Monoclonal and Polyclonal Antibody Therapy for Treating Acute Rejection in Kidney Transplant Recipients: A Systematic Review of Randomized Trial Data

Anti-thymocyte globulin for treatment of T-cell-mediated allograft rejection

Anti-thymocyte globulin (ATG) is a pivotal immunosuppressive therapy utilized in the management of T-cell-mediated rejection and steroid-resistant rejection among renal transplant recipients. Commercially available as Thymoglobulin (rabbit-derived, Sanofi, United States), ATG-Fresenius S (rabbit-derived), and ATGAM (equine-derived, Pfizer, United States), these formulations share a common mechanism of action centered on their interaction with cell surface markers of immune cells, imparting immunosuppressive effects. Although the prevailing mechanism predominantly involves T-cell depletion via the com plement-mediated pathway, alternate mechanisms have been elucidated. Optimal dosing and treatment duration of ATG have exhibited variance across ran domised trials and clinical reports, rendering the establishment of standardized guidelines a challenge. The spectrum of risks associated with ATG administration spans from transient adverse effects such as fever, chills, and skin rash in the acute phase to long-term concerns related to immunosuppression, including susceptibility to infections and malignancies. This comprehensive review aims to provide a thorough exploration of the current understanding of ATG, encom passing its mechanism of action, clinical utility in the treatment of acute renal graft rejections, specifically steroid-resistant cases, efficacy in rejection episode reversal, and a synthesis of findings from different eras of maintenance immunosuppression. Additionally, it delves into the adverse effects associated with ATG therapy and its impact on long-term graft function. Furthermore, the review underscores the existing gaps in evidence, particularly in the context of the Banff classification of rejections, and highlights the challenges faced by clinicians when navigating the available literature to strike the optimal balance between the risks and benefits of ATG utilization in renal transplantation.

Alemtuzumab as a Successful Antirejection Therapy: Experience in a Pediatric Renal Transplant Patient

Alemtuzumab is a monoclonal antibody against CD52 that is being increasingly used in renal transplantation as a lymphocyte-depleting agent. Data on alemtuzumab use in resistant rejection episodes are scarce, especially in children. Here, we present a 14-year-old renal transplant patient with acute cellular and humoral rejection who was treated with pulse steroids, plasmapheresis, and intravenous immunoglobulin with no success. He had 2 previous rejection episodes that were treated with antithymocyte globulin. In the third episode, alemtuzumab was given as a rescue therapy, and the patient benefited from the treatment. No complications were observed. Alemtuzumab can be a treatment option in pediatric patients with refractory rejection episodes.

The impact of pre-transplant donor specific antibodies on the outcome of kidney transplantation – Data from the Swiss transplant cohort study

Background

Pre-transplant donor specific antibodies (DSA), directed at non-self human leukocyte antigen (HLA) protein variants present in the donor organ, have been associated with worse outcomes in kidney transplantation. The impact of the mean fluorescence intensity (MFI) and the target HLA antigen of the detected DSA has, however, not been conclusively studied in a large cohort with a complete virtual cross-match (vXM).

Methods

We investigated the effect of pre-transplant DSA on the risk of antibody-mediated rejection (ABMR), graft loss, and the rate of eGFR decline in 411 DSA positive transplants and 1804 DSA negative controls.

Results

Pre-transplant DSA were associated with a significantly increased risk of ABMR, graft loss, and accelerated eGFR decline. DSA directed at Class I and Class II HLA antigens were strongly associated with increased risk of ABMR, but only DSA directed at Class II associated with graft loss. DSA MFI markedly affected outcome, and Class II DSA were associated with ABMR already at 500-1000 MFI, whereas Class I DSA did not affect outcome at similar low MFI values. Furthermore, isolated DSA against HLA-DP carried comparable risks for ABMR, accelerated eGFR decline, and graft loss as DSA against HLA-DR.

Conclusion

Our results have important implications for the construction and optimization of vXM algorithms used within organ allocation systems. Our data suggest that both the HLA antigen target of the detected DSA as well as the cumulative MFI should be considered and that different MFI cut-offs could be considered for Class I and Class II directed DSA.

Production, characterization, and epitope mapping of monoclonal antibodies of ribosomal protein S3 (rpS3)

Ribosomal protein S3 (rpS3), a member of 40S small ribosomal subunit, is a multifunctional protein with various extra-ribosomal functions including DNA repair endonuclease activity and is secreted from cancer cells. Therefore, antibodies with high specificity against rpS3 protein could be useful cancer biomarkers. In this study, polyclonal antibody (pAb) and monoclonal antibodies (mAbs) were raised against rpS3 protein and epitope mapping was performed for each antibody; the amino acid residues of rpS3 were scanned from amino acid 185 to 243 through peptide scanning to reveal the epitopes of each mAb. Results showed that pAb R2 has an epitope from amino acid 203 to 230, mAb M7 has an epitope from amino acid 213 to 221, and mAb M8 has an epitope from amino acid 197 to 219. Taken together, novel mAbs and pAb against rpS3 were raised and mapped against rpS3 with different specific epitopes.

