Optimization of de novo belatacept-based immunosuppression administered to renal transplant recipients

International consensus on post-transplantation diabetes mellitus

Post-transplantation diabetes mellitus (PTDM) remains a leading complication after solid organ transplantation. Previous international PTDM consensus meetings in 2003 and 2013 provided standardized frameworks to reduce heterogeneity in diagnosis, risk stratification and management. However, the last decade has seen significant advancements in our PTDM knowledge complemented by rapidly changing treatment algorithms for management of diabetes in the general population. In view of these developments, and to ensure reduced variation in clinical practice, a 3rd international PTDM Consensus Meeting was planned and held from 6-8 May 2022 in Vienna, Austria involving global delegates with PTDM expertise to update the previous reports. This update includes opinion statements concerning optimal diagnostic tools, recognition of prediabetes (impaired fasting glucose and/or impaired glucose tolerance), new mechanistic insights, immunosuppression modification, evidence-based strategies to prevent PTDM, treatment hierarchy for incorporating novel glucose-lowering agents and suggestions for the future direction of PTDM research to address unmet needs. Due to the paucity of good quality evidence, consensus meeting participants agreed that making GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) recommendations would be flawed. Although kidney-allograft centric, we suggest that these opinion statements can be appraised by the transplantation community for implementation across different solid organ transplant cohorts. Acknowledging the paucity of published literature, this report reflects consensus expert opinion. Attaining evidence is desirable to ensure establishment of optimized care for any solid organ transplant recipient at risk of, or who develops, PTDM as we strive to improve long-term outcomes.

Costimulatory Blockade and Solid Organ Transplantation: The Past, Present, and Future

Belatacept is the first costimulatory blockade agent clinically approved for transplant immunosuppression. Although more than 10 years of study have demonstrated that belatacept offers superior long-term renal allograft and patient survival compared to conventional calcineurin inhibitor (CNI)-based immunosuppression regimens, the clinical adoption of belatacept has continued to lag because of concerns of an early risk of acute cellular rejection (ACR) and various logistical barriers to its administration. In this review, the history of the clinical development of belatacept is examined, along with the findings of the seminal BENEFIT and BENEFIT-EXT trials culminating in the clinical approval of belatacept. Recent efforts to incorporate belatacept into novel CNI-free immunosuppression regimens are reviewed, as well as the experience of the Emory Transplant Center in using a tapered course of low-dose tacrolimus in belatacept-treated renal allograft patients to garner the long-term outcome benefits of belatacept without the short-term increased risks of ACR. Potential avenues to increase the clinical adoption of belatacept in the future are explored, including surmounting the logistical barriers of belatacept administration through subcutaneous administration or more infrequent belatacept dosing. In addition, belatacept conversion strategies and potential expanded clinical indications of belatacept are discussed for pediatric transplant recipients, extrarenal transplant recipients, treatment of antibody-mediated rejection (AMR), and in patients with failed renal allografts. Finally, we discuss the novel immunosuppressive drugs currently in the development pipeline that may aid in the expansion of costimulation blockade utilization.

Outcomes With Belatacept Exposure During Pregnancy in Kidney Transplant Recipients: A Case Series

BACKGROUND

Posttransplant fertility returns quickly, and female recipients of child-bearing age may conceive while on immunosuppression. However, pregnancy after transplantation confers risks to the recipient, transplant, and fetus, including gestational hypertension, preeclampsia, gestational diabetes, transplant dysfunction, preterm labor, and low birthweight infants. Additionally, mycophenolic acid (MPA) products are teratogenic. Literature evidence regarding belatacept, a selective T-cell costimulation blocker, during pregnancy and while breastfeeding is extremely limited. When female transplant recipients on a belatacept-based regimen are desirous of pregnancy or at the time of conception, transplant providers manage the immunosuppression regimen in 1 of 2 ways: (1) switch both belatacept and MPA to a calcineurin inhibitor-based regimen with or without azathioprine, which is the more common practice but requires several modifications, having potential negative outcomes; or (2) only switch MPA to azathioprine while continuing belatacept.

