Efficacy and Safety Outcomes of Extended Criteria Donor Kidneys by Subtype: Subgroup Analysis of BENEFIT-EXT at 7 Years After Transplant

New Developments and Therapeutic Drug Monitoring Options in Costimulatory Blockade in Solid Organ Transplantation: A Systematic Critical Review

PURPOSE

In this review, the authors summarized the latest developments in costimulatory blockade to prevent rejection after solid organ transplantation (SOT) and discussed possibilities for future research and the need for therapeutic drug monitoring (TDM) of these agents.

METHODS

Studies about costimulatory blockers in SOT in humans or animal transplant models in the past decade (2014-2024) were systematically reviewed in PubMed, European Union clinical trials (EudraCT), and ClinicalTrials.gov .

RESULTS

Seventy-five registered clinical trials and 58 published articles were found on costimulation blockade of the CD28-CD80/86, CD40-CD40L, and OX40-OX40L pathways. Belatacept, an antagonist of the CD28-CD80/86 pathway, is the only approved costimulatory agent in SOT, hence accounting for most of the research. Other identified costimulatory blocking agents included abatacept and CD28 antagonists tegoprubart, dazodalibep, and TNX-1500. Although tegoprubart was unsuccessful in pancreas transplantation in nonhuman primates, trials in human kidney transplantation are underway. Dazodalibep trials faced recruitment challenges. TNX-1500 was unsuccessful in animal studies and is currently not pursued in humans. After discontinuation of iscalimab (CD40-CD154 pathway antagonist) in SOT, the alternatives, bleselumab and KPL404, showed promising results in kidney transplantation and cardiac xenotransplantation. Studies on secondary costimulatory pathway antagonists, such as OX40-OX40L, have only used animal models. Despite the low interindividual variability in pharmacokinetics (PK) in all studied agents, TDM could be useful for optimizing dosing in PK/pharmacodynamic (PD) studies.

CONCLUSIONS

The routine use of costimulation blockade in SOT is hindered by problems in efficacy compared with the standard of care. Costimulatory inhibitors could be combined in a calcineurin inhibitor-free regimen. Future PK/pharmacodynamic studies in costimulatory agents and personalized medicine could warrant TDM of these agents.

Use of a Belatacept-based Immunosuppression for Kidney Transplantation From Donors After Circulatory Death: A Paired Kidney Analysis

Background

Efficacy and safety of belatacept have not been specifically reported for kidney transplantations from donors after circulatory death.

Methods

In this retrospective multicenter paired kidney study, we compared the outcome of kidney transplantations with a belatacept-based to a calcineurin inhibitor (CNI)-based immunosuppression. We included all kidney transplant recipients from donors after uncontrolled or controlled circulatory death performed in our center between February 2015 and October 2020 and treated with belatacept (n = 31). The control group included the recipients of the contralateral kidney that were treated with CNI in 8 other centers (tacrolimus n = 29, cyclosporine n = 2).

Results

There was no difference in the rate of delayed graft function. A higher incidence of biopsy-proven rejections was noted in the belatacept group (24 versus 6 episodes). Estimated glomerular filtration rate (eGFR) was significantly higher in the belatacept group at 3-, 12-, and 36-mo posttransplant, but the slope of eGFR was similar in the 2 groups. During a mean follow-up of 4.1 y, 12 patients discontinued belatacept and 2 patients were switched from CNI to belatacept. For patients who remained on belatacept, eGFR mean value and slope were significantly higher during the whole follow-up. At 5 y, eGFR was 80.7 ± 18.5 with belatacept versus 56.3 ± 22.0 mL/min/1.73 m2 with CNI (P = 0.003). No significant difference in graft and patient survival was observed.

Conclusions

The use of belatacept for kidney transplants from either uncontrolled or controlled donors after circulatory death resulted in a better medium-term renal function for patients remaining on belatacept despite similar rates of delayed graft function and higher rates of cellular rejection.

