Screening and Management of PTLD

Posttransplant lymphoproliferative disorder (PTLD) represents a heterogeneous group of lymphoproliferative diseases occurring in the setting of immunosuppression following hematopoietic stem cells transplant and solid organ transplantation. Despite its overall low incidence, PTLD is a serious complication following transplantation, with a mortality rate as high as 50% in transplant recipients. Therefore, it is important to establish for each transplant recipient a personalized risk evaluation for the development of PTLD based on the determination of Epstein-Barr virus serostatus and viral load following the initiation of immunosuppression. Due to the dynamic progression of PTLD, reflected in the diverse pathological features, different therapeutic approaches have been used to treat this disorder. Moreover, new therapeutic strategies based on the administration of virus-specific cytotoxic T cells have been developed. In this review, we summarize the available data on screening and treatment to suggest a strategy to identify transplant recipients at a higher risk for PTLD development and to review the current therapeutic options for PTLD.

A Validated LC-MS/MS Method for Performing Belatacept Drug Monitoring in Renal Transplantation

Belatacept, a CTLA4-Ig, was designed to prevent rejection and graft loss in kidney transplant recipients. This immunotherapy showed a long-term clinical benefit mainly on renal function and better glycemic control but was also associated with a higher number of severe infectious diseases, particularly CMV disease, and lymphoproliferative disease. Therapeutic drug monitoring usually guides the benefit-risk assessment of long-term immunosuppression. In this study, an analytical method by LC-MS/MS was developed in 20 microL of plasma for the belatacept quantification. Intra- and inter-assay precision and accuracy were lower than 20% for the limit of quantification, and 15% for higher concentrations. The method was implemented in our lab and provided data about the inter-variability (N = 108) and intra-variability (N = 33) of belatacept concentrations in kidney transplant recipients with a stable renal function, after conversion from a CNI- to a belatacept-based regimen.

High Dimensional Renal Profiling: Towards a Better Understanding or Renal Transplant Immune Suppression

PURPOSE OF REVIEW

The goal of this review is to discuss new approaches to avoid CNI/CCS toxicities with a focus on new biologics and new methods to understand transplant rejection at the single-cell level.

RECENT FINDINGS

Recently developed biologics hold significant promise as the next wave of therapeutics designed to promote CNI/CCS-free long-term allograft acceptance. Indeed, belatacept, soluble CTLA4-Ig, is largely devoid of CNI-like toxicities, although it is accompanied by an increased frequency of acute rejection. Besides belatacept, other biologics hold promise as CNI-free immune suppressive approaches. Finally, powerful new single cell approaches can enable characterization of cellular populations that drive rejection within the rejecting allograft.

SUMMARY

We propose that the incorporated single cell profiling into studies investigating new biologics in transplantation, could be tailored to each patient, correlated with potential biomarkers in the blood and urine, and provide a platform where therapeutic targets can be rationally defined, mechanistically-based, and exploited.

Intravenous immunoglobulins modify relapsing membranous glomerulonephritis after kidney transplantation: a case report

OBJECTIVES

Recurrence of membranous glomerulonephritis after transplant is common and is an important cause of loss of renal graft. This case supports the effect of immunoglobulins in the treatment of this disease after transplantation. It is the first report in the literature with a follow-up of more than 10 years and because of the sustained effect of the immunoglobulins, it strengthens the idea that this can alter long-term outcome.

METHODS

Single case study and search of the literature.

RESULTS

A female transplant recipient, who had an early histologically proven relapse of an idiopathic membranous glomerulonephritis and who was, before transplantation, refractory to various immunosuppressive agents. This relapsing disease has now been stable for over 10 years of intravenous immunoglobulins treatment in conjunction with belatacept and low doses of corticosteroids after gradual withdrawal of mycophenolate mofetil. This report supports the finding that immunoglobulins could influence the course of a relapse of membranous glomerulonephritis after transplantation.

