Three-year outcomes from BENEFIT-EXT: a phase III study of belatacept versus cyclosporine in recipients of extended criteria donor kidneys

Corticosteroid and calcineurin inhibitor sparing regimens in kidney transplantation

Chronic kidney disease is a major public health problem that is associated with increased risks of kidney disease progression, cardiovascular disease and death. Kidney transplantation remains the renal replacement therapy of choice for patients with end-stage kidney disease. Despite impressive strides in short-term allograft survival, there has been little improvement in long-term kidney graft survival, and rates of death with a functioning allograft remain high. Long-term safety profiles of existing immunosuppressive regimens point to a need for continued search for alternative agents. This overview discusses emerging evidence on a few promising therapeutic approaches, juxtaposes conflicting findings and highlights remaining knowledge gaps.

Is it time to give up with calcineurin inhibitors in kidney transplantation?

Calcineurin inhibitors (CNIs) represent today a cornerstone for the maintenance immunosuppressive treatment in solid organ transplantation. Nevertheless, several attempts have been made either to minimize their dosage or to avoid CNIs at all because these drugs have the severe side effect of chronic nephrotoxicity. This issue represents a frontier for renal transplantation. The principal problem is to understanding whether the poor outcome over the long-term may be ascribed to CNIs nephrotoxicity or to the inability of these drugs to control the acute and chronic rejection B cells mediated. The authors analyze extensively all the international trials attempting to withdraw, minimize or avoid the use of CNIs. Few trials undertaken in low risk patients with an early conversion from CNIs to proliferation signal inhibitors were successful, but the vast majority of trials failed to improve CNIs side effects. To date the use of a new drug, a co-stimulation blocker, seems promising in avoiding CNIs with similar efficacy, better glomerular filtration rate and an improved metabolic profile. Moreover the use of this drug is not associated with the development of donor-specific anti-human leukocyte antigen antibodies. This point has a particular relevance, because the failure of CNIs to realize good outcomes in renal transplantation has recently ascribed to their inability to control the acute and chronic rejections B-cell mediated. This paper analyzes all the recent studies that have been done on this issue that represents the real frontier that should be overcome to realize better results over the long-term after transplantation.

Expanded Criteria Donors in Kidney Transplantation: The Role of Older Donors in a Setting of Older Recipients

Kidney transplantation (KT) is the therapy of choice for end-stage renal disease (ESRD). The ESRD population is aging and so are patients waiting for KT. New strategies have been made for increasing the donor and recipient pools, and as a consequence kidneys from older donors or donors with significant comorbidities, the so-called “expanded criteria donor” (ECD) kidneys, are used for transplantation. Although good outcomes have been achieved from ECD, several issues are still waiting for clarification and need to be discussed. The concept of age matching is accepted as a method to ameliorate utilization of these allografts, but an optimal and widely accepted strategy is still not defined. The development of machine perfusion and the dual kidney transplantation are techniques which further improve the outcome of transplants from ECD, but the described experiences are scarce or coming from small single institutional reports. Also due to age-related immune dysfunction and associated comorbidities, the elderly recipients are more susceptible to immunosuppression related complications (e.g., infections and malignancy), although a widely accepted and validated immunosuppressive regimen is still lacking. In this paper, we review the issues related to KT employing allografts from marginal donors with a particular interest for the elderly patients.

Maintenance immunosuppression in renal transplantation

The need to maintain allograft recipients on immunosuppression is nearly universal. Immunosuppressive agents used in organ transplantation target one or more steps of the host alloimmune response, specifically processes related to CD4-positive T lymphocytes. Calcineurin-inhibitor based steroid-containing regimens have been the mainstay of maintenance immunosuppression over the last two decades. Newer agents have shown efficacy in this role in recent trials with comparable allograft and patient outcomes. These agents have permitted calcineurin-inhibitor minimization and steroid-sparing strategies in selected groups of patients.

Belatacept: a novel immunosuppressive agent for kidney transplant recipients

Long-term graft and patient survival remain the most significant challenges in kidney transplantation, and new therapies are needed to improve long-term outcomes. Belatacept, a first-in-class selective costimulation blocker, has been approved for prophylaxis of organ rejection in kidney transplant recipients who are positive for EBV. In Phase III trials, belatacept demonstrated superior preservation of renal function and comparable patient/graft survival compared with cyclosporine, while avoiding the renal toxicities and other adverse events associated with the use of a calcineurin inhibitor. Patients treated with belatacept had higher rates of acute rejection than cyclosporine-treated patients. However, acute rejection episodes that occurred early and did not recur were generally not associated with donor-specific antibodies, and few belatacept patients had graft loss due to rejection. The improved renal benefit with belatacept may translate into improvements in long-term graft and patient outcomes. Targeting T-cell costimulation is an important new option for maintenance immunosuppression in kidney transplant recipients.

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.

Renal-sparing regimens employing new agents

PURPOSE OF REVIEW

A persistent challenge facing the transplant community is avoiding renal compromise, whether protecting a newly placed kidney allograft or preserving native renal function after another organ has been implanted. One of the principal ways to achieve this is by altering the immunosuppressive regimen. We review some of the more important recent studies in this area.

