Randomized controlled trial of a monoclonal antibody against the interleukin-2 receptor (33B3.1) as compared with rabbit antithymocyte globulin for prophylaxis against rejection of renal allografts

Basiliximab for the therapy of acute T cell–mediated rejection in kidney transplant recipient with BK virus infection: A case report

A 66-year-old Chinese man underwent a deceased donor kidney transplantation. Induction-immunosuppressive protocol consisted of basiliximab (BAS) and methyl prednisolone (MP), followed by maintenance immunosuppression with cyclosporin (CsA), mycophenolate mofetil (MMF), and prednisone (PED). The patient’s post-transplantation course was almost uneventful, and the graft was functioning well [serum creatinine (Scr) 2.15 mg/dL]. The MMF and CsA doses were decreased 1-month post-operative as the BK virus activation was serologically positive. His Scr was elevated to 2.45 mg/dL 45 days after the transplant. A graft biopsy showed BKV nephropathy (BKVN) and acute T cell–mediated rejection (TCMR) Banff grade IIA (I2, t2, ptc2, v1, c4d1, g0, and SV40 positive). The conventional anti-rejection therapy could deteriorate his BKVN, therefore, we administered BAS to eliminate activated graft-infiltrating T cells and combined with low-dose steroid. He responded well to the therapy after two doses of BAS were given, and the kidney graft status has been stable (recent Scr 2.1 mg/dL).

Time-dependent lymphocyte count after transplantation is associated with higher risk of graft failure and death

The transplantation field requires the identification of specific risk factors associated with the level of immunosuppression. Here, our aim was to analyze the association between the number of circulating lymphocytes, monitored routinely by complete blood cell counts during outpatient visits, and patient and graft survival. In total, 2,999 kidney or combined kidney-pancreas recipients transplanted between 2000 and 2016, from two University hospitals, were enrolled. We investigated the etiological relationship between time-dependent lymphocyte count beyond one year after transplantation and patient and graft survival, viral infection and cancer risk using time-dependent multivariate Cox models. Model 1 considered kidney function at one year and model 2 as time-dependent variable. At the time of inclusion (one year after transplantation), 584 patients (19.4%) had deep lymphopenia (under 750 /mm³) and 1,072 (35.7%) had a normal count (over 1,500 /mm³). A patient with deep lymphopenia at a given follow-up time had significantly higher risks of graft failure, death and viral infection than comparable patients with a normal lymphocyte count at the same time point. Thus, after the first year of transplantation, the occurrence of deep lymphopenia within a patient's follow-up is a risk factor for long-term graft failure, death and viral infection.

Urinary cell transcriptomics and acute rejection in human kidney allografts

BACKGROUNDRNA sequencing (RNA-Seq) is a molecular tool to analyze global transcriptional changes, deduce pathogenic mechanisms, and discover biomarkers. We performed RNA-Seq to investigate gene expression and biological pathways in urinary cells and kidney allograft biopsies during an acute rejection episode and to determine whether urinary cell gene expression patterns are enriched for biopsy transcriptional profiles.METHODSWe performed RNA-Seq of 57 urine samples collected from 53 kidney allograft recipients (patients) with biopsies classified as acute T cell-mediated rejection (TCMR; n = 22), antibody-mediated rejection (AMR; n = 8), or normal/nonspecific changes (No Rejection; n = 27). We also performed RNA-Seq of 49 kidney allograft biopsies from 49 recipients with biopsies classified as TCMR (n = 12), AMR (n = 17), or No Rejection (n = 20). We analyzed RNA-Seq data for differential gene expression, biological pathways, and gene set enrichment across diagnoses and across biospecimens.RESULTSWe identified unique and shared gene signatures associated with biological pathways during an episode of TCMR or AMR compared with No Rejection. Gene Set Enrichment Analysis demonstrated enrichment for TCMR biopsy signature and AMR biopsy signature in TCMR urine and AMR urine, irrespective of whether the biopsy and urine were from the same or different patients. Cell type enrichment analysis revealed a diverse cellular landscape with an enrichment of immune cell types in urinary cells compared with biopsies.CONCLUSIONSRNA-Seq of urinary cells and biopsies, in addition to identifying enriched gene signatures and pathways associated with TCMR or AMR, revealed genomic changes between TCMR and AMR, as well as between allograft biopsies and urinary cells.

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-Gal and Anti-Neu5Gc Responses in Nonimmunosuppressed Patients After Treatment With Rabbit Antithymocyte Polyclonal IgGs

BACKGROUND

Polyclonal antihuman thymocyte rabbit IgGs (antithymocyte globulin [ATG]) are popular immunosuppressive drugs used to prevent or treat organ or bone-marrow allograft rejection, graft versus host disease, and autoimmune diseases. However, animal-derived glycoproteins are also strongly immunogenic and rabbit ATG induces serum sickness disease in almost all patients without additional immunosuppressive drugs, as seen in the Study of Thymoglobulin to arrest Type 1 Diabetes (START) trial of ATG therapy in new-onset type 1 diabetes.

METHODS

Using enzyme-linked immunosorbent assay, we analyzed serial sera from the START study to decipher the various anti-ATG specificities developed by the patients in this study: antitotal ATG, but also antigalactose-α1-3-galactose (Gal) and anti-Neu5Gc antibodies, 2 xenocarbohydrate epitopes present on rabbit IgG glycans and lacking in humans.

RESULTS

We show that diabetic patients have substantial levels of preexisting antibodies of the 3 specificities, before infusion, but of similar levels as healthy individuals. ATG treatment resulted in highly significant increases of both IgM (for anti-ATG and anti-Neu5Gc) and IgG (for anti-ATG, -Gal, and -Neu5Gc), peaking at 1 month and still detectable 1 year postinfusion.

CONCLUSIONS

Treatment with rabbit polyclonal IgGs in the absence of additional immunosuppression results in a vigorous response against Gal and Neu5Gc epitopes, contributing to an inflammatory environment that may compromise the efficacy of ATG therapy. The results also suggest using IgGs lacking these major xenoantigens may improve safety and efficacy of ATG treatment.

Anti-EBOV GP IgGs Lacking α1-3-Galactose and Neu5Gc Prolong Survival and Decrease Blood Viral Load in EBOV-Infected Guinea Pigs

Polyclonal xenogenic IgGs, although having been used in the prevention and cure of severe infectious diseases, are highly immunogenic, which may restrict their usage in new applications such as Ebola hemorrhagic fever. IgG glycans display powerful xenogeneic antigens in humans, for example α1–3 Galactose and the glycolyl form of neuraminic acid Neu5Gc, and IgGs deprived of these key sugar epitopes may represent an advantage for passive immunotherapy. In this paper, we explored whether low immunogenicity IgGs had a protective effect on a guinea pig model of Ebola virus (EBOV) infection. For this purpose, a double knock-out pig lacking α1–3 Galactose and Neu5Gc was immunized against virus-like particles displaying surface EBOV glycoprotein GP. Following purification from serum, hyper-immune polyclonal IgGs were obtained, exhibiting an anti-EBOV GP titer of 1:100,000 and a virus neutralizing titer of 1:100. Guinea pigs were injected intramuscularly with purified IgGs on day 0 and day 3 post-EBOV infection. Compared to control animals treated with IgGs from non-immunized double KO pigs, the anti-EBOV IgGs-treated animals exhibited a significantly prolonged survival and a decreased virus load in blood on day 3. The data obtained indicated that IgGs lacking α1–3 Galactose and Neu5Gc, two highly immunogenic epitopes in humans, have a protective effect upon EBOV infection.

