Immunosuppression: evolution in practice and trends, 1994-2004

Histopathological analysis of the skin of renal transplant recipients submitted to three different immunosuppression regimens

BACKGROUND

Renal transplant recipients (RTRs) use a combination of immunosuppressive agents: a corticosteroid; a calcineurin inhibitor (cyclosporine or tacrolimus) and an antimetabolic agent (azathioprine [AZA] or a mycophenolic acid precursor [MPA] ‒ Mycophenolate mofetil or sodium) or an mTOR inhibitor (mTORi) ‒ sirolimus or everolimus. These treatments increase the incidence of various neoplasms, especially non-melanoma skin cancers (NMSCs).

OBJECTIVES

To evaluate the histopathological alterations in the skin of the RTRs under three different immunosuppressive regimens: one mTORi (sirolimus or everolimus); or one antimetabolic agent (MPA or AZA), comparing them by groups and with healthy controls.

METHODS

This was an observational, cross-sectional, comparative study of 30 patients selected from the Renal Transplant Service and divided into three groups: mTORi (n = 10), MPA (n = 10), and AZA (n = 10). The control group consisted of 10 immunocompetent non-transplanted volunteers. All RTRs were using tacrolimus and prednisone. Each participant underwent two biopsies of intact skin: one in a sun-protected and another in a sun-exposed area. The specimens were analyzed without previous information on which group they belonged to.

RESULTS

The most significant histopathological change was thinning of the epidermis in the mTORi group, both in photoexposed and photoprotected skin.

STUDY LIMITATIONS

The study was conducted on a limited number of patients, which may influence the representativeness of the results.

CONCLUSIONS

Only RTRs treated with mTORi presented interruption of epidermal proliferation. These findings help to understand the influence of these different types of immunosuppressive regimens and their subsequent potential effects on carcinogenesis.

Computational studies on the functional and structural impact of pathogenic mutations in enzymes

Enzymes are critical biological catalysts involved in maintaining the intricate balance of metabolic processes within living organisms. Mutations in enzymes can result in disruptions to their functionality that may lead to a range of diseases. This review focuses on computational studies that investigate the effects of disease-associated mutations in various enzymes. Through molecular dynamics simulations, multiscale calculations, and machine learning approaches, computational studies provide detailed insights into how mutations impact enzyme structure, dynamics, and catalytic activity. This review emphasizes the increasing impact of computational simulations in understanding molecular mechanisms behind enzyme (dis)function by highlighting the application of key computational methodologies to selected enzyme examples, aiding in the prediction of mutation effects and the development of therapeutic strategies.

Effect of everolimus administration on renal function in renal transplant recipients: A systematic review and dose-response meta-analysis

Everolimus (EVL) is an effective post-transplant immunosuppressant; however, its optimal trough concentration when switching from calcineurin inhibitors (CNIs) remains unknown. The optimal dosing troughs for CNI-to-EVL switching in kidney transplant recipients were investigated. We searched multiple electronic databases (from inception to March 15, 2024) to identify double-blind or open-label randomized controlled trials evaluating groups (all ages, both sexes) that converted from CNIs to EVL and continued CNI treatment in kidney transplant recipients. Treatment responses, defined as changes in estimated glomerular filtration rate (eGFR), mortality, dropouts for any reason, and adverse events, were the outcomes. We performed a random-effects, one-stage dose-effect meta-analysis with restricted cubic splines. Nine studies were included, comprising 1872 participants. Changes in eGFR increased with increasing trough concentrations; however, the evidence was highly uncertain (95 % effective dose: 4.13 ng/mL, odds ratio [OR]: 1.31, 95 % confidence interval [CI]: 0.10-9.50). Mortality was not estimated owing to the low number of events. The evidence for the relationship between EVL trough levels and treatment discontinuation was also highly uncertain (OR: 1.31, 95 % CI: 0.10-9.39). Adverse events increased with a switch to EVL; however, this evidence was also uncertain (OR: 1.31, 95 % CI: 0.10-9.60). This study could not indicate an appropriate optimal EVL trough concentration owing to the high result uncertainty, and the results do not support the routine switch from CNIs to EVL. Further trials are required to explore the CNI-to-EVL switch timing and the effects of increased EVL dosing to establish a more definitive therapeutic strategy.

