Belatacept-based regimens versus a cyclosporine A-based regimen in kidney transplant recipients: 2-year results from the BENEFIT and BENEFIT-EXT studies. Transplantation. 2010;90:1528-1535. [PMID: 21076381 DOI: 10.1097/tp.0b013e3181ff87cd]

Belatacept for kidney transplant recipients

BACKGROUND

Most people who receive a kidney transplant die from either cardiovascular disease or cancer before their transplant fails. The most common reason for someone with a kidney transplant to lose the function of their transplanted kidney necessitating return to dialysis is chronic kidney transplant scarring. Immunosuppressant drugs have side effects that increase risks of cardiovascular disease, cancer and chronic kidney transplant scarring. Belatacept may provide sufficient immunosuppression while avoiding unwanted side effects of other immunosuppressant drugs. However, high rates of post-transplant lymphoproliferative disease (PTLD) have been reported when belatacept is used in particular kidney transplant recipients at high dosage.

OBJECTIVES

1) Compare the relative efficacy of belatacept versus any other primary immunosuppression regimen for preventing acute rejection, maintaining kidney transplant function, and preventing death. 2) Compare the incidence of several adverse events: PTLD; other malignancies; chronic transplant kidney scarring (IF/TA); infections; change in blood pressure, lipid and blood sugar control. 3) Assess any variation in effects by study, intervention and recipient characteristics, including: differences in pre-transplant Epstein Barr virus serostatus; belatacept dosage; and donor-category (living, standard criteria deceased, or extended criteria deceased).

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 1 September 2014 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCT) that compared belatacept versus any other immunosuppression regimen in kidney transplant recipients were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data for study quality and transplant outcomes and synthesized results using random effects meta-analysis, expressed as risk ratios (RR) and mean differences (MD), both with 95% confidence intervals (CI).  Subgroup analyses and univariate meta-regression were used to investigate potential heterogeneity.

MAIN RESULTS

We included five studies that compared belatacept and calcineurin inhibitors (CNI) that reported data from a total of 1535 kidney transplant recipients. Of the five studies, three (478 participants) compared belatacept and cyclosporin and two (43 recipients) compared belatacept and tacrolimus. Co-interventions included basiliximab (4 studies, 1434 recipients); anti-thymocyte globulin (1 study, 89 recipients); alemtuzumab (1 study, 12 recipients); mycophenolate mofetil (MMF, 5 studies, 1509 recipients); sirolimus (1 study, 26 recipients) and prednisone (5 studies, 1535 recipients).Up to three years following transplant, belatacept and CNI-treated recipients were at similar risk of dying (4 studies, 1516 recipients: RR 0.75, 95% CI 0.39 to 1.44), losing their kidney transplant and returning to dialysis (4 studies, 1516 recipients: RR 0.91, 95% CI 0.61 to 1.38), and having an episode of acute rejection (4 studies, 1516 recipients: RR 1.56, 95% CI 0.85 to 2.86). Belatacept-treated kidney transplant recipients were 28% less likely to have chronic kidney scarring (3 studies, 1360 recipients: RR 0.72, 95% CI 0.55 to 0.94) and also had better graft function (measured glomerular filtration rate (GFR) (3 studies 1083 recipients): 10.89 mL/min/1.73 m², 95% CI 4.01 to 17.77; estimated GFR (4 studies, 1083 recipients): MD 9.96 mL/min/1.73 m², 95% CI 3.28 to 16.64) than CNI-treated recipients. Blood pressure was lower (systolic (2 studies, 658 recipients): MD -7.51 mm Hg, 95% CI -10.57 to -4.46; diastolic (2 studies, 658 recipients): MD -3.07 mm Hg, 95% CI -4.83 to -1.31, lipid profile was better (non-HDL (3 studies 1101 recipients): MD -12.25 mg/dL, 95% CI -17.93 to -6.57; triglycerides (3 studies 1101 recipients): MD -24.09 mg/dL, 95% CI -44.55 to -3.64), and incidence of new-onset diabetes after transplant was reduced by 39% (4 studies (1049 recipients): RR 0.61, 95% CI 0.40 to 0.93) among belatacept-treated versus CNI-treated recipients.Risk of PTLD was similar in belatacept and CNI-treated recipients (4 studies, 1516 recipients: RR 2.79, 95% CI 0.61 to 12.66) and was no different among recipients who received different belatacept dosages (high versus low dosage: ratio of risk ratios (RRR) 1.06, 95% CI 0.11 to 9.80, test of difference = 0.96) or among those who were Epstein Barr virus seronegative compared with those who were seropositive before their kidney transplant (seronegative versus seropositive; RRR 1.49, 95% CI 0.15 to 14.76, test for difference = 0.73).The belatacept dose used (high versus low), type of donor kidney the recipient received (extended versus standard criteria) and whether the kidney transplant recipient received tacrolimus or cyclosporin made no difference to kidney transplant survival, incidence of acute rejection or estimated GFR. Selective outcome reporting meant that data for some key subgroup comparisons were sparse and that estimates of the effect of treatment in these groups of recipients remain imprecise.

AUTHORS' CONCLUSIONS

There is no evidence of any difference in the effectiveness of belatacept and CNI in preventing acute rejection, graft loss and death, but treatment with belatacept is associated with less chronic kidney scarring and better kidney transplant function. Treatment with belatacept is also associated with better blood pressure and lipid profile and a lower incidence of diabetes versus treatment with a CNI. Important side effects (particularly PTLD) remain poorly reported and so the relative benefits and harms of using belatacept remain unclear. Whether short-term advantages of treatment with belatacept are maintained over the medium- to long-term or translate into better cardiovascular outcomes or longer kidney transplant survival with function remains unclear. Longer-term, fully reported and published studies comparing belatacept versus tacrolimus are needed to help clinicians decide which patients might benefit most from using belatacept.

