Belatacept Rescue Therapy in Kidney Transplant Recipients With Vascular Lesions: A Case Control Study

Immunosuppression in Kidney Transplant Recipients: An Update for the General Nephrologist

Over the last 7 decades, kidney transplantation has evolved from an experiment between identical twins to becoming the gold standard treatment for end-stage kidney disease. To date, mycophenolate and calcineurin inhibitors, with or without prednisone, continue to constitute the backbone of modern maintenance immunosuppression. Despite major strides in improving acute rejection, long-term outcomes remain suboptimal with current regimens. Alternatives to calcineurin inhibitors such as belatacept and mammalian targets of rapamycin inhibitors exist; however, their wider-scale adoption remains relatively delayed due to concerns about increased rejection rates. In addition to continuing the investigation of steroid and calcineurin inhibitor sparing protocols, it is time to identify measurable surrogates for meaningful long-term graft survival. iBOX, a dynamic risk-prediction tool that predicts long-term death-censored graft failure could be a potential surrogate end point for future immunosuppression clinical trials. In this review, we summarize the landmark studies supporting current immunosuppression protocols and briefly discuss challenges and future directions.

Belatacept rescue conversion in kidney transplant recipients with vascular lesions (Banff cv score >2): a retrospective cohort study

BACKGROUND

Immunosuppression in kidney transplant recipients with decreased graft function and histological vascular changes can be particularly challenging. The impact of a late rescue conversion to belatacept on kidney graft survival in this context has never been studied.

METHODS

We report a bicentric retrospective cohort study comparing a calcineurin inhibitor (CNI) to belatacept switch versus CNI continuation in 139 kidney transplant recipients with histological kidney vascular damage (cv ≥2, g + cpt ≤1, i + t ≤1) and low estimated glomerular filtration rate (≤40 mL/min/1.73 m²). Primary outcome was death-censored graft survival.

RESULTS

During the study follow-up, 10 graft losses (14.5%) occurred in the belatacept group (n = 69) versus 26 (37.1%) in the matched CNI group (n = 70) (P = .005). Death-censored graft survival was significantly higher in the belatacept group (P = .001). At 3 years, graft survival was 84.0% in the belatacept group compared with 65.1% in the control group. Continuing CNI was an independent risk factor for graft loss [hazard ratio (HR) 3.46; P < .005]. The incidence of cellular rejection after the conversion was low (4.3% in both groups) and not significantly different between groups (P = .84). Patients switched to belatacept developed significantly less donor-specific antibodies de novo. Belatacept was an independent risk factor for the occurrence of opportunistic infections (HR 4.84; P < .005).

CONCLUSION

The replacement of CNI with belatacept in patients with decreased allograft function and vascular lesions is associated with an improvement in graft survival and represents a valuable option in a context of organ shortage. Caution should be exercised regarding the increased risk of opportunistic infection.

CD86 occupancy in belatacept-treated kidney transplant patients is not associated with clinical and infectious outcomes

The CD86 occupancy assay has been developed to measure the number of CD86 molecules unbound to belatacept, but its association with clinical outcomes has not been assessed yet. All kidney transplant patients switched to belatacept in our center between 2016 and 2018 were included. Blood samples were collected before each infusion for 1 year to assess CD86 occupancy by CD86 antibody cytometry staining on the surface of CD14⁺ monocytes. Results were expressed as the median fluorescence intensity (MFI) value of CD86 staining. At each infusion, the MFI_{Day of infusion} /MFI_{Day 0} ratio was calculated. Forty-one patients were consecutively included. After every 2-week infusion period, CD86 MFI ratio dropped from 1.00 to 0.73 [0.57-0.98], p = .07. However, this ratio progressively increased to 0.78 [0.53-1.13] at 1 year, which was not statistically different from pre-switch ratio, p = .4. Over the first year, the MFI ratio coefficient of variation was 31.58% [23.75-38.31]. MFI ratio was not different between patients with or without opportunistic infections: 0.73 [0.60-0.88] versus 0.80 [0.71-1.00], p = .2, or between patients with or without EBV DNAemia, p = .2. Despite previous in vitro results, the CD86 occupancy assay suffers from a high intra-individual variability and does not appear to be relevant to clinical outcomes.

Three-Year Outcomes in Kidney Transplant Recipients Switched From Calcineurin Inhibitor-Based Regimens to Belatacept as a Rescue Therapy

Background: The long-term benefits of conversion from calcineurin inhibitors (CNIs) to belatacept in kidney transplant recipients (KTr) are poorly documented.