A Novel CNN-Based CAD System for Early Assessment of Transplanted Kidney Dysfunction

This paper introduces a deep-learning based computer-aided diagnostic (CAD) system for the early detection of acute renal transplant rejection. For noninvasive detection of kidney rejection at an early stage, the proposed CAD system is based on the fusion of both imaging markers and clinical biomarkers. The former are derived from diffusion-weighted magnetic resonance imaging (DW-MRI) by estimating the apparent diffusion coefficients (ADC) representing the perfusion of the blood and the diffusion of the water inside the transplanted kidney. The clinical biomarkers, namely: creatinine clearance (CrCl) and serum plasma creatinine (SPCr), are integrated into the proposed CAD system as kidney functionality indexes to enhance its diagnostic performance. The ADC maps are estimated for a user-defined region of interest (ROI) that encompasses the whole kidney. The estimated ADCs are fused with the clinical biomarkers and the fused data is then used as an input to train and test a convolutional neural network (CNN) based classifier. The CAD system is tested on DW-MRI scans collected from 56 subjects from geographically diverse populations and different scanner types/image collection protocols. The overall accuracy of the proposed system is 92.9% with 93.3% sensitivity and 92.3% specificity in distinguishing non-rejected kidney transplants from rejected ones. These results demonstrate the potential of the proposed system for a reliable non-invasive diagnosis of renal transplant status for any DW-MRI scans, regardless of the geographical differences and/or imaging protocol.

The Efficacy of Rabbit Anti-Thymocyte Globulin for Acute Kidney Transplant Rejection in Patients Using Calcineurin Inhibitor and Mycophenolate Mofetil-Based Immunosuppressive Therapy

Background

T cell depleting antibody therapy with rabbit anti-thymocyte globulin (rATG) is the treatment of choice for glucocorticoid-resistant acute kidney allograft rejection (AR) and is used as first-line therapy in severe AR. Almost all studies investigating the effectiveness of rATG for this indication were conducted at the time when cyclosporine A and azathioprine were the standard of care. Here, the long-term outcome of rATG for AR in patients using the current standard immunosuppressive therapy (i.e., tacrolimus and mycophenolate mofetil) is described.

Material/Methods

Between 2002 to 2012, 108 patients were treated with rATG for AR. Data on kidney function in the year following rATG and long-term outcomes were collected.

Results

Overall survival after rATG was comparable to overall survival of all kidney transplantation patients (P=0.10). Serum creatinine 1 year after rATG was 179 μmol/L (interquartile range (IQR) 136–234 μmol/L) and was comparable to baseline serum creatinine (P=0.22). Early AR showed better allograft survival than late AR (P=0.0007). In addition, 1 year after AR, serum creatinine was lower in early AR (157 mol/L; IQR 131–203) compared to late AR (216 mol/L; IQR 165–269; P<0.05). The Banff grade of rejection, kidney function at the moment of rejection, and reason for rATG (severe or glucocorticoid resistant AR) did not influence the allograft survival.

Conclusions

Treatment of AR with rATG is effective in patients using current standard immunosuppressive therapy, even in patients with poor allograft function. Early identification of AR followed by T cell depleting treatment leads to better allograft outcomes.

Anti-thymocyte globulins in kidney transplantation: focus on current indications and long-term immunological side effects

Antithymocyte globulins (ATGs) are part of the immunosuppression arsenal currently used by clinicians to prevent or treat acute rejection in solid organ transplantation. ATG is a mixture of non-specific anti-lymphocyte immunoglobulins targeting not only T cell subsets but also several other immune and non-immune cells, rendering its precise immunoglobulin composition difficult to appreciate or to compare from one preparation to another. Furthermore, several mechanisms of action have been described. Taken together, this probably explains the efficacy and the side effects associated with this drug. Recent data suggest a long-term negative impact on allograft and patient outcomes, pointing out the need to better characterize the potential toxicity and the benefit-risk balance associated to this immunosuppressive therapy within large clinical trials.

Polyclonal and monoclonal antibodies for treating acute rejection episodes in kidney transplant recipients

BACKGROUND

Registry data shows that the incidence of acute rejection has been steadily falling. Approximately 10% to 35% of kidney recipients will undergo treatment for at least one episode of acute rejection within the first post-transplant year. Treatment options include pulsed steroid therapy, the use of an antibody preparation, the alteration of background immunosuppression, or combinations of these options. Over recent years, new treatment strategies have evolved, and in many parts of the world there has been an increase in use of tacrolimus and mycophenolate and a reduction in the use of cyclosporin and azathioprine use as baseline immunosuppression to prevent acute rejection. There are also global variations in use of polyclonal and monoclonal antibodies to treat acute rejection. This is an update of a review published in 2006.