METHODS

This case series includes 16 pregnancies in 12 recipients with exposure to belatacept throughout pregnancy and while breastfeeding. Patient information was obtained from several sources, including Transplant Pregnancy Registry International, providers at Emory University, and Columbia University, as well as literature review.

RESULTS

Pregnancy outcomes included 13 live births and 3 miscarriages. No birth defects or fetal deaths were reported in any of the live births. Seven infants were breastfed while their mothers continued belatacept. Outcomes appear comparable to those documented with the administration of calcineurin inhibitors.

CONCLUSIONS

This case series provides data supporting the continued administration of belatacept during pregnancy. Additional research will assist in developing better guidelines to counsel female transplant recipients on belatacept desiring to pursue pregnancy.

Desensitization and belatacept-based maintenance therapy in pregnancy-sensitized monkeys receiving a kidney transplant

Among sensitized patients awaiting a transplant, females are disproportionately represented, partly because of pregnancy-induced sensitization. Using female NHPs sensitized by pregnancy alone, we examined the efficacy of costimulation blockade and proteasome inhibition for desensitization. Three animals received no desensitization (control), and seven animals received weekly carfilzomib (27 mg/m2) and belatacept (20 mg/kg) before kidney transplantation. All animals received renal allografts from crossmatch-positive/maximally MHC-mismatched donors. Controls and three desensitized animals received tacrolimus-based immunosuppression. Four desensitized animals received additional belatacept with tacrolimus-based immunosuppression. Multiparous females had less circulating donor-specific antibody when compared to skin-sensitized males before transplantation. While females receiving desensitization showed only a marginal survival benefit over control females (MST = 11 days versus 63 days), additional belatacept to posttransplant maintenance significantly prolonged graft survival (MST > 164 days) and suppressed posttransplant DSA and circulating follicular helper T-like cells. This combination of therapies demonstrates great potential to reduce antibody-mediated rejection in sensitized recipients.

mTOR Inhibition Impairs the Activation and Function of Belatacept-Resistant CD4+CD57+ T Cells In Vivo and In Vitro

Calcineurin inhibitors have improved graft survival in solid-organ transplantation but their use is limited by toxicity, requiring a switch to another immunosuppressor in some cases. Belatacept is one option that has been shown to improve graft and patient survival despite being associated with a higher risk of acute cellular rejection. This risk of acute cellular rejection is correlated with the presence of belatacept-resistant T cells. We performed a transcriptomic analysis of in vitro-activated cells to identify pathways affected by belatacept in belatacept-sensitive cells (CD4⁺CD57^-) but not in belatacept-resistant CD4⁺CD57⁺ T cells. mTOR was significantly downregulated in belatacept-sensitive but not belatacept-resistant T cells. The inhibition of mTOR strongly decreases the activation and cytotoxicity of CD4⁺CD57⁺ cells. In humans, the use of a combination of mTOR inhibitor and belatacept prevents graft rejection and decreases the expression of activation markers on CD4 and CD8 T cells. mTOR inhibition decreases the functioning of belatacept-resistant CD4⁺CD57⁺ T cells in vitro and in vivo. It could potentially be used in association with belatacept to prevent acute cellular rejection in cases of calcineurin intolerance.

Three-year Outcomes After Conversion From Monthly to Every 2-month Belatacept Maintenance Therapy in Kidney Transplant Recipients: Results From a Randomized Controlled Trial

Maintenance immunosuppression with belatacept following kidney transplantation results in improved long-term graft function as compared with calcineurin inhibitors. However, broad application of belatacept has been limited, in part related to logistical barriers surrounding a monthly (q1m) infusion requirement.

Methods

To determine whether every 2-mo (q2m) belatacept is noninferior to standard q1m maintenance, we conducted a prospective, single-center randomized trial in low-immunologic-risk, stable renal transplant recipients. Here, post hoc analysis of 3-y outcomes, including renal function and adverse events, are reported.

