Blood Pressure and Graft Outcome in Renal Transplantation

Effects of the strict control of blood pressure in pediatric renal transplant recipients-ESCORT trial

OBJECTIVES

Strict BP control can retard progression of CKD in children. This prospective 3-year randomized controlled trial is aimed to investigate whether strict BP control can retard progression of chronic allograft dysfunction.

METHODS

Twenty-three pediatric patients were randomly selected to the standard BP group (STAND, target 24-hour MAP 50-95th percentile, n = 11) or the intensified BP group (INTENS, target 24-hour MAP <50th percentile, n = 12). The primary endpoint was an annual reduction in eGFR (Schwartz formula, mL/min/1.73 m² /y), secondary graft survival, BP, proteinuria, and safety.

RESULTS

A total of 21 children (age at entry 11.2 (range 6.2-16.8) years) completed the study, with 73% of children in INTENS and 70% of children in STAND group reached their goal BP. Ambulatory indexed 24-hour MAP decreased significantly in INTENS group (from 0.94 (range 0.86-1.17) to 0.85 (range 0.79-1.01, P < 0.01)) but not in STAND group (from 0.93 (range 0.85-1.07) to 0.90 (range 0.84-1.01)). Proteinuria did not change significantly in either group (22.1 mg/mmol creatinine to 15.3 in STAND group vs 25.7 to 11.8 in INTENS group). The annual reduction in eGFR did not differ between the INTENS and STAND groups (-1.9 mL/min/1.73 m² /y (range +6.4 to -14.3) vs -0.9 (range +4.0 to -8.5)).

CONCLUSION

This first randomized controlled trial on strict BP control has demonstrated that strict BP control is feasible in 73% of children but the strict BP control does not lead to retardation of graft function decline in comparison with standard BP control. However, the results need to be interpreted with caution keeping the major limitation of the study, that is, small sample size in mind.

FR104, an antagonist anti-CD28 monovalent fab' antibody, prevents alloimmunization and allows calcineurin inhibitor minimization in nonhuman primate renal allograft

Selective targeting of CD28 might represent an effective immunomodulation strategy by preventing T cell costimulation, while favoring coinhibition since inhibitory signals transmitted through CTLA-4; PD-L1 and B7 would not be affected. We previously showed in vitro and in vivo that anti-CD28 antagonists suppress effector T cells while enhancing regulatory T cell (Treg) suppression and immune tolerance. Here, we evaluate FR104, a novel antagonist pegylated anti-CD28 Fab' antibody fragment, in nonhuman primate renal allotransplantation. FR104, in association with low doses of tacrolimus or with rapamycin in a steroid-free therapy, prevents acute rejection and alloantibody development and prolongs allograft survival. However, when FR104 was associated with mycophenolate mofetil and steroids, half of the recipients rejected their grafts prematurely. Finally, we observed an accumulation of Helios-negative Tregs in the blood and within the graft after FR104 therapy, confirmed by Treg-specific demethylated region DNA analysis. In conclusion, FR104 reinforces immunosuppression in calcineurin inhibitor (CNI)-low or CNI-free protocols, without the need of steroids. Accumulation of intragraft Tregs suggested the promotion of immunoregulatory mechanisms. Selective CD28 antagonists might become an alternative CNI-sparing strategy to B7 antagonists for kidney transplant recipients.

Ambulatory blood pressure monitoring in pediatric renal transplantation

Hypertension is a common and serious complication after renal transplantation. It is an important risk factor for graft loss and adverse cardiovascular outcomes. Blood pressure (BP) in transplanted children should be measured not only by clinic BP (cBP) measurement, but also by ambulatory blood pressure monitoring (ABPM), because ABPM has distinct advantages over cBP, specifically the ability to reveal nocturnal, masked or white-coat hypertension. These types of hypertension are common in transplanted children (nocturnal hypertension 36-71 %, masked hypertension 24-45 %). It may also reveal uncontrolled hypertension in treated children, thereby improving control of hypertension. Regular use of ABPM and ABPM-guided therapy of hypertension may help to decrease cardiovascular and renal target organ damage in transplanted children. Therefore, ABPM should be routinely performed in all transplanted children at least once a year, regardless of the values of cBP.