OBJECTIVES

The aim of this systematic review was to: (1) to evaluate the relative and absolute effects of different classes of antibody preparation in preventing graft loss and resolving cellular or humoral rejection episodes when used as a treatment for first episode of rejection in kidney transplant recipients; (2) evaluate the relative and absolute effects of different classes of antibody preparation in preventing graft loss and resolving cellular or humoral rejection episodes when used as a treatment for steroid-resistant rejection in kidney transplant recipients; (3) determine how the benefits and adverse events vary for each type of antibody preparation; and (4) determine how the benefits and harms vary for different formulations of antibody within each type.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 18 April 2017 through contact with the Information Specialist using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing all mono- and polyclonal antibody preparations, given in combination with any other immunosuppressive agents, for the treatment of cellular or humoral graft rejection, when compared to any other treatment for acute rejection were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias of the included studies and extracted data. Statistical analyses were performed using a random-effects model and results expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We included 11 new studies (18 reports, 346 participants) in this update, bring the total number of included studies to 31 (76 reports, 1680 participants). Studies were generally small, incompletely reported, especially for potential harms, and did not define outcome measures adequately. The risk of bias was inadequate or unclear risk for random sequence generation (81%), allocation concealment (87%) and other bias (87%). There were, however, a predominance of low risk of bias for blinding (75%) and incomplete outcome data (80%) across all the studies. Selective reporting had a mixture of low (58%), high (29%), and unclear (13%) risk of bias.Seventeen studies (1005 participants) compared therapies for first acute cellular rejection episodes. Antibody therapy was probably better than steroid in reversing acute cellular rejection (RR 0.50, 95% CI 0.30 to 0.82; moderate certainty) and preventing subsequent rejection (RR 0.70, 95% CI 0.50 to 0.99; moderate certainty), may be better for preventing graft loss (death censored: (RR 0.80, 95% CI 0.57 to 1.12; low certainty) but there was little or no difference in death at one year. Adverse effects of treatment (including fever, chills and malaise following drug administration) were probably reduced with steroid therapy (RR 23.88, 95% CI 5.10 to 111.86; I2 = 16%; moderate certainty).Twelve studies (576 patients) investigated antibody treatment for steroid-resistant rejection. There was little or no benefit of muromonab-CD3 over ATG or ALG in reversing rejection, preventing subsequent rejection, or preventing graft loss or death. Two studies compared the use of rituximab for treatment of acute humoral rejection (58 patients). Muromonab-CD3 treated patients suffered three times more than those receiving either ATG or T10B9, from a syndrome of fever, chills and malaise following drug administration (RR 3.12, 95% CI 1.87 to 5.21; I2 = 31%), and experienced more neurological side effects (RR 13.10 95% CI 1.43 to 120.05; I2 = 36%) (low certainty evidence).There was no evidence of additional benefit from rituximab in terms of either reversal of rejection (RR 0.94, 95% CI 0.54 to 1.64), or graft loss or death 12 months (RR 1.0, 95% CI 0.23 to 4.35). Rituximab plus steroids probably increases the risk of urinary tract infection/pyelonephritis (RR 5.73, 95% CI 1.80 to 18.21).

AUTHORS' CONCLUSIONS

In reversing first acute cellular rejection and preventing graft loss, any antibody is probably better than steroid, but there is little or no difference in subsequent rejection and patient survival. In reversing steroid-resistant rejection there was little or no difference between different antibodies over a period of 12 months, with limited data beyond that time frame. In treating acute humoral rejection, there was no evidence that the use of antibody therapy conferred additional benefit in terms of reversal of rejection, or death or graft loss.Although this is an updated review, the majority of newer included studies provide additional evidence from the cyclosporin/azathioprine era of kidney transplantation and therefore conclusions cannot necessarily be extrapolated to patients treated with more contemporary immunosuppressive regimens which include tacrolimus/mycophenolate or sirolimus. However, many kidney transplant centres around the world continue to use older immunosuppressive regimes and the findings of this review remain strongly relevant to their clinical practice.Larger studies with standardised reproducible outcome criteria are needed to investigate the outcomes and risks of antibody treatments for acute rejection in kidney transplant recipients receiving contemporary immunosuppressive regimes.

Renal association clinical practice guideline in post-operative care in the kidney transplant recipient

These guidelines cover the care of patients from the period following kidney transplantation until the transplant is no longer working or the patient dies. During the early phase prevention of acute rejection and infection are the priority. After around 3-6 months, the priorities change to preservation of transplant function and avoiding the long-term complications of immunosuppressive medication (the medication used to suppress the immune system to prevent rejection). The topics discussed include organization of outpatient follow up, immunosuppressive medication, treatment of acute and chronic rejection, and prevention of complications. The potential complications discussed include heart disease, infection, cancer, bone disease and blood disorders. There is also a section on contraception and reproductive issues.Immediately after the introduction there is a statement of all the recommendations. These recommendations are written in a language that we think should be understandable by many patients, relatives, carers and other interested people. Consequently we have not reworded or restated them in this lay summary. They are graded 1 or 2 depending on the strength of the recommendation by the authors, and AD depending on the quality of the evidence that the recommendation is based on.

Effect of FTY720 (fingolimod) on graft survival in renal transplant recipients: a systematic review protocol

INTRODUCTION

Studies have shown that FTY720 has inconsistent effects in kidney transplant recipients. Several review articles on FTY720 have been published, but most have focused on the mechanism of action of FTY720. Therefore, this review aims to evaluate and determine the beneficial and harmful effects of FTY720 therapy in kidney transplant recipients.

METHODS AND ANALYSIS

We electronically searched the following databases: PubMed, Scopus, the Web of Sciences, EMBASE, Cochrane databases and the Cochrane Central Registry of Controlled Trials. Any clinical, randomised controlled trials relating to FTY720 for treating kidney transplant recipients were included without publication status or language restriction. Study selection, data extraction and assessment of study quality were performed independently by two researchers. Data were synthesised by either the fixed effects or the random effects model according to a heterogeneity test. If the extracted data were suitable for meta-analysis, STATA software was used to combine the relative risks for dichotomous outcomes, and the mean differences for continuous outcomes with 95% CIs were measured. Death, loss of function and incidence of acute kidney rejection were assessed as the primary outcomes. Renal graft function, malignancy, delayed graft function and infection were evaluated as secondary outcomes.

