Stable Renal Transplant Patients Research Articles

#1896 Monitoring of peripheral blood B cell subsets in long-surviving renal transplant patients

Abstract Background and Aims Studies of peripheral blood B cells subsets in renal transplant patients with operational tolerance off immunosuppressive therapy have identified several differences in B cell subsets. Here we studied B cells in blood lymphocytes from long-surviving renal transplant patients on immunosuppression. Populations of CD4+ T cells, CD8+ T cells, NK cells and B cells, along with subpopulations of B cells, in long-surviving renal transplant recipients were compared to healthy volunteers. We were looking for changes in B cell subsets, which may indicate transplant tolerance and potentially identify patients who could reduce immunosuppression. Method Fresh blood was taken from healthy volunteers (HV) (n = 44) and stable renal transplant patients with grafts surviving >10yrs (RT) (n = 25). T, B, and NK cells were examined using a 6-color TBNK reagent (BD) (CD3/CD4/CD8/CD45/CD19/CD16&CD56). Peripheral blood mononuclear cells were isolated from the remaining fresh blood and were stained with a panel of monoclonal antibodies (CD19/CD21/CD24/CD27/CD38/CD45/IgD/IgM) to identify subpopulations of B cells. Data was acquired on BD FACSCanto II using BD FACSDiva software (v8.0) and analysed using FlowJo. Lymphocyte populations were examined after FSC vs SSC gating and doublets exclusion. Results RT had significantly less lymphocyte counts in comparison to HV (p = 0.0156). There were no significant differences between the CD4+ T cell, CD8+ T cell, or NK cell percentages between RT and HV. B cells were markedly reduced in RT (p = 0.0001) vs HV when examined by TBNK staining. Peripheral blood mononuclear cells of HV (n = 13) and RT (n = 23) stained with a panel of B cell-related antibodies showed CD19+ cells were also significantly reduced in RT (p = 0.0006). There were less CD21hi cells (p = 0.0014) and more CD21lo (p = 0.0014) cells in RT than HV. No differences were seen between the two groups in their proportion of naïve B cells, marginal zone B cells, memory B cells, or class unswitched B cells. However, switched memory B cells were higher in RT than HV (p = 0.0181). Plasmablasts were also higher in RT compared to HV (p = 0.0491). Transitional B cells in RT appeared lower than HV on average, but this did not reach statistical significance (p = 0.1265). The ratio of Treg to B cells, RT (n = 25) showed significantly higher (p = 0.0256) proportions of activated Treg (CD4+CD25+CD127loCD45RA−Foxp3+/hi) to B cells, in comparison to HV (n = 44). There were no significant differences between the two groups in the ratio of naïve Treg (CD4+CD25+CD127loCD45RA+Foxp3+) to naïve T cells (CD4+CD45RA+Foxp3−), or highly activated Treg (CD4+CD25+CD127loCD45RA−Foxp3hi) to activated effector T cells (CD4+CD45RA−Foxp3−). Conclusion B cells were significantly lower in RT compared to HV. There were more plasmablasts and switched memory B cells in RT than HV. The ratio of activated Treg to B cells was higher in RT. This higher proportion of Treg to B cells may be clinically relevant and potentially demonstrate increased immunological suppression in long-surviving renal transplant recipients.

#1167 Examination of subsets of CD4+ lymphocyte subpopulations in long-surviving renal transplant patients