Post-transplant lymphoproliferative disorders following kidney transplantation: A literature review with updates on risk factors, prognostic indices, screening strategies, treatment and analysis of donor type

Post-transplant lymphoproliferative disorders (PTLD) is a devastating complication of kidney transplantation with an insidious presentation and potential to disseminate aggressively. This review delineates the risk factors, prognostic indexes, screening, current management algorithm and promising treatment strategies for PTLD. Kidneys from both extended criteria donors (ECD) and living donors (LD) are being increasingly used to expand the donor pool. This review also delineates whether PTLD outcomes vary based on these donor sources. While Epstein-Barr virus (EBV) is a well-known risk factor for PTLD development, the use of T-cell depleting induction agents has been increasingly implicated in aggressive, monomorphic forms of PTLD. Research regarding maintenance therapy is sparse. The international prognostic index seems to be the most validate prognostic tool. Screening for PTLD is controversial, as annual PET-CT is most sensitive but costly, while targeted monitoring of EBV-seronegative patients was more economically feasible, is recommended by the American Society of Transplantation, but is limited to a subset of the population. Other screening strategies such as using Immunoglobulin/T-cell receptor require further validation. A risk-stratified approach is taken in the treatment of PTLD. The first step is the reduction of immunosuppressants, after which rituximab and chemotherapy may be introduced if unsuccessful. Some novel treatments have also shown potential benefit in studies: brentuximab vedotin, chimeric antigen receptor T-cell therapy and EBV-specific cytotoxic T lymphocytes. Analysis of LD v DD recipients show no significant difference in incidence and mortality of PTLD but did reveal a shortened time to development of PTLD from transplant. Analysis of SCD vs ECD recipients show a higher incidence of PTLD in the ECD group, which might be attributed to longer time on dialysis for these patients, age, and the pro-inflammatory nature of these organs. However, incidence of PTLD overall is still extremely low. Efforts should be focused on optimising recipients instead. Minimising the use of T-cell depleting therapy while encouraging research on the effect of new immunosuppressants on PTLD, screening for EBV status are essential, while enabling shared decision-making during counselling when choosing kidney donor types and individualised risk tailoring are strongly advocated.

Utility of a fusion protein T-cell co-stimulation blocker Belatacept in heart transplant recipients: Real world experience from a high volume center

BACKGROUND

Belatacept (BTC), a fusion protein, selectively inhibits T-cell co-stimulation by binding to the CD80 and CD86 receptors on antigen-presenting cells (APCs) and has been used as immunosuppression in adult renal transplant recipients. However, data regarding its use in heart transplant (HT) recipients are limited. This retrospective cohort study aimed to delineate BTC's application in HT, focusing on efficacy, safety, and associated complications at a high-volume HT center.

METHODS

A retrospective cohort study was conducted of patients who underwent HT between January 2017 and December 2021 and subsequently received BTC as part of their immunosuppressive regimen. Twenty-one HT recipients were identified. Baseline characteristics, history of rejection, and indication for BTC use were collected. Outcomes included renal function, graft function, allograft rejection and mortality. Follow-up data were collected through December 2023.

RESULTS

Among 776 patients monitored from January 2017 to December 2021 21 (2.7%) received BTC treatment. Average age at transplantation was 53 years (± 12 years), and 38% were women. BTC administration began, on average, 689 [483, 1830] days post-HT. The primary indications for BTC were elevated pre-formed donor-specific antibodies in highly sensitized patients (66.6%) and renal sparing (23.8%), in conjunction with reduced calcineurin inhibitor dosage. Only one (4.8%) patient encountered rejection within a year of starting BTC. Graft function by echocardiography remained stable at 6 and 12 months posttreatment. An improvement was observed in serum creatinine levels (76.2% of patients), decreasing from a median of 1.58 to 1.45 (IQR [1.0-2.1] to [1.1-1.9]) over 12 months (p = .054). eGFR improved at 3 and 6 months compared with 3 months pre- BTC levels; however, this was not statistically significant (p = .24). Treatment discontinuation occurred in seven patients (33.3%) of whom four (19%) were switched back to full dose CNI. Infections occurred in 11 patients (52.4%), leading to BTC discontinuation in 4 patients (19%).