CONCLUSION

This case illustrates that immunoglobulins had long-lasting effects on the renal transplant although the glomerulonephritis had been resistant to other lines of therapy before transplant. We advocate that the use of immunoglobulins as a rescue therapy in refractory idiopathic membranous glomerulonephritis should be further investigated. Presently, existing evidence only comes from retrospective data and non-randomized trials.

Overview of Immunosuppressive Therapy in Solid Organ Transplantation

Mechanisms of rejection, new pharmacologic approaches, and genomic medicine are major foci for current research in transplantation. It is hoped that these new agents and personalized immunosuppression will provide for less toxic regimens that are effective in preventing both acute and chronic allograft rejection. Until new agents are available, practitioners must use various combinations of currently approved agents to find the best regimens for improved long-term outcomes.

Cutaneous Toxicities From Transplantation-Related Medications

Despite the abundance of information on cutaneous malignancies associated with solid organ transplantation in the transplant literature, there is limited information regarding nonmalignant skin changes after transplantation. There are numerous skin toxicities secondary to immunosuppressive and other transplant-related medications that can vary in presentation, severity, and prognosis. To limit associated morbidity and mortality, solid organ transplant recipient care providers should effectively identify and manage cutaneous manifestations secondary to drug toxicity. Toxicities from the following transplant-related medications will be discussed: antithymocyte globulins, systemic steroids, cyclosporine, tacrolimus, azathioprine, mycophenolate mofetil, mammalian target of rapamycin inhibitors sirolimus and everolimus, basiliximab and daclizumab, belatacept, and voriconazole.

Developing therapeutic 'arrows' with the precision of William Tell: the time has come for targeted therapies in kidney disease

PURPOSE OF REVIEW

A core mission for modern medicine is the development of precision therapeutics. Cancer therapies have been at the leading edge of this effort, while nephrology has lagged on the path to precision medicine. Breaking the stalemate, recent work revealed CD80 (B7-1) as a candidate for targeted therapy in the treatment of resistant nephrotic syndrome. This review aims to summarize the current state of our understanding of podocyte CD80 biology, its therapeutic implications and the challenges that lie ahead in essential future validation studies.

RECENT FINDINGS

The CD80 targeting agent abatacept (CTLA4-Ig), approved to treat rheumatoid arthritis, was shown to induce remission of nephrotic range proteinuria in four patients with recurrence of disease posttransplant and one patient with primary, treatment resistant nephrotic syndrome. The concept of 'CD80-positive' proteinuric kidney disease due to podocyte CD80 staining in patient kidney biopsies was introduced as a molecular biomarker to define disease and guide treatment. The mechanism of action of CTLA4-Ig in podocytes was shown to centre on β1 integrin activation in a T-cell independent fashion. Subsequent work revealed a putative role for podocyte CD80 in diabetic kidney disease.

SUMMARY

These studies have direct implications for patient care, and intense interest has focused on validating these findings in upcoming clinical trials.

CTLA4-Ig in B7-1-positive diabetic and non-diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease in the Western world. Standard treatments have ultimately proven ineffective in blocking DKD progression, thus necessitating the design of new therapies to complement glycaemic and blood pressure control. High glucose levels upregulate the immune-related molecule B7-1 in podocytes, and such an event may play a relevant role in DKD onset, suggesting that B7-1 is a suitable therapeutic target for DKD. CTLA4-Ig is a clinically available fusion protein, approved for the treatment of some autoimmune diseases, which binds B7-1 and blocks its signalling. We have previously demonstrated that CTLA4-Ig restores the physiological structure and cellular motility of podocytes challenged with high glucose in vitro and abrogates the onset of proteinuria in murine models of DKD in vivo. Notably, these beneficial effects occurred independently of any systemic immunological effects of CTLA4-Ig. While the expression of B7-1 on podocytes raises questions regarding the very nature of the podocyte as we know it, the preliminary positive effect of CTLA4-Ig on proteinuria in preclinical models and the evidence of B7-1 expression in kidney biopsies of diabetic individuals suggest a potential novel indication for CTLA4-Ig in DKD. Nonetheless, recent reports of problems with detecting podocyte B7-1 and of inconsistent therapeutic efficacy of CTLA4-Ig in proteinuric patients highlight the necessity to establish uniformly accepted protocols for the detection of B7-1 and underline the need for randomised trials with CTLA4-Ig in kidney diseases.

