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Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Conditional marketing authorization (CMA) facilitates timely access to new drugs for illnesses with unmet clinical needs, such as late graft failure after kidney transplantation. Late graft failure remains a serious, burdensome, and life-threatening condition for recipients. This article has been developed from content prepared by members of a working group within the European Society for Organ Transplantation (ESOT) for a Broad Scientific Advice request, submitted by ESOT to the European Medicines Agency (EMA), and reviewed by the EMA in 2020. The article presents the rationale for using surrogate endpoints in clinical trials aiming at improving late graft failure rates, to enable novel kidney transplantation therapies to be considered for CMA and improve access to medicines. The paper also provides background data to illustrate the relationship between primary and surrogate endpoints. Developing surrogate endpoints and a CMA strategy could be particularly beneficial for studies where the use of primary endpoints would yield insufficient statistical power or insufficient indication of long-term benefit following transplantation., Competing Interests: LH reports speaker fees from Astellas, consultancy and research support from Chiesi, consultancy for Novartis, and research support from Sandoz. RO has received grants/research support from Amgen, Astellas, and Chiesi; and speakers' bureaux/honoraria from Amgen, Astellas, Chiesi, Hansa, Neovii, Novartis, and Teva. SS has received grants/research support from Bridge to Life, Chiesi, Neovii, Novartis, Organ Recovery Systems, and Sandoz; speakers' bureaux/honoraria from Astellas, BMS, Chiesi, Novartis, OrganOx, and Sanofi; and consulting fees from Astellas, Atara, Merck, NefroHealth, Novartis, Sandoz, and Teva. DG reports consultancy agreements and scientific boards for AstraZeneca, BMS, Hansa, and Sanofi. UH has received grants/research support from Baxter, Chiesi, and Neovii; speakers' bureaux/honoraria from Chiesi and Hansa; and consulting fees from Astellas, Hansa, Neovii, Novartis, and Teva. IJ's institution has received speaker's fees from XVIVO Perfusion. MR has received lecture fees from Astellas and Chiesi; and research grant support (paid to institution) from Astellas and Chiesi for investigator-initiated studies. SS has received grants/research support from Bridge to Life, Chiesi, Neovii, Novartis, Organ Recovery Systems, and Sandoz; speakers' bureaux/honoraria from Astellas, BMS, Chiesi, Novartis, OrganOx, and Sanofi; and consulting fees from Astellas, Atara, Merck, NefroHealth, Novartis, Sandoz, and Teva. KB has received honoraria and/or research funding from Alexion, Astellas, Bristol Myers Squibb, Chiesi, Fresenius, Hansa, Hexal, Merck, Novartis, Otsuka, Pfizer, Roche, Sandoz, Siemens, and Veloxis. The remaining authors declare that the work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Naesens, Loupy, Hilbrands, Oberbauer, Bellini, Glotz, Grinyó, Heemann, Jochmans, Pengel, Reinders, Schneeberger and Budde.)

The future clinical application of animal-to-human transplantation (xenotransplantation) is of importance to society as a whole. Favourable preclinical data relevant to cell, tissue and solid organ xenotransplants have been obtained from many animal models utilizing genetic engineering and protocols of pathogen-free husbandry. Findings have reached a tipping point, and xenotransplantation of solid organs is approaching clinical evaluation, the process of which now requires close deliberation. Such discussions include considering when there is sufficient evidence from preclinical animal studies to start first-in-human xenotransplantation trials. The present article is based on evidence and opinions formulated by members of the European Society for Organ Transplantation who are involved in the Transplantation Learning Journey project. The article includes a brief overview of preclinical concepts and biology of solid organ xenotransplantation, discusses the selection of candidates for first-in-human studies and considers requirements for study design and conduct. In addition, the paper emphasizes the need for a regulatory framework for xenotransplantation of solid organs and the essential requirement for input from public and patient stakeholders., (© 2021 Steunstichting ESOT. Published by John Wiley & Sons Ltd.)

