Use of 12-Month Renal Function and Baseline Clinical Factors to Predict Long-Term Graft Survival: Application to BENEFIT and BENEFIT-EXT Trials

The effects of lymphocele formation after living donor kidney transplantation on mid-term allograft function

BACKGROUND

Despite advances in kidney transplant surgery and immunosuppression, lymphoceles remain a frequent complication in the early postoperative period following kidney transplantation, often requiring reintervention. While long-term outcomes such as patient and allograft survival are well studied, the impact of lymphocele formation on mid-term allograft function remains unclear.

METHODS

This multicentric study included 711 recipients of living donor kidney transplants to investigate the impact of lymphocele formation on mid-term graft function. Outcomes assessed included estimated glomerular filtration rate (eGFR) at 12 months, eGFR slope, and both patient and allograft survival.

RESULTS

Lymphoceles were detected in 17.4% of the recipients, with a median volume of 129 ml, and 71.8% of these patients required intervention. Patients without lymphocele formation had a significantly higher median eGFR at 12 months (52.1 ml/min/1.73 m²) compared to those with lymphoceles (48.7 ml/min/1.73 m²). Additionally, patients with lymphocele formation demonstrated a steeper median eGFR slope (-2.3 ml/min/1.73 m²/year) than those without (-0.3 ml/min/1.73 m²/year). No significant difference was observed in the composite outcome of allograft survival and patient death between the two groups.

CONCLUSION

Lymphocele formation after living donor kidney transplantation is associated with a steeper decline in graft function. They may reflect a disturbed microvasculature and warrant closer control of cardiovascular risk factors and allograft monitoring of affected patients.

CLINICAL TRIAL DETAILS

Not applicable, the study is not a clinical trial.

The effect of intraoperative inosine infusion on transplant outcomes in deceased-donor kidney transplant recipients

OBJECTIVES

It is unknown when inosine was first employed as a renoprotective agent in the context of kidney transplantation procedures. However, there is no clinical evidence to support a protective role of inosine. The aim of this study was to investigate the effect of inosine on graft recovery.

PATIENTS AND METHODS

Data related to donors and recipients were retrieved from relevant records between 2015 and 2023. A total of 1138 kidney transplant cases were identified, including 1005 recipients who received a bolus of 1000 mg inosine and 133 recipients who did not receive inosine during transplantation surgery. The endpoints of the analysis included recipient recovery after transplantation as assessed by delayed graft function (DGF), peak estimated glomerular filtration rate (eGFR) after transplantation, and unfavorable graft function recovery.

RESULTS

Given the high dimensionality of the donor and recipient variables, propensity score weighting analyses were conducted. No significant differences in the risk of DGF (OR = 0.80 [0.52, 1.22], p = 0.301), unfavorable graft function recovery (OR = 0.95 [0.61, 1.51], p = 0.842) or peak eGFR after transplantation (β = 1.61 [-4.33, 7.56], p = 0.594) were observed between the inosine and no-inosine groups via overlap weighting analysis.

CONCLUSIONS

Intraoperative infusion of 1000 mg of inosine has no effect on graft recovery after kidney transplantation. Therefore, the practice of using inosine during kidney transplantation surgery is not supported by evidence.

Tricuspid Regurgitation and Kidney Transplant Recipient Outcomes

Rationale & Objective

Kidney function can be adversely affected by significant tricuspid regurgitation (TR) owing to effects on cardiac output and systemic venous congestion. However, the impact of significant TR on short- and long-term kidney function following a kidney transplant remains uncertain.

Study Design

Retrospective observational cohort.

Setting & Participants

Kidney transplant recipients from a single center between 2016 and 2019.

Exposure

Significant TR, defined by at least moderate regurgitation, on echocardiogram before kidney transplantation.

Outcomes

Primary end points included the estimated glomerular filtration rate (eGFR) at the following 3 time points: 2 weeks, 3 months, and 1 year after transplantation. Secondary end points included major adverse cardiac events including nonfatal myocardial infarction, all-cause mortality, and hospitalization owing to cardiovascular disease.

Analytical Approach

Propensity score matching was performed in 1:3 ratio between patients treated with significant TR and controls, within a caliper 0.05 standard deviation of the propensity score, to analyze for the primary end point.

Results

Among 557 kidney transplant recipients, 26 (5%) exhibited significant TR pretransplantation. According to propensity score matching analysis, with 1:3 ratio between 24 patients with significant TR and 72 controls, the presence of significant TR was associated with a lower eGFR posttransplantation. Specifically, the mean eGFR was 41.2 mL/min/1.73 m2 compared to 53.3 mL/min/1.73 m2 at 2 weeks (P < 0.01), 50.0 mL/min/1.73 m2 versus 60.3 mL/min/1.73 m2 at 3 months (P < 0.01), and 49.4 mL/min/1.73 m2 versus 61.2 mL/min/1.73 m2 at 1 year (P < 0.01). Delayed graft function was observed in 41.7% of the patients with significant TR compared to 12.5% of those without significant TR (P < 0.01). No patients with significant TR required dialysis after 1 year. 1-year major adverse cardiac events were nonsignificantly higher among patients with significant TR (20.8% vs 8.1%; P = 0.16).

Limitations

Retrospective design and relatively small TR population.