Abstract Background and Aims Subpopulations of CD4+ cells, play a major role in mediation of rejection and tolerance to a renal transplant. This study examined subsets of CD4+ T cells and CD4+CD25+CD127lo Treg in blood of renal graft recipients with grafts surviving >10 years for changes in lymphocyte subpopulations that may indicate transplant tolerance and potentially identify patients who could reduce immunosuppression. Based on CD45RA and CD25/Foxp3 expression, Miyara et al identified five populations (Pop) within CD4+ cells. Pop I, II and III are T regulatory cells (Treg); Pop I as naïve (CD45RA+Foxp3+) Treg, Pop II as activated (CD45RA-Foxp3hi) Treg, and Pop III as cytokine secreting (CD45RA-Foxp3+) cells which also includes activated effector cells. Pop IV are activated T cells (CD45RA-Foxp3−), and Pop V are naïve T cells (CD45RA+Foxp3−). Here, we examined three Treg populations (Pop I-III) within CD4+CD25+CD127lo Treg, and Pop IV and V within CD4+ T cells. To further characterise these subpopulations, we examined chemokine receptor expression (CXCR3, CCR4, CCR6, and CCR7) to identify T helper phenotype (Th-like) of Treg populations. Th1-like Treg were identified as CCR4+CXCR3+CCR6−, Th2-like as CCR4+CXCR3-CCR6−, Th17-like as CCR4+CXCR3-CCR6+, and Th1/Th17-like as CCR4+CXCR3+CCR6+. We also examined expression of activated Treg effector molecules CD39, Class II MHC, and PD-1. Method Peripheral blood mononuclear cells (PBMC) were isolated from fresh blood collected from healthy volunteers (HV) (n = 44) and long-term stable renal transplant patients with grafts surviving >10 yrs (RT) (n = 25). Panels of monoclonal antibodies for Treg (CD4/CD25/CD127/CD45RA/Foxp3), chemokine receptors (CXCR3, CCR4, CCR6, CCR7), and Treg activation and suppression-related molecules (CD39/HLA-DR/PD-1) were also used. Data was acquired on BD FACSCanto II using BD FACSDiva software (v8.0) and analysed using FlowJo. Lymphocyte populations were examined after FSC vs SSC gating and doublets exclusion. T cell and Treg populations were analysed within CD4+ and CD4+CD25+CD127lo T cells. Results RT had lower lymphocyte counts than HV (p = 0.0156) but had a similar percentage of CD4+ T cells. Treg were significantly lower in RT compared to HV (p = 0.0012). RT patients had less naïve Treg (Pop I, p = 0.0083) and naïve effector T cells (Pop V, p = 0.0003), but had higher activated effector T cells (Pop IV, p = 0.0002) than HV. There were no differences in activated Treg Pop II or III between the two groups. There were significantly less cells expressing CXCR3 in RT than HV in Pop I (p = 0.0120), Pop II (p < 0.0001), Pop III (p < 0.0001) and Pop IV (p = 0.0047). Similarly, RT had fewer cells expressing CCR6 compared to HV in Pop II (p = 0.0019), Pop III (p = 0.0015), and Pop V (p = 0.0017). RT had lower proportions of CCR7 expressing cells in Pop I (p = 0.0035), Pop IV (p = 0.0097), and Pop V (p = 0.0002), but higher in Pop II (p = 0.0041) compared to HV. There were similar percentages of cells with Th1 and Th17-like phenotypes in both groups. However, RT had significantly more Th2-like Treg in Pop II (p = 0.0033) and Pop III (p = 0.0100), and significantly less Th1/Th17-like Treg in Pop II (p = 0.0005) and Pop III (p = 0.0017) compared to HV. There were little to no differences in the Treg activation and suppression-related molecules within subpopulations of Treg. Conclusion Long-surviving RT patients had less naïve Treg and naïve effector cells, but increased proportions of activated effector cells. There were little to no differences in the expression of Treg activation or suppression-related molecules in Treg subpopulations. Unexpectedly, activated Treg in RT had significantly higher proportions with a Th2 phenotype and significantly less Treg with a Th1/Th17 phenotype. Whether this is a consequence of immunosuppression, or a biological shift associated with tolerance, remains to be resolved. Further studies are required to investigate the relevance of these changes in identifying induction of transplant tolerance.

CYP3A5*3 and CYP3A4*22 Cluster Polymorphism Effects on LCP-Tac Tacrolimus Exposure: Population Pharmacokinetic Approach.

The aim of the study is to develop a population pharmacokinetic (PopPK) model and to investigate the influence of CYP3A5/CYP3A4 and ABCB1 single nucleotide polymorphisms (SNPs) on the Tacrolimus PK parameters after LCP-Tac formulation in stable adult renal transplant patients. The model was developed, using NONMEM v7.5, from full PK profiles from a clinical study (n = 30) and trough concentrations (C0) from patient follow-up (n = 68). The PK profile of the LCP-Tac formulation was best described by a two-compartment model with linear elimination, parameterized in elimination (CL/F) and distributional (CLD/F) clearances and central compartment (Vc/F) and peripheral compartment (Vp/F) distribution volumes. A time-lagged first-order absorption process was characterized using transit compartment models. According to the structural part of the base model, the LCP-Tac showed an absorption profile characterized by two transit compartments and a mean transit time of 3.02 h. Inter-individual variability was associated with CL/F, Vc/F, and Vp/F. Adding inter-occasion variability (IOV) on CL/F caused a statistically significant reduction in the model minimum objective function MOFV (p < 0.001). Genetic polymorphism of CYP3A5 and a cluster of CYP3A4/A5 SNPs statistically significantly influenced Tac CL/F. In conclusion, a PopPK model was successfully developed for LCP-Tac formulation in stable renal transplant patients. CYP3A4/A5 SNPs as a combined cluster including three different phenotypes (high, intermediate, and poor metabolizers) was the most powerful covariate to describe part of the inter-individual variability associated with apparent elimination clearance. Considering this covariate in the initial dose estimation and during the therapeutic drug monitoring (TDM) would probably optimize Tac exposure attainments.

Efficacy of Prolonged-release Tacrolimus After Conversion From Immediate-release Tacrolimus in Kidney Transplantation: A Retrospective Analysis of Long-term Outcomes From the ADMIRAD Study.