Rabbit antithymocyte globulin-induced serum sickness disease and human kidney graft survival

BACKGROUND

Rabbit-generated antithymocyte globulins (ATGs), which target human T cells, are widely used as immunosuppressive agents during treatment of kidney allograft recipients. However, ATGs can induce immune complex diseases, including serum sickness disease (SSD). Rabbit and human IgGs have various antigenic differences, including expression of the sialic acid Neu5Gc and α-1-3-Gal (Gal), which are not synthesized by human beings. Moreover, anti-Neu5Gc antibodies have been shown to preexist and be elicited by immunization in human subjects. This study aimed to assess the effect of SSD on long-term kidney allograft outcome and to compare the immunization status of grafted patients presenting with SSD following ATG induction treatment.

METHODS

We analyzed data from a cohort of 889 first kidney graft recipients with ATG induction (86 with SSD [SSD(+)] and 803 without SSD [SSD(-)]) from the Données Informatisées et Validées en Transplantation data bank. Two subgroups of SSD(+) and SSD(-) patients that had received ATG induction treatment were then assessed for total anti-ATG, anti-Neu5Gc, and anti-Gal antibodies using ELISA assays on sera before and after transplantation.

RESULTS

SSD was significantly associated with long-term graft loss (>10 years, P = 0.02). Moreover, SSD(+) patients exhibited significantly elevated titers of anti-ATG (P = 0.043) and anti-Neu5Gc (P = 0.007) IgGs in late post-graft samples compared with SSD(-) recipients.

CONCLUSION

In conclusion, our data indicate that SSD is a major contributing factor of late graft loss following ATG induction and that anti-Neu5Gc antibodies increase over time in SSD(+) patients.

FUNDING

This study was funded by Société d'Accélération du Transfert de Technologies Ouest Valorisation, the European FP7 "Translink" research program, the French National Agency of Research, Labex Transplantex, the Natural Science and Engineering Research Council of Canada, and the Canadian Foundation for Innovation.

Daclizumab Versus Rabbit Antithymocyte Globulin in High-Risk Renal Transplants: Five-Year Follow-up of a Randomized Study

We previously reported a randomized controlled trial in which 227 de novo deceased-donor kidney transplant recipients were randomized to rabbit antithymocyte (rATG, Thymoglobulin) or daclizumab if they were considered to be at high immunological risk, defined as high panel reactive antibodies (PRA), loss of a first kidney graft through rejection within 2 years of transplantation, or third or fourth transplantation. Patients treated with rATG had lower incidences of biopsy-proven acute rejection (BPAR) and steroid-resistant rejection at 1 year. Patients were followed to 5 years posttransplant in an observational study; findings are described here. Treatment with rATG was associated with a lower rate of BPAR at 5 years (14.2% vs. 26.0% with daclizumab; p = 0.035). Only one rATG-treated patient (0.9%) and one daclizumab-treated patient (1.0%) developed BPAR after 1 year. Five-year graft and patient survival rates, and renal function, were similar between the two groups. Overall graft survival at 5 years was significantly higher in patients without BPAR (81.0% vs. 54.8%; p < 0.001). In conclusion, rATG is superior to daclizumab for the prevention of BPAR among high-immunological-risk renal transplant recipients. Overall graft survival at 5 years was approximately 70% with either induction therapy, which compares favorably to low-risk cohorts.

IL-2 phosphorylates STAT5 to drive IFN-γ production and activation of human dendritic cells

Human dendritic cells (hDCs) produce IL-2 and express IL-2R α-chain (CD25), but the role of IL-2 in DC functions is not well defined. A recent study suggested that the main function of CD25 on hDCs was to transpresent IL-2 to activate T lymphocytes. Our results demonstrate the expression of the three chains of the IL-2R on hDCs and that IL-2 induces STAT5 phosphorylation. Interestingly, use of inhibitors of p-STAT5 revealed that IL-2 increases LPS-induced IFN-γ through STAT5 phosphorylation. Finally, we report that IL-2 increases the ability of hDCs to activate helpless CD8(+) T cells, most likely because of IL-2-triggered IFN-γ synthesis, as we previously described. For the first time, to our knowledge, we disclose that IL-2 induces monocyte-derived hDC's functional maturation and activation through IL-2R binding. Interestingly, our study suggests a direct effect of anti-CD25 mAbs on hDCs that may contribute to their clinical efficacy.

The role of Thymoglobulin induction in kidney transplantation: an update

The rabbit antithymocyte globulin Thymoglobulin first became available over 25 yr ago and is the most widely used lymphocyte-depleting preparation in solid organ transplantation. Thymoglobulin targets a wide range of T-cell surface antigens as well as natural killer-cell antigens, B-cell antigens, plasma cell antigens, adhesion molecules and chemokine receptors, resulting in profound, long-lasting T-cell depletion. Randomized studies have established the anti-rejection efficacy of Thymoglobulin in kidney transplantation. Experimental and clinical data suggest that Thymoglobulin administration may ameliorate ischemia reperfusion injury, thus reducing the incidence of delayed graft function (DGF). Studies have demonstrated the benefit of using Thymoglobulin to facilitate immunosuppression minimization, both for corticosteroid and calcineurin inhibitor (CNI) withdrawal or avoidance, with potential improvement in cardiovascular and renal outcomes. The optimal cumulative dose for Thymoglobulin induction is 6-7.5 mg/kg, with vigilant short- and long-term monitoring of hematological status. Induction with Thymoglobulin is now indicated in immunologically high-risk patients, in those at increased risk of DGF and to maintain efficacy in low-risk transplant recipients receiving steroid or CNI minimization or avoidance regimens. We suggest that in future trials Thymoglobulin be tested with costimulation signal blockers and other immunosuppressants with the objective of establishing operational tolerance.

Monitoring of nonsteroidal immunosuppressive drugs in patients with lung disease and lung transplant recipients: American College of Chest Physicians evidence-based clinical practice guidelines

OBJECTIVES

Immunosuppressive pharmacologic agents prescribed to patients with diffuse interstitial and inflammatory lung disease and lung transplant recipients are associated with potential risks for adverse reactions. Strategies for minimizing such risks include administering these drugs according to established, safe protocols; monitoring to detect manifestations of toxicity; and patient education. Hence, an evidence-based guideline for physicians can improve safety and optimize the likelihood of a successful outcome. To maximize the likelihood that these agents will be used safely, the American College of Chest Physicians established a committee to examine the clinical evidence for the administration and monitoring of immunosuppressive drugs (with the exception of corticosteroids) to identify associated toxicities associated with each drug and appropriate protocols for monitoring these agents.