Conclusions

The presence of significant TR among kidney transplant recipients was associated with a lower eGFR at 2 weeks, 3 months, and 1 year following transplant, although all remained dialysis independent at 1 year.

Predicting Long-term Outcomes in Deceased Donor Kidney Transplant Recipients Using Three Short-term Graft Characteristics

Key Points

Delayed graft function is not an ideal measure of graft function, yet is used to assess risk in kidney transplantation. We propose a model that combines it with two other measures of 90-day graft function to identify recipients at incremental risk of inferior long-term outcomes.

Background

Delayed graft function (DGF) in kidney transplant recipients is used to determine graft prognosis, make organ utilization decisions, and as an important end point in clinical trials. However, DGF is not an ideal measure of graft function. We aimed to develop and validate a model that provides incremental risk assessment for inferior patient and graft outcomes.

Methods

We included adult kidney-only deceased donor transplant recipients from 1996 to 2016. In addition to DGF, two short-term measures were used to assess risk: renal function recovery <100% (attaining half the donor's eGFR) and recipient's 90-day eGFR <30. Recipients were at no, low, moderate, or high risk if they met zero, one, two, or all criteria, respectively. Cox proportional hazard models were used to assess the independent relationship between exposure and death-censored graft failure (DCGF) and mortality.

Results

Of the 792 eligible recipients, 24.5% experienced DGF, 40.5% had renal function recovery <100%, and 6.9% had eGFR <30. Over a median follow-up of 7.3 years, the rate of DCGF was 18.7% and mortality was 25.1%. When compared with recipients at no risk, those at low, moderate, and high risk were noted to have an increase in risk of DCGF (adjusted hazard ratio [aHR], 1.53; 95% confidence interval [CI], 1.03 to 2.27; aHR, 2.84; 95% CI, 1.68 to 4.79; aHR, 15.46; 95% CI, 8.04 to 29.71) and mortality (aHR, 1.16; 95% CI, 0.84 to 1.58; aHR, 1.85; 95% CI, 1.13 to 3.07; aHR, 2.66; 95% CI, 1.19 to 5.97). When using a hierarchical approach, each additional exposure predicted the risk of DCGF better than DGF alone and 100 random bootstrap replications supported the internal validity of the risk model. In an external validation cohort deemed to be at lower risk of DCGF, similar nonsignificant trends were noted.

Conclusion

We propose a risk model that provides an incremental assessment of recipients at higher risk of adverse long-term outcomes than DGF alone. This can help advance the field of risk assessment in transplantation and inform therapeutic decision making in patients at the highest spectrum of inferior outcomes.

Surrogate Endpoints for Late Kidney Transplantation Failure

In kidney transplant recipients, late graft failure is often multifactorial. In addition, primary endpoints in kidney transplantation studies seek to demonstrate the short-term efficacy and safety of clinical interventions. Although such endpoints might demonstrate short-term improvement in specific aspects of graft function or incidence of rejection, such findings do not automatically translate into meaningful long-term graft survival benefits. Combining many factors into a well-validated model is therefore more likely to predict long-term outcome and better reflect the complexity of late graft failure than using single endpoints. If conditional marketing authorization could be considered for therapies that aim to improve long-term outcomes following kidney transplantation, then the surrogate endpoint for graft failure in clinical trial settings needs clearer definition. This Consensus Report considers the potential benefits and drawbacks of several candidate surrogate endpoints (including estimated glomerular filtration rate, proteinuria, histological lesions, and donor-specific anti-human leukocyte antigen antibodies) and composite scoring systems. The content was created from information prepared by a working group within the European Society for Organ Transplantation (ESOT). The group submitted a Broad Scientific Advice request to the European Medicines Agency (EMA), June 2020: the request focused on clinical trial design and endpoints in kidney transplantation. Following discussion and refinement, the EMA made final recommendations to ESOT in December 2020 regarding the potential to use surrogate endpoints in clinical studies that aim to improving late graft failure.

Personalized Prediction of Kidney Function Decline and Network Analysis of the Risk Factors after Kidney Transplantation Using Nationwide Cohort Data

We developed a machine-learning-based model that could predict a decrease in one-year graft function after kidney transplantation, and investigated the risk factors of the decreased function. A total of 4317 cases were included from the Korean Organ Transplant Registry (2014−2019). An XGBoost model was trained to predict the recipient’s one-year estimated glomerular filtration rate (eGFR) below 45 mL/min/1.73 m2 using 112 pre- and peri-transplantation variables. The network of model factors was drawn using inter-factor partial correlations and the statistical significance of each factor. The model with seven features achieved an area under the curve of 0.82, sensitivity of 0.73, and specificity of 0.79. The model prediction was associated with five-year graft and rejection-free survival. Post-transplantation hospitalization >25 days and eGFR ≥ 88.0 were the prominent risk and preventive factors, respectively. Donor age and post-transplantation eGFR < 59.8 were connected to multiple risk factors on the network. Therefore, careful donor−recipient matching in older donors, and avoiding pre-transplantation risk factors, would reduce the risk of graft dysfunction. The model might improve long-term graft outcomes by supporting early detection of graft dysfunction, and proactive risk factor control.