A retrospective, noninterventional chart review study examined long-term graft survival in adult kidney transplant participants in the Adherence Measurement in Stable Renal Transplant Patients Following Conversion From Prograf to Advagraf (ADMIRAD) clinical trial at 4 Belgian sites. Patients were randomized to receive once-daily PRT or twice-daily IRT for 6 mo, followed by treatment as per real-world clinical practice. Data were collected retrospectively from randomization day until December 31, 2018. Primary endpoints included efficacy failure, defined as a composite endpoint of graft loss, biopsy-confirmed acute rejection, and graft dysfunction. Secondary endpoints included overall patient survival and course of kidney function. This analysis included 78.5% of patients from ADMIRAD (n = 108 PRT; n = 64 IRT). The Kaplan-Meier survival rate without efficacy failure from randomization to year 5 was 0.741 (95% confidence interval [CI]: 0.647, 0.813) for the PRT group (n = 80), and 0.667 (95% CI: 0.536, 0.768) for the IRT group (n = 42) and remained higher for PRT throughout 10 y follow-up (P = 0.041). The Kaplan-Meier estimate of overall survival from the time of last transplant was 0.981 (95% CI: 0.928, 0.995) and 0.880 (95% CI: 0.802, 0.928) at 5 and 10 y in the PRT group. Kidney function parameters and tacrolimus trough levels remained stable over the follow-up period. Patients in the ADMIRAD study who received PRT for up to 10 y had improved long-term outcomes compared with patients receiving IRT, with a consistent effect on both graft and patient survival.

Loss of Function ABCG2 c.421C>A (rs2231142) Polymorphism Increases Steady-State Exposure to Mycophenolic Acid in Stable Renal Transplant Recipients: An Exploratory Matched Cohort Study.

Polymorphism ABCG2 c.421C>A (rs2231142) results in reduced activity of the important drug efflux transporter breast cancer-resistance protein (BCRP/ABCG2). One study has suggested that it may affect enterohepatic recirculation of mycophenolic acid (MPA). We evaluated the effect of rs2231142 on steady-state exposure to MPA in renal transplant recipients. Consecutive, stable adult (age ≥ 16years) renal transplant recipients on standard MPA-based immunosuppressant protocols (N = 68; 43 co-treated with cyclosporine, 25 with tacrolimus) underwent routine therapeutic drug monitoring after a week of initial treatment, and were genotyped for ABCG2 c.421C>A and 11 polymorphisms in genes encoding enzymes and transporters implicated in MPA pharmacokinetics. ABCG2 c.421C>A variant versus wild-type (wt) patients were matched with respect to demographic, biopharmaceutic, and genetic variables (full optimal combined with exact matching) and compared for dose-adjusted steady-state MPA pharmacokinetics [frequentist and Bayes (skeptical neutral prior) estimates of geometric means ratios, GMR]. Raw data (12 variant versus 56 wt patients) indicated around 40% higher total exposure (frequentist GMR = 1.45, 95% CI 1.10-1.91; Bayes = 1.38, 95% CrI 1.07-1.81) and around 30% lower total body clearance (frequentist GMR = 0.66, 0.58-0.90; Bayes = 0.71, 0.53-0.95) in variant carriers than in wt controls. The estimates were similar in matched data (11 variant versus 43 wt patients): exposure GMR = 1.41 (1.11-1.79) frequentist, 1.39 (1.15-1.81) Bayes, with 90.7% and 85.5% probability of GMR >1.20, respectively; clearance GMR = 0.73 (0.58-0.93) frequentist, 0.71 (0.54-0.95) Bayes. Sensitivity analysis indicated low susceptibility of the estimates to unmeasured confounding. Loss-off-function polymorphism ABCG2 c.421C>A increases steady-state exposure to MPA in stable renal transplant patients.

P8.051: Corticosteroids Withdrawal in Renal Grafted Patients: Follow-up and Outcome

Introduction: Corticosteroids are powerful antiinflamatory with immunosuppressant effects utilized in maintenance therapy following kidney transplantation and are associated with a higher rate of side events in comparison with protocols involving early corticosteroid withdrawl. The present paper reports the results of cessation of steroids in stable maintenance renal transplant patients. Patients and methods: One hundred sixty seven deceased kidney grafted patients (54% men), aged 57.5±12.4 years, with follow-up of 84 months and steroids withdrawl period of 60 months (1-198) follow-up steroid free were studied. Etiology of end stage renal disease was secondary to Glomerulonephritis 31%, Diabetes 22%, Policystic disease 14%, Tubulointerstitial nephropathy 13%, Vascular 5%, Unknown 17%. The patients were on Prednisone 5-10 mg dairy combined with Cyclosporine 50-150 mg/Tacrolimus 0.5-6 mg, associate to Mycophenolate Mophetyl 250-2.000 mg, Sodium Micophenolate, 360-900 mg or Azatioprine 50-75 mg, and Everolimus 1-4 mg. Steroids were diminished gradually in three months period and some patients receibe monotherapy only. Results: Basal serum creatinine was 1.54±0.6mg/dl and after five years followup 1.4±0.5 mg/dl. Basal blood glucose concentration was 130±12 mg/dl and after five years 109±0.8mg/dl. Weight was maintained. At 5 years, graft and patient survival were 100%. There was no acute rejection after steroids withdrawl. After withdrawl blood pressure control was achieved with less antihypertensive drugs. Lipids diminished slightly with less cholesterol-lowering drugs. Conclusion: Corticosteroids could be withdrawn safely in stable renal transplant patients and avoid morbidity and adverse events related to chronic utilization improving survival and quality of life.