CONCLUSION

In this cohort, BTC therapy was used as alternative immunosuppression for management of highly sensitized patients or for renal sparing. BTC therapy when combined with CNI dose reduction resulted in stabilization in renal function as measured through renal surrogate markers, which did not, however, reach statistical significance. Patients on BTC maintained a low rejection rate and preserved graft function. Infections were common during BTC therapy and were associated with medication pause/discontinuation in 19% of patients. Further randomized studies are needed to assess the efficacy and safety of BTC in HT recipients.

Porcine anti-human lymphocyte immunoglobulin depletes the lymphocyte population to promote successful kidney transplantation

Introduction

Porcine anti-human lymphocyte immunoglobulin (pALG) has been used in kidney transplantation, but its impacts on the lymphocyte cell pool remain unclear.

Methods

We retrospectively analyzed 12 kidney transplant recipients receiving pALG, and additional recipients receiving rabbit anti-human thymocyte immunoglobulin (rATG), basiliximab, or no induction therapy as a comparison group.

Results

pALG showed high binding affinity to peripheral blood mononuclear cells (PBMCs) after administration, immediately depleting blood lymphocytes; an effect that was weaker than rATG but stronger than basiliximab. Single-cell sequencing analysis showed that pALG mainly influenced T cells and innate immune cells (mononuclear phagocytes and neutrophils). By analyzing immune cell subsets, we found that pALG moderately depleted CD4+T cells, CD8+T cells, regulatory T cells, and NKT cells and mildly inhibited dendritic cells. Serum inflammatory cytokines (IL-2, IL-6) were only moderately increased compared with rATG, which might be beneficial in terms of reducing the risk of untoward immune activation. During 3 months of follow-up, we found that all recipients and transplanted kidneys survived and showed good organ function recovery; there were no cases of rejection and a low rate of complications.

Discussion

In conclusion, pALG acts mainly by moderately depleting T cells and is thus a good candidate for induction therapy for kidney transplant recipients. The immunological features of pALG should be exploited for the development of individually-optimized induction therapies based on the needs of the transplant and the immune status of the patient, which is appropriate for non-high-risk recipients.

Cardiovascular Risk Following Conversion to Belatacept From a Calcineurin Inhibitor in Kidney Transplant Recipients: A Randomized Clinical Trial

Rationale & Objective

In kidney transplant recipients (KTRs), a belatacept-based immunosuppressive regimen is associated with beneficial effects on cardiovascular (CV) risk factors compared with calcineurin inhibitor (CNI)-based regimens. Our objective was to compare the calculated CV risk between belatacept and CNI (predominantly tacrolimus) treatments using a validated model developed for KTRs.

Study Design

Prospective, randomized, open-label, parallel-group, investigator-initiated, international multicenter trial.

Setting & Participants

KTRs aged 18-80 years with a stable graft function (estimated glomerular filtration rate > 20 mL/min/1.73 m²), 3-60 months after transplantation, treated with tacrolimus or cyclosporine A, were eligible for inclusion.

Intervention

Continuation with a CNI-based regimen or switch to belatacept for 12 months.

Outcomes

Comparison of the change in the estimated 7-year risk of major adverse CV events and all-cause mortality, changes in traditional markers of CV health, as well as measures of arterial stiffness.

Results

Among the 105 KTRs randomized, we found no differences between the treatment groups in the predicted risk for major adverse CV events or mortality. Diastolic blood pressure, measured both centrally by using a SphygmoCor device and peripherally, was lower after the belatacept treatment than after the CNI treatment. The mean changes in traditional cardiovascular (CV) risk factors, including kidney transplant function, were otherwise similar in both the treatment groups. The belatacept group had 4 acute rejection episodes; 2 were severe rejections, of which 1 led to graft loss.