A novel monoclonal antibody to CD40 prolongs islet allograft survival

The importance of CD40/CD154 costimulatory pathway blockade in immunosuppression strategies is well-documented. Efforts are currently focused on monoclonal antibodies specific for CD40 because of thromboembolic complications associated with monoclonal antibodies directed towards CD154. Here we present the rational development and characterization of a novel antagonistic monoclonal antibody to CD40. Rhesus macaques were treated with the recombinant anti-CD40 mAb, 2C10, or vehicle before immunization with keyhole limpet hemocyanin (KLH). Treatment with 2C10 successfully inhibited T cell-dependent antibody responses to KLH without significant peripheral B cell depletion. Subsequently, MHC-mismatched macaques underwent intraportal allogeneic islet transplantation and received basiliximab and sirolimus with or without 2C10. Islet graft survival was significantly prolonged in recipients receiving 2C10 (graft survival time 304, 296, 265, 163 days) compared to recipients receiving basiliximab and sirolimus alone (graft survival time 8, 8, 10 days). The survival advantage conferred by treatment with 2C10 provides further evidence for the importance of blockade of the CD40/CD154 pathway in preventing alloimmune responses. 2C10 is a particularly attractive candidate for translation given its favorable clinical profile.

Belatacept-based regimens are associated with improved cardiovascular and metabolic risk factors compared with cyclosporine in kidney transplant recipients (BENEFIT and BENEFIT-EXT studies)

BACKGROUND

Cardiovascular disease, the most common cause of death with a functioning graft among kidney transplant recipients, can be exacerbated by immunosuppressive drugs, particularly the calcineurin inhibitors. Belatacept, a selective co-stimulation blocker, may provide a better cardiovascular/metabolic risk profile than current immunosuppressants.

METHODS

Cardiovascular and metabolic endpoints from two Phase III studies (BENEFIT and BENEFIT-EXT) of belatacept-based regimens in kidney transplant recipients were assessed at month 12. Each study assessed belatacept in more intensive (MI) and less intensive (LI) regimens versus cyclosporine A (CsA). These secondary endpoints included changes in blood pressure, changes in serum lipids, and the incidence of new-onset diabetes after transplant (NODAT).

RESULTS

A total of 1209 patients were randomized and transplanted across the two studies. Mean systolic blood pressure was 6 to 9 mm Hg lower and mean diastolic blood pressure was 3 to 4 mm Hg lower in the MI and LI groups versus CsA (P ≤ 0.002) across both studies at month 12. Non-HDL cholesterol was lower in the belatacept groups versus CsA (P<0.01 MI or LI vs. CsA in each study). Serum triglycerides were lower in the belatacept groups versus CsA (P<0.02 MI or LI vs. CsA in each study). NODAT occurred less often in the belatacept groups versus CsA in a prespecified pooled analysis (P<0.05 MI or LI vs. CsA).

CONCLUSIONS

At month 12, belatacept regimens were associated with better cardiovascular and metabolic risk profiles, with lower blood pressure and serum lipids and less NODAT versus CsA. The overall profile of belatacept will continue to be assessed over the 3-year trials.

Challenges in pediatric transplantation: the impact of chronic kidney disease and cardiovascular risk factors on long-term outcomes and recommended management strategies

Barriers to successful outcomes following pediatric transplantation have shifted from ischemic reperfusion injury and rejection to more long-term complications. Of particular concern is the high prevalence of CKD owing to preexisting damage and nephrotoxicity, as well as other CV complications such as hypertension and cardiomyopathy. All of these contribute to graft loss and shortened life expectancy, thereby limiting the success story of solid-organ transplantation. Managing CKD and related CV morbidity should be integral to the care of pediatric transplant patients, and timely detection of any irregularities would increase the chances of restoring lost kidney function. GFR is still the widely accepted indicator of renal function, and nuclear medicine techniques are the gold standard measurement methods. These methods are limited by costs, radiation exposure and substrate injection, and current practice still uses the Schwartz estimate, despite its well-documented limitations. Newer endogenous markers of GFR, such as cystatin C clearance, give a more accurate measure of true GFR but have not been embraced in the management of pediatric transplant recipients. Furthermore, indirect markers (e.g., microalbuminuria and hypertension) could also aid early detection of renal damage. The effects of mainstay immunosuppressants on kidney and heart function are varied, with available data indicating favorable outcomes with tacrolimus compared with ciclosporin. There is a need for appropriately designed and powered randomized controlled trials to validate innovative concepts for tailored immunosuppression in the pediatric population. To date, very few studies have generated long-term data in pediatric renal transplant patients - results of 1-4-yr study favored tacrolimus over ciclosporin, but other immunosuppressive agents also need to be evaluated.