Prospective De Novo Donor-Specific Antibody Monitoring in Renal Transplant Patients

De novo donor-specific antibodies (dnDSA) are associated with antibody-mediated rejection leading to kidney transplant failure. However, many transplant patients are stable with no signs of graft dysfunction at the time of dnDSA detection at screening test. We prospectively studied 26 kidney transplant patients for 3 years, with dnDSA detected using the Luminex single-antigen bead assay in a routine test. Proteinuria and estimated glomerular filtration rate were evaluated along with dnDSA monitoring at least annually. Graft loss associated with dnDSA occurred in 8 (31%) patients, 14 ± 11 months after the initial detection of dnDSA. These patients had more frequently multiple dnDSA (P=.004) and remarkable proteinuria, more than 1 g daily (P < .001). The remaining 18 patients were followed for 38 ± 15 months and considered stable as there was no deterioration regarding estimated glomerular filtration rate and proteinuria. In 7 (39%) of these patients, dnDSA waned and were not detected anymore at follow-up. Antibodies against HLA class I had a significantly (P < .001) lower mean fluorescence intensity (MFI) (2603 ± 1098) compared with those against HLA class II (11,109 ± 6414). In regression analysis, they were predictive of dnDSA wane (P=.043; odds ratio, 0.18; 95% confidence interval, 0.04-0.94). Despite fluctuations during follow-up, there was no significant change in MFI for those who retained the dnDSA. The presence of dnDSA is transient in a significant proportion of stable renal transplant patients, especially in those with antibodies against HLA class I and a low MFI. Multiple dnDSA and severe proteinuria adversely affect renal graft survival.

Profiles of B-cell subsets in immunologically stable renal allograft recipients and end-stage renal disease patients

BackgroundPost-transplantation pharmacotherapies typically employ combinations of immunosuppressive agents that have been designed for targeted inhibition of T-cells and T-cell subsets. Studies of acute and chronic effects of clinically employed immunosuppressive agents on B-cells and B-cell subsets are significantly fewer in number and warrant further investigation. Accordingly, the goal of the present cross-sectional study is to functionally evaluate differences of B-cell subsets in patients with end-stage renal disease (ESRD) and immunologically stable renal transplant patients. Patients and methodsOf 103 patients who underwent renal transplantation, 73 patients were immunologically stable without rejection or infection. Among them, 34 patients were one-year post-transplantation, and 39 patients were five-year post-transplantation. The study also included 35 ESRD patients and 36 healthy volunteers. Flow cytometry identified B-cell subsets in the study groups. ResultsRenal allograft recipients had reduced percentages of total B-cells (CD19+) and regulatory B-cells (Breg) (CD38highCD27 + CD24+) compared with healthy controls. The percentage of transitional B-cells (IgM + CD38highCD24high) and marginal zone (MZ) B-cells (IgD-CD27+) was reduced in transplant recipients compared with patients with ESRD and healthy volunteers. The highest percentage of plasma cells (PCs) (CD38highCD27 + CD24-) was in patients with ESRD. In five-year post-transplantation group, CD38lowCD21- B-cells increased when compared with the other groups. Healthy volunteers and patients with ESRD had fewer unswitched memory (UM) B-cells (IgM + IgD + CD38lowCD27+), and increased isotype switched memory (ISM) B-cells (IgM-IgD-CD38lowCD27+). There was no difference in the percentage of naïve B-cells (IgD + CD27-) among diverse groups. ConclusionsThe percentages of the total, transitional, Breg, PCs, MZ, and UM B-cell subsets in immunologically stable renal allograft recipients were significantly different from healthy controls. However, B-cell subsets in patients with ESRD were minimally different with immunologically stable renal allograft recipients.

Envarsus, a novelty for transplant nephrologists: Observational retrospective study

The aim of this study was to evaluate the trough concentrations (Cptrough) and the tacrolimus dosage regimen after the conversion of Prograf or Advagraf to Envarsus (new pharmaceutical form with MeltDose technology that improves the absorption of fat-soluble drugs) in patients with stable renal transplantation, and their renal function.We selected stable renal transplant patients who were converted to Envarsus. Two periods were defined: Baseline and Conversion (Envarsus) and they were stratified according to the pharmaceutical form used in the Baseline period. Sixty-one patients were included (24 with Advagraf and 37 with Prograf), with an average age of 52years. The mean post-transplant time at the time of conversion to Envarsus was 76.3months and the mean follow-up in the Baseline and Conversion period was 10.1months and 11.6months, respectively.In the Prograf and Envarsus group, the Cptrough medians were 6.6 vs 6.4ng/ml (p=.636), with a mean daily dose that decreased significantly from 3mg to 2mg (p<.001), respectively, maintaining the filtration rate.The median Cptrough values in the Advagraf and Envarsus groups were 5.7ng/ml and 6.3ng/ml (p=.07), with a median daily dose of 7mg and 4mg (p<.001), respectively, and the same renal function.In stable renal transplant patients, the conversion from Advagraf to Envarsus has allowed the dose of tacrolimus to be reduced by 42.9% and, in the case of Prograf, by 33.3%, maintaining similar Cptrough values, without renal function being altered.