METHODS

Committee members developed and refined a series of questions about toxicities of immunosuppressives and current approaches to administration and monitoring. A systematic review was carried out by the American College of Chest Physicians. Committee members were supplied with this information and created this evidence-based guideline.

CONCLUSIONS

It is hoped that these guidelines will improve patient safety when immunosuppressive drugs are given to lung transplant recipients and to patients with diffuse interstitial lung disease.

Cytokines in clinical and experimental transplantation

Allograft rejection is a complex process, which requires interactions between different cell types and a variety of soluble factors, such as cytokines. In this review we discuss the role of cytokines in the induction and effector phases of the rejection process and in the induction and maintenance of allospecific graft tolerance. Furthermore, we discuss the feasibility of clinical graft function monitoring by measuring cytokines and the possibilities for intervention in the cytokine network in order to inhibit graft rejection and eventually obtain graft acceptance.

Approaching the promise of operational tolerance in clinical transplantation

Long-term acceptance of transplanted organs without requirement for indefinite immunosuppression remains the ultimate goal of transplant clinicians and scientists. This clinical state of allograft acceptance termed "operational tolerance" has been elusive in routine practice. However, there are published reports of recipients where immunosuppression has been discontinued, by intention or patient noncompliance, in which the outcome is a nondestructive immune response and normal function. The question now arises how clinical operational tolerance might be achieved in the majority of recipients. This review provides an overview of current approaches to achieve operational tolerance, including the use of donor bone marrow and depletion of recipient T cells and the resistance of liver transplants to rejection. It also describes the key role of clinical immune monitoring and future approaches to tolerance induction including inhibition of T-cell signaling, manipulation of costimulatory pathways, and expansion of regulatory T cells. The principles of these experimental approaches may ultimately be extended to provide safe and effective control of transplant rejection and induction of clinical operational tolerance.

Have we overestimated the benefit of human(ized) antibodies?

The infusion of animal-derived antibodies has been known for some time to trigger the generation of antibodies directed at the foreign protein as well as adverse events including cytokine release syndrome. These immunological phenomena drove the development of humanized and fully human monoclonal antibodies. The ability to generate human(ized) antibodies has been both a blessing and a curse. While incremental gains in the clinical efficacy and safety for some agents have been realized, a positive effect has not been observed for all human(ized) antibodies. Many human(ized) antibodies trigger the development of anti-drug antibody responses and infusion reactions. The current belief that antibodies need to be human(ized) to have enhanced therapeutic utility may slow the development of novel animal-derived monoclonal antibody therapeutics for use in clinical indications. In the case of murine antibodies, greater than 20% induce tolerable/negligible immunogenicity, suggesting that in these cases humanization may not offer significant gains in therapeutic utility. Furthermore, humanization of some murine antibodies may reduce their clinical effectiveness. The available data suggest that the utility of human(ized) antibodies needs to be evaluated on a case-by-case basis, taking a cost-benefit approach, taking both biochemical characteristics and the targeted therapeutic indication into account.

A clinical scoring system highly predictive of long-term kidney graft survival

Determining early surrogate markers of long-term graft outcome is important for optimal medical management. In order to identify such markers, we used clinical information from a cross-validated French database (Données Informatisées et VAlidées en Transplantation) of 2169 kidney transplant recipients to construct a composite score 1 year after transplantation. This Kidney Transplant Failure Score took into account a series of eight accepted pre- and post-transplant risk factors of graft loss, and was subsequently evaluated for its ability to predict graft failure at 8 years. This algorithm outperformed the traditional surrogates of serum creatinine and the estimated graft filtration rate, with an area under the receiver-operator characteristic curve of 0.78. Validation on an independent database of 317 graft recipients had the same predictive capacity. Our algorithm was also able to stratify patients into two groups according to their risk: a high-risk group of 81 patients with 25% graft failure and a low-risk group of 236 patients with an 8% failure rate. Thus, although this clinical composite score predicts long-term graft survival, it needs validation in different patient groups throughout the world.

Interleukin 2 receptor antagonists for kidney transplant recipients

BACKGROUND

Interleukin 2 receptor antagonists (IL2Ra) are used as induction therapy for prophylaxis against acute rejection in kidney transplant recipients. Use of IL2Ra has increased steadily since their introduction, but the proportion of new transplant recipients receiving IL2Ra differs around the globe, with 27% of new kidney transplant recipients in the United States, and 70% in Australasia receiving IL2Ra in 2007.

OBJECTIVES

To systematically identify and summarise the effects of using an IL2Ra, as an addition to standard therapy, or as an alternative to another immunosuppressive induction strategy.

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE to identify new records, and authors of included reports were contacted for clarification where necessary.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing IL2Ra to placebo, no treatment, other IL2Ra or other antibody therapy.

DATA COLLECTION AND ANALYSIS

Data was extracted and assessed independently by two authors, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) and continuous outcomes as mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We included 71 studies (306 reports, 10,537 participants). Where IL2Ra were compared with placebo (32 studies; 5,784 patients) graft loss including death with a functioning graft was reduced by 25% at six months (16 studies: RR 0.75, 95% CI 0.58 to 0.98) and one year (24 studies: RR 0.75, 95% CI 0.62 to 0.90), but not beyond this. At one year biopsy-proven acute rejection was reduced by 28% (14 studies: RR 0.72, 95% CI 0.64 to 0.81), and there was a 19% reduction in CMV disease (13 studies: RR 0.81, 95% CI 0.68 to 0.97). There was a 64% reduction in early malignancy within six months (8 studies: RR 0.36, 95% CI 0.15 to 0.86), and creatinine was lower (7 studies: MD -8.18 micromol/L 95% CI -14.28 to -2.09) but these differences were not sustained.When IL2Ra were compared to ATG (16 studies, 2211 participants), there was no difference in graft loss at any time point, or for acute rejection diagnosed clinically, but the was benefit of ATG therapy over IL2Ra for biopsy-proven acute rejection at one year (8 studies:, RR 1.30 95% CI 1.01 to 1.67), but at the cost of a 75% increase in malignancy (7 studies: RR 0.25 95% CI 0.07 to 0.87) and a 32% increase in CMV disease (13 studies: RR 0.68 95% CI 0.50 to 0.93). Serum creatinine was significantly lower for IL2Ra treated patients at six months (4 studies: MD -11.20 micromol/L 95% CI -19.94 to -2.09). ATG patients experienced significantly more fever, cytokine release syndrome and other adverse reactions to drug administration and more leucopenia but not thrombocytopenia. There were no significant differences in outcomes according to cyclosporine or tacrolimus use, azathioprine or mycophenolate, or to the study populations baseline risk for acute rejection. There was no evidence that effects were different according to whether equine or rabbit ATG was used.