Interactions Between Donor Age and 12-Month Estimated Glomerular Filtration Rate on Allograft and Patient Outcomes After Kidney Transplantation

Reduced estimated glomerular filtration rate (eGFR) at 12-months after kidney transplantation is associated with increased risk of allograft loss, but it is uncertain whether donor age and types modify this relationship. Using Australia and New Zealand registry data, multivariable Cox proportional modelling was used to examine the interactive effects between donor age, types and 12-month eGFR on overall allograft loss. We included 11,095 recipients (4,423 received live-donors). Recipients with lowest 12-month eGFR (<30 ml/min/1.73 m²) experienced the greatest risk of allograft loss, with adjusted HR [95% CI) of 2.65 [2.38–2.95] compared to eGFR of 30–60 ml/min/1.73 m²; whereas the adjusted HR for highest eGFR (>60 ml/min/1.73 m²) was 0.67 [0.62–0.74]. The association of 12-month eGFR and allograft loss was modified by donor age (but not donor types) where a higher risk of allograft loss in recipients with lower compared with higher 12-month eGFR being most pronounced in the younger donor age groups (p < 0.01). Recipients with eGFR <30 ml/min/1.73 m² 12-months after transplantation experienced ≥2.5-fold increased risk of overall allograft loss compared to those with eGFR of >60 ml/min/1.73 m², and the magnitude of the increased risk is most marked among recipients with younger donors. Careful deliberation of other factors including donor age when considering eGFR as a surrogate for clinical endpoints is warranted.

Deep Learning Algorithms for the Prediction of Posttransplant Renal Function in Deceased-Donor Kidney Recipients: A Preliminary Study Based on Pretransplant Biopsy

Background

Posttransplant renal function is critically important for kidney transplant recipients. Accurate prediction of graft function would greatly help in deciding acceptance or discard of allocated kidneys.

Methods

: Whole-slide images (WSIs) of H&E-stained donor kidney biopsies at × 200 magnification between January 2015 and December 2019 were collected. The clinical characteristics of each donor and corresponding recipient were retrieved. Graft function was indexed with a stable estimated glomerular filtration rate (eGFR) and reduced graft function (RGF). We used convolutional neural network (CNN)-based models, such as EfficientNet-B5, Inception-V3, and VGG19 for the prediction of these two outcomes.

Results

In total, 219 recipients with H&E-stained slides of the donor kidneys were included for analysis [biopsies from standard criteria donor (SCD)/expanded criteria donor (ECD) was 191/28]. The results showed distinct improvements in the prediction performance of the deep learning algorithm plus the clinical characteristics model. The EfficientNet-B5 plus clinical data model showed the lowest mean absolute error (MAE) and root mean square error (RMSE). Compared with the clinical data model, the area under the receiver operating characteristic (ROC) curve (AUC) of the clinical data plus image model for eGFR classification increased from 0.69 to 0.83. In addition, the predictive performance for RGF increased from 0.66 to 0.80. Gradient-weighted class activation mappings (Grad-CAMs) showed that the models localized the areas of the tubules and interstitium near the glomeruli, which were discriminative features for RGF.

Conclusion

Our results preliminarily show that deep learning for formalin-fixed paraffin-embedded H&E-stained WSIs improves graft function prediction accuracy for deceased-donor kidney transplant recipients.

Donor Death Category Is an Effect Modifier Between Cold Ischemia Time and Post-transplant Graft Function in Deceased-Donor Kidney Transplant Recipients

Objectives: We aimed to analyze the effect of cold ischemia time (CIT) on post-transplant graft function through mixed-effect model analysis to reduce the bias caused by paired mate kidneys.

Methods: We reviewed all kidney transplantation records from 2015 to 2019 at our center. After applying the exclusion criteria, 561 cases were included for analysis. All donor characteristics, preservation and matching information, and recipient characteristics were collected. Transplant outcomes included delayed graft function (DGF) and estimated glomerular filtration rate (eGFR). Generalized linear mixed models were applied for analysis. We also explored potential effect modifiers, namely, donor death category, expanded criteria donors, and donor death causes.

Results: Among the 561 cases, 79 DGF recipients developed DGF, and 15 recipients who died after surgery were excluded from the eGFR estimation. The median stable eGFR of the 546 recipients was 60.39 (47.63, 76.97) ml/min/1.73 m². After adjusting for confounding covariates, CIT had a negative impact on DGF incidence [odds ratio = 1.149 (1.006, 1.313), P = 0.041]. In the evaluation of the impact on eGFR, the regression showed that CIT had no significant correlation with eGFR [β = −0.287 (−0.625, 0.051), P = 0.096]. When exploring potential effect modifiers, only the death category showed a significant interaction with CIT in the effect on eGFR (P_interaction = 0.027). In the donation after brain death (DBD) group, CIT had no significant effect on eGFR [β = 0.135 (−0.433, 0.702), P = 0.642]. In the donation after circulatory death/donation after brain death followed by circulatory death (DCD/DBCD) group, CIT had a significantly negative effect on eGFR [β= −0.700 (−1.196, −0.204), P = 0.006]. Compared to a CIT of 0–6 h, a CIT of 6–8 or 8–12 h did not decrease the post-transplant eGFR. CIT over 12 h (12–16 h or over 16 h) significantly decreased eGFR. With the increase in CIT, the regenerated eGFR worsened (P_trend = 0.011).