Envarsus, una novedad para los nefrólogos del trasplante: estudio observacional retrospectivo

The aim of this study was to evaluate the trough concentrations (Cptrough) and the tacrolimus dosage regimen after the conversion of Prograf or Advagraf to Envarsus (new pharmaceutical form with MeltDose technology that improves the absorption of fat-soluble drugs) in patients with stable renal transplantation, and their renal function.We selected stable renal transplant patients who were converted to Envarsus. Two periods were defined: Baseline and Conversion (Envarsus) and they were stratified according to the pharmaceutical form used in the Baseline period. Sixty-one patients were included (24 with Advagraf and 37 with Prograf), with an average age of 52years. The mean post-transplant time at the time of conversion to Envarsus was 76.3months and the mean follow-up in the Baseline and Conversion period was 10.1months and 11.6months, respectively.In the Prograf and Envarsus group, the Cptrough medians were 6.6 vs 6.4 ng/mL (P=.636), with a mean daily dose that decreased significantly from 3mg to 2mg (P<.001), respectively, maintaining the filtration rate.The median Cptrough values in the Advagraf and Envarsus groups were 5.7ng/mL and 6.3ng/mL (P=.07), with a median daily dose of 7mg and 4mg (P<.001), respectively, and the same renal function.In stable renal transplant patients, the conversion from Advagraf to Envarsus has allowed the dose of tacrolimus to be reduced by 42.9% and, in the case of Prograf, by 33.3%, maintaining similar Cptrough values, without renal function being altered.

Long-term blood pressure monitoring by office and 24-h ambulatory blood pressure in renal transplant patients: a longitudinal study.

Renal transplant patients have a high prevalence of nocturnal hypertension, and hypertension misclassification by office blood pressure (BP) is quite common in these patients. The potential impact of hypertension misclassification by office BP on hypertension management in this population has never been analysed. We performed a longitudinal study in a cohort of 260 clinically stable renal transplant patients. In all, 785 paired office and 24-h ambulatory blood pressure monitoring (24-hABPM) measurements over a median follow-up of 3.9 years were available in the whole cohort. A total of 74% of patients had nocturnal hypertension (>120/70 mmHg). Average office BP and 24-hABPM remained quite stable over follow-up, as did the prevalence of nocturnal hypertension, which was 77% at the last observation. However, the global agreement between office BP and average 24 h, daytime and night-time BP was unsatisfactory (k-statistics 0.10-0.26). In 193 visits (25% of all visits) where office BP indicated the need of antihypertensive therapy institution or modification (BP >140/90 mmHg), 24-hABPM was actually normal (<130/80 mmHg), while in 94 visits (12%), 24-hABPM was in the hypertensive range while office BP was normal. Overall, in 37% of visits, office BP provided misleading therapeutic indications. Hypertension misclassification by office BP is a common phenomenon in stable renal transplant patients on long-term follow-up. Office BP may lead to inappropriate therapeutic decisions in over one-third of follow-up visits in these patients.

Longitudinal profile of circulating T follicular helper lymphocytes parallels anti-HLA sensitization in renal transplant recipients.

Antibody-mediated rejection is responsible for 30%-50% of renal graft failures. Differentiation of B cells into antibody-producing plasmablasts depends on the collaboration of follicular helper T cells (Tfh). We analyzed circulating Tfh (cTfh) in kidney recipients and studied cTfh relationship with anti-HLA antibody production and graft outcome. cTfh were longitudinally analyzed in a prospective cohort of patients (n=206), pre- and posttransplantation. Clinical data, HLA sensitization, and cTfh function were recorded. Both pretransplant and 6-month posttransplant cTfh were able to derive IgG-producing plasmablasts. Pretransplant cTfh was decreased in patients, especially in those who received dialysis. However, these cells were increased in patients with previous allograft or transfusions and in HLA-sensitized recipients. After transplantation cTfh expanded, significantly more in patients who developed de novo anti-HLA antibodies than in patients who remained unsensitized. Augmented pretransplant cTfh positively correlated with higher intensity of pretransplant anti-HLA class I and with de novo anti-HLA class I and anti-HLA class II antibodies. Consistently, pretransplantation cTfh were higher in patients who experienced acute rejection (HR=1.14 [1.04-1.25]). Thus, we show a role for Tfh in anti-HLA sensitization and rejection. Multicenter studies with additional patient cohorts are needed to validate these results. Immunosuppressive drugs targeting Tfh could be useful to improve outcomes.