Belatacept for Maintenance Immunosuppression in Lung Transplantation

Belatacept is a novel immunosuppressant that blocks a T-cell costimulation pathway and is approved for use in adult kidney transplant recipients. Its safety and efficacy have not been established after lung transplantation. We present a case of a lung transplant recipient treated with belatacept. A 56-year-old man underwent bilateral lung retransplantation for bronchiolitis obliterans syndrome (BOS). In the third year posttransplant, he developed hemolytic uremic syndrome (HUS) attributed to tacrolimus. Tacrolimus was changed to sirolimus. One month later, he presented with worsening renal function and HUS attributed to sirolimus. Plasmapheresis and steroid pulse were initiated with clinical improvement, and sirolimus was switched to belatacept. He experienced no episodes of cellular rejection but developed recurrent BOS. Complications during treatment included anemia and recurrent pneumonias. The safety and efficacy of belatacept in lung transplantation remains unclear; further studies are needed.

Pharmacokinetics, pharmacodynamics, and immunogenicity of belatacept in adult kidney transplant recipients

BACKGROUND AND OBJECTIVES

Belatacept is a first-in-class, selective co-stimulation blocker recently approved for the prophylaxis of organ rejection in adult kidney transplant recipients. The objective of this study was to report the pharmacokinetics, pharmacodynamics, and immunogenicity of belatacept.

METHODS

The pharmacokinetics, pharmacodynamics (CD86 receptor occupancy), and immunogenicity of belatacept were studied in de novo adult kidney transplant recipients in phase II and III clinical studies.

RESULTS

Following multiple doses of 5 or 10 mg/kg, the geometric mean (percentage coefficient of variation) maximum serum concentration and area under the serum concentration-time curve over one dosing interval of belatacept were 136 (20%) and 238 (27%) μg/mL, and 13,587 (27%) and 21,241 (35%) μg·h/mL, respectively. The median belatacept elimination half-life was 8-9 days. Belatacept exhibited concentration-dependent binding to CD86 receptors. The pre-dose CD86 receptor occupancy by belatacept decreased from 94 to 65% between day 5 and 1 year post-transplant, with corresponding pre-dose trough serum concentrations of belatacept decreasing from ~35 to 4 μg/mL during this period. The cumulative incidence of developing anti-belatacept antibodies was 5.3% up to 3 years post-transplant and had no impact on belatacept exposure.

CONCLUSIONS

Belatacept in adult kidney transplant demonstrated linear pharmacokinetics with low variability, concentration-dependent pharmacodynamics, and a low incidence of anti-drug antibodies.

A Prospective Randomised Paired Trial of Sirolimus versus Tacrolimus as Primary Immunosuppression following Non-Heart Beating Donor Kidney Transplantation

INTRODUCTION

With calcineurin inhibitors potentiating damage from ischaemia-reperfusion injury in kidneys from donors after cardiac death we wanted to investigate the role of substituting sirolimus for tacrolimus in the delayed introduction of calcineurin inhibitor regime used in our centre.

METHOD

A prospective randomised paired open-label study was performed taking pairs of kidneys from each donor and randomising one to a tacrolimus-based regime and the other to a similar regime based on sirolimus. Graft function at one year was the primary endpoint.

RESULTS

Total 31 pairs of kidneys were randomised to each group, with 19 pairs of recipients available for analysis after post-randomisation study exclusions. Despite a higher incidence of biopsy proven acute rejection in the sirolimus group, renal allograft function was similar in both groups at three-monthly intervals up to one year post-transplant. All episodes of acute rejection in the sirolimus group occurred in the first three months. Graft and patient survival at one year was 100% in the tacrolimus group, with one death with functioning graft in the sirolimus group (95% survival). Unfortunately, 10 of the 19 patients in the sirolimus arm required switch of medication to tacrolimus due to acute rejection or intolerable drug side effects.

CONCLUSIONS

Graft survival and function were very similar in the two groups despite the higher rate of acute rejection in the sirolimus arm, raising the possibility that the damage done by acute rejection was adequately offset by the nephron-sparing effect of sirolimus compared to tacrolimus. Sirolimus may have a role as a longer-term maintenance immunosuppressant after initial treatment with a different agent such as tacrolimus or belatacept.

Belatacept-based immunosuppression in de novo liver transplant recipients: 1-year experience from a phase II randomized study

This exploratory phase II study evaluated the safety and efficacy of belatacept in de novo adult liver transplant recipients. Patients were randomized (N = 260) to one of the following immunosuppressive regimens: (i) basiliximab + belatacept high dose [HD] + mycophenolate mofetil (MMF), (ii) belatacept HD + MMF, (iii) belatacept low dose [LD] + MMF, (iv) tacrolimus + MMF, or (v) tacrolimus alone. All received corticosteroids. Demographic characteristics were similar among groups. The proportion of patients who met the primary end point (composite of acute rejection, graft loss, death by month 6) was higher in the belatacept groups (42–48%) versus tacrolimus groups (15–38%), with the highest number of deaths and grafts losses in the belatacept LD group. By month 12, the proportion surviving with a functioning graft was higher with tacrolimus + MMF (93%) and lower with belatacept LD (67%) versus other groups (90%: basiliximab + belatacept HD; 83%: belatacept HD; 88%: tacrolimus). Mean calculated GFR was 15–34 mL/min higher in belatacept-treated patients at 1 year. Two cases of posttransplant lymphoproliferative disease and one case of progressive multifocal leukoencephalopathy occurred in belatacept-treated patients. Follow-up beyond month 12 revealed an increase in death and graft loss in another belatacept group (belatacept HD), after which the study was terminated.

Kidney transplant recipients treated with belatacept exhibit increased naïve and transitional B cells

Phase III clinical studies have shown that kidney transplant (KT) recipients treated with the costimulation blocker belatacept exhibited a better renal allograft function and lower donor-specific anti-HLA immunization when compared to recipients treated with calcineurin inhibitors (CNI). We analyzed B cell phenotype in KT recipients treated with belatacept and stable renal function (N = 13). Results were compared to those observed in stable patients treated with CNI (N = 12), or with chronic antibody-mediated rejection (N = 5). Both transcriptional profile and phenotypic characterization of peripheral B cells were performed by real-time polymerase chain reaction and flow cytometry, respectively. In belatacept group, the frequency and absolute number of transitional B cells as defined by both phenotypes: CD19(+) CD24(hi) CD38(hi) and CD19(+) IgD(hi) CD38(hi) CD27(-) , as well as naïve B cells were significantly higher compared with CNI group. B cell activating factor (BAFF) and BAFF receptor mRNA levels were significantly lower in belatacept group than in CNI group. These results show for the first time that belatacept influences B cell compartment by favoring the occurrence of transitional B cells with potential regulatory properties, as described in operational tolerant patients. This role may explain the lower alloimmunization rate observed in belatacept-treated patients.