ETHICS/DISSEMINATION

This review does not require formal ethics approval because the data are not individualised. The resulting review article will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

CRD42015024648.

Advances in pharmacotherapy to treat kidney transplant rejection

INTRODUCTION

Current immunosuppressive combination therapy provides excellent prevention of T-cell-mediated rejection following renal transplantation; however, antibody-mediated rejection remains of high concern and accounts for a large number of long-term allograft losses. The recent development of protocol biopsies resulted in the definition of subclinical rejection (SCR), showing histologic evidence for rejection but unremarkable clinical course.

AREAS COVERED

This review describes the current knowledge and evidence of pharmacotherapy to treat kidney allograft rejections and covers SCR treatment options. Each substance is analyzed with regard to its classical indication and further discussed for the treatment of other forms of rejection.

EXPERT OPINION

Despite a lack of randomized trials, early acute T-cell-mediated rejection can be treated effectively in most cases without graft loss. The necessity to treat SCR is currently unclear. Due to a lack of effective therapies, new treatment approaches for antibody-mediated rejection are an urgent medical need to improve long-term outcomes. Future research should aim to better define pathophysiology and histology, stratify risk, and develop rational treatment strategies from randomized controlled trials, in order to establish the value of novel therapies in the arsenal of rejection pharmacotherapy. However, the effective prevention of rejection with minimal side effects still remains the goal in immunosuppression.

Cumulative Doses of T-Cell Depleting Antibody and Cancer Risk after Kidney Transplantation

T-cell depleting antibody is associated with an increased risk of cancer after kidney transplantation, but a dose-dependent relationship has not been established. This study aimed to determine the association between cumulative doses of T-cell depleting antibody and the risk of cancer after kidney transplantation. Using data from the Australian and New Zealand Dialysis and Transplant Registry between 1997–2012, we assessed the risk of incident cancer and cumulative doses of T-cell depleting antibody using adjusted Cox regression models. Of the 503 kidney transplant recipients with 2835 person-years of follow-up, 276 (55%), 209 (41%) and 18 (4%) patients received T-cell depleting antibody for induction, rejection or induction and rejection respectively. The overall cancer incidence rate was 1,118 cancers per 100,000 patient-years, with 975, 1093 and 1377 cancers per 100,000 patient-years among those who had received 1–5 doses, 6–10 doses and >10 doses, respectively. There was no association between cumulative doses of T cell depleting antibody and risk of incident cancer (1–5: referent, 6–10: adjusted hazard ratio (HR) 1.19, 95%CI 0.48–2.95, >10: HR 1.42, 95%CI 0.50–4.02, p = 0.801). This lack of association is contradictory to our hypothesis and is likely attributed to the low event rates resulting in insufficient power to detect significant differences.

Clinical aspects: focusing on key unique organ-specific issues of renal transplantation

Kidney transplantation is the treatment of choice for patients with end-stage renal disease because of improved patient survival and quality of life as compared with dialysis. Successful transplantation requires the prompt recognition and appropriate management of both the immediate posttransplant surgical and medical complications as well as subsequent issues like recurrent disease and chronic rejection that affect long-term graft survival. Guidelines for understanding and managing some of the more important early and late kidney-specific transplant problems, including urologic complications, delayed graft function, acute and chronic rejection, BK polyoma virus infection, and recurrent glomerular disease, are reviewed.

A comprehensive and quantitative analysis of the major specificities in rabbit antithymocyte globulin preparations

Antithymocyte globulin (ATG) preparations are used for treatment and prevention of graft rejection episodes, graft versus host disease and aplastic anemia. The immunomodulatory and immuosuppressive properties of ATGs are mediated by their interaction with a large variety of antigens expressed on immune and nonimmune cell populations. We have conducted a comprehensive analysis on antibody specificities contained in rabbit ATGs in clinical use, ATG-Fresenius (ATG-F) and Thymoglobulin (THG). We have used retroviral expression cloning to identify novel ATG antigens and demonstrate that together with ATG antigens described earlier, these molecules account for the majority of ATG antibodies directed to human cells. Moreover, we have employed cell lines engineered to express antigens at high levels to quantify the antibodies directed to each ATG antigen. We have used cell lines expressing the T cell receptor complex, CD2 and CD28 to remove antibodies to these antigens from ATG preparations and demonstrate that this treatment abrogated the ability of ATGs to induce activation and forkhead box P3 expression in T cells. Comprehensive information and differences on the antigens targeted by ATG-F and THG as well as novel approaches to assess their functional properties are the basis for a better understanding of their immunomodulatory capacities and might eventually translate into improved ATG-based regimen.

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.