Resistive Index of Renal Grafts

The resistive index (RI) reflects the resistance to blood flow caused by the distal vascular bed. Objective To determine the relation of intrarenal RI to systemic cardiovascular and nephropathy risk factors in renal transplant recipients (RTRs). To establish whether RI varies according to the measurement site (interlobar or cortical arteries) to assess the influence of the vessel diameter. Material and Methods Vascular Doppler ultrasound of both the renal graft and carotid arteries was performed in 84 stable renal transplant patients more than 3 months post-transplant. Definition of RI: (Peak Systolic Velocity (PSV)-End Diastolic Velocity (EDV))[Fraction Slash]PSV. RI < 0.75 was determined as normal and ≥ 0.75 as increased. Carotid findings were described as intima-media thickness, as follows: normal < 1 mm, increased 1 1.4 mm, and plaque > 1.5 mm. Results Distribution by sex: 34 men (40, 5%), and age: 47.8 +/-13.8. Sixty-six RTRs were transplanted from cadaveric donors (CD) (78.5%), out of whom 17 were transplanted from expanded criteria donors, according to UNOS. The other 18 were transplanted from living donors (LD) (21.5%). The variables analyzed that were statistically associated with increased RI were: age 51.1 vs. 43.9, p=0.002; post-transplant time (months) 104.5 vs. 62.5, p=0.029; MDRD (ml/min) 47.5 vs. 59.3, p=0.014; previous cardiovascular events 10 vs. 2, p=0.028; and carotid plaque (≥1.5 mm) 26/44 vs. 14/40, p=0.027. When performing a multivariate analysis, the age and post-transplant time (months) variables were statistically significant, with p=0.004 and p=0.044 respectively. Diabetes and delayed graft function showed an associative trend with the highest resistive index, without reaching significant values. Conclusion The RI measurement site is not determining as values were similar in cortical and interlobar arteries, thus inferring that the vascular area of more distal arteries does not determine RI. An increased RI would reflect the ageing of both the patient and organ, associated with cardiovascular risk factors. Further studies are needed to verify these data.

SLEEP DISORDERED BREATHING IN RENAL TRANSPLANT PATIENTS

Objective: Sleep disordered breathing (SDB) is a pervasive problem in stage 5 CKD patients maintained on regular dialysis treatment. Renal transplantation improves SDB but the longitudinal, long term evolution of SDB after kidney grafting has not been investigated. The issue is relevant because renal transplantation abolishes uremic toxicity but introduces classical risk factors for SDB, like overweight and obesity. Design and method: We investigated the long term evolution of polysomnographic recordings in 221 stable renal transplant patients. Overall 404 recordings over a median time of 3 years (interquartile range 2 – 4) were performed. Longitudinal analysis was performed by the linear mixed model (LMM). Results: The apnea-hypopnea index (AHI) in renal transplant patients was 5.44 ± SD 0.75 and the corresponding number of O2 desaturation (Des O2) episodes was 4.40 ± 0.60. The number of patients with AHI > 5 (the threshold for identifying mild SDB) rose from 25% at baseline to 43% at the end of the follow up. Over follow-up the AHI rose to 9.94 ± 2.37 (P < 0.001) and the number of desaturation episodes to 5.55 ± 2.1 (P = 0.010) which went along with a decline in the mean O2-saturation overnight (Mean SatO2: from 95.08 ± 0.14 to 94.64 ± 0.32,P = 0.001). LMM showed that age, sex, BMI, ESA treatment but neither eGFR nor the presence of proteinuria associated with the AHI. On multivariate analyses only male gender (3.42; 95%CI: 0.35 to 6.49; P = 0.003) and BMI (0.87; 95% CI 0.46 to 1.27; P < 0.001) associated with the AHI evolution over follow-up. Similar associations were registered also for the other parameters of SDB (Des O2, Mean Sat O2). Conclusions: Even though renal transplantation produces an early improvement in SDB in renal transplant patients, this treatment does not stabilize the disturbance which gradually re-emerges over longitudinal observation. Among risk factors underlying the risk of SDB re-emergence after transplantation the rise in BMI, i.e. a modifiable risk factor, appears to be of paramount importance. Tackling the surge of SDB after transplantation is of obvious relevance because this disturbance is a potent driver of sympathetic over-activity and of the attendant risk of cardiovascular events in this population.

Prediction of Free from Total Mycophenolic Acid Concentrations in Stable Renal Transplant Patients: A Population-Based Approach.