Methods: A single-center retrospective work to study first-time CNI to belatacept conversion as a rescue therapy [eGFR <30 ml/min/1.73 m², chronic histological lesions, or CNI-induced thrombotic microangiopathy (TMA)]. Patient and kidney allograft survivals, eGFR, severe adverse events, donor-specific antibodies (DSA), and histological data were recorded over 36 months after conversion.

Results: We included N = 115 KTr. The leading cause for switching was chronic histological lesions with non-optimal eGFR (56.5%). Three years after conversion, patient, and death-censored kidney allograft survivals were 88% and 92%, respectively, eGFR increased significantly from 31.5 ± 17.5 to 36.7 ± 15.7 ml/min/1.73 m² (p < 0.01), the rejection rate was 10.4%, OI incidence was 5.2 (2.9–7.6) per 100 person-years. Older age was associated with death, eGFR was not associated with death nor allograft loss. No patient developed dnDSA at M36 after conversion. CNI-induced TMA disappeared in all cases without eculizumab use. Microvascular inflammation and chronic lesions remained stable.

Conclusion: Post-KT conversion from CNIs to belatacept, as rescue therapy, is safe and beneficial irrespective of the switch timing and could represent a good compromise facing organ shortage. Age and eGFR at conversion should be considered in the decision whether to switch.

Temporal trends and current use of de novo belatacept in kidney transplant recipients in the United States

The adoption of de novo belatacept in kidney transplant (kTx) recipients was hampered by an increased risk of acute cellular rejection (ACR) with variation in adopted belatacept based immunosuppressive therapies across centers. We used data from the Scientific Registry of Transplant Recipients (SRTR) to evaluate the temporal trends in belatacept use and describe the associated induction and maintenance regimens in US adult kTx recipients transplanted between June 2011 and December 2018. The number of patients receiving de novo-belatacept based immunosuppressive therapy increased from .74% in 2011 to 3.11% in 2016. In 2016, 66/207 centers used de novo belatacept-based regimen with 3.03% using it in over 50% of their patients. The use of T-cell depleting agents increased with time. Since 2012, the rate of calcineurin inhibitor (CNI) use in combination with belatacept remained stable around 50% and ∼30% remained under belatacept/CNI combination at 1-year post-transplantation. The adoption of belatacept as de novo immunosuppressive regimen has been slow and its use remains low in the United States. Various regimens have been used to modulate the risk of ACR. Further studies evaluating the long-term outcomes of these regimens and assessing their safety especially with regard to the risk of infection are needed.

Belatacept-based immunosuppressive regimen in HIV-positive kidney transplant recipients

Background

Kidney allograft survival in human immunodeficiency virus (HIV)-positive patients is lower than that in the general population. Belatacept increases long-term patient and allograft survival rates when compared with calcineurin inhibitors (CNIs). Its use in HIV-positive recipients remains poorly documented.

Methods

We retrospectively report a French cohort of HIV-positive kidney allograft recipients who were switched from CNI to belatacept, between June 2012 and December 2018. Patient and allograft survival rates, HIV immunovirological and clinical outcomes, acute rejection, opportunistic infections (OIs) and HLA donor-specific antibodies (DSAs) were analysed at 3 and 12 months, and at the end of follow-up (last clinical visit attended after transplantation). Results were compared with HIV-positive recipients group treated with CNI.

Results

Twelve patients were switched to belatacept 10 (2–25) months after transplantation. One year after belatacept therapy, patient and allograft survival rates scored 92% for both, two (17%) HIV virological rebounds occurred due to antiretroviral therapy non-compliance, and CD4⁺ and CD8⁺ T-cell counts remained stable over time. Serious adverse events included two (17%) acute steroid-resistant T-cell-mediated rejections and three (25%) OIs. Kidney allograft function significantly increased over the 12 post-switch months (P = 0.009), and DSAs remained stable at 12 months after treatment. The control group showed similar results in terms of patient and kidney allograft survival rates, DSA characteristics and proteinuria

Conclusions

Switch from CNI to belatacept can be considered safe and may increase long-term kidney allograft survival in HIV-positive kidney allograft recipients. These results need to be confirmed in a larger cohort.

Opportunistic infections after conversion to belatacept in kidney transplantation

BACKGROUND

Belatacept (bela) rescue therapy seems to be a valuable option for calcineurin inhibitor chronic toxicity in kidney transplantation. Nevertheless, the risk of infection associated with bela is not well reported.

METHODS

We report the rate of opportunistic infections (OPI) after a switch to bela in a multicentric cohort of 280 kidney transplant patients.