Lymphodepletional strategies in transplantation

Because lymphocytes were shown to mediate transplant rejection, their depletion has been studied as a mechanism of preventing rejection and perhaps inducing immunologic tolerance. Agents that profoundly deplete lymphocytes have included monoclonal antibodies, cytotoxic drugs, and radiation. We have studied several such agents but focused on antibodies that deplete not only peripheral blood lymphocytes, but also lymph node lymphocytes. Depletion of lymph node T lymphocytes appears to permit peripheral tolerance at least for T cells in animal models. Nevertheless, B-cell responses may be resistant to such approaches, and T memory cells are likewise relatively resistant to depleting antibodies. We review the experimental and clinical approaches to depletion strategies and outline some of the pitfalls of depletion, such as limitations of currently available agents, duration of tolerance, infection, and malignancy. It is notable that most tolerogenic strategies that have been attempted experimentally and clinically include depleting agents even when they are not named as the underlying strategy. Thus, there is an implicitly acknowledged role for reducing the precursor frequency of donor antigen-specific lymphocytes when approaching the daunting goal of transplant tolerance.

In vivo depletion of leukocytes and platelets following injection of T cell-specific antibodies into mice

In vivo T cell depletion experiments are widely used to establish the role of these cells in a variety of immunological processes. Different clones of monoclonal antibody targeting the CD3 molecular complex (mainly 145-2C11 and 17A2) have been successfully used for T cell depletion. In the present work, we assessed the specificity of monoclonal antibody-mediated CD3 T cell depletion in mouse peripheral blood. We showed that treatment of BALB/C mice with monoclonal antibodies (clones 145-2C11 and 17A2) not only efficiently depletes T cells in vivo, but also leads to a substantial reduction in B cell, granulocyte and platelet counts. In contrast, T cell depletion using a combination of anti-CD4 and anti-CD8 antibodies was efficient and produced less deleterious effects on other blood cell populations. Therefore, the results obtained from T cell depletion experiments using anti-CD3 antibodies must be interpreted with caution prior to draw definitive conclusions on the role of T cells in a given immunological process.

Long-term stability of T-cell activation and transduction components critical to the processing of clinical batches of gene-engineered T cells

BACKGROUND AIMS

The generation of gene-modified T cells for clinical adoptive T-cell therapy is challenged by the potential instability and concomitant high financial costs of critical T-cell activation and transduction components. As part of a clinical trial to treat patients with metastatic renal cell cancer with autologous T cells engineered with a chimeric antigen receptor (CAR) recognizing carboxy-anhydrase-IX (CAIX), we evaluated functional stability of the retroviral vector, T-cell activation agent Orthoclone OKT3 (Janssen-Cilag, Beerse, Belgium) monoclonal antibody (mAb) and the transduction promoting agent RetroNectin (Takara, Otsu, Japan).

METHODS

Carboxy-anhydrase-IX chimeric antigen receptor retrovirus-containing culture supernatants (RTVsups) were generated from two packaging cell lines, Phoenix-Ampho (BioReliance, Sterling, UK) and PG13, and stored at -80°C over 10 years and 14 years. For Orthoclone OKT3 and RetroNectin, aliquots for single use were prepared and stored at -80°C. Transduction efficiencies of both batches of RTVsups were analyzed using the same lots of cryopreserved donor peripheral blood mononuclear cells, Orthoclone OKT3 and RetroNectin over time.

RESULTS

We revisit here an earlier report on the long-term functional stability of the RTVsup, observed to be 9 years, and demonstrate that this stability is at least 14 years. Also, we now demonstrate that Orthoclone OKT3 and RetroNectin are functionally stable for periods of at least 6 years and 10 years.

CONCLUSIONS

High-cost critical components for adoptive T-cell therapy can be preserved for ≥10 years when prepared in aliquots for single use and stored at -80°C. These findings may significantly facilitate, and decrease the financial risks of, clinical application of gene-modified T cells in multicenter studies.

Treatment of steroid-resistant acute renal allograft rejection with alemtuzumab

Steroid-resistant renal allograft rejections are commonly treated with rabbit antithymocyte globulin (RATG), but alemtuzumab could be an effective, safe and more convenient alternative. Adult patients with steroid-resistant renal allograft rejection treated with alemtuzumab (15-30 mg s.c. on 2 subsequent days) from 2008 to 2012 (n = 11) were compared to patients treated with RATG (2.5-4.0 mg/kg bodyweight i.v. for 10-14 days; n = 20). We assessed treatment-failure (graft loss, lack of improvement of graft function or need for additional anti-rejection treatment), infections during the first 3 months after treatment and infusion-related side effects. In both groups, the median time-interval between rejection and transplantation was 2 weeks, and approximately 75% of rejections were classified as Banff-IIA or higher. Three alemtuzumab-treated patients (27%) experienced treatment failure, compared to eight RATG treated patients (40%, p = 0.70). There was no difference in the incidence of infections. There were mild infusion-related side-effects in three alemtuzumab-treated patients (27%), and more severe infusion-related side effects in 17 RATG-treated patients (85%, p = 0.013). Drug related costs of alemtuzumab-treatment were lower than of RATG-treatment (€1050 vs. €2024; p < 0.01). Alemtuzumab might be an effective therapy for steroid-resistant renal allograft rejections. In contrast to RATG, alemtuzumab is nearly devoid of infusion-related side-effects. These data warrant a prospective trial.

Graft-specific immune cells communicate inflammatory immune responses after brain death

BACKGROUND

Donor brain death (BD) triggers inflammatory graft activation that leads to impaired graft quality and outcome. We used a mouse BD model to investigate graft inflammation in cardiac transplants from immune-competent and immune-deficient donor animals. Effects of donor T-cell depletion were tested in an additional group of cardiac transplant recipients.