Limitations

The heterogeneous baseline estimated glomerular filtration rate and time from transplantation to trial enrollment in the participants. A limited study duration of 1 year.

Conclusions

We found no effects on the calculated CV risk by switching to the belatacept treatment. Participants in the belatacept group had not only lower central and peripheral diastolic blood pressure but also a higher rejection rate.

Funding

The trial has received a financial grant from Bristol-Myers Squibb.

Trial Registration

EudraCT no. 2013-001178-20.

Kidney transplant outcome of expanded criteria donors after circulatory death

The increase in the number of patients on the kidney transplant waiting list has led to an attempt to increase the number of potential donors by incorporating candidates that previously would not have been considered optimal, including donors after cardiac death (DCD) and those with "expanded" criteria (ECD). Recipients of controlled DCD (cDCD) grafts suffer more delayed graft function (DGF), but have a long-term evolution comparable to those of brain-dead donors, which has allowed an increase in the number of cDCD transplants in different countries in recent years. In parallel, the use of cDCD with expanded criteria (cDCD/ECD) has increased in recent years in different countries, allowing the waiting list for kidney transplantation to be shortened. The use of these grafts, although associated with a higher frequency of DGF, offers similar or only slightly lower long-term graft survival than those of brain death donors with expanded criteria. Different studies have observed that cDCD/ECD graft recipients have worse kidney function than cDCD/standard and DBD/ECD. Mortality associated with cDCD/ECD graft transplantation mostly relates to the recipient age. Patients who receive a cDCD/≥60 graft have better survival than those who continue on the waiting list, although this fact has not been demonstrated in recipients of cDCD/>65 years. The use of this type of organ should be accompanied by the optimization of surgical times and the shortest possible cold ischemia.

The Relationship between Timing of Pretransplant Kidney Biopsy, Graft Loss, and Survival in Kidney Transplantation: An Italian Cohort Study

INTRODUCTION

Kidney biopsy is performed to assess if an extended criteria graft can be used for transplantation. It may be performed before or after cross-clamping during organ procurement. This study aims to evaluate whether the timing of biopsy may modify cold ischemia times (CIT) and/or graft outcomes.

METHODS

Kidney transplants performed in our center from January 2007 to December 2017 were analyzed. Grafts with preimplantation kidney biopsy were included. Biopsies were performed during surgical back table (ex situ kidney biopsy [ESKB]) until 2012 and since then before the aortic cross-clamping (in situ kidney biopsy [ISKB]). To overcome biases owing to different distributions, a propensity score model was developed. The study population consists in 322 patients, 115 ESKB, and 207 ISKB.

RESULTS

CIT was significantly lower for ISKB (730 min ISKB vs. 840 min ESKB, p value = 0.001). In both crude (OR 0.27; 95% confidence interval, 95% CI 0.12-0.60; p value = 0.002) and adjusted analyses (OR 0.37; 95% CI 0.14-0.94; p value = 0.039), ISKB was associated with a reduced odd of graft loss when compared to ESKB.

DISCUSSION/CONCLUSION

Performing preimplantation kidney biopsy during the recovery, prior to the aortic cross-clamping, may be a strategy to reduce CIT and improve transplant outcomes.