Kidney paired donation (KPD) is a valuable tool to overcome immunological barriers in living donor transplantation. While small national registries encounter difficulties in finding compatible matches, multi-national KPD may be a useful strategy to facilitate transplantation. The Czech (Prague) and Austrian (Vienna) KPD programs, both initiated in 2011, were merged in 2015. A bi-national algorithm allowed for ABO- and low-level HLA antibody-incompatible exchanges, including the option of altruistic donor-initiated domino chains. Between 2011 and 2019, 222 recipients and their incompatible donors were registered. Of those, 95.7% (Prague) and 67.9% (Vienna) entered into KPD registries, and 81 patients received a transplant (95% 3-year graft survival). Inclusion of ABO-incompatible pairs in the Czech program contributed to higher KPD transplant rates (42.6% vs. 23.6% in Austria). After 2015 (11 bi-national match runs), the median pool size increased to 18 pairs, yielding 33 transplants (8 via cross-border exchanges). While matching rates doubled in Austria (from 9.1% to 18.8%), rates decreased in the Czech program, partly due to implementation of more stringent HLA antibody thresholds. Our results demonstrate the feasibility of merging small national KPD programs to increase pool sizes and may encourage the implementation of multi-national registries to expand the full potential of KPD., (© 2020 Steunstichting ESOT. Published by John Wiley & Sons Ltd.)

Although separate prediction models for donors and recipients were previously published, we identified a need to predict outcomes of donor/recipient simultaneously, as they are clearly not independent of each other. We used characteristics from transplantations performed at the Oslo University Hospital from 1854 live donors and from 837 recipients of a live donor kidney transplant to derive Cox models for predicting donor mortality up to 20 years, and recipient death, and graft loss up to 10 years. The models were developed using the multivariable fractional polynomials algorithm optimizing Akaike's information criterion, and optimism-corrected performance was assessed. Age, year of donation, smoking status, cholesterol and creatinine were selected to predict donor mortality (C-statistic of 0.81). Linear predictors for donor mortality served as summary of donor prognosis in recipient models. Age, sex, year of transplantation, dialysis vintage, primary renal disease, cerebrovascular disease, peripheral vascular disease and HLA mismatch were selected to predict recipient mortality (C-statistic of 0.77). Age, dialysis vintage, linear predictor of donor mortality, HLA mismatch, peripheral vascular disease and heart disease were selected to predict graft loss (C-statistic of 0.66). Our prediction models inform decision-making at the time of transplant counselling and are implemented as online calculators., (© 2020 The Authors. Transplant International published by John Wiley & Sons Ltd on behalf of Steunstichting ESOT.)

Most research in transplant medicine includes statistical analysis of observed data. Too often authors solely rely on P-values derived by statistical tests to answer their research questions. A P-value smaller than 0.05 is typically used to declare "statistical significance" and hence, "proves" that, for example, an intervention has an effect on the outcome of interest. Especially in observational studies, such an approach is highly problematic and can lead to false conclusions. Instead, adequate estimates of the observed size of the effect, for example, expressed as the risk difference, the relative risk or the hazard ratio, should be reported. These effect size measures have to be accompanied with an estimate of their precision, like a 95% confidence interval. Such a duo of effect size measure and confidence interval can then be used to answer the important question of clinical relevance., (© 2019 The Authors. Transplant International published by John Wiley & Sons Ltd on behalf of Steunstichting ESOT.)

Recognition of non-self structures on donor cells represents the main immunological barrier in solid organ transplantation. The human leukocyte antigens (HLA) are considered the most important non-self (allo)antigens in transplantation. Long-term graft attrition is mainly caused by the formation of alloreactive antibodies that are directed against non-self structures (i.e., epitopes) on cell surface proteins. Recently published data provided evidence for a similar importance of non-HLA mismatches between donors and recipients in acute rejection as well as long-term kidney allograft survival. These data suggest a broader concept of immunological non-self that goes beyond HLA incompatibility and expands the current concept of polymorphic non-self epitopes on cell surface molecules from HLA to non-HLA targets. Amino acid substitutions caused by single nucleotide variants in protein-coding genes or complete loss of gene expression represent the basis for polymorphic residues in both HLA and non-HLA molecules. To better understand these novel insights in non-HLA alloimmunity, we will first review basic principles of the alloimmune response with a focus on the HLA epitope concept in donor-specific antibody formation before discussing key publications on non-HLA antibodies., (© 2019 The Authors. Transplant International published by John Wiley & Sons Ltd on behalf of Steunstichting ESOT.)