Balancing immunotherapy and corticosteroids in cancer treatment: dilemma or paradox?

Corticosteroids are widely used to prevent and treat chemotherapy-induced nausea and vomiting (CINV) due to their pleiotropic biological effects. However, concerns have been raised about their immunosuppressive properties when combined with immunotherapy. Specifically, their potential impact on the efficacy of immunotherapy, mainly immune checkpoint inhibitors (ICIs), remains a subject of debate. This manuscript discusses the mechanisms by which corticosteroids mitigate CINV, the challenges associated with their concurrent use with immunotherapy, and emerging therapeutic strategies evaluating dexamethasone-free regimens. A careful balance must be struck in corticosteroid use to effectively manage CINV while optimizing the outcomes of immunotherapy.

The association between serum tacrolimus concentrations and BK viruria in kidney transplant recipients

The objective of this study was to examine the association between serum tacrolimus trough levels and the detection of BK viruria in kidney transplant recipients. We conducted a retrospective study and included kidney transplant recipients who underwent BK viruria screening during 2018-2021. Serum tacrolimus trough levels, urine BK viral load, and potential risk factors were collected. Statistical analysis was performed to identify the association between the serum tacrolimus trough levels and the detection of BK virus in urine (defined as positive BK viruria), as well as to determine the cumulative incidence and risk factors for BK viruria. Out of 243 recipients, 76 had positive BK viruria. The average serum tacrolimus trough level was significantly higher among the positive BK viruria group compared to the BK viruria-negative group. High HLA mismatch was identified as a risk factor for BK viruria. Approximately half of the recipients with average serum tacrolimus trough levels exceeding 10 ng/mL would develop BK viruria early. This study found an association between the average serum tacrolimus trough level and the detection of BK viruria. High HLA mismatch and an average serum tacrolimus trough level exceeding 10 ng/mL should be regarded as a risk for BK viruria.

Drug delivery strategies for local immunomodulation in transplantation: Bridging the translational gap

Drug delivery strategies for local immunomodulation hold tremendous promise compared to current clinical gold-standard systemic immunosuppression as they could improve the benefit to risk ratio of life-saving or life-enhancing transplants. Such strategies have facilitated prolonged graft survival in animal models at lower drug doses while minimizing off-target effects. Despite the promising outcomes in preclinical animal studies, progression of these strategies to clinical trials has faced challenges. A comprehensive understanding of the translational barriers is a critical first step towards clinical validation of effective immunomodulatory drug delivery protocols proven for safety and tolerability in pre-clinical animal models. This review overviews the current state-of-the-art in local immunomodulatory strategies for transplantation and outlines the key challenges hindering their clinical translation.

Update on Maintenance Immunosuppression in Intestinal Transplantation

Outcomes in intestinal transplantation remain hampered by higher rates of rejection than any other solid organs. However, maintenance immunosuppression regimens have largely remained unchanged despite advances in therapies for induction and treatment of rejection and graft-versus-host disease. Recently, there have been a small number of new maintenance therapies attempted, and older agents have been used in new ways to achieve better outcomes. The authors herein review the traditional maintenance therapies and their mechanisms and then consider updates in new therapies and new ways of using old therapies for maintenance immunosuppression after intestinal transplantation.

Demographic Trends in Liver Transplant Survivors After 3 Decades of Program Implementation: The Impact of Cohort and Period Effects on Life Expectancy

Background

Demographic analyses may reveal current patterns of change in the outcomes of rapidly developing medical procedures because they incorporate the period perspective.

Methods

We analyzed the changes in size, age structure, and hospitalizations in the population of liver transplantation (LT) survivors in our center during the last 30 y (n = 1114 patients) and generated projections, including life expectancy (LE), considering cohort and period effects. Life tables were used to project the complete LE (overall 1990-2020 experience), the cohort LE (according to the decade of surgery: 1990-2000, 2000-2010, and 2010-2020), and the period LE (current 2015-2020 experience).

Results

The population of LT recipients in follow-up continued to experience progressive growth and aging since 1990 (492 patients [41.9% >65 y] in 2020), and the magnitude of these phenomena may double in the next 30 y. However, the number of admissions and days of admission has been decreasing. The complete LE at LT was 12.4 y, whereas the period LE was 15.8 y. The cohort LE (limited to 10 y) was 5.3, 6.3, and 7.3 y for the 1990-2000, 2000-2010, and 2010-2020 cohorts, respectively.