METHODS

We analyzed systemic and graft-specific inflammatory activation after BD in donors and in syngeneic recipients of hearts retrieved from BD donors. To dissect the role of donor-specific immune cells in communicating BD-triggered inflammation, immune-deficient T-cell-, B-cell-, and natural killer cell-deficient Rag2/double knockout mice and naïve C57BL6 treated with anti-thymocyte globulin (Thymoglobulin; Genzyme Transplant, Cambridge, MA) were observed.

RESULTS

Donor BD boosted lymphocyte activation in donors and recipients of syngeneic BD grafts. Lymphocyte activation was mitigated in recipients of immune-deficient and Thymoglobulin-treated BD donor grafts. Likewise, systemic and intra-graft levels of inflammatory cytokines interleukin -1, interleukin-6, interferon-γ, and tumor necrosis factor-α were significantly reduced in immune-deficient and anti-thymocyte globulin-treated recipients. Dense lymphocyte infiltrates were detected in the hearts from untreated BD donors; in contrast, the hearts from donors treated with Thymoglobulin demonstrated a preserved structure with minimal infiltrates comparable with naïve controls.

CONCLUSION

BD triggers inflammatory graft activation communicated through intra-graft immune cells. Donor treatment with Thymoglobulin prevented inflammatory immune activation and improved graft quality to levels comparable to living donor organs.

Safety and efficacy of alemtuzumab in the treatment of late acute renal allograft rejection

Safety and efficacy of alemtuzumab in the treatment of AR in children after renal transplantation is unknown. Five episodes of refractory late AR in three children (three episodes in patient 1 and a single episode in patients 2 and 3 occurring after 7-23 months of transplantation) were treated with one dose of alemtuzumab as a rescue therapy. Four episodes (Banff IA-IB) in patients 1 and 2 reversed fully or partially with alemtuzumab, whereas patient 3 with Banff IB-IIA AR failed to respond. Patient 1 had recurrent AR 5, 13, and 15 months later; first two episodes responded to retreatment with alemtuzumab, and the last episode was not treated causing allograft failure. Patient 2 had steroid-responsive AR after two months and had a functioning allograft 25 months later. A transient reduction in all lymphocyte subsets except natural killer cells occurred in all patients. Patient 3 (treated with steroids, Thymoglobulin(R) , intravenous immunoglobulin, and rituximab prior to alemtuzumab) suffered many bacterial infections during one-yr period after therapy. However, symptomatic viral infections were not observed in any of the children. Treatment with alemtuzumab may prolong allograft survival in multidrug-resistant AR but may not prevent recurrent AR in non-adherent children.

Immunosuppression in the era of biological agents

Immunosuppression is the mayor mechanism to prevent allograft rejection and to induce tolerance. Since the first solid organ transplant, the development of safe and effective immunosuppressive regimens was a constant over the last decades. A lot of immunosuppressants have been discovered, and today the immunosuppressive agents are classified in two broad groups: Xenobiotic immunosuppressants and biological immunosuppressants. Xenobiotics, like corticoids and calcineurin and mTOR inhibitors, mainly interfere with the intracellular molecular mechanisms of the various types of cells involved in the immune response and generally these immunosuppressants are used early on in the transplantation process to prevent rejection as well as in long-term maintenance therapy. On the other hand, target molecules of biological immunosuppressants are on the surface of these immunological cells and normally in clinical immunosuppressive protocols have been used as auxiliary agents of xenobiotics to prevent rejection as well as in the treatment of acute rejection. However, these xenobiotics and biological agents have multiple side effects; that is why there has been a search for new drugs to minimise these side effects and to improve patients' quality of life. In this way, new biological agents have been proposed as maintenance immunosuppressive agents. The majority of these new immunosuppressive agents are polyclonal or monoclonal antibodies and recently the so-called fusion proteins may be the start of a new era of biological immunosuppression for maintenance regimens.

Antibody immunosuppressive therapy in solid-organ transplant: Part I

Currently, a wide variety of both polyclonal and monoclonal antibodies are being routinely utilized to prevent and treat solid organ rejection. More commonly, these agents are also administered in order to delay introduction of calcineurin inhibitors, especially in patients with already compromised renal function. While these antibody therapies dramatically reduced the incidence of acute rejection episodes and improved both short and long-term graft survival, they are also associated with an increased incidence of opportunistic infections and neoplastic complications. Therefore, effective patient management must necessarily balance these risks against the potential benefits of the therapy.

Antithymocyte treatment of steroid-resistant acute rejection in renal transplantation

To evaluate the outcome of early (ER <3 months) and late (LR >3 months) episodes of corticosteroid resistant acute allograft rejection (CRR) treated with anti-thymocyte globulin (ATG) in pediatric renal allograft recipients. Retrospective study of 15 children, mean age 13.2 y, who received ATG for the treatment of biopsy proven CRR over a 15 year period. Seven children received ATG for ER (median 26 days post transplantation) and 8 for LR (median 763 days). There was a significant improvement in the 3 month eGFR (70.3 ml/min/1.73m(2), SD 22.3, p = 0.018) when compared with the value prior to ATG treatment (23.3 ml/min/1.73m(2), SD 10.2) in the ER group. In the LR group (4 DSA positive) there was no improvement in the eGFR at 3 months (42 ml/min/1.73m(2), SD 10.5, p = 0.32) when compared with the value prior to ATG (38 ml/min/1.73 m(2), SD 9.7). At final review, eGFR in the ER group was 72.3 ml/min/1.73m(2) (SD 33) vs. 37.7 ml/min/1.73m(2) (SD 17.9) in the LR group after a mean follow up of 10.4 y and 1.2 y, respectively. ATG therapy in CRR is associated with reversal of rejection and excellent graft outcome in children with ER. The benefits remain uncertain in LR, the etiology of which is multifactorial.