Renal transplantation reduces the dramatically elevated risk of cardiovascular death in dialysis patients. We previously showed that left atrial diameter before transplantation predicts cardiovascular and overall mortality. Now, we investigated the association of changes in cardiac morphology after transplantation and mortality. We retrospectively analyzed data from the Austrian transplant repository using multivariable Cox and competing risk models and multivariable logistic regression for the prediction of changes in cardiac morphology. We identified 414 patients with a median follow-up of 8 years and observed a significant progression of mean diameter of left atrium (LA), right atrium and right ventricle and a significant regression of left ventricle. Complete case analysis of 243 patients with a regression of initially enlarged LA diameter had a significantly lower risk of adjusted overall and cardiovascular mortality; hazard ratio (HR 0.45, 95% CI 0.30-0.69, P < 0.001, 124 deaths), and HR of 0.43 [95% CI 0.21-0.92, P = 0.029, 48 cardiovascular (CV) deaths], respectively. Only age at transplantation was significantly associated with regression of LA (OR 0.75, 95% CI 0.60-0.93, P = 0.007). Patients with regression of LA after kidney transplantation exhibited a lower overall and CV mortality risk. Besides age, peritoneal dialysis and antihypertensive therapy were mediators of LA regression., (© 2018 The Authors. Transplant International published by John Wiley & Sons Ltd on behalf of Steunstichting ESOT.)

This review focuses on the emerging concept of genomewide genetic variation as basis of an alloimmune response. Chronic antibody-mediated rejection is the major cause of long-term graft loss and growing evidence supports the clinical relevance of HLA but also non-HLA related alloimmune responses. Several polymorphic gene products have been identified as minor histocompatibility antigens. The formation of donor-specific alloantibodies is driven by indirect allorecognition of donor-derived peptides representing a form of conventional T-cell response. With the availability of high-throughput sequencing and genotyping technologies, the identification of genomewide genetic variation and thus mismatches between organ donors and graft recipients has become feasible. First clinical data linking genetic polymorphism and clinical outcome have been published and larger studies are currently under way. Protein arrays have successfully been used to identify a large variety of non-HLA antibodies in kidney transplant recipients and the availability of customizable peptide arrays made screening for linear epitopes on an individual patient level feasible. This review provides a summary of the recent findings in histocompatibility matching in the field of solid organ transplantation and complements it with a clear workflow for assessing the impact of genetic differences in protein-coding genes in solid organ transplantation., (© 2017 Steunstichting ESOT.)

Immortal time bias is a problem arising from methodologically wrong analyses of time-dependent events in survival analyses. We illustrate the problem by analysis of a kidney transplantation study. Following patients from transplantation to death, groups defined by the occurrence or nonoccurrence of graft failure during follow-up seemingly had equal overall mortality. Such naive analysis assumes that patients were assigned to the two groups at time of transplantation, which actually are a consequence of occurrence of a time-dependent event later during follow-up. We introduce landmark analysis as the method of choice to avoid immortal time bias. Landmark analysis splits the follow-up time at a common, prespecified time point, the so-called landmark. Groups are then defined by time-dependent events having occurred before the landmark, and outcome events are only considered if occurring after the landmark. Landmark analysis can be easily implemented with common statistical software. In our kidney transplantation example, landmark analyses with landmarks set at 30 and 60 months clearly identified graft failure as a risk factor for overall mortality. We give further typical examples from transplantation research and discuss strengths and limitations of landmark analysis and other methods to address immortal time bias such as Cox regression with time-dependent covariables., (© 2017 Steunstichting ESOT.)

ADHERE was a randomized, open-label, Phase IV study comparing renal function at Week 52 postkidney transplant, in patients who received prolonged-release tacrolimus-based immunosuppressive regimens. On Days 0-27, patients received prolonged-release tacrolimus (initially 0.2 mg/kg/day), corticosteroids, and mycophenolate mofetil (MMF). Patients were randomized on Day 28 to receive either prolonged-release tacrolimus plus MMF (Arm 1) or prolonged-release tacrolimus (≥25% dose reduction on Day 42) plus sirolimus (Arm 2). The primary endpoint was glomerular filtration rate by iohexol clearance (mGFR) at Week 52. Secondary endpoints included eGFR, creatinine clearance (CrCl), efficacy failure (patient withdrawal or graft loss), and patient/graft survival. Tolerability was analyzed. The full-analysis set comprised 569 patients (Arm 1: 287; Arm 2: 282). Week 52 mean mGFR was similar in Arm 1 versus Arm 2 (40.73 vs. 41.75 ml/min/1.73 m 2 ; P = 0.405), as were the secondary endpoints, except composite efficacy failure, which was higher in Arm 2 versus 1 (18.2% vs. 11.5%; P = 0.002) owing to a higher postrandomization withdrawal rate due to adverse events (AEs) (14.4% vs. 5.2%). Results from this study show comparable renal function between arms at Week 52, with fewer AEs leading to study discontinuation with prolonged-release tacrolimus plus MMF (Arm 1) versus lower dose prolonged-release tacrolimus plus sirolimus (Arm 2)., (© 2016 The Authors. Transplant International published by John Wiley & Sons Ltd on behalf of Steunstichting ESOT.)