A population pharmacokinetic (PK) protein-binding model was developed to (1) predict free mycophenolic acid (fMPA) based on total MPA (tMPA) concentrations in renal transplant patients, to establish the therapeutic range of fMPA through pharmacokinetic-pharmacodynamic studies; and (2) provide a guideline for dosing mycophenolate mofetil (MMF). Full PK profiles of 56 patients (from five different occasions) during the first year after transplantation who were treated with oral MMF and cyclosporine, or macrolides (either tacrolimus or sirolimus), were analysed. fMPA protein-binding was modelled using nonlinear mixed effects modelling (NONMEM). The influence of physiological factors and coadministered immunosupressant was studied. A two-compartment model with first-order absorption and elimination, linear protein binding and enterohepatic circulation (EHC) best described the PK of MPA. Different recycling rate constants were considered depending on the coadministered immunosuppressant. The protein-binding rate constant (KB [relative standard error, RSE%]) increased nonlinearly with renal function according to K B=43.1 (3.13)·(CLCR/59.51)0.394(10.66)h-1. Furthermore, fMPA plasma clearance, given by clearance of the free mycophenolic acid (CLfMPA), CLfMPA=410 (RSE%3.00)·(1+CsA·0.594 (22.39))L/h, was 59.4% greater in cyclosporine-treated patients than in macrolide-treated patients, leading to lower MPA exposures. External evaluation proved acceptable area under the plasma concentration-time curve and trough concentration predictions. A reliable protein-binding population PK model was developed for prediction of fMPA or tMPA from each other and for dose guiding in stable renal transplant recipients.

Relationship Between Vitamin D Deficiency and Metabolic Syndrome in Renal Transplant Patients in Mashhad, Iran

Background: Vitamin D is a lipophilic hormone that affects homeostasis of calcium and phosphorus. Recent studies have shown that vitamin D deficiency may be a risk factor for metabolic syndrome (MS). Also, metabolic syndrome is highly prevalent in renal transplant patients and it can be associated with graft survival reduction. Objectives: This study aimed at investigating the relationship between vitamin D deficiency and MS in renal transplant patients. Methods: This cross-sectional study was performed on 86 stable renal transplant patients in warm seasons of 2014. Metabolic syndrome was diagnosed using the modified Asian adult treatment panel III (ATP III) criteria. Patients were classified based on their serum 25-hydroxy vitamin D levels: normal (> 30 ng/mL), insufficiency (16 - 30 ng/mL), and deficiency (< 16 ng/mL). Patients with a history of the malabsorption syndrome, alcoholism, taking vitamin D supplementations in the last 2 months, pretransplant diabetes mellitus, and pregnancy were excluded from the study. Results: Fifty percent of the patients had MS, consisting of 48 males (55.8%) and 38 females (44.2%). The mean age of the MS group was significantly higher than the non-MS group. The body mass index in the MS group was significantly higher than the non-MS group (P = 0.001). The mean serum vitamin D level in the MS group was lower, but this difference was not significant (P = 0.914). Conclusions: Although the serum vitamin D level was lower in MS patients, it was not significant. Also, due to the high prevalence of both MS and vitamin D deficiency among renal transplant patients, we did not find any significant relation between vitamin D deficiency and MS.

A Steady-State Head-to-Head Pharmacokinetic Comparison of All FK-506 (Tacrolimus) Formulations (ASTCOFF): An Open-Label, Prospective, Randomized, Two-Arm, Three-Period Crossover Study.

This two‐sequence, three‐period crossover study is the first pharmacokinetic (PK) study to compare all three innovator formulations of tacrolimus (twice‐daily immediate‐release tacrolimus capsules [IR‐Tac]; once‐daily extended‐release tacrolimus capsules [ER‐Tac]; novel once‐daily tacrolimus tablets [LCPT]). Stable renal transplant patients were dosed with each drug for 7 days, and blood samples were obtained over 24 h. Thirty subjects were included in the PK analysis set. A conversion factor of 1:1:0.80 for IR‐Tac:ER‐Tac:LCPT was used; no dose adjustments were permitted during the study. The median (interquartile range) total daily dose was 6.0 (4.0–8.0) mg for IR‐Tac and ER‐Tac and 4.8 (3.3–6.3) for LCPT. Significantly higher exposure on a per milligram basis, lower intraday fluctuation and prolonged time (Tmax) to peak concentration (Cmax) were found for LCPT versus IR‐Tac or ER‐Tac. ER‐Tac showed no differences versus IR‐Tac in exposure, Cmax, Tmax or fluctuation. The observed exposure of IR‐Tac was used to normalize exposure for LCPT and ER‐Tac, resulting in the following recommended total daily dose conversion rates: IR‐Tac:ER‐Tac, +8%; IR‐Tac:LCPT, −30%; ER‐Tac:LCPT, −36%. After exposure normalization, Cmax was ~17% lower for LCPT than for IR‐Tac or ER‐Tac; Cmin was ~6% lower for LCPT compared with IR‐Tac and 3% higher compared with ER‐Tac.

Effect of Breakfast on the Exposure of the Once-Daily Tacrolimus Formulation in Stable Kidney Transplant Recipients.