Kidney transplant outcome of expanded criteria donors after circulatory death

The increase in the number of patients on the kidney transplant waiting list has led to an attempt to increase the number of potential donors by incorporating candidates that previously would not have been considered optimal, including donors after cardiac death (DCD) and those with "expanded" criteria (ECD). Recipients of controlled DCD (cDCD) grafts suffer more delayed graft function (DGF), but have a long-term evolution comparable to those of brain-dead donors, which has allowed an increase in the number of cDCD transplants in different countries in recent years. In parallel, the use of cDCD with expanded criteria (cDCD/ECD) has increased in recent years in different countries, allowing the waiting list for kidney transplantation to be shortened. The use of these grafts, although associated with a higher frequency of DGF, offers similar or only slightly lower long-term graft survival than those of brain death donors with expanded criteria. Different studies have observed that cDCD/ECD graft recipients have worse kidney function than cDCD/standard and brain death/ECD. Mortality associated with cDCD/ECD graft transplantation mostly relates to the recipient age. Patients who receive a cDCD/≥60 graft have better survival than those who continue on the waiting list, although this fact has not been demonstrated in recipients of cDCD/>65 years. The use of this type of organ should be accompanied by the optimization of surgical times and the shortest possible cold ischemia.

Impaired renal function before kidney procurement has a deleterious impact on allograft survival in very old deceased kidney donors

As the use of elderly kidney donors for transplantation is increasing with time, there is a need to understand which factors impact on their prognosis. No data exist on the impact of an impaired renal function (IRF) in such population. 116 kidney recipients from deceased kidney donors over 70 years were included from 2005 to 2015 in a single-center retrospective study. IRF before organ procurement was defined as a serum creatinine above 1.0 mg/dl or a transient episode of oligo-anuria. Mean ages for donors and recipients were respectively 74.8 ± 3.5 and 66.7 ± 8.0. Graft survival censored for death at 5 years was of 77%. Using a multivariate analysis by Cox model, the only predictor of graft loss present in the donor was IRF before organ procurement (HR 4.2 CI95[1.8–9.7]). IRF was also associated with significant lower estimated glomerular filtration rates up to 1 year post-transplantation. By contrast, KDPI score (median of 98 [96–100]), was not associated with the risk of graft failure. Then, IRF before kidney procurement may define a risk subgroup among very-old deceased kidney donors, in whom pre-implantatory biopsies, dual kidney transplantation or calcineurin inhibitor-free immunosuppressive regimen could help to improve outcomes.

[Very-old deceased donors in kidney transplantation: How far can we go?]

In order to increase the pool of organ donors, kidney transplantation from very old-donors, notably aged more than 70, is increasing. Compared to the United States, where the use of these grafts does not reach 5%, in France it reaches over 20%. Kidney aging is determined by a progressive glomerusclerosis, interstitial fibrosis, and nephrosclerosis, responsible of a linear decrease of glomerular filtration rate with time. Aging in kidney transplantation goes along also with an increased immunogenicity and risk of ischemia-reperfusion injuries. Hence, the prognosis of these transplantations is worse than those from younger donors, even though it remains better than dialysis. Data is lacking on risk factors of graft loss in this specific population. Hypothermic perfusion machine, pre-implantation kidney biopsy, dual kidney transplantation and immunosuppressive strategies have been evaluated to improve the long-term prognosis of these grafts.

Outcomes and implications of a single brain death examination policy on organ donation outcomes at a high-volume trauma center

BACKGROUND

Despite current neurological guidelines that a single brain death examination (SBDE) is sufficient to determine brain death, a vast majority of hospitals still use a two brain death examination (TBDE) policy based on historical practice. The purpose of this study was to analyze the outcomes and implications of an SBDE policy compared with a TBDE policy with respect to organ donation outcomes.

METHODS

We retrospectively reviewed all adult patients declared dead by neurological criteria between 2010 and 2018 at a high-volume trauma center. The study population was divided into SBDE and TBDE cohorts. Primary outcomes included time to organ donation, terminal donor creatinine and bilirubin, and number of procured and transplanted organs.