Anemia is a highly prevalent disorder in recipients of renal allografts. Despite its frequent occurrence, there is still uncertainty with regard to treatment targets and treatment options. This includes questions on appropriate iron management, the choice and dosage of erythropoietin stimulating agents, criteria for the timing of treatment initiation and the targeted hemoglobin values. The review summarizes available data on recent therapeutic strategies for post transplant anemia, as well as for post transplant erythrocytosis, another hematological disorder, that has decreased in recent years., (© 2012 The Authors. Transplant International © 2012 European Society for Organ Transplantation.)

Anemia is a common problem after renal transplantation. Therefore, the patients are treated with erythropoietin stimulating agents (ESAs). The varying response to treatment contributes to hemoglobin variability, which might be associated with mortality. We conducted a retrospective cohort study of first kidney allograft recipients between 1990 and 2008 represented in the Austrian Transplant Registry. We included 1441 patients of whom 683 received ESAs at any time after transplantation. Cox regression with cubic splines and linear estimates and the purposeful selection algorithm of covariables were used. The measure of variability was the moving standard deviation computed at three monthly intervals for the entire graft life. The hazard ratio (HR) of mortality and graft loss in the spline models increased with hemoglobin variability. The linear HR for mortality was 2.35 (95% confidence interval 1.75-3.17, P<0.001) and functional graft loss 2.45 (1.76-3.40, P<0.001). In an adjusted Cox model (ESA use, hemoglobin, age, diabetes, days on dialysis, eGFR, biopsy confirmed acute rejection and year of transplantation), hemoglobin variability was associated with mortality (HR: 2.11; 1.51-2.94; P<0.001). No association with functional graft loss could be detected (HR: 1.34; 0.93-1.93; P=0.121). These findings suggest that hemoglobin variability is associated with mortality of renal allograft recipients., (© 2012 The Authors. Transplant International © 2012 European Society for Organ Transplantation.)

The increased use of older and/or marginal donor organs in liver transplantation over the last decade calls for strategies to minimize ischaemic reperfusion (I/R) injury to prevent early graft failure. Tacrolimus, a very potent and effective calcineurin inhibitor, was selected because of its ability to ameliorate I/R injury. A randomized, blinded, controlled single-centre trial of 26 liver transplant recipients was performed between February 2008 and December 2009. Donor organs were randomized to be perfused intraportally during liver transplantation with 1.5 l 5% albumin infusion containing either 20 ng/ml tacrolimus or placebo. The primary end point was liver function as assessed by aspartate transaminase (AST) or alanine transaminase (ALT) levels 6 days after transplantation. Treatment effectiveness was tested by transcriptome-wide analysis of biopsies. There was no difference in the primary end point, i.e. AST (IU/l) and ALT (IU/l) at day 6 after transplantation between groups. Furthermore, choleastatic parameters as well as parameters of liver synthesis were not different between groups. However, tacrolimus treatment suppressed inflammation and immune response in the transplanted liver on a genome-wide basis. Intrahepatic administration of tacrolimus did not result in a reduction of AST and ALT within the first week after transplantation., (© 2011 The Authors. Transplant International © 2011 European Society for Organ Transplantation.)

The aim of this study was to assess gene expression levels of four biomarker candidates [lipocalin 2 (LCN2), the kidney injury molecule 1 (HAVCR1), netrin 1, and the cysteine-rich, angiogenic inducer, 61] in the tubulointerstitial and the glomerular compartment of zero-hour kidney biopsies in order to predict developing delayed graft function (DGF). Thirty-four needle kidney biopsy samples of deceased donors were manually microdissected. Relative gene expression levels were determined by real-time RT-PCR. For the validation of the biomarker candidates, we calculated a mixed model comparing kidneys with DGF, primary function and control samples from the healthy parts of tumor nephrectomies. Significant biomarker candidates were analyzed together with donor age in multivariable regression models to determine the prognostic value. Expression levels of LCN2 and HAVCR1 in the tubulointerstitium were significantly upregulated in the DGF group (LCN2: fold change = 3.78, P = 0.031 and HAVCR1: fold change = 3.44, P = 0.010). Odds ratios of both genes could not reach significance in the multivariable model together with donor age. The area under the curve of the receiver operating characteristic ranges between 0.75 and 0.83. LCN2 and HAVCR1 gene expression levels in zero-hour biopsies show potential to act as early biomarkers for DGF., (© 2010 The Authors. Transplant International © 2010 European Society for Organ Transplantation.)