The once-daily Tacrolimus formulation (Tac ONCE-DAILY) has to be taken on an empty stomach. This is inconvenient for patients and may hamper compliance. The influence of food intake on the exposure of Tac ONCE-DAILY is unknown in transplant recipients. We compared the pharmacokinetics (PKs) of Tac ONCE-DAILY in stable kidney transplant recipients under fasted and fed conditions. In an open-label, single-center, cross-over PK study, 27 stable kidney white transplant recipients (17 male, 10 female) treated with Tac ONCE-DAILY under fasted conditions were enrolled. Two 10-point 24-hour blood concentration time profiles [area under the blood concentration time curve from time 0 to 24 hours (AUC0-24)] were collected under steady state conditions. The primary objective was to investigate the effect of food on the PKs and relative bioavailability of Tac ONCE-DAILY. Twenty-seven stable renal transplant patients provided 1 AUC0-24 under fasted and fed conditions, respectively. AUC0-24, C24, and Cmax, were lower in the fed state and Tmax was 1 hour postponed. The 90% confidence interval ratio (fed: fasted) for AUC0-24 was 0.81-0.91 and for C24 0.82-0.92 (both P < 0.001). The majority (60%) had no significant change, but the change in AUC0-24 ranged from -38% to +29%. One trough level was below the target range after fed intake. When Tac ONCE-DAILY is ingested with standard continental breakfast, AUC0-24 and C24 decrease overall, with C24 in the therapeutic range in almost all patients. The convenient fed intake could promote therapy adherence. Given the possible significant change in exposure, we advise monitoring of the tacrolimus trough level 1 week after fed ingestion of Tac ONCE-DAILY.

A Pilot Study of Continuous Infusion of Mycophenolate Mofetil for Prophylaxis of Graft-versus-Host-Disease in Pediatric Patients

Mycophenolate mofetil (MMF), an ester prodrug of mycophenolic acid (MPA), is used increasingly for graft-versus-host disease (GVHD) prophylaxis. Empiric fixed-dose-escalation strategies in pediatric hematopoietic cell transplantation (HCT) recipients have failed to achieve target MPA exposure. We evaluated the safety and feasibility of a pharmacokinetics-based dosing approach using a novel continuous infusion (CI) method of administration of MMF in pediatric HCT recipients. All patients received a myeloablative conditioning with cyclosporine A and MMF for GVHD prophylaxis. MMF was initiated on day 0 at a dose of 15 mg/kg every 8 hours. Based on steady-state pharmacokinetics, MMF was converted to CI to target a total MPA AUC0-24 of 40 to 80 μg·hour/mL. The MMF dose was adjusted to maintain a total MPA steady-state concentration (Css) of 1.7 to 3.3 μg/mL. During the CI schedule, MPA AUC0-24 was maintained at a mean of 40.1 μg·hour/mL (range, 20.6 to 63.8), and 17 of 19 patients (89%) achieved MPA Css within target of 1.7 to 3.3 μg/mL. Eighteen of 19 patients (95%) achieved neutrophil engraftment at a median of 13 days (range, 8 to 41) post-transplant and platelet engraftment at 39 days (range, 17 to 298) days post-transplant. Six of 18 assessable patients (33%) developed stages II to IV acute GVHD and 2 of 15 (13%) developed chronic GVHD. The MMF dose was reduced in 9 patients due to gastrointestinal symptoms (n = 6), low blood counts (n = 4), and viral infection (n = 3). Five patients with acute lymphoblastic leukemia relapsed, of whom 4 have died. Fifteen of 19 patients are alive with a median follow-up of 2.4 years (range, .4 to 4.9), with 3-year event-free and overall survival rates of 68% and 79%, respectively. In this pilot study of pharmacokinetically directed MMF dosing, we observed no toxic deaths, excellent engraftment, and low rates of grades III to IV acute and chronic GVHD. We found significantly lower half-life and higher drug clearance in pediatric HCT recipients compared with stable pediatric renal transplant patients or adult transplant patients. This regimen deserves further validation in a larger cohort of pediatric patients undergoing myeloablative transplantation.

A Single Center, Open-label, Randomized Pilot Study to Evaluate the Safety and Efficacy of Tacrolimus Modified Release, ADVAGRAF, Versus Tacrolimus Twice Daily, PROGRAF, in Stable Renal Recipients (SINGLE)

BackgroundCompliance with immunosuppressive regimens may affect clinical outcomes in renal transplant recipients. The aim of this study was to assess the safety and efficacy of standard-dose tacrolimus modified-release (TAC-MR) once daily versus tacrolimus (TAC) twice daily in stable renal transplant recipients. MethodsNinety-nine stable renal transplant recipients were randomized to receive standard-dose tacrolimus twice daily or standard-dose modified-release tacrolimus once daily on a 1:1 (mg:mg) basis. The primary end point was the incidence of adverse events (AEs) in both groups. Secondary end points included biopsy-proven acute rejection, graft survival, patient survival, clinical indicators, and change in score of questionnaire. ResultsThe incidence of AEs was not different between the TAC and TAC-MR groups (56.0% vs 53.1%, P > .05). There were no significant differences in mean calculated glomerular filtration rate, blood pressure, glycosylated hemoglobulin (HbA1c), blood concentration of tacrolimus, and drug compliance. The scores of all items in the 36-item short form health survey (SF-36) were not different between groups, except for vitality. With respect to the subject questionnaire, there was no difference in question scores between the two treatment groups. ConclusionA regimen of TAC-MR once daily can be considered as an effective and safe alternative formulation of tacrolimus in stable renal transplant patients.