Effects of body weight variation in obese kidney recipients: a retrospective cohort study

Background. Obese kidney allograft recipients have worse results in kidney transplantation (KT). However, there is lack of information regarding the effect of body mass index (BMI) variation after KT. The objective of the study was to evaluate the effects of body weight changes in obese kidney transplant recipients. Methods. In this study we used data from the Catalan Renal Registry that included KT recipients from 1990 to 2011 (n ¼ 5607). The annual change in post-transplantation BMI was calculated. The main outcome variables were delayed graft function (DGF), estimated glomerular filtration rate (eGFR) and patient and graft survival. Results. Obesity was observed in 609 patients (10.9%) at the time of transplantation. The incidence of DGF was significantly higher in obese patients (40.4% versus 28.3%; P < 0.001). Baseline obesity was significantly associated with worse short- and long-term graft survival (P < 0.05) and worse graft function during the follow-up (P < 0.005). BMI variations in obese patients did not improve eGFR or graft or patient survival. Conclusions. Our conclusion is that in obese patients, decreasing body weight after KT does not improve either short-term graft outcomes or long-term renal function

Influence of the circadian timing system on Tacrolimus pharmacokinetics and pharmacodynamics after kidney transplantation

Introduction: Tacrolimus is the backbone immunosuppressant after solid organ transplantation. Tacrolimus has a narrow therapeutic window with large intra- and inter-patient pharmacokinetic variability leading to frequent over- and under-immunosuppression. While routine therapeutic drug monitoring (TDM) remains the standard of care, tacrolimus pharmacokinetic variability may be influenced by circadian rhythms. Our aim was to analyze tacrolimus pharmacokinetic/pharmacodynamic profiles on circadian rhythms comparing morning and night doses of a twice-daily tacrolimus formulation. Methods: This is a post-hoc analysis from a clinical trial to study the area under curve (AUC) and the area under effect (AUE) profiles of calcineurin inhibition after tacrolimus administration in twenty-five renal transplant patients. Over a period of 24 h, an intensive sampling (0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 12.5, 13, 13.5, 14, 15, 20, and 24 h) was carried out. Whole blood and intracellular tacrolimus concentrations and calcineurin activity were measured by UHPLC-MS/MS. Results: Whole blood and intracellular AUC12-24 h and Cmax achieved after tacrolimus night dose was significantly lower than after morning dose administration (AUC0-12 h) (p < 0.001 for both compartments). AUE0-12 h and AUE12-24 h were not statistically different after morning and night doses. Total tacrolimus daily exposure (AUC0-24 h), in whole blood and intracellular compartments, was over-estimated when assessed by doubling the morning AUC0-12 h data. Conclusion: The lower whole blood and intracellular tacrolimus concentrations after night dose might be influenced by a distinct circadian clock. This significantly lower tacrolimus exposure after night dose was not translated into a significant reduction of the pharmacodynamic effect. Our study may provide conceptual bases for better understanding the TDM of twice-daily tacrolimus formulation

Acute Kidney Injury Following Chimeric Antigen Receptor T-Cell Therapy for B-Cell Lymphoma in a Kidney Transplant Recipient

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy is a newer and effective therapeutic option approved for patients with relapsed/refractory acute lymphoblastic leukemia and diffuse large B-cell lymphoma. Acute kidney injury is a complication of CAR T-cell therapy that can result in kidney failure. In most cases, it is thought to be related to hemodynamic changes due to cytokine release syndrome. Kidney biopsy in this clinical scenario is usually not performed. We report on a kidney transplant recipient in his 40s who developed a posttransplant lymphoproliferative disorder of B-cell origin refractory to conventional treatments and received anti-CD19 CAR T-cell therapy as compassionate treatment. Beginning on day 12 after CAR T-cell infusion, in the absence of clinical symptoms, a progressive decline in estimated glomerular filtration rate of the kidney graft occurred. A subsequent allograft biopsy showed mild tubulointerstitial lymphocyte infiltrates, falling into a Banff borderline-changes category and resembling an acute immunoallergic tubulointerstitial nephritis. Neither CAR T cells nor lymphomatous B cells were detected within the graft cellular infiltrates, suggesting an indirect mechanism of kidney injury. Although kidney graft function partially recovered after steroid therapy, the posttransplant lymphoproliferative disorder progressed and the patient died 7 months later