Results

One hundred sixty-three patients received treatment in the q1m control group (n = 82) or q2m study group (n = 81). Renal allograft function as measured by baseline-adjusted estimated glomerular filtration rate was not significantly different between groups (time-averaged mean difference of 0.2 mL/min/1.73 m²; 95% confidence interval: -2.5, 2.9). There were no statistically significant differences in time to death or graft loss, freedom from rejection, or freedom from donor-specific antibodies (DSAs). During the extended 12- to 36-mo follow-up, 3 deaths, 1 graft loss occurred in the q1m group, compared with 2 deaths, and 2 graft losses in the q2m group. In the q1m group, 1 patient developed DSAs and acute rejection. In the q2m group, 3 patients developed DSAs and 2 associated with acute rejection.

Conclusions

Based on the similar renal function and survival at 36 mo compared with q1m, q2m belatacept is a potentially viable maintenance immunosuppressive strategy in low immunologic risk kidney transplant recipients that may facilitate increased clinical utilization of costimulation blockade-based immunosuppression.

Impact of belatacept and tacrolimus on cytomegalovirus viral load control and relapse in moderate and high-risk cytomegalovirus serostatus kidney transplant recipients

BACKGROUND

Belatacept improves long-term graft survival, but control of some primary viral infections may be impaired. We evaluated the impact of belatacept and tacrolimus on cytomegalovirus (CMV) viral control, remission and relapse in CMV high-risk and moderate-risk recipients.

METHODS

Using a multistate Markov model, we evaluated viral load state transitions of 173 kidney transplant recipients with at least one episode of viremia within 1 year after transplant: state 1, undetectable/low viral load; state 2, moderate viremia; and state 3, severe viremia.

RESULTS

Among high-risk recipients, belatacept-treated recipients exhibited a significantly higher probability of entering moderate viremia (.36; 95% CI = .31, .41) than tacrolimus-treated recipients (.20; 95% CI = .13, .29). The expected number of days in viremic states differed. High-risk belatacept-treated recipients persisted in moderate viremia for significantly longer (128 days, 95% CI = 110, 146) than did tacrolimus-treated recipients (70.0 days, 95% CI = 45.2, 100) and showed a trend of shorter duration in low/undetectable viral load state (172 days, 95% CI = 148, 195) than did tacrolimus-treated recipients (239 days, 95% CI = 195, 277). Moderate-risk recipients showed better viral load control and with no differences by immunosuppression.

CONCLUSION

High-risk belatacept-treated recipients showed defects in sustaining viral control relative to tacrolimus-treated recipients. Avoidance of initial use belatacept in high-risk recipients or development of modified management protocols should be considered.

New immunosuppressive agents in transplantation

Immunosuppressive agents have enabled the development of allogenic transplantation during the last 40 years, allowing considerable improvement in graft survival. However, several issues remain such as the nephrotoxicity of calcineurin inhibitors, the cornerstone of immunosuppressive regimens and/or the higher risk of opportunistic infections and cancers. Most immunosuppressive agents target T cell activation and may not be efficient enough to prevent allo-immunization in the long term. Finally, antibody mediated rejection due to donor specific antibodies strongly affects allograft survival. Many drugs have been tested in the last decades, but very few have come to clinical use. The most recent one is CTLA4-Ig (belatacept), a costimulation blockade molecule that targets the second signal of T cell activation and is associated with a better long term kidney function than calcineurin inhibitors, despite an increased risk of acute cellular rejection. The research of new maintenance long-term immunosuppressive agents focuses on costimulation blockade. Agents inhibiting CD40-CD40 ligand interaction may enable a good control of both T cells and B cells responses. Anti-CD28 antibodies may promote regulatory T cells. Agents targeting this costimulation pathways are currently evaluated in clinical trials. Immunosuppressive agents for ABMR treatment are scarce since anti-CD20 agent rituximab and proteasome inhibitor bortezomib have failed to demonstrate an interest in ABMR. New drugs focusing on antibodies removal (imlifidase), B cell and plasmablasts (anti-IL-6/IL-6R, anti-CD38…) and complement inhibition are in the pipeline, with the challenge of their evaluation in such a heterogeneous pathology.