Projecting long-term graft and patient survival after transplantation

OBJECTIVE

In spite of increases in short-term kidney transplant survival rates and reductions in acute rejection rates, increasing long-term graft survival rates remains a major challenge. The objective here was to project long-term graft- and survival-related outcomes occurring among renal transplant recipients based on short-term outcomes including acute rejection and estimated glomerular filtration rates observed in randomized trials.

METHODS

We developed a two-phase decision model including a trial phase and a Markov state transition phase to project long-term outcomes over the lifetimes of hypothetical renal graft recipients who survived the trial period with a functioning graft. Health states included functioning graft stratified by level of renal function, failed graft, functioning regraft, and death. Transitions between health states were predicted using statistical models that accounted for renal function, acute rejection, and new-onset diabetes after transplant and for donor and recipient predictors of long-term graft and patient survival. Models were estimated using data from 38,015 renal transplant recipients from the United States Renal Data System. The model was populated with data from a 3-year, randomized phase III trial comparing belatacept to cyclosporine.

RESULTS

The decision model was well calibrated with data from the United States Renal Data System. Long-term extrapolation of Belatacept Evaluation of Nephroprotection and Efficacy as Firstline Immunosuppression Trial was projected to yield a 1.9-year increase in time alive with a functioning graft and a 1.2 life-year increase over a 20-year time horizon.

CONCLUSIONS

This is the first long-term follow-up model of renal transplant patients to be based on renal function, acute rejection, and new-onset diabetes. It is a useful tool for undertaking comparative effectiveness and cost-effectiveness studies of immunosuppressive medications.

2B4 (CD244) induced by selective CD28 blockade functionally regulates allograft-specific CD8+ T cell responses

Blockade of CD28 signals results in the up-regulation of 2B4 on primary CD8⁺ effectors and plays a critical role in controlling antigen-specific CD8⁺ T cell responses.

Mounting evidence in models of both autoimmunity and chronic viral infection suggests that the outcome of T cell activation is critically impacted by the constellation of co-stimulatory and co-inhibitory receptors expressed on the cell surface. Here, we identified a critical role for the co-inhibitory SLAM family member 2B4 (CD244) in attenuating primary antigen-specific CD8⁺ T cell responses in the presence of immune modulation with selective CD28 blockade. Our results reveal a specific up-regulation of 2B4 on antigen-specific CD8⁺ T cells in animals in which CD28 signaling was blocked. However, 2B4 up-regulation was not observed in animals treated with CTLA-4 Ig (abatacept) or CD28 blockade in the presence of anti–CTLA-4 mAb. 2B4 up-regulation after CD28 blockade was functionally significant, as the inhibitory impact of CD28 blockade was diminished when antigen-specific CD8⁺ T cells were deficient in 2B4. In contrast, 2B4 deficiency had no effect on CD8⁺ T cell responses during unmodified rejection or in the presence of CTLA-4 Ig. We conclude that blockade of CD28 signals in the presence of preserved CTLA-4 signals results in the unique up-regulation of 2B4 on primary CD8⁺ effectors, and that this 2B4 expression plays a critical functional role in controlling antigen-specific CD8⁺ T cell responses.

Obesity and metabolic syndrome in kidney transplantation

The epidemic of obesity and metabolic syndrome (MS) contributes to the rapid growth of chronic kidney disease (CKD) and end-stage renal disease (ESRD). There is a reverse epidemiology, known as the "obesity paradox," in ESRD patients receiving maintenance dialysis. Obese patients are routinely referred for kidney transplant, and they have more surgical and medical complications than non-obese patients. However, compared to dialysis, kidney transplant provides a survival benefit for obese patients. After kidney transplant, obese patients tend to gain more body weight, and non-obese patients can develop new-onset obesity/MS. Obesity/MS is not only associated with serious morbidities, but also compromises the long-term graft and patient survival. The immunosuppressive drugs commonly used as maintenance therapy, including corticosteroids, calcineurin inhibitors and mammalian target-of-rapamycin inhibitors, contribute to obesity/MS. Development of novel immunosuppressive drugs free of metabolic adverse effects is needed, so that the full potential and benefits of kidney transplantation can be realized.

Novel immunosuppressive agents in kidney transplantation

Excellent outcomes have been achieved in the field of renal transplantation. A significant reduction in acute rejection has been attained at many renal transplant centers using contemporary immunosuppressive, consisting of an induction agent, a calcineurin inhibitor, an antiproliferative agent plus or minus a corticosteroid. Despite improvements with these regimens, chronic allograft injury and adverse events still persist. The perfect immunosuppressive regimen would limit or eliminate calcineurin inhibitors and/or corticosteroid toxicity while providing enhanced allograft outcomes. Potential improvements to the calcineurin inhibitor class include a prolonged release tacrolimus formulation and voclosporin, a cyclosporine analog. Belatacept has shown promise as an agent to replace calcineurin inhibitors. A novel, fully-human anti-CD40 monoclonal antibody, ASKP1240, is currently enrolling patients in phase 2 trials with calcineurin minimization and avoidance regimens. Another future goal of transplant immunosuppression is effective and safe treatment of allograft rejection. Novel treatments for antibody mediated rejection include bortezomib and eculizumab. Several investigational agents are no longer being pursed in transplantation including the induction agents, efalizumab and alefacept, and maintenance agents, sotrastaurin and tofacitinib. The purpose of this review is to consolidate the published evidence of the effectiveness and safety of investigational immunosuppressive agents in renal transplant recipients.