Conclusions

The target population of our medical care after LT is growing and aging. The prevalence of both of these phenomena is expected to increase in the coming years and is associated with a current improvement in LE. However, the hospitalization burden associated with LT survivors is declining. The period effect should be considered for generating up-to-date information on these current trends, which are crucial when designing health policies for LT survivors.

What is the role of microbial biotechnology and genetic engineering in medicine?

Microbial products are essential for developing various therapeutic agents, including antibiotics, anticancer drugs, vaccines, and therapeutic enzymes. Genetic engineering techniques, functional genomics, and synthetic biology unlock previously uncharacterized natural products. This review highlights major advances in microbial biotechnology, focusing on gene-based technologies for medical applications.

Role of Complement-dependent Cytotoxicity Crossmatch and HLA Typing in Solid Organ Transplant

BACKGROUND

Solid organ transplantation is a life-saving medical operation that has progressed greatly because of developments in diagnostic tools and histocompatibility tests. Crossmatching for complement-dependent cytotoxicity (CDC) and human leukocyte antigen (HLA) typing are two important methods for checking graft compatibility and reducing the risk of graft rejection. HLA typing and CDC crossmatching are critical in kidney, heart, lung, liver, pancreas, intestine, and multi-organ transplantation.

METHODS

A systematic literature search was conducted on the internet, using PubMed, Scopus, and Google Scholar databases, to identify peer-reviewed publications about solid organ transplants, HLA typing, and CDC crossmatching.

CONCLUSION

Recent advances in HLA typing have allowed for high-resolution evaluation, epitope matching, and personalized therapy methods. Genomic profiling, next-generation sequencing, and artificial intelligence have improved HLA typing precision, resulting in better patient outcomes. Artificial intelligence (AI) driven virtual crossmatching and predictive algorithms have eliminated the requirement for physical crossmatching in the context of CDC crossmatching, boosting organ allocation and transplant efficiency. This review elaborates on the importance of HLA typing and CDC crossmatching in solid organ transplantation.

The Virulence Factor Macrophage Infectivity Potentiator (Mip) Influences Branched-Chain Amino Acid Metabolism and Pathogenicity of Legionella pneumophila

Legionella pneumophila (Lp) is a common etiological agent of bacterial pneumonia that causes Legionnaires' disease (LD). The bacterial membrane-associated virulence factor macrophage infectivity potentiator (Mip) exhibits peptidyl-prolyl-cis/trans-isomerase (PPIase) activity and contributes to the intra- and extracellular pathogenicity of Lp. Though Mip influences disease outcome, little is known about the metabolic consequences of altered Mip activity during infections. Here, we established a metabolic workflow and applied mass spectrometry approaches to decipher how Mip activity influences metabolism and pathogenicity. Impaired Mip activity in genetically engineered Lp strains decreases intracellular replication in cellular infection assays, confirming the contribution of Mip for Lp pathogenicity. We observed that genetic and chemical alteration of Mip using the PPIase inhibitors rapamycin and FK506 induces metabolic reprogramming in Lp, specifically branched-chain amino acid (BCAA) metabolism. Rapamycin also inhibits PPIase activity of mammalian FK506 binding proteins, and we observed that rapamycin induces a distinct metabolic signature in human macrophages compared to bacteria, suggesting potential involvement of Mip in normal bacteria and in infection. Our metabolic studies link Mip to alterations in BCAA metabolism and may help to decipher novel disease mechanisms associated with LD.

Developing supervised machine learning algorithms to evaluate the therapeutic effect and laboratory-related adverse events of cyclosporine and tacrolimus in renal transplants

BACKGROUND

Single nucleotide polymorphisms influence the effects of tacrolimus and cyclosporine in renal transplants.

AIM

We set out to use machine learning algorithms (MLAs) to identify variables that predict the therapeutic effects and adverse events following tacrolimus and cyclosporine administration in renal transplant patients.

METHOD

We sampled 120 adult renal transplant patients (on cyclosporine or tacrolimus). Generalized linear model (GLM), support vector machine (SVM), artificial neural network (ANN), Chi-square automatic interaction detection, classification and regression tree, and K-nearest neighbors were the chosen MLAs. The mean absolute error (MAE), relative mean square error (RMSE), and regression coefficient (β) with a 95% confidence interval (CI) were used as the model parameters.