RESULTS

A total of 327 patients comprised the study population: 66.7% SBDE (n = 218 of 327 patients) and 33.3% TBDE (n = 109 of 327 patients). The SBDE group had a shorter median time from examination to procurement (38 vs. 44 hours, p = 0.02) as well as lower terminal donor creatinine (1.1 vs. 1.35 mg/dL, p = 0.004) and bilirubin (0.8 vs. 1.1 mg/dL, p = 0.04). Furthermore, the SBDE group had a significantly greater proportion of kidneys (90.6% vs. 81.6%, p = 0.02), lungs (11.8% vs. 4.6%, p = 0.02), and total organs (58.2% vs. 46.6%; p = 0.0001) procured with intent to transplant and a greater proportion of total organs transplanted (53.1% vs. 42.4%, p = 0.0004). Multivariable regression analysis confirmed that SBDE was independently associated with a shorter time to procurement, lower terminal creatinine, and increased number of procured organs.

CONCLUSION

These data highlight the potential benefit of an SBDE policy with regards to organ donation outcomes at a high-volume trauma center and should facilitate future randomized prospective studies to more rigorously test this hypothesis.

LEVEL OF EVIDENCE

Therapeutic/Care Management, level IV.

Mechanisms and clinical applications of immunosuppressive medications

Immunosuppressive medications and regimens have evolved with significant advancements in the understanding of the immunologic process after solid organ transplantation. Medications can block the communication between antigen-presenting cells and T-cells, the activation and proliferation of T-cells, antibody production by plasma cells, and the activation of the complement system by antibodies. T-cell depleting antibodies and interleukin-2 receptor blockers are commonly used during induction therapy. Calcineurin inhibitors, antimetabolites, antiproliferative agents, and corticosteroids are commonly used in maintenance therapy regimens. These medications decrease the rates of rejection episodes and markedly increase the survival rates of short-term grafts. However, in terms of the survival rate of long-term grafts, there is still room for improvement. Opportunistic infections, development of cancer, metabolic diseases, and calcineurin inhibitor toxicity are hurdles in the improvement in survival rates of long-term grafts. Therefore, many efforts are being taken to overcome these hurdles, such as the development of new drugs, individualization of immunosuppression, and induction of immune tolerance.

Belatacept-based immunosuppression: A calcineurin inhibitor-sparing regimen in heart transplant recipients

Belatacept (BTC) is indicated for prophylaxis of graft rejection in adults receiving a renal transplant (Tx). This retrospective observational study (three centers) included all heart transplant recipients receiving BTC between January 2014 and October 2018. Forty EBV+ patients mean GFR 35 ± 20 mL/min/m² were identified, among whom belatacept was initiated during the first 3 months after transplantation in 12 patients, and later in 28 patients. Several patients were multiorgan transplant recipients. Study outcomes were GFR, safety, and changes in immunosuppressive therapy. The main reason for switching to BTC was to preserve renal function, resulting in discontinuation of CNI and changes in immunosuppressive therapy in 76% of cases. At study closeout, 24/40 patients were still on BTC therapy. GFR was improved (+59%, P = .0002*) within 1 month, particularly in the early group. More episodes of rejection were observed among "late" patients (1 death). Sixteen treatment discontinuations were recorded: GFR recovery (n = 4), DSA no longer detectable (n = 1), compliance issues (n = 3), poor venous access (n = 2), multiple infections (n = 1), 1 death (fungal lung infection), and treatment failure (n = 4). Median follow-up was 24 months. Four patients developed de novo DSA (MFI<1500). BTC is an effective alternative immunosuppressive for postoperative transient kidney failure, stabilizing delayed renal function, with acceptable safety profile under careful monitoring.

Efficacy and Safety of Belatacept Treatment in Renal Allograft Recipients at High Cardiovascular Risk-A Single Center Experience