Conclusion: Considering the effect of paired mate kidneys, the risk of DGF increased with prolonged CIT. The donor death category was an effect modifier between CIT and eGFR. Prolonged CIT did not reduce the eGFR level in recipients from DBDs but significantly decreased the eGFR in recipients from DCDs/DBCDs. This result indicates the potential biological interaction between CIT and donor death category.

Defining a minimal clinically meaningful difference in 12-month estimated glomerular filtration rate for clinical trials in deceased donor kidney transplantation

BACKGROUND

A Minimal Clinically Meaningful Difference (MCMD) has not been defined for Estimated glomerular filtration rate (eGFR). Our goal was to define the MCMD for eGFR anchored to kidney graft failure.

METHODS

A systematic review of studies with 12-month eGFR and subsequent renal graft failure was conducted. For observational studies, we calculated hazard ratio (HR) differences between adjacent eGFR intervals weighted by population distribution. Interventional trials yielded therapeutically induced changes in eGFR and failure risk. OPTN data analysis divided 12-month eGFR into bands for Cox regressions comparing adjacent eGFR bands with a death-censored graft survival outcome.

RESULTS

Observational studies indicated that lower eGFR was associated with increased death-censored graft failure risk; each 5 ml/min/1.73 m2 12-month eGFR band associated with a weighted incremental HR = 1.12 to 1.23. Clinical trial data found a 5 ml/min/1.73 m2 difference was associated with incremental HR = 1.16 to 1.35. OPTN analyses showed weighted mean HRs across 10, 7, and 5 ml/min/1.73 m2 bands of 1.47, 1.30, and 1.19.

CONCLUSIONS

A 5 ml/min/1.73 m2 difference in 12-month eGFR was consistently associated with ~20% increase in death-censored graft failure risk. The magnitude of effect has been interpreted as clinically meaningful in other disease states and should be considered the MCMD in renal transplantation clinical trials.

Development and validation of routine clinical laboratory data derived marker-based nomograms for the prediction of 5-year graft survival in kidney transplant recipients

Background: To develop and validate predictive nomograms for 5-year graft survival in kidney transplant recipients (KTRs) with easily-available laboratory data derived markers and clinical variables within the first year post-transplant.

Methods: The clinical and routine laboratory data from within the first year post-transplant of 1289 KTRs was collected to generate candidate predictors. Univariate and multivariate Cox analyses and LASSO were conducted to select final predictors. X-tile analysis was applied to identify optimal cutoff values to transform potential continuous factors into category variables and stratify patients. C-index, calibration curve, dynamic time-dependent AUC, decision curve analysis, and Kaplan-Meier curves were used to evaluate models’ predictive accuracy and clinical utility.

Results: Two predictive nomograms were constructed by using 0–6- and 0–12- month laboratory data, and showed good predictive performance with C-indexes of 0.78 and 0.85, respectively, in the training cohort. Calibration curves showed that the prediction probabilities of 5-year graft survival were in concordance with actual observations. Additionally, KTRs could be successfully stratified into three risk groups by nomograms.

Conclusions: These predictive nomograms combining demographic and 0–6- or 0–12- month markers derived from post-transplant laboratory data could serve as useful tools for early identification of 5-year graft survival probability in individual KTRs.

Is the Living Donor Kidney Profile Index Valuable in Japanese Patients?

INTRODUCTION

The Living Kidney Donor Profile Index (LKDPI) was recently proposed in the United States to evaluate living donor quality. Japan has a largely different renal transplant circumstance, such as a high ABO incompatibility rate. The aim of this study was to validate the LKDPI among the Japanese population and adjust the score.

METHODS

We performed a retrospective analysis of 133 living donors in renal transplant in our institution. We analyzed the clinical characteristics and outcomes, and created a modified LKDPI score considering the favorable ABO incompatible kidney transplant outcomes in Japan.

RESULTS

Median (interquartile range [IQR]) donor age was 59 (51 to 65) and median (IQR) body mass index was 22.9 kg/m² (20.9 to 25.2). ABO incompatibility rate was 28.5%. Median (IQR) donor estimated glomerular filtration rate (eGFR) (Chronic Kidney Disease Epidemiology Collaboration equation) was 108.7 mL/min/1.73 m² (99.9 to 115.5). The 1-year graft survival rate was 98.5%, and the 3-year graft survival rate was 97%. The incidence of antibody mediated rejection was 5.2%. The median (IQR) LKDPI score was 30.2 (11.8 to 46.8). This was significantly higher than the previously reported score in the United States, which was 12.8 (-0.8 to 27.2). The modified LKDPI (mLKDPI) score was 23.2 (4.1 to 35.1). LKDPI and mLKDPI did not show a diagnostic value in graft survival; however, LKDPI and mLKDPI showed significant diagnostic value in eGFR at 1 year (area under the curve [AUC]=0.627, P = .017; and AUC=0.673, P = .01).

CONCLUSION

Our outcomes had better survival even though with higher ABO incompatibility rate. According to original LKDPI, our donor pool is higher than the general US population. In this study, lower LKDPI tended to be associated with good allograft function, and mLKDPI has better diagnostic value than LKDPI. To compare internationally, an adjusted model for Japan might be necessary based on the outcomes of a large population.

Prognostic value for long-term graft survival of estimated glomerular filtration rate and proteinuria quantified at 3 months after kidney transplantation

Background

The estimated glomerular filtration rate (eGFR) measured at 1 year is the usual benchmark applied in kidney transplantation (KT). However, acting on earlier eGFR values could help in managing KT during the first post-operative year. We aimed to assess the prognostic value for long-term graft survival of the early (3 months) quantification of eGFR and proteinuria following KT.