Abatacept in B7-1-positive proteinuric kidney disease

Abatacept (cytotoxic T-lymphocyte–associated antigen 4–immunoglobulin fusion protein [CTLA-4–Ig]) is a costimulatory inhibitor that targets B7-1 (CD80). The present report describes five patients who had focal segmental glomerulosclerosis (FSGS) (four with recurrent FSGS after transplantation and one with primary FSGS) and proteinuria with B7-1 immunostaining of podocytes in kidney-biopsy specimens. Abatacept induced partial or complete remissions of proteinuria in these patients, suggesting that B7-1 may be a useful biomarker for the treatment of some glomerulopathies. Our data indicate that abatacept may stabilize β1-integrin activation in podocytes and reduce proteinuria in patients with B7-1–positive glomerular disease.

Diagnosis and management of antibody-mediated rejection: current status and novel approaches

Advances in multimodal immunotherapy have significantly reduced acute rejection rates and substantially improved 1-year graft survival following renal transplantation. However, long-term (10-year) survival rates have stagnated over the past decade. Recent studies indicate that antibody-mediated rejection (ABMR) is among the most important barriers to improving long-term outcomes. Improved understanding of the roles of acute and chronic ABMR has evolved in recent years following major progress in the technical ability to detect and quantify recipient anti-HLA antibody production. Additionally, new knowledge of the immunobiology of B cells and plasma cells that pertains to allograft rejection and tolerance has emerged. Still, questions regarding the classification of ABMR, the precision of diagnostic approaches, and the efficacy of various strategies for managing affected patients abound. This review article provides an overview of current thinking and research surrounding the pathophysiology and diagnosis of ABMR, ABMR-related outcomes, ABMR prevention and treatment, as well as possible future directions in treatment.

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.

Biologic agents in islet transplantation

Islet transplantation is today an accepted modality for treating selected patients with frequent hypoglycemic events or severe glycemic lability. Despite tremendous progress in islet isolation, culture, and preservation, clinical use is still restricted to a limited subset, and lifelong immunosuppression is required. Issues surrounding limited islet revascularization and immune destruction remain. One of the major challenges is to prevent alloreactivity and recurrence of autoimmunity against β-cells. These two hurdles can be effectively reduced by immunosuppressive therapy combining induction and maintenance treatments. The introduction of highly potent and selective biologic agents has significantly reduced the frequency of acute rejection and has prolonged graft survival, while minimizing the complications of this therapeutic scheme. This review will address the most important biological agents used in islet transplantation. We provide a historical perspective of their introduction into clinical practice and their role in current clinical protocols, aiming at improved engraftment efficiency, increased long-term survival, and better overall results of clinical islet transplantation.

Current trends in immunosuppressive therapies for renal transplant recipients

PURPOSE

Current trends in immunosuppressive therapies for renal transplant recipients are reviewed.

SUMMARY

The common premise for immunosuppressive therapies in renal transplantation is to use multiple agents to work on different immunologic targets. The use of a multidrug regimen allows for pharmacologic activity at several key steps in the T-cell replication process and lower dosages of each individual agent, thereby producing fewer drug-related toxicities. In general, there are three stages of clinical immunosuppression: induction therapy, maintenance therapy, and treatment of an established acute rejection episode. Only immunosuppressive therapies used for maintenance therapy are discussed in detail in this review. The most common maintenance immunosuppressive agents can be divided into five classes: (1) the calcineurin inhibitors (CNIs) (cyclosporine and tacrolimus), (2) costimulation blockers (belatacept), (3) mammalian target of rapamycin inhibitors (sirolimus and everolimus), (4) antiproliferatives (azathioprine and mycophenolic acid derivatives), and (5) corticosteroids. Immunosuppressive regimens vary among transplantation centers but most often include a CNI and an adjuvant agent, with or without corticosteroids. Selection of appropriate immunosuppressive regimens should be patient specific, taking into account the medications' pharmacologic properties, adverse-event profile, and potential drug-drug interactions, as well as the patient's preexisting diseases, risk of rejection, and medication regimen.