RESULTS

For a stable dose of tacrolimus, the MAEs (RMSEs) of GLM, SVM, and ANN were 1.3 (1.5), 1.3 (1.8), and 1.7 (2.3) mg/day, respectively. GLM revealed that the POR*28 genotype and age significantly predicted the stable dose of tacrolimus as follows: POR*28 (β -1.8; 95% CI -3, -0.5; p = 0.006), and age (β -0.04; 95% CI -0.1, -0.006; p = 0.02). For a stable dose of cyclosporine, MAEs (RMSEs) of 93.2 (103.4), 79.1 (115.2), and 73.7 (91.7) mg/day were observed with GLM, SVM, and ANN, respectively. GLM revealed the following predictors of a stable dose of cyclosporine: CYP3A5*3 (β -80.8; 95% CI -130.3, -31.2; p = 0.001), and age (β -3.4; 95% CI -5.9, -0.9; p = 0.007).

CONCLUSION

We observed that various MLAs could identify significant predictors that were useful to optimize tacrolimus and cyclosporine dosing regimens; yet, the findings must be externally validated.

Applying machine learning to the pharmacokinetic modeling of cyclosporine in adult renal transplant recipients: a multi-method comparison

Objective: The aim of this study was to identify the important factors affecting cyclosporine (CsA) blood concentration and estimate CsA concentration using seven different machine learning (ML) algorithms. We also assessed the predictability of established ML models and previously built population pharmacokinetic (popPK) model. Finally, the most suitable ML model and popPK model to guide precision dosing were determined.

Methods: In total, 3,407 whole-blood trough and peak concentrations of CsA were obtained from 183 patients who underwent initial renal transplantation. These samples were divided into model-building and evaluation sets. The model-building set was analyzed using seven different ML algorithms. The effects of potential covariates were evaluated using the least absolute shrinkage and selection operator algorithms. A separate evaluation set was used to assess the ability of all models to predict CsA blood concentration. R squared (R2) scores, median prediction error (MDPE), median absolute prediction error (MAPE), and the percentages of PE within 20% (F20) and 30% (F30) were calculated to assess the predictive performance of these models. In addition, previously built popPK model was included for comparison.

Results: Sixteen variables were selected as important covariates. Among ML models, the predictive performance of nonlinear-based ML models was superior to that of linear regression (MDPE: 3.27%, MAPE: 34.21%, F20: 30.63%, F30: 45.03%, R2 score: 0.68). The ML model built with the artificial neural network algorithm was considered the most suitable (MDPE: −0.039%, MAPE: 25.60%, F20: 39.35%, F30: 56.46%, R2 score: 0.75). Its performance was superior to that of the previously built popPK model (MDPE: 5.26%, MAPE: 29.22%, F20: 33.94%, F30: 51.22%, R2 score: 0.68). Furthermore, the application of the most suitable model and the popPK model in clinic showed that most dose regimen recommendations were reasonable.

Conclusion: The performance of these ML models indicate that a nonlinear relationship for covariates may help to improve model predictability. These results might facilitate the application of ML models in clinic, especially for patients with unstable status or during initial dose optimization.

[Update: Immunosuppression in organ transplantation]

Immunosuppression is an essential prerequisite for successful transplantation. In order to reduce the sometimes-considerable side effects, combination therapies with different agents are used. This article aims to provide an up-to-date overview of immunosuppression after liver and kidney transplantation.

Influence of Calcineurin Inhibitor Choice on Outcomes in Kidney Transplant Recipients Aged ≥60 Y: A Collaborative Transplant Study Report

BACKGROUND

Patients aged ≥60 y represent the fastest growing population among kidney transplant recipients and waitlist patients. They show an elevated infection risk and are frequently transplanted with multiple human leukocyte antigen mismatches. Whether the choice of calcineurin inhibitor influences graft survival, mortality, or key secondary outcomes such as infections in this vulnerable recipient population is unknown.

METHODS

A total of 31 177 kidney transplants from deceased donors performed between 2000 and 2019 at European centers and reported to the Collaborative Transplant Study were analyzed using multivariable Cox and logistic regression analyses. All recipients were ≥60 y old and received tacrolimus (Tac) or cyclosporine A on an intention-to-treat basis, combined with mycophenolic acid or azathioprine plus/minus steroids.