A phase III study of belatacept versus cyclosporine in kidney transplants from extended criteria donors (BENEFIT-EXT study)

Recipients of extended criteria donor (ECD) kidneys are at increased risk for graft dysfunction/loss, and may benefit from immunosuppression that avoids calcineurin inhibitor (CNI) nephrotoxicity. Belatacept, a selective costimulation blocker, may preserve renal function and improve long-term outcomes versus CNIs. BENEFIT-EXT (Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial-EXTended criteria donors) is a 3-year, Phase III study that assessed a more (MI) or less intensive (LI) regimen of belatacept versus cyclosporine in adult ECD kidney transplant recipients. The co-primary endpoints at 12 months were composite patient/graft survival and a composite renal impairment endpoint. Patient/graft survival with belatacept was similar to cyclosporine (86% MI, 89% LI, 85% cyclosporine) at 12 months. Fewer belatacept patients reached the composite renal impairment endpoint versus cyclosporine (71% MI, 77% LI, 85% cyclosporine; p = 0.002 MI vs. cyclosporine; p = 0.06 LI vs. cyclosporine). The mean measured glomerular filtration rate was 4-7 mL/min higher on belatacept versus cyclosporine (p = 0.008 MI vs. cyclosporine; p = 0.1039 LI vs. cyclosporine), and the overall cardiovascular/metabolic profile was better on belatacept versus cyclosporine. The incidence of acute rejection was similar across groups (18% MI; 18% LI; 14% cyclosporine). Overall rates of infection and malignancy were similar between groups; however, more cases of posttransplant lymphoproliferative disorder (PTLD) occurred in the CNS on belatacept. ECD kidney transplant recipients treated with belatacept-based immunosuppression achieved similar patient/graft survival, better renal function, had an increased incidence of PTLD, and exhibited improvement in the cardiovascular/metabolic risk profile versus cyclosporine-treated patients.

A phase III study of belatacept-based immunosuppression regimens versus cyclosporine in renal transplant recipients (BENEFIT study)

Belatacept, a costimulation blocker, may preserve renal function and improve long-term outcomes versus calcineurin inhibitors in kidney transplantation. This Phase III study (Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial) assessed a more intensive (MI) or less intensive (LI) regimen of belatacept versus cyclosporine in adults receiving a kidney transplant from living or standard criteria deceased donors. The co-primary endpoints at 12 months were patient/graft survival, a composite renal impairment endpoint (percent with a measured glomerular filtration rate (mGFR) <60 mL/min/1.73 m(2) at Month 12 or a decrease in mGFR > or =10 mL/min/1.73 m(2) Month 3-Month 12) and the incidence of acute rejection. At Month 12, both belatacept regimens had similar patient/graft survival versus cyclosporine (MI: 95%, LI: 97% and cyclosporine: 93%), and were associated with superior renal function as measured by the composite renal impairment endpoint (MI: 55%; LI: 54% and cyclosporine: 78%; p < or = 0.001 MI or LI versus cyclosporine) and by the mGFR (65, 63 and 50 mL/min for MI, LI and cyclosporine; p < or = 0.001 MI or LI versus cyclosporine). Belatacept patients experienced a higher incidence (MI: 22%, LI: 17% and cyclosporine: 7%) and grade of acute rejection episodes. Safety was generally similar between groups, but posttransplant lymphoproliferative disorder was more common in the belatacept groups. Belatacept was associated with superior renal function and similar patient/graft survival versus cyclosporine at 1 year posttransplant, despite a higher rate of early acute rejection.