The effect of intracellular tacrolimus exposure on calcineurin inhibition in immediate- and extended-release tacrolimus formulations

Despite intensive monitoring of whole blood tacrolimus concentrations, acute rejection after kidney transplantation occurs during tacrolimus therapy. Intracellular tacrolimus concentrations could better reflect exposure at the site of action and its pharmacodynamics (PD). Intracellular pharmacokinetic (PK) profile following different tacrolimus formulations (immediate-release (TAC-IR) and extended-release (TAC-LCP)) remains unclear. Therefore, the aim was to study intracellular tacrolimus PK of TAC-IR and TAC-LCP and its correlation with whole blood (WhB) PK and PD. A post-hoc analysis of a prospective, open-label, crossover investigator-driven clinical trial (NCT02961608) was performed. Intracellular and WhB tacrolimus 24 h time-concentration curves were measured in 23 stable kidney transplant recipients. PD analysis was evaluated measuring calcineurin activity (CNA) and simultaneous intracellular PK/PD modelling analysis was conducted. Higher dose-adjusted pre-dose intracellular concentrations (C0 and C24) and total exposure (AUC0-24) values were found for TAC-LCP than TAC-IR. Lower intracellular peak concentration (Cmax) was found after TAC-LCP. Correlations between C0, C24 and AUC0-24 were observed within both formulations. Intracellular kinetics seems to be limited by WhB disposition, in turn, limited by tacrolimus release/absorption processes from both formulations. The faster intracellular elimination after TAC-IR was translated into a more rapid recovery of CNA. An Emax model relating % inhibition and intracellular concentrations, including both formulations, showed an IC50, a concentration to achieve 50% CNA inhibition, of 43.9 pg/million cells

Sustained inhibition of calcineurin activity with a Melt‐Dose Once‐daily Tacrolimus formulation in renal transplant recipients

Tacrolimus (Tac) is the cornerstone calcineurin inhibitor in transplantation. Extended-release Meltdose formulation (Tac-LCP) offers better bioavailability compared with immediate-release formulation (Tac-IR). We postulated that the less fluctuating pharmacokinetic (PK) profile of Tac-LCP might maintain a sustained inhibition of calcineurin activity (CNA) between dose intervals. Higher concentrations (peak plasma concentration (Cmax )) after Tac-IR may not result in a more potent CNA inhibition due to a capacity-limited effect. This study was aimed at evaluating the pharmacodynamic (PD)/PK profiles of Tac-IR compared with Tac-LCP. An open-label, prospective, nonrandomized, investigator-driven study was conducted. Twenty-five kidney transplant recipients receiving Tac-IR were switched to Tac-LCP. Before and 28 days after conversion, intensive CNA-PD and PK sampling were conducted using ultra-high-performance liquid chromatography-tandem accurate mass spectrometry. PD nonlinear mixed effects model was performed in Phoenix-WinNonlin. Statistically significant higher Cmax (P < 0.001) after Tac-IR did not result in lower CNA as compared with after Tac-LCP (P = 0.860). Tac-LCP showed a statistically more maintained CNA inhibition between dose intervals (area under the effect-time curve from 0 to 24 hours (AUE0-24h )) compared with Tac-IR, in which CNA returned to predose levels after 4 hours of drug intake (373.8 vs. 290.5 pmol RII·h/min·mg prot, Tac-LCP vs. Tac-IR; P = 0.039). No correlation was achieved between any PD and PK parameters in any formulations. Moreover, Tac concentration to elicit a 50% of the maximum response (half-maximal inhibitory concentration) was 9.24 ng/mL. The higher Cmax after Tac-IR does not result in an additional CNA inhibition compared with Tac-LCP attributable to a capacity-limited effect. Tac-LCP may represent an improvement of the PD of Tac due to the more sustained CNA inhibition during dose intervals

