short- and medium-term outcomes, this entity will become more of an issue. In fact, in some areas of the world, nowadays malignancies are the leading cause of death.

Renal ischemia: does sex matter?

Renal ischemia is a common complication in the perioperative period that leads to a high rate of morbidity and mortality. As in other forms of ischemia (i.e., cardiac, neurologic), the incidence and outcome of renal ischemia is strikingly sex-specific. Sexual dimorphism in response to renal injury has been noted for many years, but is now the subject of both clinical and experimental research. Clinically, women experience a lower incidence of perioperative acute renal failure, with the exception of cardiac surgery. Experimental science is now producing tantalizing clues that sex steroids, both male and female, play a role in the kidney's response to ischemia. In this review, we evaluated sex differences in perioperative renal failure and in the pathophysiology of renal ischemia/reperfusion injury. Although much work remains to characterize the biological mechanisms involved, the data are sufficient to support consideration of gender and the use of medications that impact steroid availability in the perioperative plan of care.

Calcineurin inhibitor withdrawal after renal transplantation with alemtuzumab: clinical outcomes and effect on T-regulatory cells

To address the results of calcineurin inhibitor (CNI) withdrawal after alemtuzumab induction relative to CNI continuation, we performed a pilot randomized clinical trial in renal allograft recipients on CNI, a mycophenolic acid derivative and steroids after the first 2 months posttransplantation. Forty patients were randomized to taper off CNI or to maintain it, and followed for at least 1 year. Four patients in the withdrawal group were treated for acute rejection while no patient received antirejection treatment in the control group. Two control patients withdrew CNI due to nephrotoxicity. Estimated GFR was similar in both groups after 1 year. Flow cytometry of CD4(+)CD25(+)CTLA-4(+)FoxP3(+) regulatory T cells (Treg) demonstrated a significant increase in Treg percentages in the peripheral blood of alemtuzumab-treated patients on CNI early postransplant. Furthermore, the increased Treg percentages in the withdrawal cohort were unchanged at month 6 postenrollment, whereas they decreased significantly in those patients maintained on CNI. Patients withdrawn from CNI after alemtuzumab trend toward a higher rejection rate, but most patients can be weaned from a CNI using this regimen. With the exception of maintaining increased Treg levels, the benefits are not appreciable in this short follow-up, and a larger randomized trial is justified.

Association of four DNA polymorphisms with acute rejection after kidney transplantation

Renal transplant outcomes exhibit large inter-individual variability, possibly on account of genetic variation in immune-response mediators and genes influencing the pharmacodynamics/pharmacokinetics of immunosuppressants. We examined 21 polymorphisms from 10 genes in 237 de novo renal transplant recipients participating in an open-label, multicenter study [Cyclosporine Avoidance Eliminates Serious Adverse Renal-toxicity (CAESAR)] investigating renal function and biopsy-proven acute rejection (BPAR) with different cyclosporine A regimens and mycophenolate mofetil. Genes were selected for their immune response and pharmacodynamic/pharmacokinetic relevance and were tested for association with BPAR. Four polymorphisms were significantly associated with BPAR. The ABCB1 2677T allele tripled the odds of developing BPAR (OR: 3.16, 95% CI [1.50-6.67]; P=0.003), as did the presence of at least one IMPDH2 3757C allele (OR: 3.39, 95% CI [1.42-8.09]; P=0.006). BPAR was almost fivefold more likely in patients homozygous for IL-10 -592A (OR: 4.71, 95% CI [1.52-14.55]; P=0.007) and twice as likely in patients with at least one A allele of TNF-alpha G-308A (OR: 2.18, 95% CI [1.08-4.41]; P=0.029). There were no statistically significant interactions between polymorphisms, or the different treatment regimens. Variation in genes of immune response and pharmacodynamic/pharmacokinetic relevance may be important in understanding acute rejection after renal transplant.

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.

Prostate cancer in renal transplant recipients

BACKGROUND

We conducted a retrospective multi-centre study to determine the characteristics of prostate cancer in renal transplant recipients (RTR) and to analyse the relation with immunosuppressive maintenance therapies.

METHODS

Patients from 19 French transplant centres diagnosed with prostate cancer at least 1 year after kidney transplantation were included in this study. Data regarding demographics, kidney transplantation, prostate cancer and immunosuppressive treatment were analysed.

RESULTS

Sixty-two patients met the eligibility criteria for this study. Thirty-eight patients (61.3%) received calcineurin inhibitors (CNI) and azathioprine (AZA) with or without steroids, twenty received CNI with or without steroids (32.2%) and four received CNI and mycophenolate mofetil (6.5%). Patients with CNI and AZA immunosuppressive therapy presented more high-stage cancer (T3 and T4) when compared to patients receiving CNI alone (47.5% versus 15%, respectively, P = 0.03). A non-significant increase in lymph node invasion was found in patients receiving CNI and AZA compared to patients receiving CNI alone (21% versus 5%, P = 0.16). In the multivariate analysis, the immunosuppressive regimen with CNI and AZA was the only independent risk factor for locally advanced disease (P = 0.007).

CONCLUSION

Our results showed that RTR are at risk for early occurrence and for locally advanced prostate cancer, especially when they received a CNI and AZA maintenance immunosuppressive therapy.

Reduced exposure to calcineurin inhibitors in renal transplantation

BACKGROUND

Immunosuppressive regimens with the fewest possible toxic effects are desirable for transplant recipients. This study evaluated the efficacy and relative toxic effects of four immunosuppressive regimens.