RECENT FINDINGS

Over the past year, two new immunosuppressive agents have received attention. An immunoselective biologic agent, belatacept, continued to demonstrate a sustained benefit in renal function when compared with a cyclosporine-based regimen. In a phase 2 multicenter study, sotrastaurin, a protein kinase C inhibitor, has shown promise in preserving renal graft function but lacks potency as an immunosuppressive agent. A known agent, everolimus, in combination with reduced doses of calcineurin inhibitors or with other agents, continues to be in the forefront as a promising renal-sparing option. Finally, further investigation into mycophenolate mofetil has shown that it has some advantages as a long-term agent when used in monotherapy.

SUMMARY

The new therapies investigated show some promise as potential alternative agents. As no drug regimen yet demonstrates an overwhelming benefit over calcineurin inhibitors, particularly regarding overall efficacy, efforts should continue to move forward toward the goal of minimizing chronic kidney disease.

Endogenous expression of B7-H4 improves long-term murine islet allograft survival

BACKGROUND

Allograft rejection is one of the main obstacles for islet transplantation. B7-H4 plays a key role in maintaining T-cell homeostasis by reducing T-cell proliferation and cytokine production. In this study, we investigated whether the endogenous expression of B7-H4 in β cells from B7-H4 transgenic mice enhances islet allograft survival.

METHODS

B7-H4 transgenic C57BL/6 (B6) mice (RIP.B7-H4) were developed by inserting the entire B7-H4 open reading frame under the rat insulin promoter (RIP). B7-H4 protein expression was examined by flow cytometric analysis and immunohistochemical staining. Islet allograft survival was investigated in streptozotocin-induced diabetic recipient BALB/c (H-2d) mice transplanted with 400 islets from RIP.B7-H4 (H-2b) mice under the kidney capsule. The recipient control group received islets from wild-type B6 donors.

RESULTS

B7-H4 protein was significantly up-regulated in isolated islets from RIP.B7-H4 compared with wild-type B6 mice (56%±23% vs. 3%±1.2%). B7-H4 was coexpressed with insulin, but not glucagon, suggesting that B7-H4 is expressed in a β-cell-specific manner. Recipient BALB/c mice transplanted with RIP.B7-H4 islets established euglycemia for 42.3±18.4 days (mean±SD; n=9) compared with controls at 23.1±7.8 days (mean±SD; n=12; P<0.004, log-rank test).

CONCLUSIONS

The endogenous expression of B7-H4 in donor β cells from transgenic mice prolongs islet allograft survival, confirming the negative role of B7-H4 in regulating alloreactive T-cell responses.

The external validation of the cardiovascular risk equation for renal transplant recipients: applications to BENEFIT and BENEFIT-EXT trials

BACKGROUND

Renal transplant recipients (RTRs) have increased cardiovascular disease risk. Recently, major adverse cardiac event (MACE) and mortality risk calculators for prevalent RTRs were developed. We aimed to externally validate these risk equations in an international transplant database and subsequently demonstrate application to 2 clinical trials: Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial (BENEFIT) and Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial-EXTended criteria donors (BENEFIT-EXT).

METHODS

The 7-year risk calculators were developed using data from the ALERT trial and validated for discrimination and calibration in the Patient Outcomes in Renal Transplantation (PORT) study cohort. The outlier laboratory readings were trimmed to the 99th percentile observed in the PORT database. Diabetes mellitus, LDL-cholesterol, and serum creatinine values 3 years posttransplantation were used when applying the calculators to BENEFIT and BENEFIT-EXT trial treatment arms.

RESULTS

MACE could be predicted using a 7-variable model. The area under the ROC curve was 0.738 in ALERT and 0.740 in PORT, indicating preserved discrimination. In PORT, the calibration of the model indicated significant underestimation of risk in decile 5 and 9. Total mortality could be predicted using a 6-variable model. The area under the ROC curve was 0.734 in ALERT and 0.721 in PORT, indicating preserved discrimination. In PORT, the calibration of the model indicated significant underestimation of risk in decile 7 and significant overestimation in the highest risk decile. In BENEFIT and BENEFIT-EXT trial, the calculator estimated that belatacept use may result in reduction in MACE (>20%) and mortality (∼18%-30%).

CONCLUSION

The MACE and mortality risk calculators for prevalent RTRs have been externally validated and found suitable for generic risk stratification.