Donor/Recipient HLA Molecular Mismatch Scores Predict Primary Humoral and Cellular Alloimmunity in Kidney Transplantation

Donor/recipient molecular human leukocyte antigen (HLA) mismatch predicts primary B-cell alloimmune activation, yet the impact on de novo donor-specific T-cell alloimmunity (dnDST) remains undetermined. The hypothesis of our study is that donor/recipient HLA mismatches assessed at the molecular level may also influence a higher susceptibility to the development of posttransplant primary T-cell alloimmunity. In this prospective observational study, 169 consecutive kidney transplant recipients without preformed donor-specific antibodies (DSA) and with high resolution donor/recipient HLA typing were evaluated for HLA molecular mismatch scores using different informatic algorithms [amino acid mismatch, eplet MM, and Predicted Indirectly Recognizable HLA Epitopes (PIRCHE-II)]. Primary donor-specific alloimmune activation over the first 2 years posttransplantation was assessed by means of both dnDSA and dnDST using single antigen bead (SAB) and IFN-γ ELISPOT assays, respectively. Also, the predominant alloantigen presenting pathway priming DST alloimmunity and the contribution of main alloreactive T-cell subsets were further characterized in vitro. Pretransplantation, 78/169 (46%) were DST+ whereas 91/169 (54%) DST-. At 2 years, 54/169 (32%) patients showed detectable DST responses: 23/54 (42%) dnDST and 31/54 (57%) persistently positive (persistDST+). 24/169 (14%) patients developed dnDSA. A strong correlation was observed between the three distinct molecular mismatch scores and they all accurately predicted dnDSA formation, in particular at the DQ locus. Likewise, HLA molecular incompatibility predicted the advent of dnDST, especially when assessed by PIRCHE-II score (OR 1.014 95% CI 1.001-1.03, p=0.04). While pretransplant DST predicted the development of posttransplant BPAR (OR 5.18, 95% CI=1.64-16.34, p=0.005) and particularly T cell mediated rejection (OR 5.33, 95% CI=1.45-19.66, p=0.012), patients developing dnDST were at significantly higher risk of subsequent dnDSA formation (HR 2.64, 95% CI=1.08-6.45, p=0.03). In vitro experiments showed that unlike preformed DST that is predominantly primed by CD8+ direct pathway T cells, posttransplant DST may also be activated by the indirect pathway of alloantigen presentation, and predominantly driven by CD4+ alloreactive T cells in an important proportion of patients. De novo donor-specific cellular alloreactivity seems to precede subsequent humoral alloimmune activation and is influenced by a poor donor/recipient HLA molecular matching

Combining sensitive crossmatch assays with donor/recipient human leukocyte antigen eplet matching predicts living-donor kidney transplant outcome

Introduction: Despite the different assays available for immune-risk stratification before living-donor kidney transplantation (LDKT), the precise type and number of tests to perform remain uncertain. Methods: In a cohort of 330 consecutive LDKT patients, all of which were complement-dependent cyto- toxicity (CDC) crossmatch negative, we retrospectively analyzed the impact on main clinical outcomes of most sensitive immunoassays (complement-dependent cytotoxicity panel-reactive antibody [CDC-PRA], flow cytometry crossmatch [FC-XM], donor-specific antibodies [DSAs], and their complement-binding capacity DSA-C3d]), together with donor/recipient HLA eplet matching. Mean follow-up was 67 months (range 24 190 months). Results: Of 330 patients, 35 (11%) showed a CDC-PRA >20%; 17 (5%) FC-XMþ; 30 (9%) DSAþ, 18(5%) DSA- C3dþ, with low overlapping results (10 patients positive in all donor-specific tests). Unlike HLA allele compatibility, the mean number of HLA class II eplet mismatches was higher in LDKT patients with positive baseline test results. DSA-C3dþ showed higher mean fluorescence intensity (MFI) DSA, with a cut-off MFI of 6192 accurately predicting complement fixation (area under the curve 1⁄4 0.85, P 1⁄4 0.008). Although all assays were associated with acute rejection (AR), only DSA-C3dþ (odds ratio [OR] 1⁄4 6.64, P 1⁄4 0.038) or high MFI-DSA (OR 1⁄4 7.54, P 1⁄4 0.038) independently predicted AR. Likewise, poorly HLA class II eplet matched patients were at higher risk for AR, particularly patients with negative baseline test results (OR 1⁄4 1.14, P 1⁄4 0.019). Finally, previous AR and FC-XMþ/DSAþ, regardless of C3d positivity, indepen- dently predicted graft loss. Conclusion: Combining FC-XM and solid-phase assays with the evaluation of donor/recipient HLA eplet mismatches, are most accurate tools for immune-risk stratification prior LDKT