RESULTS

Forty-two OPI occurred in 34 patients (12.1%), on average 10.8 ± 11.3 months after the switch. With a cumulative exposure of 5128 months of bela treatment, we found an incidence of 0.008 OPI/month of exposure, and 9.8 OPI/100 person-years. The most common OPI was cytomegalovirus (CMV) disease in 18/42 OPI (42.9%) and pneumocystis pneumonia in 12/42 OPI (28.6%). Two patients presented a progressive multifocal leucoencephalopathy and two patients developed a cerebral Epstein-Barr virus-induced post-transplant lymphoproliferative disease. OPI led to death in 9/34 patients (26.5%) and graft failure in 4/34 patients (11.8%). In multivariate analysis, estimated glomerular filtration rate <25/mL/min/1.73 m2 on the day of the switch and the use of immunosuppressive agents before transplantation were associated with the occurrence of OPI. We found a higher rate of infection-related hospitalization (24.1 versus 12.3/100 person-years, P = 0.0007) and also a higher rate of OPI (13.2 versus 6.7/100 person-years, P = 0.005) in the early conversion group (within 6 months).

CONCLUSIONS

The risk of OPI is significant post-conversion to bela and may require additional monitoring and prophylactic therapy, particularly regarding pneumocystis pneumonia and CMV disease. These data need to be confirmed in a larger case-control study.

Impact of belatacept conversion on kidney transplant function, histology, and gene expression - a single-center study

Prior studies on belatacept conversion from calcineurin inhibitor (CNI) have been limited by an absence of postconversion surveillance biopsies that could underestimate subclinical rejection, or a case-controlled design. A total of 53 adult patients with allograft dysfunction underwent belatacept conversion (median: 6 months) post-transplant. At a median follow-up = 2.5 years, patient survival was 94% with a death-censored graft survival of 85%. Seven (13%) patients had acute rejection (including 3 subclinical) at median 6 months postconversion. Overall, eGFR improved (P = <0.001) from baseline = 31±15 to 40.2 ± 17.6 ml/min/1.73m² by 6 months postconversion, but then stayed stable. This improvement was also observed (P < 0.001) in comparison with a propensity matched control cohort on CNI, where eGFR stayed stable (mean ~ 32ml/min/1.72m² ) over 2-year follow-up. Patients converted < 6 months post-transplant were more likely to have a long-term improvement in kidney function. Paired gene expression analysis of 30 (of 53) consecutive pre- and postconversion surveillance biopsies did not reveal changes in inflammation/acute injury; although atrophy-fibrosis score worsened (mean = 0.28 to 0.44; P = 0.005). Thus, improvement in renal function with belatacept conversion occurred early and then sustained in comparison with controls where renal function remained unchanged overtime. We were unable to show molecular signals that could be related to CNI administration and regressed after withdrawal.

Costimulation Blockade in Kidney Transplant Recipients

Costimulation between T cells and antigen-presenting cells is essential for the regulation of an effective alloimmune response and is not targeted with the conventional immunosuppressive therapy after kidney transplantation. Costimulation blockade therapy with biologicals allows precise targeting of the immune response but without non-immune adverse events. Multiple costimulation blockade approaches have been developed that inhibit the alloimmune response in kidney transplant recipients with varying degrees of success. Belatacept, an immunosuppressive drug that selectively targets the CD28-CD80/CD86 pathway, is the only costimulation blockade therapy that is currently approved for kidney transplant recipients. In the last decade, belatacept therapy has been shown to be a promising therapy in subgroups of kidney transplant recipients; however, the widespread use of belatacept has been tempered by an increased risk of acute kidney transplant rejection. The purpose of this review is to provide an overview of the costimulation blockade therapies that are currently in use or being developed for kidney transplant indications.

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.

Conversion to Belatacept in Maintenance Kidney Transplant Patients: A Retrospective Multicenter European Study

BACKGROUND

The use of belatacept is not yet approved for maintenance in kidney transplant patients. This retrospective multicenter European study aimed to assess the efficacy and safety of conversion to belatacept in a large cohort of patients in a real-life setting and to identify the predictive factors for improved kidney function after the switch.

METHODS

Two hundred nineteen maintenance kidney transplant patients from 5 European kidney transplant centers were converted to belatacept at 21.2 months (0.1-337.1 months) posttransplantation, mainly because of impaired kidney function. Thirty-two patients were converted to belatacept within the first 3 months posttransplantation. The mean duration of follow-up was 21.9 ± 20.2 months.