CONCLUSION

Advancements in transplant immunosuppression have resulted in a significant reduction in acute cellular rejection and a modest increase in long-term patient and graft survival. Because the optimal immunosuppression regimen is still unknown, immunosuppressant use should be influenced by institutional preference and tailored to the immunologic risk of the patient and adverse-effect profile of the drug.

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.

Adenovirus mediated CTLA4Ig transgene therapy alleviates abortion by inhibiting spleen lymphocyte proliferation and regulating apoptosis in the feto-placental unit

Pregnancy is thought to be a state of immunological tolerance. The mechanisms underlying this phenomenon are still poorly understood. In our previous study, adenovirus mediated CTLA4Ig transgene (Ad-CTLA4Ig) therapy was demonstrated to improve pregnancy outcome in an abortion-prone mouse model by skewing the Th2/Th1 cytokine balance, expanding peripheral CD4(+) CD25(+) regulatory T cell populations and inducing indoleamine 2,3 dioxygenase (IDO) mRNA expression at the maternal-fetal interface. However, it is still not clear whether other mechanisms are involved in the protective effect of CTLA-4 on pregnancy outcome in abortion-prone matings. In this study, we focused on the effect of CTLA4Ig on spleen lymphocyte proliferation and apoptosis at the maternal-fetal interface. We demonstrated that Ad-CTLA4Ig therapy inhibited the proliferation of CBA/J splenocytes and IL-2 secretion in response to DBA/2 stimulator cells in the abortion-prone mice model. Ad-CTLA4Ig therapy also skewed cytokine production toward a Th2 bias and regulated the expression of anti-apoptosis factor Bcl-2 and pro-apoptosis factor Bax at the maternal-fetal interface. However, it did not influence the apoptosis and cell cycles of splenocytes in pregnant CBA/J mice. On the whole, these findings indicated that Ad-CTLA4Ig therapy could ameliorate the outcome of spontaneous abortion by inhibiting proliferation of maternal spleen lymphocytes and regulating apoptosis in the feto-placental unit.

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.

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.

Belatacept Post Kidney Transplantation

Objective:

To review the use of belatacept as an alternative to calcineurin inhibitor-based regimens for maintenance immunosuppression in renal transplant recipients.

Data Sources:

To provide an extensive overview of the pharmacology, pharmacokinetics, efficacy, and safety of belatacept, a MEDLINE/PubMed search (1980–December 2011) was performed for all articles evaluating belatacept's properties and patient outcomes, as well as abstracts from recent meetings, using key words belatacept, pharmacology, efficacy, pharmacokinetics, and safety.

Study Selection/Data Extraction:

Phase 2 and 3 studies in humans describing use, adverse reactions, pharmacology, pharmacokinetics, efficacy, and safety of belatacept were identified and reviewed. Other articles were identified through PubMed.

Data Synthesis:

Belatacept, a costimulation blocker, is a biologic recombinant fusion protein that has been shown to prevent acute cellular rejection in kidney transplant recipients and preserve renal function. It was recently approved by the FDA as an antirejection immunosuppressant agent for use in kidney transplant recipients. It is the first biologic agent used for maintenance immunosuppression. It acts as an antagonist to CD80 and CD86 receptors located on the surface of antigen presenting cells, thereby blocking CD28 T-cell activation and, thus, preventing acute rejection. In comparison with patients receiving other current therapies, patients on belatacept have demonstrated superior renal function with comparable outcomes in patient and graft survival.

Conclusions:

Belatacept has potential for use as an alternative to current maintenance immunosuppression regimens, with potentially fewer adverse effects.