RESULTS

The risk of 3-y death-censored graft loss and patient mortality did not differ significantly between Tac- and cyclosporine A-treated patients (hazard ratio 0.98 and 0.95, P = 0.74 and 0.20, respectively). No difference was found in the overall risk of hospitalization for infection (hazard ratio = 0.95, P = 0.19); however, a lower incidence of rejection treatment (hazard ratio = 0.81, P < 0.001) was observed in Tac-treated patients. Assessment of pathogen-specific hospitalizations revealed no difference in the risk of hospitalization due to bacterial infection (odds ratio = 1.00, P = 0.96), but a significantly higher risk of hospitalization due to human polyomavirus infection was found among Tac-treated patients (odds ratio = 2.45, P = 0.002). The incidence of de novo diabetes was higher for Tac-based immunosuppression (odds ratio = 1.79, P < 0.001).

CONCLUSIONS

Calcineurin inhibitor selection has no significant influence on death-censored graft survival, mortality, and overall infection risk in ≥60-y-old kidney transplant recipients.

Factors Affecting Time-Varying Clearance of Cyclosporine in Adult Renal Transplant Recipients: A Population Pharmacokinetic Perspective

AIM

The pharmacokinetic (PK) properties of cyclosporine (CsA) in renal transplant recipients are patient- and time-dependent. Knowledge of this time-related variability is necessary to maintain or achieve CsA target exposure. Here, we aimed to identify factors explaining variabilities in CsA PK properties and characterize time-varying clearance (CL/F) by performing a comprehensive analysis of CsA PK factors using population PK (popPK) modeling of long-term follow-up data from our institution.

METHODS

In total, 3674 whole-blood CsA concentrations from 183 patients who underwent initial renal transplantation were analyzed using nonlinear mixed-effects modeling. The effects of potential covariates were selected according to a previous study and well-accepted theoretical mechanisms. Model-informed individualized therapeutic regimens were also evaluated.

RESULTS

A two-compartment model adequately described the data and the estimated mean CsA CL/F was 32.6 L h^-1 (relative standard error: 5%). Allometrically scaled body size, hematocrit (HCT) level, CGC haplotype carrier status, and postoperative time may contribute to CsA PK variability. The CsA bioavailability in patients receiving a prednisolone dose (PD) of 80 mg was 20.6% lower than that in patients receiving 20 mg. A significant decrease (52.6%) in CL/F was observed as the HCT increased from 10.5% to 60.5%. The CL/F of the non-CGC haplotype carrier was 14.4% lower than that of the CGC haplotype carrier at 3 months post operation.

CONCLUSIONS

By monitoring body size, HCT, PD, and CGC haplotype, changes in CsA CL/F over time could be predicted. Such information could be used to optimize CsA therapy. CsA dose adjustments should be considered in different postoperative periods.

Computational validation of ABCB1 gene polymorphism and its effect on tacrolimus dose concentration/levels in renal transplant individuals of South India

Patients with end-stage renal failure require hemodialysis and peritoneal dialysis; however, kidney transplantation is considered a better treatment option for renal failure patients, improving their quality of life and longevity. Among several potent immunosuppressive agents, tacrolimus (TAC) has shown progressive improvement in the graft survival rates after renal transplantation. Fifty kidney transplant patients undergoing TAC immunosuppressive treatment were included. The human genomic DNA was isolated using the phenol-chloroform extraction procedure. CYP3A5*6, CYP3A5*2, and ABCB1 exon 21 G2677 T/A polymorphisms were genotyped using the polymerase chain reaction-restriction fragment length polymorphism method. Fisher's exact test and Chi-square analysis were performed to analyze the data, where p < 0.05 was considered statistically significant. In addition, we implemented bioinformatics studies on ABCB1 protein to determine the mutation's effect sequentially and structurally. Among the genotyped single nucleotide polymorphisms (SNPs), SNPs of CYP3A5*2 and CYP3A5*6 did not vary in the studied population. The concentration/dose (C/D) ratio of TT genotype of the ABCB1 gene was higher (95% CI: 177.38-269.46) when compared to TA and AA. However, there were no substantial differences between the ABCB1 genotypes and TAC C/D ratio (p = 0.953). The TAC dose mg/kg/day (p = 0.002) and C/D ratio (p = 0.004) exhibited a statistically significant difference. However, no significant difference was found with respect to the ABCB1 gene between the non-toxicity and toxicity groups. Mutation and residue interaction analysis results showed that the S893T mutation destabilizes the ABCB1 protein, thus reducing the protein's flexibility. The present study demonstrated a substantial relationship between the TAC dose and C/D ratio, including the non-toxicity and toxicity groups. However, no possible correlation was observed between the ABCB1 gene polymorphism and renal transplant.