Belatacept is an attractive option for immunosuppression after renal transplantation. Renal allograft function is superior when compared to calcineurin inhibitor (CNI) based therapy in “de novo” treated patients and it has also been proposed that individuals at high cardiovascular (CV) risk may benefit most. In this retrospective cohort study, we assessed the efficacy and safety of treating patients at high cardiovascular risk with Belatacept (n = 34, for 1194 observation months) when compared to a matched control group of 150 individuals under CNI immunosuppression (for 7309 months of observation). The estimated glomerular filtration rate (eGFR) increased for patients taking Belatacept but decreased during CNI-based therapy (+2.60 vs. −0.89 mL/min/1.73 m²/year, p = 0.006). In a multivariate Cox regression model, Belatacept remained the only significant factor associated with the improvement of eGFR (HR 4.35, 95%CI 2.39–7.93). Belatacept treatment was not a significant risk factor for renal allograft rejection or graft loss. In terms of safety, the only significant risk factor for de novo cardiovascular events was a pre-existing cerebrovascular disease, but Belatacept was not associated with a significant risk reduction. Belatacept treatment was not associated with an increased risk of severe infections, cytomegalo virus (CMV) or BK-virus reactivation, malignancy or death in the multivariate Cox regression analysis. Belatacept is an efficient and safe option for patients after renal transplantation at high cardiovascular risk.

[Focusing on kidney transplantation in the elderly]

Due to the increase in life expectancy and the ageing of end-stage renal disease patients, the number of patients older than 65 years receiving a kidney transplant has been continuously growing over the last fifteen years. The benefits of renal transplantation compared to dialysis in terms of survival and quality of life have been shown in selected recipients over 65, or 70 years. However, the age remains the main limiting factor for the access to the waiting list, and the reluctance of the clinicians can be explained by the multiple comorbidities of these candidates, their limited life expectancy or the shortage of grafts. The challenge is to select the candidates who can benefit from renal transplantation, thanks to rigorous cardiovascular and neoplastic evaluation before enrolment and by taking into account the specific characteristics of elderly patients. The living donor appears to be the ideal option for elderly recipients, the alternative being the extended criteria donor, allowing waiting times to be limited. The choice of immunosuppressive therapy is also crucial in these patients at high risk of infectious and cardiovascular complications in whom the occurrence of acute rejection can have severe consequences. There are currently no specific recommendations for immunosuppression in elderly recipients, and we would need large-scale randomized studies to improve the prognosis of renal transplantation in this population.

Successful Treatment of T Cell-Mediated Acute Rejection with Delayed CTLA4-Ig in Mice

Clinical observations that kidney transplant recipients receiving belatacept who experienced T cell-mediated acute rejection can be successfully treated and subsequently maintained on belatacept-based immunosuppression suggest that belatacept is able to control memory T cells. We recently reported that treatment with CTLA4-Ig from day 6 posttransplantation successfully rescues allografts from acute rejection in a BALB/c to C57BL/6 heart transplant model, in part, by abolishing B cell germinal centers and reducing alloantibody titers. Here, we show that CTLA4-Ig is additionally able to inhibit established T cell responses independently of B cells. CTLA4-Ig inhibited the in vivo cytolytic activity of donor-specific CD8⁺ T cells, and the production of IFNγ by graft-infiltrating T cells. Delayed CTLA4-Ig treatment did not reduce the numbers of graft-infiltrating T cells nor prevented the accumulation of antigen-experienced donor-specific memory T cells in the spleen. Nevertheless, delayed CTLA4-Ig treatment successfully maintained long-term graft acceptance in the majority of recipients that had experienced a rejection crisis, and enabled the acceptance of secondary BALB/c heart grafts transplanted 30 days after the first transplantation. In summary, we conclude that delayed CTLA4-Ig treatment is able to partially halt ongoing T cell-mediated acute rejection. These findings extend the functional efficacy of CTLA4-Ig therapy to effector T cells and provide an explanation for why CTLA4-Ig-based immunosuppression in the clinic successfully maintains long-term graft survival after T cell-mediated rejection.