Cardiovascular complications after transplantation: treatment options in solid organ recipients

Premature cardiovascular disease is the commonest cause of death in solid organ transplant recipients, with coronary artery disease, sudden cardiac death and heart failure being highly prevalent. There are unique factors leading to CV disease in organ transplant recipients that include underlying comorbidities, and metabolic effects of immunosuppression. As a consequence management strategies developed in the general population may have limited benefit. In this review, we will focus on renal transplantation, where most research has been carried out and, despite incomplete understanding of the disease process, the incidence of cardiovascular disease appears to be falling.

Risk of posttransplant lymphoproliferative disorder associated with use of belatacept

Purpose

Published evidence on a rare but serious malignancy associated with use of the first biological agent approved for long-term maintenance immunosuppression in renal transplant recipients is reviewed.

Summary

Belatacept (Nulojix, Bristol-Myers Squibb) is approved by the Food and Drug Administration for use in combination therapy to prevent renal graft rejection in patients who are Epstein-Barr virus seropositive. Belatacept appears to offer some advantages over calcineurin inhibitor-based regimens (e.g., no need for therapeutic drug monitoring), but its use poses a risk of posttransplant lymphoproliferative disorder (PTLD), a rapidly progressing and often lethal malignancy. The efficacy and safety of more-intensive and less-intensive belatacept regimens were established in two Phase III clinical trials, which found that rates of patient and graft survival were comparable to those in cyclosporine users; belatacept was shown to be superior in preserving renal function. The occurrence of PTLD, particularly PTLD involving the central nervous system, in 0–4% of belatacept-treated patients in clinical trials prompted postmarketing initiatives: (1) implementation of a risk evaluation and mitigation strategy (REMS) program to help ensure the safe and proper use of belatacept, (2) longitudinal studies to better define the risks and outcomes of belatacept therapy, and (3) a manufacturer-created patient registry to track belatacept use and encourage voluntary reporting of associated adverse events.

Conclusion

Appropriate patient selection and adherence to REMS requirements, including patient counseling and facilitation of registry enrollment, are essential in mitigating the increased risk of PTLD associated with belatacept therapy.

A surgeons' guide to renal transplant immunopathology, immunology, and immunosuppression

The response to allografting involves adaptive and innate immune mechanisms. In the adaptive system, activated T cells differentiate to cytotoxic effectors that attack the graft and trigger B cells to differentiation to plasma cells that produce anti-HLA antibodies. The innate immune system recognizes antigens in a non-specific manner and recruits immune cells to the graft through the productions of chemotactic factors, and activation of cytokines and the complement cascade. In the kidney the tubules and the endothelium are the targets of the rejection response. Immune suppression is effective in modulating the adaptive immune system effect on graft histology.

Long-term belatacept exposure maintains efficacy and safety at 5 years: results from the long-term extension of the BENEFIT study

The Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial randomized patients receiving a living or standard criteria deceased donor kidney transplant to a more (MI) or less intensive (LI) regimen of belatacept or cyclosporine A (CsA). The 5-year results of the long-term extension (LTE) cohort are reported. A total of 456 (68.5% of intent-to-treat) patients entered the LTE at 36 months; 406 patients (89%) completed 60 months. Between Months 36 and 60, death occurred in 2%, 1% and 5% of belatacept MI, belatacept LI and CsA patients, respectively; graft loss occurred in 0% belatacept and 2% of CsA patients. Acute rejection between Months 36 and 60 was rare: zero belatacept MI, one belatacept LI and one CsA. Rates for infections and malignancies for Months 36-60 were generally similar across belatacept groups and CsA, respectively: fungal infections (14%, 15%, 12%), viral infections (21%, 18%, 16%) and malignancies (6%, 6%, 9%). No new posttransplant lymphoproliferative disorder cases occurred after 36 months. Mean calculated GFR (MDRD, mL/min/1.73 m(2) ) at Month 60 was 74 for belatacept MI, 76 for belatacept LI and 53 for CsA. These results show that the renal function benefit and safety profile observed in belatacept-treated patients in the early posttransplant period was sustained through 5 years.

Long-term exposure to belatacept in recipients of extended criteria donor kidneys

Patients in the BENEFIT-EXT study received extended criteria donor kidneys and a more intensive (MI) or less intensive (LI) belatacept immunosuppression regimen, or cyclosporine A (CsA). Patients who remained on assigned therapy through year 3 were eligible to enter a long-term extension (LTE) study. Three hundred four patients entered the LTE (n = 104 MI; n = 113 LI; n = 87 CsA), and 260 continued treatment through year 5 (n = 91 MI; n = 100 LI; n = 69 CsA). Twenty patients died during the LTE (n = 5 MI; n = 9 LI; n = 6 CsA), and eight experienced graft loss (n = 2 MI; n = 1 LI; n = 5 CsA). Three patients experienced an acute rejection episode (n = 2 MI; n = 1 LI). The incidence rate of serious adverse events, viral infections and fungal infections was similar across groups during the LTE. There were four cases of posttransplant lymphoproliferative disorder (PTLD) from the beginning of the LTE to year 5 (n = 3 LI; n = 1 CsA); two of three PTLD cases in the LI group were in patients who were seronegative for Epstein-Barr virus (EBV(-)) at transplantation. Mean ± SD calculated GFR at year 5 was 55.9 ± 17.5 (MI), 59.0 ± 29.1 (LI) and 44.6 ± 16.4 (CsA) mL/min/1.73 m(2) . Continued treatment with belatacept was associated with a consistent safety profile and sustained improvement in renal function versus CsA over time.

Fundamental immunology of skin transplantation and key strategies for tolerance induction

Transplantation of allogeneic or xenogeneic skin grafts can evoke strong immune responses that lead to acute rejection of the graft tissues. In this process, donor-derived dendritic cells play crucial roles in the triggering of such immune responses. Both the innate and acquired host immune systems participate in graft rejection. At present, the rejection of skin grafts cannot be well-controlled by ordinary systemic immunosuppression therapy. Although several strategies for the long-term survival of allogeneic or xenogeneic skin grafts have been demonstrated in animal models, the induction of long-term tolerance to skin grafts is still a great challenge in clinical settings. In this article, we review the progress in the understanding of immune responses to skin grafts and discuss the possible methods that can decrease the immunogenicity of graft tissues and improve the survival of skin grafts, especially those included in preoperative pre-treatments.