A prospective controlled, randomized clinical trial of kidney transplant recipients developed personalized tacrolimus dosing using model-based Bayesian Prediction

For three decades, tacrolimus (Tac) dose adjustment in clinical practice has been calculated empirically according to the manufacturer’s labeling based on a patient’s body weight. Here, we developed and validated a Population pharmacokinetic (PPK) model including pharmacogenetics (cluster CYP3A4/CYP3A5), age, and hematocrit. Our study aimed to assess the clinical applicability of this PPK model in the achievement of Tac Co (therapeutic trough Tac concentration) compared to the manufacturer’s labelling dosage. A prospective two-arm, randomized, clinical trial was conducted to determine Tac starting and subsequent dose adjustments in 90 kidney transplant recipients. Patients were randomized to a control group with Tac adjustment according to the manufacturer’s labeling or the PPK group adjusted to reach target Co (6-10 ng/ml) after the first steady state (primary endpoint) using a Bayesian prediction model (NONMEM). A significantly higher percentage of patients from the PPK group (54.8%) compared with the control group (20.8%) achieved the therapeutic target fulfilling 30% of the established superiority margin defined. Patients receiving PPK showed significantly less intra-patient variability compared to the control group, reached the Tac Co target sooner (5 days vs 10 days), and required significantly fewer Tac dose modifications compared to the control group within 90 days following kidney transplant. No statistically significant differences occurred in clinical outcomes. Thus, PPK-based Tac dosing offers significant superiority for starting Tac prescription over classical labeling-based dosing according to the body weight, which may optimize Tac-based therapy in the first days following transplantation

SARS‐CoV‐2‐specific serological and functional T cell immune responses during acute and early COVID‐19 convalescence in solid organ transplant patients

International audienceThe description of protective humoral and T cell immune responses specific against SARS-CoV-2 has been reported among immunocompetent (IC) individuals developing COVID-19 infection. However, its characterization and determinants of poorer outcomes among the at-risk solid organ transplant (SOT) patient population have not been thoroughly investigated. Cytokine-producing T cell responses, such as IFN-γ, IL-2, IFN-γ/IL-2, IL-6, IL-21, and IL-5, against main immunogenic SARS-CoV-2 antigens and IgM/IgG serological immunity were tracked in SOT (n = 28) during acute infection and at two consecutive time points over the following 40 days of convalescence and were compared to matched IC (n = 16) patients admitted with similar moderate/severe COVID-19. We describe the development of a robust serological and functional T cell immune responses against SARS-CoV-2 among SOT patients, similar to IC patients during early convalescence. However, at the infection onset, SOT displayed lower IgG seroconversion rates (77% vs. 100%; p = .044), despite no differences on IgG titers, and a trend toward decreased SARS-CoV-2-reactive T cell frequencies, especially against the membrane protein (7 [0-34] vs. 113 [15-245], p = .011, 2 [0-9] vs. 45 [5-74], p = .009, and 0 [0-2] vs. 13 [1-24], p = .020, IFN-γ, IL-2, and IFN-γ/IL-2 spots, respectively). In summary, our data suggest that despite a certain initial delay, SOT population achieve comparable functional immune responses than the general population after moderate/severe COVID-19