Methods

The 3-, 6- and 12-month eGFR using the Modified Diet in Renal Disease equation (eGFR_MDRD) was determined and proteinuria was measured in 754 patients who underwent their first KT between 2000 and 2010 (with a mean follow-up of 8.3 years) in our centre. Adjusted associations with graft survival were estimated using a multivariable Cox model. The predictive accuracy was estimated using the C-index and net reclassification index. These same analyses were measured in a multicentre validation cohort of 1936 patients.

Results

Both 3-month eGFR_MDRD and proteinuria were independent predictors of return to dialysis (all P < 0.05) and there was a strong correlation between eGFR at 3 and 12 months (Spearman’s ρ = 0.76). The predictive accuracy of the 3-month eGFR was within a similar range and did not differ significantly from the 12-month eGFR in either the derivation cohort [C-index 62.6 (range 57.2–68.1) versus 66.0 (range 60.1–71.9), P = 0.41] or the validation cohort [C-index 69.3 (range 66.4–72.1) versus 71.7 (range 68.7–74.6), P = 0.25].

Conclusion

The 3-month eGFR was a valuable predictor of the long-term return to dialysis whose predictive accuracy was not significantly less than that of the 12-month eGFR in multicentre cohorts totalling >2500 patients. Three-month outcomes may be useful in randomized controlled trials targeting early therapeutic interventions.

Economic impacts of alternative kidney transplant immunosuppression: A national cohort study

Understanding the economic implications of induction and maintenance immunosuppression (ISx) is important in developing personalized kidney transplant (KTx) care. Using data from a novel integrated data set including financial records from the University Health System Consortium, Medicare, and pharmacy claims (2007-2014), we estimated the differences in the impact of induction and maintenance ISx regimens on transplant hospitalization costs and Medicare payments from KTx to 3 years. Use of thymoglobulin (TMG) significantly increased transplant hospitalization costs ($12 006; P = .02), compared with alemtuzumab and basiliximab. TMG resulted in lower Medicare payments in posttransplant years 1 (-$2058; P = .05) and 2 (-$1784; P = .048). Patients on steroid-sparing ISx incurred relatively lower total Medicare spending (-$10 880; P = .01) compared with patients on triple therapy (tacrolimus, antimetabolite, and steroids). MPA/AZA-sparing, mammalian target of rapamycin inhibitors-based, and cyclosporine-based maintenance ISx regimens were associated with significantly higher payments. Alternative ISx regimens were associated with different KTx hospitalization costs and longer-term payments. Future studies of clinical efficacy should also consider cost impacts to define the economic effectiveness of alternative ISx regimens.

Decreasing Estimated Glomerular Filtration Rate Is Associated With Increased Risk of Hospitalization After Kidney Transplantation

INTRODUCTION

Following renal transplantation, decreased renal function is associated with increased risk of cardiovascular disease, graft loss and mortality. We investigated whether declining renal function was associated with hospitalization post-transplant.

METHODS

Adult, first-time, kidney transplant recipients between 2004 and 2006 from the United Network for Organ Sharing database and hospitalizations one year after the 6-month post-transplant follow-up visit were examined. Generalized linear models explored the relationship between estimated glomerular filtration rate (eGFR) measured at 6 months and the number of hospitalizations in the following year.

RESULTS

Of 15,778 kidney transplant recipients, 19.1% were admitted in the year after the 6-month follow-up visit. Among those hospitalized, the mean number of hospitalizations was 1.71 and increased with decreasing eGFR. In multivariable models, a decrease in eGFR was significantly associated with increased hospitalizations: for every 10 ml/min/1.73m² decrease in eGFR, there was an 11% increase in hospitalization rate (p <0.001). Lower eGFR after the first 6 months following transplantation was associated with an increase in late hospitalizations among adult kidney transplant recipients.

DISCUSSION

Identifying patients with declining eGFR and other risk factors may help prevent morbidity and mortality associated with hospitalization post-transplantation.

Costimulation Blockade in Kidney Transplantation: An Update

In the setting of solid-organ transplantation, calcineurin inhibitor (CNI)-based therapy remains the cornerstone of immunosuppression. However, long-term use of CNIs is associated with some degree of nephrotoxicity. This has led to exploring the blockade of some costimulation pathways as an efficient immunosuppressive tool instead of using CNIs. The only agent already in clinical use and approved by the health authorities for kidney transplant patients is belatacept (Nulojix), a fusion protein that interferes with cytotoxic T lymphocyte-associated protein 4. Belatacept has been demonstrated to be as efficient as cyclosporine-based immunosuppression and is associated with significantly better renal function, that is, no nephrotoxicity. However, in the immediate posttransplant period, significantly more mild/moderate episodes of acute rejection have been reported, favored by the fact that cytotoxic T lymphocyte-associated protein pathway has an inhibitory effect on the alloimmune response; thereby its inhibition is detrimental in this regard. This has led to the development of antibodies that target CD28. The most advanced is FR104, it has shown promise in nonhuman primate models of autoimmune diseases and allotransplantation. In addition, research into blocking the CD40-CD154 pathway is underway. A phase II study testing ASK1240, that is, anti-CD40 antibody has been completed, and the results are pending.