[Four new drugs on the market: abiraterone, belatacept, vandetanib and fidaxomycine]

Among the 35 new molecular entities approved by the FDA in 2011, 17 were particularly notable for their significant contributions to the health of patients, including abiraterone acetate, vandetanib, belatacept and fidaxomicin. Thus, abiraterone acetate, namely Zytiga®, was included as the first in a new class of drugs to treat late-stage prostate cancer. The ability of Zytiga® to prolong survival in these patients was considered as significant because they have few other treatments options and the benefits of Zytiga® outweighed the risks of reported side-effects. Vandetanib, namely Caprelsa®, was also considered as a relevant drug since it represents the first drug approved to treat particularly aggressive medullary thyroid cancer, an orphan disease. Despite huge progress in transplantation, renal transplantation remains a serious problem since patients treated with the calcineurin inhibitors cyclosporine and tacrolimus are at high risk of developing renal injury. With longer follow-up, the novel immunosuppressant belatacept continued to show better renal function compared with a cyclosporine-based regimen, as well as a consistent safety profile and comparable efficacy. It was approved by the Food and Drug Administration in June 2011 for the prophylaxis of organ rejection in adult recipients of a kidney transplant acting by a selective T-cell costimulation blocker given as an infusion. Clostridium difficile is currently the most important cause of infectious diarrhea in the United States. Fidaxomicin, a macrolide antibiotic, was recently approved for treatment of these infections (CDIs). It could be an alternative treatment for infection with C. difficile, with similar efficacy and safety to vancomycin. Fidaxomicin has minimal activity against Bacteroides species, which may be advantageous in maintaining colonization resistance and protecting the gastrointestinal tract from colonization by C. difficile.

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.

Belatacept and sirolimus prolong nonhuman primate renal allograft survival without a requirement for memory T cell depletion

Belatacept is an inhibitor of CD28/B7 costimulation that is clinically indicated as a calcineurin inhibitor (CNI) alternative in combination with mycophenolate mofetil and steroids after renal transplantation. We sought to develop a clinically translatable, nonlymphocyte depleting, belatacept-based regimen that could obviate the need for both CNIs and steroids. Thus, based on murine data showing synergy between costimulation blockade and mTOR inhibition, we studied rhesus monkeys undergoing MHC-mismatched renal allotransplants treated with belatacept and the mTOR inhibitor, sirolimus. To extend prior work on costimulation blockade-resistant rejection, some animals also received CD2 blockade with alefacept (LFA3-Ig). Belatacept and sirolimus therapy successfully prevented rejection in all animals. Tolerance was not induced, as animals rejected after withdrawal of therapy. The regimen did not deplete T cells. Alefecept did not add a survival benefit to the optimized belatacept and sirolimus regimen, despite causing an intended depletion of memory T cells, and caused a marked reduction in regulatory T cells. Furthermore, alefacept-treated animals had a significantly increased incidence of CMV reactivation, suggesting that this combination overly compromised protective immunity. These data support belatacept and sirolimus as a clinically translatable, nondepleting, CNI-free, steroid-sparing immunomodulatory regimen that promotes sustained rejection-free allograft survival after renal transplantation.

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.

Chronic renal allograft damage after transplantation: what are the reasons, what can we do?

PURPOSE OF REVIEW

Chronic renal allograft damage is one of the main problems after kidney transplantation. This review enumerates causes, describes available therapeutic options, and discusses options of the future.

RECENT FINDINGS

Alloantigen-dependent and alloantigen-independent factors are responsible for allograft damage. Prevention of renal allograft damage starts with interventions that occur surrounding the explantation in cadaveric organs. These include the use of dopamine or machine perfusion systems.Followed by the critical phase of ischemia/reperfusion injury, the LCN2/lipocalin-2, HAVCR1, and p38 MAPK pathway are new players involved in that process. Innate immunity plays a part, too. Cold ischemia time is associated with genes of apoptosis. Nondonor-specific antibodies like antihuman leukocyte antibodies-Ia or angiotensin type 1 receptor may also play a role. Recent research indicates that genetic polymorphism like the Ficolin-2 Ala258Ser polymorphism and the mannose-binding lectin-2 polymorphism are involved in that process. New therapeutic options are rare and in the future. However, there is some evidence that drugs interfering with metalloproteinases, sexual hormones like dihydroandrosterone, and mesenchymal stem cell therapy may be of importance.

SUMMARY

Taken together, although the understanding of chronic rejection has improved, the available therapeutic options remain scarce.

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.

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.

Are calcineurin inhibitors-free regimens ready for prime time?

The goal of research in transplant therapeutics is to achieve safe and effective immunosuppression strategies that allow durable engraftment free of toxicities. The calcineurin inhibitors (CNIs) regimens, because of their inherent toxicities (including nephrotoxicity), have been unable to meet these promises. Over the past decade acute cellular rejection decreased dramatically with a concomitant robust increase in 1-year graft survival; however, long-term graft outcome showed only modest improvement. This is due in part to the toxicities of the immunosuppressive drugs. The quest for a toxicity-free-CNI-free regimen has been both intense and frustrating. A turning point in CNIs-free therapy may have occurred with the recent approval of belatacept, which represents a new paradigm in immunosuppression: biological therapy for chronic immunosuppression devoid of the usual toxicities associated with the CNIs. Belatacept, a fusion receptor protein, blocks costimulation signals necessary for the activation of T cells. Although costimulation blockade has not been shown to induce tolerance, it can provide safe and effective immunosuppression without renal or cardiovascular toxicities. The approval of belatacept in both the United States and Europe for use in renal transplantation will finally push CNI-free regimens into prime time. Novel biologics such as ASKP1240 (a human anti-CD40 monoclonal antibody) and one small molecule, tofacitinib, may advance further the use of CNI-free regimens in organ transplantation.

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.