Induction immunosuppressive therapies in renal transplantation

PURPOSE

Induction immunosuppressive therapies for patients undergoing renal transplantation are reviewed.

SUMMARY

The goal of induction therapy is to prevent acute rejection during the early posttransplantation period by providing a high degree of immunosuppression at the time of transplantation. Induction therapy is often considered essential to optimize outcomes, particularly in patients at high risk for poor short-term outcomes. All of the induction immunosuppressive agents currently used are biological agents and are either monoclonal (muromonab-CD3, daclizumab, basiliximab, alemtuzumab) or polyclonal (antithymocyte globulin [equine] or antithymocyte globulin [rabbit]) antibodies. Although antithymocyte globulin (rabbit) is not labeled for induction therapy, it is used for this purpose more than any other agent. Basiliximab is not considered as potent an immunosuppressive agent but has a much more favorable adverse-effect profile compared with antithymocyte globulin (rabbit) and is most commonly used in patients at low risk for acute rejection. Rituximab is being studied for use as induction therapy but to date has not demonstrated any significant benefits over placebo. While head-to-head data are available comparing most induction agents, the final decision on the most appropriate induction therapy for a transplant recipient is highly dependent on preexisting medical conditions, donor characteristics, and the maintenance immunosuppressive regimen to be used.

CONCLUSION

No standard induction immunosuppressive regimen exists for patients undergoing renal transplantation. Antithymocyte globulin (rabbit) is the most commonly used agent, whereas basiliximab appears safer. The choice of regimen depends on the preferences of clinicians and institutions.

The antibody paradigm: present and future development as a scaffold for biopharmaceutical drugs

Early studies of the humoral immune response revealed an apparent paradox: an infinite diversity of antibody specificities encoded within a finite genome. In consequence antibodies became a focus of interest for biochemists and geneticists. It resulted in the elucidation of the basic structural unit, the immunoglobulin (Ig) domain, comprised of ~ 100 amino acid residues that generate the characteristic "immunoglobulin (Ig) fold". The Ig fold has an anti-parallel ß-pleated sheet (barrel) structure that affords structural stability whilst the ß-bends allow for essentially infinite structural variation and functional diversity. This versatility is reflected in the Ig domain being the most widely utilised structural unit within the proteome. Human antibodies are comprised of multiple Ig domains and their structural diversity may be enhanced through the attachment of oligosaccharides. This review summarizes our current understanding of the immunoglobulin structure/function relationships and the application of protein and oligosaccharide engineering to further develop the Ig domain as a scaffold for the generation of new and novel antibody based therapeutics.

Immunosuppression armamentarium in 2010: mechanistic and clinical considerations

Effective immunosuppression is the key to successful organ transplantation, with success being defined as minimal rejection risk with concomitant minimal drug toxicities. Despite the general recognition of this fact, a paucity of appropriate clinical trials in children has contributed to lack of standardization of clinical management regimens, resulting in an extensive diversity of favored approaches. Nonetheless, although consensus has not been reached on the ideal approach to immunosuppression in pediatric transplantation, new drug therapies have contributed to a continuing improvement in graft and patient survival. Future clinical research must focus on diminishing the extensive burden of toxicities of these therapeutic agents in children.

KDIGO clinical practice guideline for the care of kidney transplant recipients

The 2009 Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline on the monitoring, management, and treatment of kidney transplant recipients is intended to assist the practitioner caring for adults and children after kidney transplantation. The guideline development process followed an evidence-based approach, and management recommendations are based on systematic reviews of relevant treatment trials. Critical appraisal of the quality of the evidence and the strength of recommendations followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. The guideline makes recommendations for immunosuppression, graft monitoring, as well as prevention and treatment of infection, cardiovascular disease, malignancy, and other complications that are common in kidney transplant recipients, including hematological and bone disorders. Limitations of the evidence, especially on the lack of definitive clinical outcome trials, are discussed and suggestions are provided for future research.

Antibody-based immunosuppressive agents for corneal transplantation

The progress in antibody engineering over the last 20 years has created the tools for the development of novel antibody-based drugs and constructs, such as small antibody fragments, suitable for topical administration. In rheumatology, oncology, transplantation medicine and ophthalmology, therapeutic antibody constructs, and antibody fragments have been responsible for the clinical progress seen over the last decade. Although antibody-based therapies have become a well-established immunosuppressive option in solid organ transplantation, there are only very few reports with regard to corneal transplantation. The following review explains some of the important aspects of engineered antibody-based therapeutic agents and summarises the current use of such immunosuppressive therapies in transplantation medicine and corneal transplantation.

Pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on mycophenolate mofetil comedication

BACKGROUND

The aim of this substudy within a prospective, multicenter, placebo-controlled trial was to assess the pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on comedication with mycophenolate mofetil (MMF).

METHODS

Eighty-two patients aged 3 to 18 years, receiving cyclosporine microemulsion, MMF, corticosteroids, and basiliximab or placebo were investigated. Basiliximab serum concentrations were determined by ELISA, CD25+, and CD122+ T lymphocytes by flow cytometry.