Tuberous sclerosis complex (TSC) is caused by constitutively activated mammalian target of rapamycin (mTOR) resulting in nonmalignant tumours of several organs and consequently renal failure. Recent reports suggest a possible beneficial role of the mTOR-inhibitor (mTOR-I) sirolimus for TSC; however, safety and efficiency of sirolimus in TSC patients after renal transplantation, both as primary immunosuppressant as well as anti-proliferative agent, are still undefined. Moreover, it is currently unknown whether the TSC mutation affects the primary immune response in these patients. In this article, we report on three TSC patients after renal transplantation who have been converted from a calcineurin-inhibitor (CNI)-based immunosuppression to sirolimus. During 2 years of follow-up, renal allograft function was stable or even improved, and no significant sirolimus-associated side-effects were noted. Beneficial effects of sirolimus against TSC were detected in the skin, along with improved spirometric measurements and an arrest of astrocytoma progression. We show that the inflammatory immune response was significantly altered in TSC patients as compared with controls and sirolimus potently affected both inflammatory cytokine production and vascular endothelial growth factor levels in these patients. Larger studies are warranted to further examine the relationship between clinical parameters and the molecular response to mTOR-inhibition in TSC patients after renal transplantation.

Summary We recently showed in a randomized control trial that steroid pretreatment of the deceased organ donor suppressed inflammation in the transplant organ but did not reduce the rate or duration of delayed graft function (DGF). This study sought to elucidate such of those factors that caused DGF in the steroid-treated subjects. Genome-wide gene expression profiles were used from 20 steroid-pretreated donor-organs and were analyzed on the level of regulatory protein-protein interaction networks. Significance analysis of microarrays (SAM) yielded 63 significantly down-regulated sequences associated with DGF that could be functionally categorized according to Protein ANalysis THrough Evolutionary Relationships ontologies into two main biologic processes: transport (P < 0.001) and metabolism (P < 0.001). The identified genes suggest hypoxia as the cause of DGF, which cannot be counterbalanced by steroid treatment. Our data showed that molecular pathways affected by ischemia such as transport and metabolism are associated with DGF. Potential interventional targeted therapy based on these findings includes peroxisome proliferator-activated receptor agonists or caspase inhibitors.

All immunosuppressive medications require a learning curve that enables clinicians to improve the therapeutic index of agents. Mammalian target of rapamycin (mTOR) inhibitors are potentially a less nephrotoxic form of immunosuppression than calcineurin inhibitors (CNIs) that has been used in kidney transplant recipients for more than two decades. This drug class has a novel immunosuppressive action, probably mediated in part through inhibition of growth receptor signaling mechanisms. In addition, it has a unique drug toxicity, which is partially dose-related. This medication class also possesses antiproliferative activity, which may be useful in-post-transplant patients with increased atherosclerotic and malignancy risks. mTOR inhibitors have been utilized for de novo immunosuppression with CNIs, corticosteroids, and antimetabolites. mTOR inhibitors also have been used as CNI-sparing agents both early and late post-transplant. Much debate remains over how to best utilize mTOR inhibition in kidney transplantation.

Antithymocyte globuline (ATG) and OKT3 have been used for treatment of severe biopsy confirmed acute renal allograft rejection (BCAR). We report results on graft and patient survival including 399 subjects diagnosed with BCAR treated with either ATG or OKT3. Multivariable analyses including Banff scores were performed following three different strategies to account for confounding variables. Fifty per cent of subjects in the OKT3 group had a functioning graft 6.3 years after diagnosis of BCAR, but 74% of ATG patients' grafts were still functioning at that time point (log rank P = 0.006). Median actual graft survival was only 4.6 years in the OKT3 subjects, but 9.5 years for ATG-treated patients (log rank P = 0.004). Multivariable analysis revealed that the risk for functional graft loss was significantly elevated in the OKT3 compared to ATG patients (HR = 1.79, 95% CI 1.06-3.02, P = 0.029). The risk for actual graft loss, counting death as event, was also significantly elevated in the OKT3 patients (HR = 1.73, 95% CI 1.09-2.74, P = 0.019). The hazard of death was not different between the groups (HR = 1.55, 95% CI 0.87-2.77, P = 0.137). These data suggest that rejecting renal allografts treated with ATG exhibit longer graft survival than OKT3 treated transplant kidneys. Causal inference, however, cannot be drawn from this associational study.