Belatacept in kidney transplantation

PURPOSE OF REVIEW

In June 2011 the US Food and Drug Administration approved belatacept (Nulojix; Bristol-Myers Squibb, Princeton, New Jersey, USA) for the prophylaxis of organ rejection in adult kidney transplant recipients. This review will discuss the use of belatacept for the prevention of acute rejection as part of a maintenance immunosuppression regimen.

RECENT FINDINGS

Belatacept is a selective costimulation blocker designed to provide effective immunosuppression while avoiding the toxicities associated with calcineurin inhibitors. Phase 3 trial data have demonstrated that belatacept is noninferior to cyclosporine in 1-year patient and allograft survival. Three-year data demonstrate an ongoing improvement in mean measured glomerular filtration rate in belatacept-treated versus cyclosporine-treated patients. Overall, there seemed to be an improvement in cardiometabolic parameters in patients treated with belatacept compared with cyclosporine. There was a trend toward higher rates of early rejection episodes in patients treated with belatacept. One safety issue that must be considered when using belatacept is the potential for increased risk of posttransplant lymphoproliferative disease, especially in Epstein-Barr virus-seronegative recipients or patients treated with lymphocyte-depleting agents.

SUMMARY

Belatacept is the first new agent available in kidney transplant that may achieve the goal of improved long-term renal function.

Risk Evaluation and Mitigation Strategies: A Focus on Belatacept

Objective

To review the elements and components of the risk evaluation and mitigation strategies (REMS) for the costimulation blocker belatacept and associated implications for health care providers working with transplant recipients.

Data Sources and Extraction

The MEDLINE and EMBASE databases (January 1990 to March 2012) were searched by using risk evaluation and mitigation strategies, REMS, belatacept, and organ transplant as search terms (individual organs were also searched). Retrieved articles were supplemented with analysis of information obtained from the Federal Register, the Food and Drug Administration, and the manufacturer of belatacept.

Data Synthesis

REMS are risk-management strategies implemented to ensure that a product's benefits outweigh its known safety risks. Although belatacept offers a novel strategy in maintenance immunosuppression and was associated with superior renal function compared with cyclosporine in phase 2 and 3 trials, belatacept is also associated with increased risk of posttransplant lymphoproliferative disorder and central nervous system infections. The Food and Drug Administration required development of a REMS program as part of belatacept's approval process to ensure safe and appropriate use of the medication and optimization of its risk-benefit profile. Conclusion—Elements of the belatacept REMS include a medication guide that must be dispensed with each infusion and a communication plan. In the management of a complex population of patients, it is essential that those who care for transplant recipients, and patients, recognize the implications of potential and known risks of belatacept. The REMS program aims to facilitate careful selection and education of patients and vigilant monitoring.

Functional Characteristics of C-terminal Lysine to Cysteine Mutant Form of CTLA-4Ig

CTLA-4Ig is regarded as an inhibitory agent of the T cell proliferation via blocking the costimulatory signal which is essential for full T cell activation. To improve applicability, we developed the CTLA-4Ig-CTKC in which the c-terminal lysine had been replaced by cysteine through single amino acid change. The single amino acid mutation of c-terminus of CTLA-4Ig was performed by PCR and was checked by in vitro transcription and translation. DNA construct of mutant form was transfected to Chinese hamster ovary (CHO) cells by electroporation. The purified proteins were confirmed by Western blot and B7-1 binding assay for their binding ability. The suppressive capacity of CTLA-4Ig-CTKC was evaluated by the mixed lymphocyte reaction (MLR) and in the allogeneic pancreatic islet transplantation model. CTLA-4Ig-CTKC maintained binding ability to B7-1 molecule and effectively inhibits T cell proliferation in MLR. In the murine allogeneic pancreatic islet transplantation, short-term treatment of CTLA-4Ig-CTKC prolonged the graft survival over 100 days. CTLA-4Ig-CTKC effectively inhibits immune response both in MLR and in allogeneic islet transplantation model, indicating that single amino acid mutation does not affect the inhibitory function of CTLA-4Ig. CTLA-4Ig-CTKC can be used in vehicle-mediated drug delivery system such as liposome conjugation.

Costimulation blockade: current perspectives and implications for therapy

T cells must be activated before they can elicit damage to allografts, through interaction of their T cell receptor (TCR) with peptide-MHC complex and through accessory molecules. Signaling through accessory molecules or costimulatory molecules is a critical way for the immune system to fine tune T cell activation. An emerging therapeutic strategy is to target selective molecules involved in the process of T cell activation using biologic agents, which do not impact TCR signaling, thus only manipulating the T cells, which recognize alloantigen. Costimulatory receptors and their ligands are attractive targets for this strategy and could be used both to prevent acute graft rejection as well as for maintenance immunosuppression. Therapeutic agents targeting costimulatory molecules, notably belatacept, have made the progression from the bench, through nonhuman primate studies and into the clinic. This overview describes some of the most common costimulatory molecules, their role in T cell activation, and the development of reagents, which target these pathways and their efficacy in transplantation.

Belatacept and sirolimus prolong nonhuman primate islet allograft survival: adverse consequences of concomitant alefacept therapy

Calcineurin inhibitors (CNI) and steroids are known to promote insulin resistance, and their avoidance after islet transplantation is preferred from a metabolic standpoint. Belatacept, a B7-specific mediator of costimulation blockade (CoB), is clinically indicated as a CNI alternative in renal transplantation, and we have endeavored to develop a clinically translatable, belatacept-based regimen that could obviate the need for both CNIs and steroids. Based on the known synergy between CoB and mTOR inhibition, we studied rhesus monkeys undergoing MHC-mismatched islet allotransplants treated with belatacept and the mTOR inhibitor, sirolimus. To extend prior work on CoB-resistant rejection, some animals also received CD2 blockade with alefacept (LFA3-Ig). Nine rhesus macaques were rendered diabetic with streptozotocin and underwent islet allotransplantation. All received belatacept and sirolimus; six also received alefacept. Belatacept and sirolimus significantly prolonged rejection-free graft survival (median 225 days compared to 8 days in controls receiving basiliximab and sirolimus; p = 0.022). The addition of alefacept provided no additional survival benefit, but was associated with Cytomegalovirus reactivation in four of six animals. No recipients produced donor-specific alloantibodies. The combination of belatacept and sirolimus successfully prevents islet allograft survival in rhesus monkeys, but induction with alefacept provides no survival benefit and increases the risk of viral reactivation.