Hypertension after renal transplantation

Hypertension is a common and serious complication after renal transplantation. It is an important risk factor for graft loss and morbidity and mortality of transplanted children. The etiology of posttransplant hypertension is multifactorial: native kidneys, immunosuppressive therapy, renal-graft artery stenosis, and chronic allograft nephropathy are the most common causes. Blood pressure (BP) in transplanted children should be measured not only by casual BP (CBP) measurement but also regularly by ambulatory BP monitoring (ABPM). The prevalence of posttransplant hypertension ranges between 60% and 90% depending on the method of BP measurement and definition. Left ventricular hypertrophy is a frequent type of end-organ damage in hypertensive children after transplantation (50-80%). All classes of antihypertensive drugs can be used in the treatment of posttransplant hypertension. Hypertension control in transplanted children is poor; only 20-50% of treated children reach normal BP. The reason for this poor control seems to be inadequate antihypertensive therapy, which can be improved by increasing the number of antihypertensive drugs. Improved hypertension control leads to improved long-term graft and patient survival in adults. In children, there is a great potential for antihypertensive treatment that could also result in improved graft and patient survival.

Tracking of blood pressure and its impact on graft function in pediatric renal transplant patients

We studied tracking of BP and its impact on GFR in 44 PRTP followed for 56 months. Three months PT 77% had elevated SBP percentile. First year SBP and DBP correlated positively with final values (p < 0.0001, 0.0002, respectively). Pretransplant and three month PT SBP correlated positively (p = 0.02). At one yr, SBP and DBP were inversely associated with GFR (p = 0.002, p < 0.0001, respectively). SBP and BMI were positively associated at all time points. DBP was significantly higher in deceased recipients throughout the study period. Final DBP was higher (p = 0.03) and GFR lower (p = 0.04) in African-American patients. Patients with end-stage renal disease caused by glomerular disease had higher SBP (p = 0.03) and DBP (p = 0.04) than those with congenital malformations. GFR at one-yr PT (p = 0.02) and end of study (p = 0.003) was significantly lower in patients with high BP. Moreover, patients who maintained a normal systolic BP throughout the study had a significantly higher final GFR than those who were hypertensive at both time points [84 (normal BP throughout) vs. 52 mL/min/1.73 m(2) (high BP throughout), p = 0.02]. We conclude that PT hypertension is common in PRTP and predicts lower GFR.

Dietary Phytosterols Reduce Cyclosporine-Induced Hypercholesterolemia in Apolipoprotein E-Knockout Mice

BACKGROUND

Cyclosporine-induced hypercholesterolemia is a major concern after solid organ transplantation. Reducing this side effect of cyclosporine by dietary agents may be safe, cost-effective, and attractive to both patients and health professionals.

METHODS

In this study, the interactions between dietary phytosterols (2% w/w) and cyclosporine (0.02% w/w) in regard to blood cyclosporine concentrations, lipoprotein profile, and histological and morphometrical features of atherosclerotic lesions were studied over 14 weeks in apolipoprotein E-knockout mice.

RESULTS

Cyclosporine alone increased plasma non-HDL cholesterol, and triglyceride concentrations and reduced HDL-cholesterol levels as compared to controls. However, these changes were not associated with further increases in atherogenesis as compared to controls. Unlike cyclosporine, phytosterols reduced non-HDL cholesterol and atherosclerosis, and increased HDL-cholesterol concentrations, as compared to the control group. The addition of dietary phytosterols to cyclosporine reduced the extent of cyclosporine-induced hypercholesterolemia, but not cyclosporine-induced hypertriglyceridemia. The extent of atherosclerosis in the combination therapy group was significantly lower than that in the control group or cyclosporine-treated group. Blood cyclosporine concentrations were comparable between the two groups of cyclosporine-treated and the combination therapy groups at the end of the study.

CONCLUSION

This study suggests that simultaneous consumption of dietary phytosterols and cyclosporine may attenuate posttransplant hypercholesterolemia associated with the immunosuppressive cyclosporine. Additional studies are required to understand the mechanisms by which dietary phytosterols reduce cyclosporine-induced hypercholesterolemia.