Impact of everolimus on survival after liver transplantation for hepatocellular carcinoma

BACKGROUND/AIMS

This study aimed to investigate whether everolimus (EVR) affects long-term survival after liver transplantation (LT) in patients with hepatocellular carcinoma (HCC).

METHODS

The data from 303 consecutive patients with HCC who had undergone LT from January 2012 to July 2018 were retrospectively reviewed. The patients were divided into two groups: 1) patients treated with EVR in combination with calcineurin inhibitors (CNIs) (EVR group; n=114) and 2) patients treated with CNI-based therapy without EVR (non-EVR group; n=189). Time to recurrence (TTR) and overall survival (OS) after propensity score (PS) matching were compared between the groups, and prognostic factors for TTR and OS were evaluated.

RESULTS

The EVR group exhibited more aggressive tumor biology than the non-EVR group, such as a higher number of tumors (P=0.003), a higher prevalence of microscopic vascular invasion (P=0.017) and exceeding Milan criteria (P=0.029). Compared with the PS-matched non-EVR group, the PS-matched EVR group had significantly better TTR (P<0.001) and OS (P<0.001). In multivariable analysis, EVR was identified as an independent prognostic factor for TTR (hazard ratio [HR], 0.248; P=0.001) and OS (HR, 0.145; P<0.001).

CONCLUSION

Combined with CNIs, EVR has the potential to prolong long-term survival in patients undergoing LT for HCC. These findings warrant further investigation in a well-designed prospective study.

Prevention of vascular-allograft rejection by protecting the endothelial glycocalyx with immunosuppressive polymers

Systemic immunosuppression for the mitigation of immune rejection after organ transplantation causes adverse side effects and constrains the long-term benefits of the transplanted graft. Here we show that protecting the endothelial glycocalyx in vascular allografts via the enzymatic ligation of immunosuppressive glycopolymers under cold-storage conditions attenuates the acute and chronic rejection of the grafts after transplantation in the absence of systemic immunosuppression. In syngeneic and allogeneic mice that received kidney transplants, the steric and immunosuppressive properties of the ligated polymers largely protected the transplanted grafts from ischaemic reperfusion injury, and from immune-cell adhesion and thereby immunocytotoxicity. Polymer-mediated shielding of the endothelial glycocalyx following organ procurement should be compatible with clinical procedures for transplant preservation and perfusion, and may reduce the damage and rejection of transplanted organs after surgery.

A Population Pharmacokinetic Model Does Not Predict the Optimal Starting Dose of Tacrolimus in Pediatric Renal Transplant Recipients in a Prospective Study: Lessons Learned and Model Improvement

Background and Objective

Bodyweight-based dosing of tacrolimus is considered standard care. Currently, at first steady state, a third of pediatric kidney transplant recipients has a tacrolimus pre-dose concentration within the target range. We investigated whether adaptation of the starting dose according to a validated dosing algorithm could increase this proportion.

Methods

This was a multi-center, single-arm, prospective trial with a planned interim analysis after 16 patients, in which the tacrolimus starting dose was based on bodyweight, cytochrome P450 3A5 genotype, and donor status (living vs. deceased donor).

Results

At the interim analysis, 31% of children had a tacrolimus pre-dose concentration within the target range. As the original dosing algorithm was poorly predictive of tacrolimus exposure, the clinical trial was terminated prematurely. Next, the original model was improved by including the data of the children included in this trial, thereby doubling the number of children in the model building cohort. Data were best described with a two-compartment model with inter-individual variability, allometric scaling, and inter-occasion variability on clearance. Cytochrome P450 3A5 genotype, hematocrit, and creatinine influenced the tacrolimus clearance. A new starting dose model was developed in which the cytochrome P450 3A5 genotype was incorporated. Both models were successfully internally and externally validated.