AUTHORS' CONCLUSIONS

Given a 38% risk of rejection, per 100 recipients compared with no treatment, nine recipients would need treatment with IL2Ra to prevent one recipient having rejection, 42 to prevent one graft loss, and 38 to prevent one having CMV disease over the first year post-transplantation. Compared with ATG treatment, ATG may prevent some experiencing acute rejection, but 16 recipients would need IL2Ra to prevent one having CMV, but 58 would need IL2Ra to prevent one having malignancy. There are no apparent differences between basiliximab and daclizumab. IL2Ra are as effective as other antibody therapies and with significantly fewer side effects.

Specific antibodies induced by DNA vaccination with extracellular domain of CD25 gene protect against ConA-induced autoimmune hepatitis

Antibodies to CD25 (anti-CD25) were used clinically to achieve immunosuppression in autoimmune disease, while the possibility of anti-antibodies generation influenced its efficiency. Here we reported that DNA vaccine encoding the extracellular domain of murine CD25 gene (pCD25-ECD) elicited anti-CD25 antibody production in BALB/c mice and subsequently prevents the host against ConA-induced autoimmune hepatitis. We found that serum CD25-specific antibodies were generated after vaccination with pCD25-ECD. Moreover, high levels of IL-4, IL-10 and anti-CD25 antibody were produced by splenocytes of vaccinated mice after CD25 protein restimulation in vitro. Furthermore, we demonstrated that the vaccinated mice suffered less from liver injury induced by ConA, accompanied by the reduction of pathogenic CD4+ T cells. Finally, we showed that the immunized serum could cause cytolysis of activated CD4+ T cells in vitro, depending on complements activation. Our study showed pCD25-ECD induced self anti-CD25 antibodies which executed immunosuppression in autoimmune hepatitis via antibody-complement pathway.

Evolving trends in induction therapy

A decade of spectacular innovation in maintenance immunosuppressive drugs has resulted in dramatic reductions in acute rejection and improvement in short- and long-term outcomes after renal transplantation. However, the new drugs continue to lack specificity, many require frequent therapeutic drug monitoring, and all of them are associated with acute and chronic toxicities. The new biologic agents, monoclonal antibodies, and receptor-fusion proteins lack immunogenicity, have long half-life and prolonged biologic effects, require intermittent administration, and have minimal toxicity. The specificity and selectively of the targets of the new biologic agents render them less toxic than the oral maintenance drugs and thus could possibly replace those drugs most frequently associated with long-term toxicity such as the corticosteroids and the calcineurin inhibitors.

Protein therapeutics: a summary and pharmacological classification

Once a rarely used subset of medical treatments, protein therapeutics have increased dramatically in number and frequency of use since the introduction of the first recombinant protein therapeutic--human insulin--25 years ago. Protein therapeutics already have a significant role in almost every field of medicine, but this role is still only in its infancy. This article overviews some of the key characteristics of protein therapeutics, summarizes the more than 130 protein therapeutics used currently and suggests a new classification of these proteins according to their pharmacological action.

The pathogenesis and clinical management of cytomegalovirus infection in the organ transplant recipient: the end of the 'silo hypothesis'

PURPOSE OF REVIEW

Cytomegalovirus infection is initiated when tumor necrosis factor binds to the cytomegalovirus receptors of latently infected cells, resulting in the reactivation of the virus and the production of clinical disease of two types: direct infection causing pneumonia, mononucleosis, colitis and other viral-related syndromes, and indirect infection in which an array of cytokines are released by the host that produce much the same effect as does the rejection process.

RECENT FINDINGS

These effects fall into three categories: allograft injury, an increase in superinfection with opportunistic pathogens and an increase in the incidence of B cell lymphoproliferative disease. Other factors that modulate the clinical impact of reactivated cytomegalovirus in the transplant patient include the past experience of the host with the virus (primary infection, donor seropositive and recipient seronegative), the degree of major histocompatibility complex mismatch, the viral burden and the amount of calcineurin inhibitor the patient receives.

SUMMARY

Optimal therapy for diagnosing, treating and preventing these indirect effects still remains to be defined; the direct effects, in contrast, are well managed with valganciclovir.

Efficacy of anti-IL-2 receptor antibodies compared to no induction and to antilymphocyte antibodies in renal transplantation

The relative efficacy of anti-IL-2 receptor antibodies (IL2R Abs) and antilymphocyte antibodies in preventing acute rejection and improving graft survival after renal transplantation is poorly defined. In particular, the benefits of these agents in specific subgroups, such as recipients with different degrees of HLA mismatch, are unknown. Using the SRTR database, we compared IL2R Abs to no induction and to antilymphocyte antibody induction in 48 948 first renal transplant recipients in the United States between 1998 and 2003 with respect to acute rejection and graft failure. IL2R Abs decreased acute rejection at 6 months (OR: 0.81(0.75-0.87)), and reduced graft failure (HR: 0.90(0.84-0.95)), compared to no induction over a follow-up of 1059 days. Compared to IL2R Abs, antilymphocyte Abs were associated with decreased acute rejection (OR: 0.90(0.83-0.99)) at 1 year, but were not associated with improved graft survival (OR: 1.08(1.00-1.18)) over a follow-up of 732 days. The benefit of IL2R Abs in reducing acute rejection increased significantly with greater HLA mismatch (p = 0.007). IL2R Abs remain an important option in the management of renal transplant patients, and may be particularly useful in specific patient subsets.

Acute sensory neuropathy associated with rabbit antithymocyte globulin

Rabbit antithymocyte globulin (RATG) is indicated for the treatment of acute renal transplant rejection and has also been shown to be effective as an induction immunosuppressive agent after renal transplantation. We report a patient that developed a painful sensory neuropathy within an hour of receiving RATG. The neuropathic symptoms resolved within a month, and a careful review of his medications, exposures and comorbid conditions revealed no other causes of neuropathy. Since the administration of RATG and onset of symptoms were so closely related temporally and the symptoms resolved after the cessation of RATG, we believe it is likely this medication led to the development of neuropathy.

Suppression of the cell-mediated immune response by a Fas-immunoglobulin fusion protein

INTRODUCTION

Immunosuppressive agents must not only be effective in impairing the host's allo-immune response, but should also be selective in targeting only those elements of the immune system activated by the allograft. The fact that allo-activated T cells express surface protein molecules that are not typically present on resting T cells can be exploited to specifically target this population. Fas ligand is one such molecule whose cell surface expression on T cells is dramatically up-regulated upon activation.

METHODS

We constructed a murine fusion protein by linking the extracellular domain of Fas to the Fc region of IgG2a. The rationale being to selectively target activated T cells via binding of its Fas moiety to cell surface Fas ligand, and then to allow the Fc moiety to invoke its usual effector mechanisms resulting in the destruction of the allo-activated T cell. Here, we describe the design and expression of Fas-IgG2a and characterize several key in vitro and in vivo properties of this fusion protein including its ability to impact on both cell-mediated immune responses and cellular apoptotic activity using a murine model of delayed-type hypersensitivity.

RESULTS

In vitro, our Fas-IgG2a construct bound activated T cells via FasL and invoked cytotoxicity. In vivo, it demonstrated a prolonged half-life characteristic of an immunoglobulin-like molecule. Most significantly, it suppressed the cell-mediated immune response and diminished cellular apoptotic activity in lymphoid tissue in our murine model.