Belatacept for the prophylaxis of organ rejection in kidney transplant patients: an evidence-based review of its place in therapy

BACKGROUND

Belatacept is a novel immunosuppressive therapy designed to improve clinical outcomes associated with kidney transplant recipients while minimizing use of calcineurin inhibitors (CNIs).

METHODS

We searched for clinical trials related to administration of belatacept to kidney transplant patients compared to various immunosuppression regimens, as well as for studies that utilized data from belatacept trials to validate new surrogate measures. The purpose of this review is to consolidate the published evidence of belatacept's effectiveness and safety in renal transplant recipients to better elucidate its place in clinical practice.

RESULTS

Analysis of the results from the Belatacept Evaluation of Nephroprotection and Effi-cacy as First-Line Immunosuppressive Trial (BENEFIT) study, a de novo trial that compared cyclosporine (CsA)-based therapy to belatacept-based therapy in standard criteria donors, found a significant difference in mean estimated glomerular filtration rate (eGFR) of 13-15 mL/min/1.73 m(2) and 23-27 mL/min/1.73 m(2) at 1 year and 7 years, respectively. The BENEFIT-EXT study was similarly designed with the exception that it included extended criteria donors. Renal function improved significantly for the more intensive belatacept group in all years of the BENEFIT-EXT study; however, it was not significant in the less intensive group until 5 years after transplant. Belatacept regimens resulted in lower blood pressure, cholesterol levels, and incidence of new-onset diabetes after transplant compared to CsA-based regimens. Results from conversion of CNIs to belatacept therapy, dual therapy of belatacept with sirolimus, and belatacept with corticosteroid avoidance therapy are also included in this article.

CONCLUSION

The evidence reviewed in this article suggests that belatacept is an effective alternative in kidney transplant recipients. Compared to CNI-based therapy, belatacept-based therapy results in superior renal function and similar rates of allograft survival. In terms of safety, belatacept was shown to have lower incidence of hypertension, hyperlipidemia, and diabetes; however, incidence of posttransplantation lymphoproliferative disorder and the cost of belatacept may hinder use of this medication.

Acute and Chronic Allograft Dysfunction in Kidney Transplant Recipients

Allograft dysfunction after a kidney transplant is often clinically asymptomatic and is usually detected as an increase in serum creatinine level with corresponding decrease in glomerular filtration rate. The diagnostic evaluation may include blood tests, urinalysis, transplant ultrasonography, radionuclide imaging, and allograft biopsy. Whether it occurs early or later after transplant, allograft dysfunction requires prompt evaluation to determine its cause and subsequent management. Acute rejection, medication toxicity from calcineurin inhibitors, and BK virus nephropathy can occur early or later. Other later causes include transplant glomerulopathy, recurrent glomerulonephritis, and renal artery stenosis.

Belatacept prophylaxis against organ rejection in adult kidney-transplant recipients

End-stage renal disease is a major health problem worldwide, with kidney transplantation being the treatment of choice. Calcineurin inhibitors are still the cornerstone of immunosuppressive therapy. However, they have well-known nephrotoxic affects and increase the risk of cardiovascular disease and cancer. In contrast, belatacept is a biological immunosuppressive agent that inhibits the T-cell co-stimulation. It is approved by the US Food and Drug Administration and the European Medicine Agency for use in adult kidney-transplant recipients to prevent acute rejection. Developmental studies show that belatacept is as efficient as calcineurin inhibitors at preventing acute rejection. In addition, kidney function is better and cardiovascular risk factors are reduced in patients given belatacept. Herein, the authors review the published evidence concerning the efficacy and safety of belatacept and discuss its potential specific indications.

Long-term outcome of belatacept therapy in de novo kidney transplant recipients - a case-match analysis

While belatacept has shown favorable short- and midterm results in kidney transplant recipients, only projections exist regarding its potential impact on long-term outcome. Therefore, we performed a retrospective case-match analysis of the 14 belatacept patients originally enrolled in the phase II multicenter trial at our center. Fifty six cyclosporine (CyA)-treated patients were matched according to age at transplantation, first/retransplant, and donor type. Ten years after kidney transplantation, kidney function remained superior in belatacept-treated patients compared with the CyA control group. Moreover, none of the belatacept-treated patients had donor-specific antibodies ≥10 years post-transplantation compared with 38.5% of tested CyA-treated subject (0/10 vs. 5/13; P = 0.045). Notably, however, patient and graft survival was virtually identical in both groups (71.4% vs. 71.3%; P = 0.976). In the present single-center study population, patients treated with belatacept demonstrated a patient and graft survival at 10 years post-transplant which was comparable to that of similarly selected CNI-treated patients. Larger studies with sufficient statistical power are necessary to definitively determine long-term graft survival with belatacept.

Factors affecting eGFR 5-year post-deceased donor renal transplant: analysis and predictive model

AIM

Long-term survival of renal allografts has improved over the last 20 years. However, less is known about current expectations for long-term allograft function as determined by estimated glomerular filtration rate (eGFR). The aim of this study was to investigate factors which affect graft function at 5 years' post-renal transplantation. The statistically significant factors were then used to construct a predictive model for expected eGFR at five years' post-transplant.