Chemotherapy and Transplantation: The Role of Immunosuppression in Malignancy and a Review of Antineoplastic Agents in Solid Organ Transplant Recipients

It is estimated that solid organ transplant recipients have a two- to fourfold greater overall risk of malignancy than the general population. Some of the most common malignancies after transplant include skin cancers and posttransplant lymphoproliferative disorder. In addition to known risk factors such as environmental exposures, genetics, and infection with oncogenic viruses, immunosuppression plays a large role in the development of cancer through the loss of the immunosurveillance process. The purpose of this article is to explain the role of immunosuppression in cancer and to review the classes of chemotherapeutics. The field of anticancer drugs is continually expanding and developing, with limited data on use in transplant recipients. This article aims to provide information on class review, adverse effects, dose adjustments, and drug interactions that are pertinent to the care of transplant recipients.

Fc-Silent Anti-CD154 Domain Antibody Effectively Prevents Nonhuman Primate Renal Allograft Rejection

The advent of costimulation blockade provides the prospect for targeted therapy with improved graft survival in transplant patients. Perhaps the most effective costimulation blockade in experimental models is the use of reagents to block the CD40/CD154 pathway. Unfortunately, successful clinical translation of anti-CD154 therapy has not been achieved. In an attempt to develop an agent that is as effective as previous CD154 blocking antibodies but lacks the risk of thromboembolism, we evaluated the efficacy and safety of a novel anti-human CD154 domain antibody (dAb, BMS-986004). The anti-CD154 dAb effectively blocked CD40-CD154 interactions but lacked crystallizable fragment (Fc) binding activity and resultant platelet activation. In a nonhuman primate kidney transplant model, anti-CD154 dAb was safe and efficacious, significantly prolonging allograft survival without evidence of thromboembolism (Median survival time 103 days). The combination of anti-CD154 dAb and conventional immunosuppression synergized to effectively control allograft rejection (Median survival time 397 days). Furthermore, anti-CD154 dAb treatment increased the frequency of CD4⁺ CD25⁺ Foxp3⁺ regulatory T cells. This study demonstrates that the use of a novel anti-CD154 dAb that lacks Fc binding activity is safe without evidence of thromboembolism and is equally as potent as previous anti-CD154 agents at prolonging renal allograft survival in a nonhuman primate preclinical model.

Glomerular Diseases and Renal Transplantation: Pathogenic Pathways and Evolution of Therapeutic Interventions

Glomerular diseases and renal transplantation are the main fields of nephrology in which the immune system plays a prevalent role. Glomerular diseases have traditionally been attributed to auto-immune conditions, whereas allograft rejection has been considered an allo-immune response. However, common immunopathologic mechanisms that include Toll-like receptors, complement and B-cell activation, as well as genetic and infectious factors appear to be involved in the pathogenesis of both entities. Novel therapeutic regimens directed against specific targets of the immune system show promising results in glomerulopathies as well as in renal transplantation.

Efficacy and Safety Outcomes of Extended Criteria Donor Kidneys by Subtype: Subgroup Analysis of BENEFIT-EXT at 7 Years After Transplant

The phase III Belatacept Evaluation of Nephroprotection and Efficacy as First-Line Immunosuppression Trial-Extended Criteria Donors Trial (BENEFIT-EXT) study compared more or less intensive belatacept-based immunosuppression with cyclosporine (CsA)-based immunosuppression in recipients of extended criteria donor kidneys. In this post hoc analysis, patient outcomes were assessed according to donor kidney subtype. In total, 68.9% of patients received an expanded criteria donor kidney (United Network for Organ Sharing definition), 10.1% received a donation after cardiac death kidney, and 21.0% received a kidney with an anticipated cold ischemic time ≥24 h. Over 7 years, time to death or graft loss was similar between belatacept- and CsA-based immunosuppression, regardless of donor kidney subtype. In all three donor kidney cohorts, estimated mean GFR increased over months 1-84 for belatacept-based treatment but declined for CsA-based treatment. The estimated differences in GFR significantly favored each belatacept-based regimen versus the CsA-based regimen in the three subgroups (p < 0.0001 for overall treatment effect). No differences in the safety profile of belatacept were observed by donor kidney subtype.