CONCLUSION

Fas-IgG2a is a novel agent for delivering target-specific immunosuppression with potential applicability in the transplant setting.

Late ureteral stenosis following renal transplantation: risk factors and impact on patient and graft survival

The aim of this retrospective study of a cohort of 1787 consecutive kidney transplantations was to analyze the risk factors associated with the occurrence of ureteral stenosis and the impact of ureteral stenosis on graft and patient survival. Between January 1990 and December 2002, 1787 renal transplantations were performed at our center. Only stenosis observed after the first month, were considered. Among the parameters studied were: donor age and serum creatinine before procurement; recipient age, cold ischemia time, delayed graft function (DGF), number of arteries and the presence of a double J stent. The follow-up parameters were the number and timing of acute rejection episodes, cytomegalovirus (CMV) infection, acute pyelonephritis, renal function and death. Ureteral stenosis occurred in 4.1% of patients and was correlated with donor age > 65 years (p = 0.001), kidneys with more than 2 arteries (p = 0.009) and DGF (p = 0.016). Ureteral stenosis did not affect 10-year patient and graft survival rates, which were respectively 90% and 64% for the stenosis group, 86% and 63% for the no-stenosis group (p = NS). These data suggest an important role for donor age, number of renal arteries and DGF for the occurrence of ureteral stenosis following renal transplantation.

Basiliximab (Simulect) reduces acute rejection among sensitized kidney allograft recipients

AIMS

Our goal was to evaluate the efficacy and safety of basiliximab (Simulect) as immunosuppressive induction therapy for the prevention of acute allograft rejection among sensitized kidney recipients.

METHODS

Fifty-six adult recipients receiving cadaveric kidney transplant with panel reactive antibody class I ranging from 30% to 50% and or class II 30% to 80% were randomized at about a 2:1 ratio to the Simulect group (36 patients) or matching control group (20 patients). All patients received baseline triple immunosuppressive therapy with cyclosporine (Neoral), mycophenolate mofetil, and steroids. Simulect was given in two doses of 20 mg each on day 0 (2 hours before operation) and day 4 after transplantation.

RESULTS

There was no hyperacute rejection in either group and delayed graft function occurred in three control patients. The incidence of acute rejection during the first 3 months was 11.1% in the Simulect group compared with 50% in the placebo group (77.8% reduction, P < .01). No apparent adverse and toxic events were recorded in the Simulect group. The mean daily dose of steroids was significantly higher in the control group 2 to 4 weeks posttransplantation. No clinically meaningful differences in the mean dose of cyclosporine were observed between the two groups; in addition, there were no statistically significant differences in the rate of patient or graft survival.

CONCLUSIONS

On the basis of appropriate selection of the donor and recipient, Simulect is effective and safety for the sensitized recipients as immunosuppressive induction therapy.

Ureteral necrosis after kidney transplantation: risk factors and impact on graft and patient survival

BACKGROUND

Ischemia, the main cause of ureteral necrosis in renal transplantation, cannot alone explain the late occurrence of some fistulas beyond the first postoperative month. The aim of this study, performed on a cohort of 1,629 consecutive kidney transplantations, was to analyze the risk factors implicated in the occurrence of ureteral necrosis and its impact on graft and patient survival.

METHODS

Between January 1990 and December 2001, 1,629 renal transplantations were performed in the authors' center. All biologic and clinical data were computerized in a cross-audited and validated data bank (Données Informatisées et Validées en Transplantation). The parameters studied were donor age, gender, cause of death and serum creatinine before procurement; and recipient age, gender, initial disease, panel reactive antibody, retransplantation, cold ischemia time, delayed graft function, human leukocyte antigen incompatibilities, induction and maintenance immunosuppression, right or left kidney, number of arteries, site of transplantation and the presence or not of a double-J stent. The follow-up parameters were the number and timing of acute rejection episodes, cytomegalovirus (CMV) infection (viremia, polymerase chain reaction), and acute pyelonephritis. Ureteral histologic analysis was performed in 25 cases (necrosis, leukocyte infiltration, and CMV or BK virus inclusions). Uni- and multivariate statistical tests were used (alpha risk at 5%). All of the patients with ureteral necrosis had undergone neoureterocystostomy or ureteral anastomosis with the native ureter but with a systematic double-J stent.

RESULTS

Ureteral necrosis occurred in 52 of the 1,629 patients (3.2%) and was significantly and independently correlated with donor age (P=0.041) and delayed graft function (P=0.016). CMV infections were also higher in the necrosis group (P=0.001), but donor CMV status was not statistically different between the two groups (36.2% vs. 36.7%). Ureteral histologic studies showed CMV and BK virus inclusions in 4 and 2 cases, respectively, and arterial and venous thrombosis in 4 and 16 cases, respectively. No pattern of ureteral rejection was observed. Ureteral necrosis did not affect the 10-year patient and graft survival, which were 87% and 66%, respectively, for the necrosis group and 86% and 58%, respectively, for the control group (P=not significant).

CONCLUSIONS

The authors' data provide new information concerning a classic surgical complication after kidney transplantation. The link they have identified between the occurrence of ureteral necrosis, donor age, and delayed graft function reemphasizes the interdependence between surgical and medical complications in kidney transplantation.

Sequential protocols using basiliximab versus antithymocyte globulins in renal-transplant patients receiving mycophenolate mofetil and steroids

BACKGROUND

Sequential anti-thymocyte globulins (ATG)/cyclosporine immunosuppression has two main advantages: delayed introduction of the nephrotoxic drug cyclosporine and prevention of acute rejection. Basiliximab, a recently developed chimeric monoclonal antibody that selectively depletes the minor subpopulation of activated T lymphocytes, has been shown to reduce the incidence of acute rejection when used with cyclosporine introduced on day 1.

METHODS

This open, randomized, multicenter study was undertaken to compare the safety and efficacy of ATG versus basiliximab induction therapy (IT) with delayed introduction of cyclosporine for microemulsion (Neoral) in 105 low immunologic risk renal-transplant patients receiving mycophenolate mofetil and steroids.

RESULTS

One-year patient and graft survival rates were 98.1% and 94.2%, respectively, in the basiliximab group (n = 52), and 98.1% and 96.2% in the ATG group (n = 53). The incidence of biopsy-confirmed acute rejection was comparable (basiliximab 9.6%, ATG 9.4%), as were key parameters of renal function, notably serum creatinine levels, time-to-nadir serum creatinine, and the number of patients requiring posttransplantation dialysis (basiliximab 28.8%, ATG 30.2%). However, significantly fewer patients in the basiliximab group experienced cytomegalovirus (CMV) infection, leukopenia, and thrombocytopenia, and this without any significant difference in any other key safety parameters (including the incidences of serum sickness, fever, lymphoma, and infections in general).

CONCLUSIONS

Both ATG and basiliximab, when used for IT in a sequential protocol, are equally effective in terms of graft and patient survival as well as at preventing acute rejection. However, basiliximab is associated with a lower incidence of certain key adverse events, namely CMV infection, leukopenia, and thrombocytopenia.