METHODS

We retrospectively reviewed all adult patients who received a renal transplant in the Republic of Ireland between 1990 and 2004. Data collected included era of transplantation (1990-1994, 1995-1999, 2000-2004), donor and recipient age and gender, number of human leucocyte antigen mismatches, cold ischemia time (CIT), number of prior renal transplants, immunosuppressive regimen used and acute rejection episodes. Estimated GFR was calculated at 5 years after transplantation from patient data using the Modified Diet in Renal Disease (MDRD) equation. Consecutive sampling was used to divide the study population into two equal unbiased groups of 489 patients. The first group (derivation cohort) was used to construct a predictive model for eGFR five years' post-transplantation, the second (validation cohort) to test this model.

RESULTS

Nine hundred and seventy eight patients were analyzed. The median age at transplantation was 43 years (range 18-78) and 620 (63.4%) were male. One hundred and seventy five patients (17.9%) had received a prior renal transplant. Improved eGFR at five years' post-transplantation was associated with tacrolimus-based combination immunosuppression, younger donor age, male recipient, absence of cytomegalovirus disease and absence of acute rejection episodes as independently significant factors (p < 0.05). The predictive model developed using these factors showed good correlation between predicted and actual median eGFR at five years. The model explained 20% of eGFR variability. The validation model findings were consistent with the derivation model (21% variability of eGFR explained by model using same covariates on new data).

CONCLUSION

The predictive model we have developed shows good correlation between predicted and actual median eGFR at five years' post-transplant. Applications of this model include comparison of current and future therapy options such as new immunosuppressive regimens.

Co-stimulatory blockade with belatacept in kidney transplantation

Calcineurin inhibitors (CNIs) are the cornerstone of immunosuppression after transplantation but can exert negative effects on chronic allograft function and metabolic profile. Belatacept, a selective co-stimulation blocker of T cells, is the first biologic agent approved for maintenance immunosuppression in kidney transplantation. Studies reveal better preservation of glomerular filtration rate and improved metabolic end points with belatacept when compared to CNIs. Increased incidence of acute rejection is noted with belatacept but overall graft survival looked similar at 5 years. Risk for posttransplant lymphoproliferative disorder is higher in Epstein-Barr virus-seronegative recipients of belatacept. Belatacept seems to be a promising drug, and further experience with its use will define its future role.

Influence of renal function on long-term graft survival and patient survival in renal transplant recipients

OBJECTIVES

Renal function post kidney transplantation is an outcome of interest for both clinicians and regulators evaluating immunosuppressive treatments post-transplantation. The current review sought to provide a synopsis of currently available literature examining the relationship between post-transplantation renal function and long-term graft survival and patient survival.

METHODS

A systematic literature review was performed using the PubMed, EMBASE and Cochrane Library databases. The search strategy was designed based on high level Medical Subject Heading (MeSH) terms and designed to capture studies published in English to 2012 and identified a total of 2683 unique hits; for inclusion studies were required to have >100 patients. Following two rounds of screening, a total of 27 studies were included in the final review (26 of which were identified via the literature review and one study was identified via searches of the reference sections of included studies).

RESULTS

The consensus among studies was that lower post-transplantation GFR, in particular 12 month GFR, was consistently and significantly associated with an increased risk for overall graft loss, death-censored graft loss and all-cause mortality in both univariate and multivariate analyses. The magnitude of the association between reduced GFR and outcomes was greater for death-censored graft loss versus overall graft loss and for graft loss in comparison with overall patient mortality. The predictive utility of GFR alone in predicting long-term outcomes was reported to be limited.

CONCLUSIONS

Lower GFR and greater rates of decline in GFR post-transplantation are associated with an increased risk for graft loss (overall and death-censored) and all-cause mortality; however, the predictive utility of GFR alone in predicting long-term outcomes is limited.

Kidney transplantation outcomes from expanded criteria donors, standard criteria donors or living donors older than 60 years

OBJECTIVES

To evaluate outcomes in kidney allograft recipients from donors with expanded criteria (ECD) versus standard criteria (SCD) or living donors (LD) >60 years.

METHODS

We studied all patients who received a kidney between 2005 and 2011, focusing in recipients of kidneys from deceased ECD, SCD and LD >60 years. ECD was any deceased donor >60 years or >50 years with two of the following: hypertension (HTN), stroke as the cause of death, or serum creatinine >1.5 mg/dL. We recorded characteristics of the transplant procedure, patient, graft survival and renal function 1 year after transplantation and at the end of follow-up.

RESULTS

Six-hundred and five patients were transplanted between 2005 and 2011 in our department. There were 142 (25.1%) transplantations from ECD, 192 (33.98%) from SCD and 96 (16.99%) from LDs older than 60 years. In a mean follow-up time of 36.4 months, graft survival rates were similar for all groups. Calculated GFR was found statistically different between the ECD and SCD groups, but still satisfactory at first year, and at end of follow-up time. Comparison of the patients, who received transplants from ECD, even older than 70 years, and those from LD >60 years revealed equivalent renal function in short and long term.

CONCLUSIONS

Utilization of marginal kidneys effectively doubled our deceased transplant volume in the period 2005-2011. Patients' and graft survival were shown similar at the end of follow-up for all groups. Renal outcomes were shown equivalent between the ECD and LD >60 years groups, and although significantly lower between the ECD and the SCD group, were still very satisfactory.