Preservation of Antiviral Immunologic Efficacy Without Alloimmunity After Switch to Belatacept in Calcineurin Inhibitor-Intolerant Patients

Introduction

Belatacept has shown potential for prevention of rejection after kidney transplantation, given its demonstration of reduced nephrotoxicity in combination with absence of significant incidence of rejection. However, concerns have been raised regarding increased risk of viral infection.

Methods

We set out to explore the impact of the switch to belatacept on alloimmune and antiviral immunity through the study of patients switched from calcineurin inhibitor (CNI) to belatacept within 3 months of kidney transplantation compared with a matched cohort of control patients on a CNI-based regimen.

Results

After the switch to belatacept, immune phenotyping demonstrated a decrease in naive and an increase in terminally differentiated effector memory (TMRA) T cells, with no significant difference compared with control patients. Donor-specific immune response, measured by intracellular cytokine staining (ICS), did not change significantly either by single or double cytokine secretion, but it was associated with the appearance of donor-specific antibody (DSA) in the control but not the belatacept cohort (P = 0.039 for naive and P = 0.002 for TMRA subtypes). Increased incidence of de novo DSA development was observed in the control group (P = 0.035). Virus-specific immune response, as measured by ICS in response to cytomegalovirus (CMV) or Epstein-Barr virus (EBV), was similar in both groups and stable over time.

Conclusion

We found that belatacept use was associated with an absence of alloreactivity without impact on immune phenotype, while preserving the antiviral immune response, for patients switched from a CNI-based regimen. In parallel, the antiviral immune response against CMV and EBV was preserved after the belatacept switch (clinicaltrials.gov: NCT01953120).

Delayed Graft Function in Kidney Transplant: Risk Factors, Consequences and Prevention Strategies

Background. Delayed graft function is a frequent complication of kidney transplantation that requires dialysis in the first week posttransplant. Materials and Methods. We searched for the most relevant articles in the National Institutes of Health library of medicine, as well as in transplantation, pharmacologic, and nephrological journals. Results. The main factors that may influence the development of delayed graft function (DGF) are ischemia–reperfusion injury, the source and the quality of the donated kidney, and the clinical management of the recipient. The pathophysiology of ischemia–reperfusion injury is complex and involves kidney hypoxia related to the duration of warm and cold ischemia, as well as the harmful effects of blood reperfusion on tubular epithelial cells and endothelial cells. Ischemia–reperfusion injury is more frequent and severe in kidneys from deceased donors than in those from living donors. Of great importance is the quality and function of the donated kidney. Kidneys from living donors and those with normal function can provide better results. In the peri-operative management of the recipient, great attention should be paid to hemodynamic stability and blood pressure; nephrotoxic medicaments should be avoided. Over time, patients with DGF may present lower graft function and survival compared to transplant recipients without DGF. Maladaptation repair, mitochondrial dysfunction, and acute rejection may explain the worse long-term outcome in patients with DGF. Many different strategies meant to prevent DGF have been evaluated, but only prolonged perfusion of dopamine and hypothermic machine perfusion have proven to be of some benefit. Whenever possible, a preemptive transplant from living donor should be preferred.

Harnessing the B Cell Response in Kidney Transplantation - Current State and Future Directions

Despite dramatic improvement in kidney transplantation outcomes over the last decades due to advent of modern immunosuppressive agents, long-term outcomes remain poor. Antibody-mediated rejection (ABMR), a B cell driven process, accounts for the majority of chronic graft failures. There are currently no FDA-approved regimens for ABMR; however, several clinical trials are currently on-going. In this review, we present current mechanisms of B cell response in kidney transplantation, the clinical impact of sensitization and ABMR, the B cell response under current immunosuppressive regimens, and ongoing clinical trials for ABMR and desensitization treatment.