Historical controlled trial of OKT3 versus basiliximab induction therapy in simultaneous pancreas-renal transplantation

Simultaneous pancreas-kidney (SPK) transplant recipients are at high immunological risk of rejection. Antibody induction is beneficial but lymphocyte-depleting therapy is associated with a high incidence of side-effects. We performed a historical controlled trial to compare OKT3 versus anti-CD25 antibody (basiliximab) induction therapy with regard to patient, kidney and pancreas survival, as well as to examine for any differences in acute rejection, graft function, and infective complications. Twenty-eight consecutive SPK transplants were performed at the Monash Medical Centre between December 1997 and November 2001. Anti CD3 monoclonal antibody (OKT3) was used prior to March 2000 (n = 12) and basiliximab was used after (n = 16), both in combination with cyclosporin, mycophenolate, and prednisolone. A retrospective comparison of outcomes was performed. At 6 months, patient (100 vs 100%), kidney (91.7 vs 91.7%) and pancreas (75 vs 83.3%) survival were similar in the OKT3 and basiliximab groups, respectively. A minority of subjects in each group remained free from rejection (42% basiliximab vs 25% on OKT3, P = NS). Renal function was superior in the basiliximab group (mean calculated creatinine clearance 79.4 +/- 11.9 vs 54.5 +/- 15.9 mL/min for basiliximab vs OKT3, P < 0.001). The incidence of major opportunistic infection was lower in basiliximab-treated patients (9 vs 50% in the OKT3 group, P = 0.033). Basiliximab was associated with similar 6-month patient, kidney and pancreas survival, superior renal function and less opportunistic infection as compared with OKT3 induction therapy in SPK transplants. Basiliximab is at least as effective and is safer than OKT3 for induction therapy in SPK transplantation.

DNA vaccination with CD25 protects rats from adjuvant arthritis and induces an antiergotypic response

Ab's to the alpha-chain of the IL-2 receptor (anti-CD25) are used clinically to achieve immunosuppression. Here we investigated the effects of DNA vaccination with the whole CD25 gene on the induction of rat adjuvant arthritis. The DNA vaccine protected the rats and led to a shift in the cytokine profile of T cells responding to disease target antigens from Th1 to Th2. The mechanism of protection was found to involve the induction of an antiergotypic response, rather than the induction of anti-CD25 Ab's. Antiergotypic T cells respond to activation molecules, ergotopes, expressed on syngeneic activated, but not resting, T cells. CD25-derived peptides function as ergotopes that can be recognized by the antiergotypic T cells. Antiergotypic T cells taken from control sick rats did not proliferate against activated T cells and secreted mainly IFN-gamma. In contrast, antiergotypic cells from CD25-DNA-protected rats proliferated against activated T cells and secreted mainly IL-10. Protective antiergotypic T cells were found in both the CD4+ and CD8+ populations and expressed alpha/beta or gamma/delta T cell receptors. Antiergotypic alpha/beta T cells were MHC restricted, while gamma/delta T cells were MHC independent. Thus, CD25 DNA vaccination may induce protection from autoimmunity by inducing a cytokine shift in both the antiergotypic response and the response to the antigens targeted in the disease.

DNA vaccination with CD25 protects rats from adjuvant arthritis and induces an antiergotypic response

Ab's to the alpha-chain of the IL-2 receptor (anti-CD25) are used clinically to achieve immunosuppression. Here we investigated the effects of DNA vaccination with the whole CD25 gene on the induction of rat adjuvant arthritis. The DNA vaccine protected the rats and led to a shift in the cytokine profile of T cells responding to disease target antigens from Th1 to Th2. The mechanism of protection was found to involve the induction of an antiergotypic response, rather than the induction of anti-CD25 Ab's. Antiergotypic T cells respond to activation molecules, ergotopes, expressed on syngeneic activated, but not resting, T cells. CD25-derived peptides function as ergotopes that can be recognized by the antiergotypic T cells. Antiergotypic T cells taken from control sick rats did not proliferate against activated T cells and secreted mainly IFN-gamma. In contrast, antiergotypic cells from CD25-DNA-protected rats proliferated against activated T cells and secreted mainly IL-10. Protective antiergotypic T cells were found in both the CD4+ and CD8+ populations and expressed alpha/beta or gamma/delta T cell receptors. Antiergotypic alpha/beta T cells were MHC restricted, while gamma/delta T cells were MHC independent. Thus, CD25 DNA vaccination may induce protection from autoimmunity by inducing a cytokine shift in both the antiergotypic response and the response to the antigens targeted in the disease.

Basiliximab in association with tacrolimus and steroids in caucasian cadaveric renal transplanted patients: significant decrease in early acute rejection rate and hospitalization time

Safety and tolerability of basiliximab in renal transplantation have been proven in different immunosuppressive regimens. Few informations are available about the association of basiliximab with tacrolimus and steroids. We present a retrospective analysis performed in Caucasian cadaveric renal transplant recipients, comparing a basiliximab, tacrolimus and steroids induction protocol (GrA: 51 patients) with a tacrolimus and steroids protocol (GrB: 46 patients). A significant decrease in acute rejection rate in the first 3 months (2.0% vs. 17.4%; p < 0.01) was noted. Interestingly, the recipients in GrA were at major immunologic risk for the younger age of recipients, the greater number of mismatches and the higher rate of second transplants. The hospitalization times resulted reduced of 5.3 d in GrA vs. GrB (20.8 d vs. 26.1 d; p < 0.05). The adverse events patterns and profiles were similar in the two treatments groups. One patient in each group had a post-transplant lymphoprolipherative disorder. No significant difference was found in patient and graft survival. According to the results of this study, in a Caucasian adult population, basiliximab in association with tacrolimus and steroids is a safe and efficacious tool for acute rejection prevention and it is cost saving by reducing the hospitalization times.

Simulect induction facilitates neoral-based steroid-free immunosuppression in primary kidney transplant recipients

This study compares outcomes of kidney transplantation with two distinct induction protocols Basiliximab (Simulect) versus Muromonab (OTK 3) in the setting of cyclosporine (Neoral)-based immunosuppression. Postinduction protocols included either total prednisone avoidance or prednisone sparing versus standard prednisone dosing. Two hundred forty five adult patients receiving kidney transplantation between 1995 and 2000 were included in the study. Treatment in group 1 was OKT 3 + Neoral + adjunct + standard prednisone; group 2, Simulect + Neoral + adjunct + steroid sparing; group 3, Simulect + Neoral + adjunct + no prednisone. The demographics between all groups were similar. The mean (+/- SD) trough cyclosporine levels at 1 month were 276 +/- 128 versus 291 +/- 180 versus 398 +/- 365 (P=.020); at 3 months were 261 +/- 120 versus 280 +/- 152 versus 399 +/- 408 (P=.32); at 12 month were 235 +/- 144 versus 245 +/- 154 versus 234 +/- 132 (P=.96). Creatinine clearance at 1 month was 59 +/- 24 versus 58 +/- 18 versus 47 +/- 23 mL/min (P=.004); at 3 months was 66 +/- 28 versus 62 +/- 22 versus 53 +/- 25 mL/min (P=.007); at 12 months was 68 +/- 38 versus 65 +/- 22 versus 64 +/- 29 mL/min (P=.556). Serum creatinine at 1 month was 1.8 +/- 0.9 versus 1.6 +/- 1.2 versus 2.8 +/- 2.21 mg/dL (P=.005); at 3 months was 1.7 +/- 0.6 versus 1.9 +/- 1.0 versus 2.3 +/- 1.3 mg/dL (P=.007); at 12 months was 1.9 +/- 1.3 versus 2.1 +/- 1.0 versus 2.3 +/- 1.7 mg/dL (P=.179). The incidence of acute rejection within 1 year in the respective groups were 28% versus 15% versus 16%. Therefore, we conclude that using Simulect in transplant recipients results in long-term patient and graft survival similar to those achieved with OKT 3. The use of Simulect resulted in significant reduction in clinical rejection incidence within the first year regardless of steroid use. Thus, the use of Simulect allows complete steroid avoidance in Neoral-based immunosuppression regimen.