Advances in targeting cell surface signalling molecules for immune modulation

The past decade has witnessed a surge in the development of immunomodulatory approaches to combat a broad range of human diseases, including cancer, viral infections, autoimmunity and inflammation as well as in the prevention of transplant rejection. Immunomodulatory approaches mostly involve the use of monoclonal antibodies or recombinant fusion proteins that target cell surface signalling molecules on immune cells to drive immune responses towards the desired direction. Advances in our understanding of the human immune system, along with valuable lessons learned from the first generation of therapeutic biologics, are aiding the design of the next generation of immunomodulatory biologics with better therapeutic efficacy, minimized adverse effects and long-lasting clinical benefit. The recent encouraging results from antibodies targeting programmed cell death protein 1 (PD1) and B7 homolog 1 (B7H1; also known as PDL1) for the treatment of various advanced human cancers show that immunomodulatory therapy has come of age.

The role of innate and adaptive immunity in Parkinson's disease

In recent years, inflammation has become implicated as a major pathogenic factor in the onset and progression of Parkinson's disease. Understanding the precise role for inflammation in PD will likely lead to understanding of how sporadic disease arises. In vivo evidence for inflammation in PD includes microglial activation, increased expression of inflammatory genes in the periphery and in the central nervous system (CNS), infiltration of peripheral immune cells into the CNS, and altered composition and phenotype of peripheral immune cells. These findings are recapitulated in various animal models of PD and are reviewed herein. Furthermore, we examine the potential relevance of PD-linked genetic mutations to altered immune function and the extent to which environmental exposures that recapitulate these phenotypes, which may lead to sporadic PD through similar mechanisms. Given the implications of immune system involvement on disease progression, we conclude by reviewing the evidence supporting the potential efficacy of immunomodulatory therapies in PD prevention or treatment. There is a clear need for additional research to clarify the role of immunity and inflammation in this chronic, neurodegenerative disease.

Belatacept utilization recommendations: an expert position

INTRODUCTION

There is a continuing need for an immunosuppressive therapy that offers a high benefit-risk profile for renal transplant recipients, supporting long-term patient and graft survival while minimizing cumulative nephrotoxicity and other side effects. Belatacept , the first biological agent developed for primary maintenance immunosuppression, was recently approved for use in Europe. Belatacept combined with corticosteroids and a mycophenolic acid is indicated for prophylaxis of graft rejection in adults receiving renal transplant. Its use is contraindicated in Epstein-Barr virus seronegative or serostatus unknown patients due to increased risk of developing posttransplant lymphoproliferative disorder.

AREAS COVERED

This review provides practical recommendations for the use of belatacept, based on safety and efficacy data from Phase II and Phase III clinical trials in de novo kidney transplant recipients.

EXPERT OPINION

Treatment with belatacept is associated with improved long-term graft function, making belatacept an important option for prevention of kidney allograft rejection. Furthermore, efficacy and safety data over several years of therapy suggest that belatacept is particularly suitable for long-term immunosuppression, and the selective targeting offered by belatacept may help avoid some of the non-specific chronic safety risks associated with calcineurin inhibitors and steroids. Future studies will clarify the optimal regimen for belatacept usage.

Effect of maintenance immunosuppressive drugs on virus pathobiology: evidence and potential mechanisms

Recent evidence suggesting a potential anti-CMV effect of mTORis is of great interest to the transplant community. However, the concept of an immunosuppressant with antiviral properties is not new, with many accounts of the antiviral properties of several agents over the years. Despite these reports, to date, there has been little effort to collate the evidence into a fuller picture. This manuscript was developed to gather the evidence of antiviral activity of the agents that comprise a typical immunosuppressive regimen against viruses that commonly reactivate following transplant (HHV1 and 2, VZV, EBV, CMV and HHV6, 7, and 8, HCV, HBV, BKV, HIV, HPV, and parvovirus). Appropriate immunosuppressive regimens posttransplant that avoid acute rejection while reducing risk of viral reactivation are also reviewed. The existing literature was disparate in nature, although indicating a possible stimulatory effect of tacrolimus on BKV, potentiation of viral reactivation by steroids, and a potential advantage of mammalian target of rapamycin (mTOR) inhibition in several viral infections, including BKV, HPV, and several herpesviruses.

Belatacept for prevention of acute rejection in adult patients who have had a kidney transplant: an update

In June 2011, the US Food and Drug Administration approved belatacept for the prophylaxis of organ rejection in adult kidney transplant recipients. This review discusses the use of belatacept for the prevention of acute rejection as part of a maintenance immunosuppression regimen. Belatacept is a selective costimulation blocker designed to provide effective immunosuppression while avoiding the toxicities associated with calcineurin inhibitors. Phase III trial data have demonstrated that belatacept is noninferior to cyclosporine in 1-year patient and allograft survival. Three-year data demonstrate an ongoing improvement in mean measured glomerular filtration rate in belatacept-treated versus cyclosporine-treated patients. However, the rate of acute rejection was higher in belatacept-treated patients compared with cyclosporine. Specifically, there was a higher incidence of Banff type II rejections in patients treated with belatacept. Despite the higher Banff grade, rejections on belatacept were not associated with other factors associated with poor outcomes, such as the development of donor-specific antibodies or reduced estimated glomerular filtration rate. One safety issue that must be considered when using belatacept is the potential for increased risk of post-transplant lymphoproliferative disease. There were more cases of post-transplant lymphoproliferative disease in belatacept-treated patients, especially in recipients seronegative for Epstein–Barr virus or patients treated with lymphocyte-depleting agents. Therefore, belatacept can be recommended for use in Epstein–Barr virus antibody-positive recipients.