A nonquantitative summary of the current evidence suggests that calcineurin inhibitor (CNI) minimization and also CNI-free protocols are safe and efficient when used after the initial 3 months post-transplantation. In fact, the largest study so far showed that low-dose CNI in combination with mycophenolate mofetil (MMF) and steroids performed better than standard dose cyclosporine A (CsA). If CsA is used in combination with a mammalian target of rapamycin-Inhibitor (mTOR-I) considerable dose reduction of both drugs is required. A better choice than using both drug groups in lower doses together may be the withdrawal of CsA from this combination after 3-12 months. Later withdrawals or conversions to an mTOR-I failed to show additional benefit in terms of graft function or survival but caused less post-transplant malignancies. With improved short- and medium-term outcomes, this entity will become more of an issue. In fact, in some areas of the world, nowadays malignancies are the leading cause of death.

Post-transplant renal osteopathy (ROP) remains a serious problem, which contributes to substantial long-term morbidity of the graft recipients. Bone loss is most pronounced during the first months after engraftment; concerning bone density development in long-term transplant recipients, controversial data exist. The clinical impact of ROP is a marked increase in fracture rate following kidney transplantation compared with both general population and patients on dialysis treatment. The following review will focus on post-transplant ROP and discuss its epidemiology, the clinical features, factors contributing to the pathogenesis of this complication, as well as the evaluation, prevention and treatment options available for kidney allograft recipients.

This study compared 3-year health-related quality-of-life (HRQL) outcomes of sirolimus (SRL)-treated kidney transplant patients after elimination of cyclosporine (CsA) with patients continuing on a combined CsA and SRL regimen. A randomized, multi-country, open-label, clinical trial was performed. 430 kidney transplant patients were randomly assigned to SRL+corticosteroids (ST) (n = 215) or SRL+CsA+ST (n = 215) therapy after an initial 3-month period of combined SRL+CsA+ST treatment. HRQL was measured using the Kidney Transplant Questionnaire (KTQ) and the SF-36 Health Survey at month 3 (time of randomization) and months 12, 24, and 36 post-transplantation. Mixed-model ancova was used to evaluate treatment differences in HRQL outcomes. HRQL scores were available for 361 (86.4%) eligible study patients. Significant treatment-by-assessment time interactions, favoring SRL+ST, were found on KTQ fatigue (P = 0.0005), emotions (P = 0.028), and appearance scores (P = 0.006). Statistically significant treatment-by-assessment time interactions were observed for SF-36 vitality (P = 0.0001), general health (P = 0.011), social function (P = 0.020), and role-physical scores (P = 0.049). Vitality scores improved in the SRL+ST group (mean 3.5-point change) over 36 months, compared with decreases in the SRL+CsA+ST group (mean -3.2-point change). SRL-based therapy with early CsA-elimination results in fewer appearance-related problems, less fatigue, greater vitality, and improved general health status and social functioning compared with continuous SRL+CsA+ST treatment.

Sirolimus (SRL) has a concentration-related effect on hematopoiesis. In this study, 430 renal transplant recipients were randomized (1:1) 3 months post-transplantation to continue SRL-cyclosporine (CsA)-steroids (ST) or to have CsA withdrawn (SRL-ST). Over 5 years, on therapy calculated glomerular filtration rate (GFR), hematological indices, erythropoietin (EPO) use, and rates of mild, moderate, and severe anemia were determined. Longitudinal analyses using linear mixed models examined covariates predicting hemoglobin (Hgb) levels. Mean Hgb was significantly lower with SRL-ST at 6 months; but subsequently became significantly higher (at 2 years, 129 vs. 135 g/l, SRL-CsA-ST vs. SRL-ST, P<0.001). Mean corpuscular volume was low with both therapies, and significantly lower with SRL-ST. EPO use was similar in the two groups, approximately 30% during the first year and 10% thereafter. The incidence of anemia was significantly higher with SRL-CsA-ST>or=2 years. At year 5, only 39.1% of SRL-CsA-ST patients had normal Hgb vs. 68.5% of SRL-ST patients. GFR and recipient age as well as the interaction term x treatment time were significant covariates predicting Hgb. CsA withdrawal followed by SRL immunotherapy resulted in significantly less anemia than SRL-CsA-ST, despite twofold higher SRL exposure. This suggests that the improvement in GFR accompanying CsA withdrawal may mitigate the effect of SRL on hematopoiesis. (ClinicalTrials.gov number: NCT00428064).