Islet transplantation in patients with diabetes mellitus: choice of immunosuppression

Islet transplantation offers patients with type 1 diabetes mellitus freedom from long-term insulin therapy and a degree of metabolic control that is far superior to injected insulin. The hope is that near-perfect glucose control sustained over time will prevent progression of secondary diabetic complications. The selection of optimal immunosuppressive agents for islet transplantation has been a formidable challenge, given the need to overcome both autoimmune and alloimmune barriers, as well as the potential toxicity of immunosuppressive agents on transplanted islets. Early strategies relied on protocols that had proven success in solid organ transplantation and consisted of azathioprine, cyclosporine and corticosteroids. Under these protocols, fewer than 10% of patients were able to achieve insulin independence. The development of the 'Edmonton Protocol' dramatically transformed clinical outcomes in islet transplantation in recent years through the introduction of a more potent, less diabetogenic, and corticosteroid-free immunosuppressive regimen consisting of sirolimus, low-dose tacrolimus, and induction anti-interleukin-2 receptor antibody. While insulin independence rates under this protocol have been highly successful, patients must be maintained on lifelong immunosuppression. While the risk of malignancy, post-transplant lymphoma and sepsis have been low and diminishing in transplanted patients to date, fears of these complications and a host of drug-related adverse effects have precluded broader application. Patients undergoing islet transplantation today must exchange insulin for chronic immunosuppressive therapy, and therefore the procedure can only be justified in patients with very unstable forms of diabetes, or in those with another solid organ allograft who already endure the risks of immunosuppression. Advances in more specific and less toxic immunosuppressive agents together with progress in better understanding the biology of diabetes will lead to more suitable strategies to control both alloimmune and recurrent autoimmune reactions. These protocols, ultimately aimed at establishing tolerance, are an essential pre-requisite to move towards providing islet transplantation earlier in the course of the disease, including transplantation in children. This review addresses the evolution of immunosuppressive strategies in islet transplantation, and highlights some novel agents in pre-clinical development or in early clinical trials that may offer considerable promise in facilitating the induction of tolerance.

Drug immunosuppression therapy for adult heart transplantation. Part 1: immune response to allograft and mechanism of action of immunosuppressants

In the early days of transplantation, immunosuppression therapy was rather broad and nonspecific, mainly using high-dose corticosteroids and azathioprine. Thereafter we progressively narrowed the target of immunosuppressive strategy starting with polyclonal antibodies. The introduction of cyclosporine, OKT3, and tacrolimus further narrowed the target on the T-cell pathways. More recently mycophenolate mofetil progressively took the place of azathioprine with its higher lymphocyte specificity and sirolimus and interleukin-2 receptor antibodies were introduced. In this field in constant movement the aim is to find a drug or a regimen that provides optimal immunosuppression therapy with minimal side effects, in other words to find the right balance between overimmunosuppression and underimmunosuppression therapy. This review is divided into two parts. The first part will provide a basic understanding of the immunologic response to allograft and explain how conventional and recently introduced immunosuppressive agents work. The second part will describe the clinical application of immunosuppressive drugs to provide practical information for those in charge of heart transplant recipients.

Interleukin 2 receptor antagonists for renal transplant recipients: a meta-analysis of randomized trials1

BACKGROUND

Interleukin 2 receptor antagonists (IL-2Ra) are increasingly used to treat renal transplant recipients. This study aims to systematically identify and summarize the effects of using IL-2Ra as induction immunosuppression, as an addition to standard therapy, or as an alternative to other antibody therapy.

METHODS

Databases, reference lists, and abstracts of conference proceedings were searched extensively to identify relevant randomized controlled trials in all languages. Data were synthesized using the random effects model. Results are expressed as relative risk (RR), with 95% confidence intervals (CI).

RESULTS

A total of 117 reports from 38 trials involving 4,893 participants were included. When IL-2Ra were compared with placebo (17 trials; 2,786 patients), graft loss was not significantly different at 1 year (14 trials: RR 0.84; CI 0.64-1.10) or 3 years (4 trials: RR 1.08; CI 0.71-1.64). Acute rejection was significantly reduced at 6 months (12 trials: RR 0.66; CI 0.59-0.74) and at 1 year (10 trials: RR 0.67; CI 0.60-0.75). At 1 year, cytomegalovirus infection (7 trials: RR 0.82; CI 0.65-1.03) and malignancy (9 trials: RR 0.67; CI 0.33-1.36) were not significantly different. When IL-2Ra were compared with other antibody therapy, no significant differences in treatment effects were demonstrated, but IL-2Ra had significantly fewer side effects.

CONCLUSIONS

Given a 40% risk of rejection, seven patients would need treatment with IL-2Ra in addition to standard therapy, to prevent one patient from undergoing rejection, with no definite improvement in graft or patient survival. There is no apparent difference between basiliximab and daclizumab.

Interleukin 2 receptor antagonists for kidney transplant recipients

BACKGROUND

Interleukin 2 receptor antagonists (IL2Ra) are used as induction therapy for prophylaxis against acute rejection in kidney transplant recipients. Use of IL2Ra has increased steadily, with 38% of new kidney transplant recipients in the United States, and 23% in Australasia receiving IL2Ra in 2002.

OBJECTIVES

This study aims to systematically identify and summarise the effects of using an IL2Ra, as an addition to standard therapy, or as an alternative to other antibody therapy.

SEARCH STRATEGY

The Cochrane Renal Group's specialised register (June 2003), the Cochrane Controlled Trials Register (in The Cochrane Library issue 3, 2002), MEDLINE (1966-November 2002) and EMBASE (1980-November 2002). Reference lists and abstracts of conference proceedings and scientific meetings were hand-searched from 1998-2003. Trial groups, authors of included reports and drug manufacturers were contacted.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing IL2Ra to placebo, no treatment, other IL2Ra or other antibody therapy.

DATA COLLECTION AND ANALYSIS

Data was extracted and quality assessed independently by two reviewers, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) with 95% confidence intervals (CI).