METHODS

We randomly assigned 1645 renal-transplant recipients to receive standard-dose cyclosporine, mycophenolate mofetil, and corticosteroids, or daclizumab induction, mycophenolate mofetil, and corticosteroids in combination with low-dose cyclosporine, low-dose tacrolimus, or low-dose sirolimus. The primary end point was the estimated glomerular filtration rate (GFR), as calculated by the Cockcroft-Gault formula, 12 months after transplantation. Secondary end points included acute rejection and allograft survival.

RESULTS

The mean calculated GFR was higher in patients receiving low-dose tacrolimus (65.4 ml per minute) than in the other three groups (range, 56.7 to 59.4 ml per minute). The rate of biopsy-proven acute rejection was lower in patients receiving low-dose tacrolimus (12.3%) than in those receiving standard-dose cyclosporine (25.8%), low-dose cyclosporine (24.0%), or low-dose sirolimus (37.2%). Allograft survival differed significantly among the four groups (P=0.02) and was highest in the low-dose tacrolimus group (94.2%), followed by the low-dose cyclosporine group (93.1%), the standard-dose cyclosporine group (89.3%), and the low-dose sirolimus group (89.3%). Serious adverse events were more common in the low-dose sirolimus group than in the other groups (53.2% vs. a range of 43.4 to 44.3%), although a similar proportion of patients in each group had at least one adverse event during treatment (86.3 to 90.5%).

CONCLUSIONS

A regimen of daclizumab, mycophenolate mofetil, and corticosteroids in combination with low-dose tacrolimus may be advantageous for renal function, allograft survival, and acute rejection rates, as compared with regimens containing daclizumab induction plus either low-dose cyclosporine or low-dose sirolimus or with standard-dose cyclosporine without induction. (ClinicalTrials.gov number, NCT00231764 [ClinicalTrials.gov].).

Individualized mycophenolate mofetil dosing based on drug exposure significantly improves patient outcomes after renal transplantation

Efficacy and safety of mycophenolate mofetil (MMF) may be optimized with individualized doses based on therapeutic monitoring of its active metabolite, mycophenolic acid (MPA). In this 12-month study, 137 renal allograft recipients from 11 French centers receiving basiliximab, cyclosporine A, MMF and corticosteroids were randomized to receive either concentration-controlled doses or fixed-dose MMF. A novel Bayesian estimator of MPA AUC based on three-point sampling was used to individualize doses on posttransplant days 7 and 14 and months 1, 3 and 6. The primary endpoint was treatment failure (death, graft loss, acute rejection and MMF discontinuation). Data from 65 patients/group were analyzed. At month 12, the concentration-controlled group had fewer treatment failures (p = 0.03) and acute rejection episodes (p = 0.01) with no differences in adverse event frequency. The MMF dose was higher in the concentration-controlled group at day 14 (p < 0.0001), month 1 (p < 0.0001) and month 3 (p < 0.01), as were median AUCs on day 14 (33.7 vs. 27.1 mg*h/L; p = 0.0001) and at month 1 (45.0 vs. 30.9 mg*h/L; p < 0.0001). Therapeutic MPA monitoring using a limited sampling strategy can reduce the risk of treatment failure and acute rejection in renal allograft recipients 12 months posttransplant with no increase in adverse events.

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.

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.

Tacrolimus exposure and evolution of renal allograft histology in the first year after transplantation

Tacrolimus has a narrow therapeutic window and is characterized by a large inter-individual variability in bioavailability. The impact of tacrolimus exposure on subclinical evolution of graft histology has not been studied in renal recipients. This analysis included 239 protocol biopsies (obtained at implantation, 3 and 12 months) of 120 consecutive kidney recipients treated with tacrolimus, mycophenolate mofetil (MMF) and corticosteroids. Biopsies were scored according to the Banff 2001 criteria and a chronicity score was calculated. Prospective pharmacokinetic data were included in the analysis (5544 tacrolimus predose blood concentrations and tacrolimus AUC(0-12) at 3 and 12 months). Higher donor age and higher number of human leukocyte antigen-DR (HLA-DR) mismatches were independent predictors of subclinical acute rejection at 3 months, present in 8.7% of patients. The number of HLA-DR mismatches was independently associated with biopsy-proven clinical acute rejection. Biopsy-proven acute rejection episodes and low mean tacrolimus exposure were independently associated with higher increase in chronicity scores between 3 and 12 months after transplantation. This observational study suggests that rejection phenomena and immune-mediated mechanisms remain important in the early progression of chronic allograft pathology. Tacrolimus doses or systemic exposure were not associated with lesions of calcineurin inhibitor nephrotoxicity, suggesting that other factors determine susceptibility to tacrolimus nephrotoxicity.

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.

Can mTOR inhibitors reduce the risk of late kidney allograft failure?

The most frequent causes of late kidney allograft failure are chronic rejection, nonalloimmune injury and death, all of which may depend on the characteristics of the donor and recipient, but may also be influenced by the type of immunosuppression. Combining calcineurin inhibitors (CNIs) and corticosteroids offers potent immunosuppression, but may also cause side effects leading to progressive graft dysfunction or an increased risk of death. New immunosuppressive strategies may come from the availability of inhibitors of mTOR, a downstream effector of phosphatidylinositol-3 kinase that provides the signal for cell proliferation by phosphorylating a cascade of kinases. Recent trials have shown that it is possible to minimize the dose or withdraw CNIs a few weeks after transplantation when they are combined with mTOR inhibitors and their combination may also make it possible to minimize or avoid the use of corticosteroids. Moreover, by inhibiting the signal for cell proliferation, mTOR inhibitors may reduce the replication of cytomegalovirus inside host cells, prevent transplant vasculopathy, and exert anti-oncogenic activity. All of these characteristics offer a ray of hope for reducing the risk of long-term allograft failure.