The incidence of postischemic acute renal allograft failure (ARF) occurs in roughly 25% of cadaveric donor kidney recipients. This high rate remained virtually unchanged over the last decades despite modification in recipient management and modern immunosuppressive strategies. It has recently been shown that among other reasons, the systemic inflammation in the brain death cadaveric organ donor contributes to subsequent ARF in the recipient. This review focuses on the consequences of ischemia and reperfusion on the cellular level and offers potential solutions for the reduction of ARF. Genome-wide gene expression analysis together with sophisticated biostatistical analysis made it possible to identify several candidate gene products and proteins that may act as specific and sensitive biomarker for renal inflammation and ischemia. These markers may be very helpful in the clinical management of patients with a high a priori risk of subsequent ARF such as recipients of marginal donor kidneys. Ongoing clinical trials will evaluate whether immunosuppression of the cadaveric organ donor before organ harvest will have the potential to reduce inflammation in the transplant kidney and subsequently lead to a reduction in the rate of ARF.

Tolerance induction by mixed chimerism and costimulation blockade is a promising approach to avoid immunosuppression, but the molecular basis of tolerant T lymphocytes remains elusive. We investigated the genome-wide gene expression profile of murine T lymphocytes after tolerance induction by allogeneic bone marrow transplantation (BMT) and costimulatory blockade using the anti-CD40L antibody MR1. Molecular functions, biological processes, cellular locations, and coregulation of identified genes were determined. A total of 113 unique genes exhibited a significant differential expression between the lymphocytes of MR1-treated Tolerance (TOL) and untreated recipients Control (CTRL). The majority of genes upregulated in the TOL group are involved in several signal transduction cascades such as members of the MAPKKK cascade (IL6, Tob2, Stk39, and Dusp24). Other genes involved in lymphocyte differentiation and highly expressed in the TOL group are lymphotactin, the estrogen receptors (ERs) and the suppressor of cytokine signaling 7. Common transcription factors such as ER 1 alpha, GATA-binding protein 1, insulin promoter factor 1, and paired-related homeobox 2 could be identified in the promoter regions of upregulated genes in the TOL group. These data suggest that T lymphoctes of tolerant mice exhibit a distinct molecular expression profile, which needs to be evaluated in other experimental tolerance models to determine whether it is a universal signature of tolerance.

We report the 48-month results of a trial testing whether withdrawal of cyclosporine (CsA) from a sirolimus (SRL)-CsA-steroid (ST) regimen would impact renal allograft survival. Eligible patients receiving SRL-CsA-ST from transplantation were randomly assigned at 3 months to remain on triple therapy (SRL-CsA-ST, n = 215) or to have CsA withdrawn and SRL trough concentrations increased (SRL-ST, n = 215). SRL-ST therapy resulted in significantly better graft survival, either when including death with a functioning graft as an event (84.2% vs. 91.5%, P = 0.024) or when censoring it (90.6% vs. 96.1%, P = 0.026). Calculated glomerular filtration rate (43.8 vs. 58.3 ml/min, P < 0.001) and mean arterial blood pressure (101.3 vs. 97.1 mmHg, P = 0.047) were also improved with SRL-ST. Differences in the incidences of biopsy-proven acute rejection after randomization (6.5% vs. 10.2%, SRL-CsA-ST versus SRL-ST, respectively) and mortality (7.9% vs. 4.7%) were not significant. SRL-CsA-ST-treated patients had significantly higher incidences of adverse events generally associated with CsA, whereas those in the SRL-ST group experienced greater frequencies of events commonly related to higher trough levels of SRL. In conclusion, early withdrawal of CsA from a SRL-CsA-ST regimen rapidly improves renal function and ultimately results in better graft survival.