Introduction to the use of belatacept: a fusion protein for the prevention of posttransplant kidney rejection

The development of new immunosuppressive drugs for kidney transplantation resulted both in better short-term outcomes and in decreased metabolic, cardiovascular, and nephrotoxicity risk. Belatacept belongs to a new class of immunosuppressive drugs that selectively inhibits T-cell activation by preventing CD28 activation and by binding its ligands B7-1 and B7-2. The result is an inactivation of costimulatory pathways. A comparative analysis of the BENEFIT and BENEFIT-EXT datasets showed belatacept regimens resulted in better cardiovascular and metabolic risk profiles than did cyclosporin A (CsA) regimens: belatacept likewise outperformed CsA in terms of lower blood pressure and serum lipids and less new onset diabetes after transplantation. About 20% of belatacept-treated patients developed adverse effects which included anemia, pyrexia, neutropenia, diarrhea, urinary tract infection, headache, and peripheral edema. At present, belatacept does not seem to predispose patients to a higher rate of infection than CsA maintenance immunosuppression. The risk of posttransplant lymphoproliferative diseases was higher in Epstein-Barr virus (EBV)-seronegative patients than in EBV-seropositive patients, but the risk may be reduced by use of a less intensive regimen and avoidance of EBV-negative patients and of patients whose pretransplant EBV serology is unknown. Belatacept provides a new option for immunosuppressive therapy in kidney transplantation, but needs further evaluation in terms of the late effects that may derive from prolonged blockage of the costimulatory system and the induction of tolerance status.

Current state of renal transplant immunosuppression: Present and future

For kidney transplant recipients, immunosuppression commonly consists of combination treatment with a calcineurin inhibitor, an antiproliferative agent and a corticosteroid. Many medical centers use a sequential immunosuppression regimen where an induction agent, either an anti-thymocyte globulin or interleukin-2 receptor antibody, is given at the time of transplantation to prevent early acute rejection which is then followed by a triple immunosuppressive maintenance regimen. Very low rejection rates have been achieved at many transplant centers using combinations of these agents in a variety of protocols. Yet, a large number of recipients suffer chronic allograft injury and adverse events associated with drug therapy. Regimens designed to limit or eliminate calcineurin inhibitors and/or corticosteroid use are actively being pursued. An ideal immunosuppressive regimen limits toxicity and prolongs the functional life of the graft. This article contains a critical analysis of clinical data on currently available immunosuppressive strategies and an overview of therapeutic moieties in development.

[Recent options in drug therapy after solid organ transplantation]

Solid organ transplantation has shown improvement in patient and graft survival rates due to the development of immunosuppression in the last fifty years; however only the last two decades led to the development of new, baseline immunosuppressive drugs that avoid the unlikely side effects of calcineurin inhibitors, especially nephrotoxicity. The transplanted organ is foreign to the host and, therefore, it induces a complex immune response of the recipient. In this review, a brief outline of immune response is given, followed by the introduction of new immunosuppressive drugs acting via variant pathways. These are compounds which are already in use or becoming shortly available and are potential future alternatives for the calcineurin inhibitors. This paper highlights the role of co-stimulation blockade with belatacept and the recently even more intensively studied field of tolerance induction.

In vivo CYP3A4 activity, CYP3A5 genotype, and hematocrit predict tacrolimus dose requirements and clearance in renal transplant patients

Tacrolimus is metabolized by CYP3A4 and CYP3A5 and is characterized by a narrow therapeutic index and highly variable pharmacokinetics. This cross-sectional study in 59 renal transplant patients investigated the relationship among in vivo CYP3A4 activity (assessed using midazolam as a drug probe), CYP3A5 genotype on the one hand, and tacrolimus pharmacokinetics on the other hand, taking into account other potential determinants of tacrolimus disposition. In vivo CYP3A4 activity and CYP3A5 genotype explain 56-59% of variability in tacrolimus dose requirements and clearance, contributing ~25 and 30%, respectively. Hematocrit explains an additional 4-14%. These data indicate that CYP3A4- and CYP3A5-mediated tacrolimus metabolisms are major determinants of tacrolimus disposition in vivo and explain a substantial part of the clinically observed high interindividual variability in tacrolimus pharmacokinetics. Furthermore, these data provide a potential basis for a comprehensive approach to predicting tacrolimus dose requirement in individual patients and hence provide a strategy to tailor immunosuppressive therapy in transplant recipients.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

A novel monoclonal antibody to CD40 prolongs islet allograft survival

The importance of CD40/CD154 costimulatory pathway blockade in immunosuppression strategies is well-documented. Efforts are currently focused on monoclonal antibodies specific for CD40 because of thromboembolic complications associated with monoclonal antibodies directed towards CD154. Here we present the rational development and characterization of a novel antagonistic monoclonal antibody to CD40. Rhesus macaques were treated with the recombinant anti-CD40 mAb, 2C10, or vehicle before immunization with keyhole limpet hemocyanin (KLH). Treatment with 2C10 successfully inhibited T cell-dependent antibody responses to KLH without significant peripheral B cell depletion. Subsequently, MHC-mismatched macaques underwent intraportal allogeneic islet transplantation and received basiliximab and sirolimus with or without 2C10. Islet graft survival was significantly prolonged in recipients receiving 2C10 (graft survival time 304, 296, 265, 163 days) compared to recipients receiving basiliximab and sirolimus alone (graft survival time 8, 8, 10 days). The survival advantage conferred by treatment with 2C10 provides further evidence for the importance of blockade of the CD40/CD154 pathway in preventing alloimmune responses. 2C10 is a particularly attractive candidate for translation given its favorable clinical profile.