Detecting, preventing, and treating non-adherence to immunosuppression after kidney transplantation

Medication non-adherence (MNA) is a major issue in kidney transplantation and it is associated with increased risk of rejection, allograft loss, patients’ death and higher healthcare costs. Despite its crucial importance, it is still unclear what are the best strategies to diagnose, prevent and treat MNA. MNA can be intentional (deliberate refusal to take the medication as prescribed) or unintentional (non-deliberate missing the prescribed medication). Its diagnosis may rely on direct methods, aiming at measuring drug ingestions, or indirect methods that analyse the habits of patients to adhere to correct drug dose (taking adherence) and interval (time adherence). Identifying individual risk factors for MNA may provide the basis for a personalized approach to the treatment of MNA. Randomized control trials performed so far have tested a combination of strategies, such as enhancing medication adherence through the commitment of healthcare personnel involved in drug distribution, the use of electronic reminders, therapy simplification or various multidisciplinary approaches to maximize the correction of individual risk factors. Although most of these approaches reduced MNA in the short-term, the long-term effects on MNA and, more importantly, on clinical outcomes remain unclear. In this review, we provide a critical appraisal of traditional and newer methods for detecting, preventing and treating non-adherence to immunosuppression after kidney transplantation from the perspective of the practising physician.

Belatacept Conversion in Kidney After Liver Transplantation

Background.

Costimulatory blockade with belatacept has demonstrated long-term benefits in renal transplantation, but de novo use in liver transplant recipients has resulted in increased rejection, graft loss, and death. However, belatacept conversion as a calcineurin inhibitor (CNI) avoidance strategy has not been studied and may be of benefit in liver transplantation where CNI-induced renal dysfunction and toxicity are barriers to improved outcomes.

Methods.

Using clinical data extracted from our institutional medical record, we report on 8 patients who underwent kidney after liver transplantation and were treated with belatacept-based immunosuppression and transient CNI therapy.

Results.

All patients tolerated belatacept therapy without any patient deaths or graft losses. No episodes of rejection, de novo donor-specific antibody formation, or major systemic infections were observed, and all patients demonstrated preserved liver and excellent renal allograft function. Patients received belatacept for a median duration of 13.2 mo, and at a median follow-up of 15.9 mo post–kidney transplant, 6 of 8 patients continued on belatacept with 3 completely off and 3 poised to transition off CNI.

Conclusions.

These findings are the first evidence that in liver transplant recipients requiring subsequent kidney transplantation, belatacept-based therapy can potentially facilitate CNI-free maintenance immunosuppression. This supports the possibility of belatacept conversion in stand-alone liver transplant recipients as a viable method of CNI avoidance.

Benefit of Belatacept in Cord Blood-Derived Regulatory T Cell-Mediated Suppression of Alloimmune Response

The role of Regulatory T cells (Tregs) in tolerance induction post-transplantation is well-established, but Tregs adoptive transfer alone without combined immunosuppressants have failed so far in achieving clinical outcomes. Here we applied a set of well-designed criteria to test the influence of commonly used immunosuppressants (belatacept, tacrolimus, and mycophenolate) on cord blood-derived Tregs (CB-Tregs). Our study shows that while none of these immunosuppressants modulated the stability and expression of homing molecules by CB-Tregs, belatacept met all other selective criteria, shown by its ability to enhance CB-Tregs-mediated in vitro suppression of the allogeneic response without affecting their viability, proliferation, mitochondrial metabolism and expression of functional markers. In contrast, treatment with tacrolimus or mycophenolate led to reduced expression of functional molecule GITR in CB-Tregs, impaired their viability, proliferation and mitochondrial metabolism. These findings indicate that belatacept could be considered as a candidate in Tregs-based clinical immunomodulation regimens to induce transplant tolerance.