MAIN RESULTS

One hundred and seventeen reports from 38 trials involving 4893 participants were included. Where IL2Ra were compared with placebo (17 trials; 2786 patients), graft loss was not significantly different at one (RR 0.83, 95% CI 0.66 to 1.04) or three years (RR 0.88, 95% CI 0.64 to 1.22). Acute rejection (AR) was significantly reduced at six months (RR 0.66, 95% CI 0.59 to 0.74) and at one year (RR 0.67, 95% CI 0.60 to 0.75). At one year, cytomegalovirus (CMV) infection (RR 0.82, 95% CI 0.65 to 1.03) and malignancy (RR 0.67, 95% CI 0.33 to 1.36) were not significantly different. Where IL2Ra were compared with other antibody therapy no significant differences in treatment effects were demonstrated, but adverse effects strongly favoured IL2Ra.

REVIEWER'S CONCLUSIONS

Given a 40% risk of rejection, seven patients would need treatment with IL2Ra to prevent one patient having rejection, with no definite improvement in graft or patient survival. There is no apparent difference between basiliximab and daclizumab. IL2Ra are as effective as other antibody therapies and with significantly fewer side effects

Prophylactic use of the IL-2 receptor-specific monoclonal antibody LO-Tact-1 with cyclosporin A and steroids in renal transplantation

LO-Tact-1 is a rat anti-human monoclonal antibody which is directed to the 55-kDa alpha-chain of the interleukin 2 (IL2) receptor. We conducted a pilot trial in 15 first-time cadaveric renal transplant patients undergoing for immunosuppression a 14-day course of LO-Tact-1 (10 mg i.v. daily) together with cyclosporine, low dose steroids (0.5 mg/kg) and azathioprine. Results showed a good immunosuppressive effect, as measured by the similar incidence of acute rejection episodes (0.6 per patient) when compared with 20 patients treated during the same period with our standard quadruple prophylactic combination with higher initial doses of steroids (2 mg/kg) and antilymphocyte globulin (ALG) instead of LO-Tact-1 (0.4 per patient). At 2 years post-transplant, graft survival was 93%, and only 1 patient lost his kidney by rejection. No local or general adverse effect of antibody administration was encountered, and haematological changes remained of minor importance. Local bacterial infection was observed in 3 patients, but viral diseases (including cytomegalovirus, CMV) remained exceptional. In contrast, severe clinical CMV infections occurred in 3 patients (15%) treated by ALG. Nine of 15 patients developed rat-specific antibodies, but only 4 before the completion of LO-Tact-1 treatment, without any correlation with the further development of acute rejection. Patients who suffered rejection had lower LO-Tact-1 levels and higher soluble IL2 receptor levels during the period of infusion, suggesting the crucial importance of pharmacokinetic monitoring to adjust individual doses.

Basiliximab: efficacy and tolerability in adults and children

An open, single arm, prospective clinical trial to assess the efficacy and safety of basiliximab (Simulect) combined with cyclosporine microemulsion (Neoral), steroids, and azathioprine was performed in four centers in Chile, two adult and two pediatric. The 23 patients who were enrolled were followed for 12 months. There were four acute rejection episodes (three adults and one child) and three graft losses (two adults and one child) during the study. Renal function in both adult and pediatric patients at 6 and 12 months was good. Basiliximab was well tolerated. The incidence of infections was low, with only one CMV infection. There were no deaths.

CONCLUSIONS

The incidence of acute rejection episodes among renal allograft recipients treated with basiliximab is low, showing that the drug is well tolerated. In particular the number of CMV infections is extremely low.

Identification of the antibodies involved in B-cell crossmatch positivity in renal transplantation

BACKGROUND

The significance of a positive B-cell crossmatch (BCM) in kidney transplantation has always been controversial in the evaluation of its implications on graft survival and specificity of the antibodies involved.

METHODS

We have investigated the sera of 62 recipients of a kidney allograft transplanted across a positive BCM (T negative) for the presence of autoantibodies and anti-human leukocyte antigen (HLA) class I and II antibodies, using a combination of lymphocytotoxicity, enzyme-linked immunosorbent assay (ELISA), and flow cytometry tests. The controls were the 930 patients transplanted over the same period of time with a negative T and BCM.

RESULTS

Autoantibodies were detected in 16%, and donor specific anti-HLA class II antibodies, mainly DQ, in 23% of the patients. None had antibodies against donor HLA class I. The target of the antibodies was not identified in 61%. Graft survival was comparable in the controls and in the +BCM patients, with nondonor-specific HLA reactivity. Patients with donor-specific anti-HLA class II antibodies had lower early graft survival and a higher incidence of vascular rejection. However, long-term allograft survival was similar to that of the other groups.

CONCLUSION

These data suggest that in 77% of the patients, BCM positivity was not related with anti-HLA antibodies, and, in this case, graft survival was similar to that of the -BCM controls. In a minority of patients, anti-HLA class II antibodies were responsible for the +BCM, and their presence was associated with lower early, but not long-term, graft survival. Consequently, a +BCM should not systematically contraindicate kidney transplantation.

Randomized double-blind study of immunoprophylaxis with basiliximab, a chimeric anti-interleukin-2 receptor monoclonal antibody, in combination with mycophenolate mofetil-containing triple therapy in renal transplantation

BACKGROUND

Acute rejection remains a major problem in renal transplantation. Immunoprophylaxis with basiliximab (Simulect) has achieved significant reductions in acute rejection episodes in renal allograft recipients receiving dual immunosuppression. This study explored the tolerability and cumulative benefit of combining basiliximab with triple-drug therapy-cyclosporine (USP Modified, Neoral), mycophenolate mofetil, and steroids.

METHODS

In a randomized, double-blind, placebo-controlled, multicenter study, 123 kidney transplant recipients received either basiliximab at 20 mg before transplantation (day 0) and 20 mg on day 4 (n=59), or placebo (n=64). All received triple-drug immunosuppression and were followed for 6 months.

RESULTS

Tolerability of basiliximab was equivalent to placebo, with no increase in serious adverse events, infection, malignancy, or posttransplant lymphoproliferative disorder. At 6 months, there were trends in favor of basiliximab over placebo in the incidences of first biopsy-confirmed acute rejection (15.3% vs. 26.6%, P=NS) and of acute rejection treated with antibody (5.1% vs. 15.6%, P=NS). Kaplan-Meier estimates at 4 weeks and 6 months were significantly in favor of basiliximab treatment for first acute rejection, biopsy-confirmed rejection, rejection episodes treated with antibody therapy, and treatment failure. Renal function improved more rapidly in the basiliximab group, with mean creatinine clearance at week 2 being 54.7 mL/min versus 43.2 mL/min for placebo (P=0.034). At 12 months, patient survival was 100% in both groups; graft survival was 94.9% with basiliximab and 92.2% with placebo.

CONCLUSIONS

Basiliximab immunoprophylaxis is safe, well tolerated, and shows a trend toward reduction in number of acute rejection episodes in renal transplant patients receiving cyclosporine, mycophenolate mofetil, and steroids.