Improvement in renal function in kidney transplant recipients switched from cyclosporine or tacrolimus to belatacept: 2-year results from the long-term extension of a phase II study

Kidney transplant recipients who switched from a calcineurin inhibitor (CNI) to belatacept demonstrated higher calculated glomerular filtration rates (cGFRs) at 1 year in a Phase II study. This report addresses whether improvement was sustained at 2 years in the long-term extension (LTE). Patients receiving cyclosporine or tacrolimus were randomized to switch to belatacept or continue CNI. Of 173 randomized patients, 162 completed the 12-month main study and entered the LTE. Two patients (n = 1 each group) had graft loss between Years 1-2. At Year 2, mean cGFR was 62.0 ml/min (belatacept) vs. 55.4 ml/min (CNI). The mean change in cGFR from baseline was +8.8 ml/min (belatacept) and +0.3 ml/min (CNI). Higher cGFR was observed in patients switched from either cyclosporine (+7.8 ml/min) or tacrolimus (+8.9 ml/min). The frequency of acute rejection in the LTE cohort was comparable between the belatacept and CNI groups by Year 2. All acute rejection episodes occurred during Year 1 in the belatacept patients and during Year 2 in the CNI group. There were more non-serious mucocutaneous fungal infections in the belatacept group. Switching to a belatacept-based regimen from a CNI-based regimen resulted in a continued trend toward improved renal function at 2 years after switching.

Tolerogenic therapies in transplantation

Since the concept of immunologic tolerance was discovered in the 1940s, the pursuit of tolerance induction in human transplantation has led to a rapid development of pharmacologic and biologic agents. Short-term graft survival remains an all-time high, but successful withdrawal of immunosuppression to achieve operational tolerance rarely occurs outside of liver transplantation. Collaborative efforts through the NIH sponsored Immune Tolerance Network and the European Commission sponsored Reprogramming the Immune System for Establishment of Tolerance consortia have afforded researchers opportunity to evaluate the safety and efficacy of tolerogenic strategies, investigate mechanisms of tolerance, and identify molecular and genetic markers that distinguish the tolerance phenotype. In this article, we review traditional and novel approaches to inducing tolerance for organ transplantation, with an emphasis on their translation into clinical trials.

Belatacept : a new biological agent for maintenance immunosuppression in kidney transplantation

INTRODUCTION

Over the past decades, calcineurin inhibitors (CNIs) have become the cornerstone of transplant immunosuppression. CNIs can exert negative effects on chronic allograft function along with cardiovascular (CV) and metabolic adverse effects. Belatacept , a selective co-stimulation blocker of T cells, is the first US FDA (06/2011) and EMEA (06/2011) approved biologic agent for maintenance immunosuppression in renal transplantation.

AREAS COVERED

The authors critically reviewed the literature over the last few years comparing belatacept with current standard of maintenance immunosuppression including CNIs in kidney transplantation.

EXPERT OPINION

Despite the increased incidence and severity of acute rejection with belatacept in Phase II and III studies, a better preservation of GFR and reduced incidence of chronic allograft nephropathy was observed as compared with CNIs. Patient and graft survivals were similar over 3- and 5-year follow-up post-transplantation. Incidence of adverse events were similar between the groups, but the risk of post-transplant lymphoproliferative disorder, predominantly involving CNS, was higher in Epstein-Barr virus seronegative recipients on belatacept, especially with a more intensive regimen. CV and metabolic end points were more favorable in belatacept versus CNI groups with similar incidences of diabetes after transplantation. Belatacept seems to be a promising drug for the future, but long-term outcomes are awaited.

CTLA4Ig prevents alloantibody formation following nonhuman primate islet transplantation using the CD40-specific antibody 3A8

Islet transplantation to treat type 1 diabetes has been limited in part by toxicities of current immunosuppression and recipient humoral sensitization. Blockade of the CD28/CD80/86 and CD40/CD154 pathways has shown promise to remedy both these limitations, but translation has been hampered by difficulties in translating CD154-directed therapies. Prior CD40-directed regimens have led to prolonged islet survival, but fail to prevent humoral allosensitization. We therefore evaluated the addition of CTLA4Ig to a CD40 blockade-based regimen in nonhuman primate (NHP) alloislet transplantation. Diabetic rhesus macaques were transplanted allogeneic islets using the CD40-specific antibody 3A8, basiliximab induction, and sirolimus with or without CTLA4Ig maintenance therapy. Allograft survival was determined by fasting blood glucose levels and flow cytometric techniques were used to test for donor-specific antibody (DSA) formation. CTLA4Ig plus 3A8, basiliximab and sirolimus was well tolerated and induced long-term islet allograft survival. The addition of CTLA4Ig prevented DSA formation, but did not facilitate withdrawal of the 3A8-based regimen. Thus, CTLA4Ig combines with a CD40-specific regimen to prevent DSA formation in NHPs, and offers a potentially translatable calcineurin inhibitor-free protocol inclusive of a single investigational agent for use in clinical islet transplantation without relying upon CD154 blockade.

CD28 family and chronic rejection: "to belatacept...And beyond!"

Kidneys are one of the most frequently transplanted human organs. Immunosuppressive agents may prevent or reverse most acute rejection episodes; however, the graft may still succumb to chronic rejection. The immunological response involved in the chronic rejection process depends on both innate and adaptive immune response. T lymphocytes have a pivotal role in chronic rejection in adaptive immune response. Meanwhile, we aim to present a general overview on the state-of-the-art knowledge of the strategies used for manipulating the lymphocyte activation mechanisms involved in allografts, with emphasis on T-lymphocyte costimulatory and coinhibitory molecules of the B7-CD28 superfamily. A deeper understanding of the structure and function of these molecules improves both the knowledge of the immune system itself and their potential action as rejection inducers or tolerance promoters. In this context, the central role played by CD28 family, especially the relationship between CD28 and CTLA-4, becomes an interesting target for the development of immune-based therapies aiming to increase the survival rate of allografts and to decrease autoimmune phenomena. Good results obtained by the recent development of abatacept and belatacept with potential clinical use aroused better expectations concerning the outcome of transplanted patients.

[Perspectives in pediatric renal transplantation]

New immunosuppressive drugs are administered in adults after renal transplantation to prevent toxicities (nephrotoxicity, cardiovascular complications…). Among these, Belatacept exhibited exciting results and its indication in pediatric patients will have to be validated, especially in EBVpositive recipients. Rituximab, bortezomide and eculizumab are also currently being evaluated in protocols of desensitization and in the treatment of humoral rejections. An individually tailored immunosuppressive regimen might be considered in the future, based on the study of certain polymorphisms or on immune status and alloreactivity determined by new biomarkers. Finally, the development of EBV and cmV vaccines would prevent these infections after transplantation.