Pharmacokinetics of recombinant bifunctional fusion proteins

INTRODUCTION

The development of biotechnology has enabled the creation of various recombinant fusion proteins as a new class of biotherapeutics. The uniqueness of fusion proteins lies in their ability to fuse two or more protein domains, providing vast opportunities to generate novel combinations of functions. Pharmacokinetic (PK) studies, which are critical components in preclinical and clinical drug development, have not been fully explored for fusion proteins. The lack of general PK models and study guidelines has become a bottleneck for translation of fusion proteins from basic research to the clinic.

AREAS COVERED

This article reviews the current status of PK studies for fusion proteins, covering the processes that affect PK. According to their PK properties, a classification of fusion proteins is suggested along with examples from the clinic or under development. Current limitations and future perspectives for PK of fusion proteins are also discussed.

EXPERT OPINION

A PK model for bifunctional fusion proteins is presented to highlight the importance of mechanistic studies for a thorough understanding of the PK properties of fusion proteins. The model suggests investigating the receptor binding and subsequent intracellular disposition of individual domains, which can have dramatic impact on the PK of fusion proteins.

Current status of immunosuppressive agents for solid organ transplantation in children

Immunosuppression after organ transplantation is complex and ever evolving. Over the past two decades, newer immunosuppressive agents have been introduced with an aim to provide better patient and graft survival. Improved therapeutic strategies have been developed offering the option to use combinations of drugs with non-overlapping toxicities. There are, however, only a few clinical studies with robust data to rationalize the use of these agents in children. This review will discuss the newer immunosuppressive agents used for solid organ transplant, their current status in post-transplant management and prevention of allograft rejection.

Immunosuppressive monoclonal antibodies: current and next generation

Monoclonal antibodies (mAbs) are well-established therapeutics, as evidenced by the large number of Food and Drug Administration-approved mAbs for the treatment of cancers, and inflammatory or autoimmune diseases, and for the prevention and treatment of solid organ transplant rejection. Although, in many cases, mAbs have improved patient survival, they are also associated with an increased incidence of opportunistic infections. We review here the current and next generation of mAbs and the risks that infectious disease specialists should be aware of.

Ipilimumab: a novel immunostimulatory monoclonal antibody for the treatment of cancer

Ipilimumab (Yervoy, developed by Medarex and Bristol-Myers Squibb) is a fully human monoclonal IgG1κ antibody against the cytotoxic T-lymphocyte antigen-4 (CTLA-4), an immune-inhibitory molecule expressed in activated T cells and in suppressor T regulatory cells. Interaction of the monoclonal antibody with CTLA-4 blocks inhibitory signals generated through this receptor and enhances T cell activation, leading to increased antitumor responses. Ipilimumab has been approved by FDA in March 2011 as monotherapy (3mg/kg every 3 weeks for 4 doses) for the treatment of advanced (unresectable or metastatic) melanoma both in pre-treated or chemotherapy naïve patients. Four months later, ipilimumab has received a rapid approval by the European Commission, after a positive opinion from the Committee for Medicinal Products for Human Use. However, the indication in the EU is limited to previously-treated patients with advanced melanoma. Ipilimumab is the first agent that has demonstrated to improve overall survival in patients with metastatic melanoma, which has a very poor prognosis, in randomized phase III clinical trials. The patterns of tumour response to ipilimumab differ from those observed with cytotoxic chemotherapeutic agents, since patients may have a delayed yet durable response and obtain long-term survival benefit despite an initial tumour growth. The major draw-back of ipilimumab is the induction of immune-related adverse effects; the latter can be life-threatening, unless promptly managed with immunosuppressive agents (most frequently corticosteroids) according to specific guidelines. Further development of ipilimumab includes its use in the neoadjuvant or adjuvant high-risk melanoma setting and for the treatment of other refractory and advanced solid tumours, either as single agent or in combination with additional immunostimulating agents or molecularly targeted therapies.