RESULTS

The actuarial rate of patients still on belatacept-based therapy was 77.6%. Mean estimated glomerular filtration rate increased from 32 ± 16.4 at baseline to 38 ± 20 mL/min per 1.73 m (P < 0.0001) at last follow-up. Conversion to belatacept before 3 months posttransplantation was the main predictive factor for a significant increase in estimated glomerular filtration rate (of 5 and 10 mL/min per 1.73 m at 3 and 12 months after the switch, respectively). Eighteen patients (8.2%) presented with an acute rejection episode after conversion; 3 developed a donor-specific antibody. Overall efficacy and safety were good, including for the 35 patients that had a donor-specific antibody at conversion.

CONCLUSIONS

The conversion to belatacept was effective, especially when performed early after transplantation.

Conversion from tacrolimus to belatacept improves renal function in kidney transplant patients with chronic vascular lesions in allograft biopsy

Background

Conversion from tacrolimus to belatacept has been shown to be beneficial for an increasing number of kidney transplant (KT) patients. Predicting factors for favorable outcomes are still unknown. We aimed to investigate whether histological vascular lesions at the time of conversion might correlate with greater improvement in renal function post-conversion.

Methods

The study was conducted on a retrospective cohort of 34 KT patients converted from tacrolimus to belatacept. All patients underwent an allograft biopsy prior to conversion. We analyzed the evolution of the estimated glomerular filtration rate (eGFR) at 3 and 12 months after conversion.

Results

Median time to conversion was 6 (2–37.2) months post-transplant. About 52.9% of patients had moderate-to-severe chronic vascular lesions (cv2–3). We observed an increase in eGFR in the whole cohort from 35.4 to 41 mL/min/1.73 m² at 3 months (P = 0.032) and 43.7 at 12 months (P = 0.013). Nine patients experienced acute rejection post-conversion, with one graft loss observed beyond the first year after conversion. Patients with cv2–3 had significant improvement in eGFR at 12 months (+8.6 mL/min/1.73 m²; 31.6 to 40.2 mL/min/1.73 m²; P = 0.047) compared with those without these lesions (+6.8 mL/min/1.73 m²; 40.9 to 47.7 mL/min/1.73 m²; P = 0.148).

Conclusions

Conversion from tacrolimus to belatacept has a beneficial effect in terms of renal function in KT patients. This benefit might be more significant in patients with cv in the biopsy.

Belatacept for maintenance immunosuppression in cardiothoracic transplantation: The potential frontier

Current immunosuppressive regimens with calcineurin inhibitors have improved the management of patients after transplantation. However, their adverse effects are linked to increased morbidity and limit the long-term survival of heart and lung transplant recipients. Belatacept, a costimulation inhibitor interfering with the interaction between CD28 on T cells and the B7 ligands on antigen presenting cells, has shown success and is currently approved for use in renal transplant recipients. Furthermore, it lacks many of the cardiovascular, metabolic, neurologic, and renal adverse of effects of calcineurin inhibitors that have the largest impact on long-term survival in cardiothoracic transplant. Additionally, it requires no therapeutic drug monitoring and is only administered once a month. Limitations to belatacept use have been observed that must be considered when comparing immunosuppression options. Despite this, maintenance immunosuppression with belatacept has the potential to improve outcomes in cardiothoracic transplant recipients, as it has with kidney transplant recipients. However, no large clinical trials investigating belatacept for maintenance immunosuppression in heart and lung transplant recipients exist. There is a large need for focused research of belatacept in cardiothoracic transplantation. Belatacept is a viable treatment option for maintenance immunosuppression, and it is reasonable to pursue more evidence in cardiothoracic transplant recipients.

Belatacept/CTLA4Ig: an update and critical appraisal of preclinical and clinical results

INTRODUCTION

The B7/CD28/CTLA4 signaling cascade is the most thoroughly studied costimulatory pathway and blockade with CTLA4Ig (abatacept) or its derivative belatacept has emerged as a valuable option for pharmacologic immune modulation. Several clinical studies have ultimately led to the approval of belatacept for immunosuppression in kidney transplant recipients. Areas covered: This review will discuss the immunological background of costimulation blockade and recent preclinical data and clinical results of CTLA4Ig/belatacept. Expert commentary: The development of belatacept is a major advance in clinical transplantation. However, in spite of promising results in preclinical and clinical trials, clinical use remains limited at present, in part due to increased rates of acute rejection. Recent efforts showing encouraging progress in refining such protocols might be a step toward harnessing the full potential of costimulation blockade-based immunosuppression.