RESULTS

Basiliximab clearance adjusted to body surface area was significantly (P<0.05) greater in children versus adults, but the relatively higher basiliximab dose given to children yielded similar exposure compared with adolescents. A cross-study comparison revealed that MMF reduced basiliximab clearance and prolonged CD25 saturation duration from approximately 5 weeks in the absence of MMF to 10 weeks in the presence of MMF. Basiliximab led to a marked reduction of CD25+ T-cell fraction during the first 8 to 10 weeks posttransplant, but did not specifically affect CD122+ T cells. The majority of biopsy-proven acute rejection episodes (BPAR) were observed after interleukin (IL) 2-R desaturation, whereas about a quarter of BPARs occurred despite adequate IL2-R blockade.

CONCLUSIONS

The currently recommended basiliximab dose for pediatric patients, when used with cyclosporine microemulsion and corticosteroids, yielded adequate drug exposure in children and adolescents also under MMF comedication. The observation that about a quarter of BPARs occurred despite adequate IL2-R blockade suggests that another T-cell activation pathway independent of the IL-2/IL-2R pathway is operative, for example, the IL-15 signaling pathway.

Anti-CD3 preconditioning separates GVL from GVHD via modulating host dendritic cell and donor T-cell migration in recipients conditioned with TBI

Host dendritic cells (DCs) play a critical role in initiating graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL), and separation of GVL from GVHD remains a major challenge in the treatment of hematologic malignancies by allogeneic hematopoietic cell transplantation (HCT). Here, we show that preconditioning with anti-CD3 monoclonal antibody before conditioning with total body irradiation (TBI) prevents GVHD but retains GVL in a HCT model of major histocompatibility complex (MHC)-mismatched C57BL/6 donor to BALB/c host. Prevention of GVHD is associated with inhibition of donor T-cell expression of homing and chemokine receptors, and inhibition of GVHD target tissue expression of chemokines. Furthermore, inhibition of donor T-cell expression of gut homing alpha4beta7 and chemokine receptor (CCR)9 by anti-CD3 preconditioning results from a reduction of CD103(+) DCs in draining mesenteric lymph nodes (LNs), which is associated with down-regulation of DC expression of CCR7, a receptor required for tissue DC migration to draining LNs. These results indicate that anti-CD3 preconditioning reduces not only tissue release of chemokines but also prevents tissue DC migration to draining LNs and subsequently reduces the capacity of DCs of draining LNs to imprint donor T-cell tissue tropism. Therefore, modulation of host DCs by anti-CD3 preconditioning before HCT represents a new approach for separating GVL from GVHD.

New aspect of immunosuppressive treatment in liver transplantation. How could you induce tolerance in liver transplantation?

New immunosuppressive strategies have improved short- and long-term graft survival. The current aim is to decrease the intensity of the immunosuppressive regimen, in an attempt to limit side effects and the direct toxicity of calcineurin inhibitor (CNI) for kidney function. We describe here current experience in liver and liver-kidney transplantation, the mechanism of tolerance and the immunosuppressive strategy used in liver transplantation.

Polyclonal and monoclonal antibodies for treating acute rejection episodes in kidney transplant recipients

BACKGROUND

Registry data shows that between 15-35% kidney recipients will undergo treatment for at least one episode of acute rejection within the first post transplant year. Treatment options include pulsed steroid therapy, the use of an antibody preparation, the alteration of background immunosuppression, or combinations of these options. In 2002, in the US, 61.4% patients with an acute rejection episode received steroids, 20.4% received an antibody preparation and 18.2% received both.

OBJECTIVES

To determine the benefits and harms of mono- or polyclonal antibodies (Ab) used to treat acute rejection in kidney transplant recipients.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (in The Cochrane Library, issue 2, 2005), MEDLINE (1966-June 2005), EMBASE (1980-June 2005), and the specialised register of the Cochrane Renal Group (June 2005).

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing all mono- and polyclonal antibody preparations, given in combination with any other immunosuppressive agents, for the treatment of acute graft rejection, when compared to any other treatment for acute rejection.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trials for eligibility and quality, and extracted data. Results are expressed as relative risk (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Twenty one trials (49 reports, 1387 patients) were identified. Trials were generally small, incompletely reported, especially for potential harms, and did not define outcome measures adequately. Fourteen trials (965 patients) compared therapies for first rejection episodes. Ab was better than steroid in reversing rejection (RR 0.57, 95% CI 0.38 to 0.87) and preventing graft loss (death censored RR 0.74, CI 0.58 to 0.95) but there was no difference in preventing subsequent rejection or death at one year. Seven trials (422 patients) investigated Ab treatment of steroid-resistant rejection. There was no benefit of muromonab-CD3 over ATG or ALG in either reversing rejection, preventing subsequent rejection, preventing graft loss or death.

AUTHORS' CONCLUSIONS

In reversing first rejection, any antibody is better than steroid and also prevents graft loss, but subsequent rejection and patient survival are not significantly different. In reversing steroid-resistant rejection the effects of different antibodies are also not significantly different. Given the clinical problem caused by acute rejection, data are very sparse, and clinically important differences in outcomes between widely used interventions have not been excluded. Standardised reproducible outcome criteria are needed.