The rate of decline of glomerular filtration rate is a predictor of long-term graft outcome after kidney transplantation

BACKGROUND

To improve the long-term outcome of kidney transplantation (KT), it is important to identify and take active steps to reduce the number or severity of novel risk factors. We investigated whether changes in estimated glomerular filtration rate over the first year after KT (ΔeGFR12-3) was associated with long-term renal allograft function and survival.

METHODS

Four hundred twenty-eight allograft recipients transplanted between 1990 and 2001 underwent ΔeGFR12-3 calculation using the equation: ΔeGFR12-3 = ([eGFR at 12 months post-KT - eGFR at 3 months post-KT]/[eGFR at 3 months post-KT]) × 100%. Recipients were divided into 3 groups according to their ΔeGFR12-3: group I (n = 150), ΔeGFR12-3 ≥ 10%; group II (n = 151), 10 > ΔeGFR12-3 ≥ -10%; and group III (n = 127), ΔeGFR12-3 < -10%. Multiple linear regression analysis was used to adjust for confounding variables that may affect long-term renal allograft function, and Kaplan-Meier analysis, to compare allograft survival.

RESULTS

At a mean follow-up of 120 ± 58 months, we observed 112 renal allograft losses. The ΔeGFR over 10 years post-KT (ΔeGFR120-3) was significantly associated with the serum uric acid levels at 3 months post-transplantation and ΔeGFR12-3. Group III showed poor renal allograft survival; group I, 194 ± 8 months; group II, 197 ± 7 month and; group III, 163 ± 4 months; (log-rank test, P < .05). A Cox proportional hazard model revealed ΔeGFR12-3 to be independently associated with future renal allograft loss (hazard ratio, 0.981; 95% confidence interval, 0.974-0.992).

CONCLUSION

Our results suggested that ΔeGFR12-3 may be an independent predictor of kidney allograft survival. Routine application of eGFR is strongly recommended to identify patients at risk for chronic allograft dysfunction.

Long-term belatacept exposure maintains efficacy and safety at 5 years: results from the long-term extension of the BENEFIT study

The Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial randomized patients receiving a living or standard criteria deceased donor kidney transplant to a more (MI) or less intensive (LI) regimen of belatacept or cyclosporine A (CsA). The 5-year results of the long-term extension (LTE) cohort are reported. A total of 456 (68.5% of intent-to-treat) patients entered the LTE at 36 months; 406 patients (89%) completed 60 months. Between Months 36 and 60, death occurred in 2%, 1% and 5% of belatacept MI, belatacept LI and CsA patients, respectively; graft loss occurred in 0% belatacept and 2% of CsA patients. Acute rejection between Months 36 and 60 was rare: zero belatacept MI, one belatacept LI and one CsA. Rates for infections and malignancies for Months 36-60 were generally similar across belatacept groups and CsA, respectively: fungal infections (14%, 15%, 12%), viral infections (21%, 18%, 16%) and malignancies (6%, 6%, 9%). No new posttransplant lymphoproliferative disorder cases occurred after 36 months. Mean calculated GFR (MDRD, mL/min/1.73 m(2) ) at Month 60 was 74 for belatacept MI, 76 for belatacept LI and 53 for CsA. These results show that the renal function benefit and safety profile observed in belatacept-treated patients in the early posttransplant period was sustained through 5 years.

Belatacept: a novel immunosuppressive agent for kidney transplant recipients

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

The cost implications of first anniversary renal function after living, standard criteria deceased and expanded criteria deceased donor kidney transplantation

OBJECTIVES

To quantify relationships of post-transplant renal function with healthcare costs after kidney transplantation.

METHODS

Clinical and billing records for Medicare-insured kidney transplant recipients (1995-2003) were drawn from the US Renal Data System. Estimated glomerular filtration rate (eGFR) at 1-year post-transplant was computed with the abbreviated Modification of Diet in Renal Disease equation. Associations of eGFR with total Medicare payments in the second and third post-transplant years were examined by multivariate non-linear regression with spline forms. Adjustment covariates were drawn from the survival prediction model developed by the UNOS Kidney Allocation Review Committee.

RESULTS

The sample comprised 7103 living donor (LD), 22,110 standard criteria deceased (SCD), and 2594 expanded criteria deceased (ECD) donor transplant recipients. Regardless of donor type, lower 1-year eGFR was associated with significantly increased expenditures during the second and the third years post-transplant. Marginal costs began to increase as eGFR fell below 45 mL/min/1.73 m(2) and rose in an accelerating manner. Compared to a reference eGFR of 75 mL/min/1.73 m(2), 1-year eGFR of 20 ml/min/1.73 m(2) in SCD recipients was associated with ∼$17,500 and $18,200 higher adjusted payments in the second and third post-transplant years, respectively. Patterns were similar among recipients of LD and ECD transplants.

LIMITATIONS

The study sample was limited to Medicare beneficiaries who survived with allograft function to the first transplant anniversary, which may limit generalizability of the findings. eGFR is a surrogate measure of renal function. The design is retrospective and changes in post-transplant management may alter long-term cost implication of renal function.

CONCLUSIONS

Decreased renal function is significantly associated with higher healthcare expenditures following kidney transplantation. Post-transplant eGFR may be a useful metric for discriminating the economic impact of care strategies that differentially affect renal function.