Conclusions

The weight-normalized starting dose of tacrolimus should be higher in patients with a lower bodyweight and in those who are cytochrome P450 3A5 expressers.

Electronic supplementary material

The online version of this article (10.1007/s40262-019-00831-8) contains supplementary material, which is available to authorized users.

Immunosuppression Regimen Use and Outcomes in Older and Younger Adult Kidney Transplant Recipients: A National Registry Analysis

BACKGROUND

Although the population of older transplant recipients has increased dramatically, there are limited data describing the impact of immunosuppression regimen choice on outcomes in this recipient group.

METHODS

National data for US Medicare-insured adult kidney recipients (N = 67 362; 2005-2016) were examined to determine early immunosuppression regimen and associations with acute rejection, death-censored graft failure, and mortality using multivariable regression analysis in younger (18-64 y) and older (>65 y) adults.

RESULTS

The use of antithymocyte globulin (TMG) or alemtuzumab (ALEM) induction with triple maintenance immunosuppression (reference) was less common in older compared with younger (36.9% versus 47.0%) recipients, as was TMG/ALEM + steroid avoidance (19.2% versus 20.1%) and mammalian target of rapamycin inhibitor (mTORi)-based (6.7% versus 7.7%) treatments. Conversely, older patients were more likely to receive interleukin (IL)-2-receptor antibody (IL2rAb) + triple maintenance (21.1% versus 14.7%), IL2rAb + steroid avoidance (4.1% versus 1.8%), and cyclosporine-based (8.3% versus 6.6%) immunosuppression. Compared with older recipients treated with TMG/ALEM + triple maintenance (reference regimen), those managed with TMG/ALEM + steroid avoidance (adjusted odds ratio [aOR], 0.440.520.61) and IL2rAb + steroid avoidance (aOR, 0.390.550.79) had lower risk of acute rejection. Older patients experienced more death-censored graft failure when managed with Tac + antimetabolite avoidance (adjusted hazard [aHR], 1.411.782.25), mTORi-based (aHR, 1.702.142.71), and cyclosporine-based (aHR, 1.411.782.25) regimens, versus the reference regimen. mTORi-based and cyclosporine-based regimens were associated with increased mortality in both older and younger patients.

CONCLUSIONS

Lower-intensity immunosuppression regimens (eg, steroid-sparing) appear beneficial for older kidney transplant recipients, while mTORi and cyclosporine-based maintenance immunosuppression are associated with higher risk of adverse outcomes.

Efficacy and Safety of Everolimus With Reduced Tacrolimus in Liver Transplant Recipients: 24-month Results From the Pooled Analysis of 2 Randomized Controlled Trials

BACKGROUND AND METHODS

Data from 2 randomized liver transplant trials (N = 772; H2304 [deceased donor, n = 488], H2307 [living donor, n = 284]) were pooled to further evaluate the efficacy and safety of everolimus with reduced tacrolimus (EVR + rTAC) versus standard tacrolimus (sTAC) regimen at month 24.

RESULTS

EVR + rTAC was comparable to sTAC for composite efficacy failure of treated biopsy-proven acute rejection, graft loss, or death (9.8% versus 10.8%; difference, -1.0%; 95% confidence interval, -5.4 to 3.4; P = 0.641) at month 24. EVR + rTAC was superior to sTAC for the mean change in estimated glomerular filtration rate (eGFR) from randomization to month 24 (-8.37 versus -13.40 mL/min/1.73 m2; P = 0.001). A subanalysis of renal function by chronic kidney disease (CKD) stage at randomization showed significantly lower decline in eGFR from randomization to month 24 for patients with CKD stage 1/2 (eGFR ≥ 60 mL/min/1.73 m2) in EVR + rTAC group versus sTAC (-12.82 versus -17.67 mL/min/1.73 m2, P = 0.009). In patients transplanted for hepatocellular carcinoma (HCC) beyond Milan criteria, HCC recurrence was numerically lower although not statistically significant with EVR + rTAC versus sTAC group (5.9% [1 of 17] versus 23.1% [6 of 26], P = 0.215), while comparable in patients within Milan criteria (2.9% [3 of 102] versus 2.1% [2 of 96], P = 1.000), irrespective of pretransplant alpha-fetoprotein levels.

CONCLUSIONS

EVR + rTAC versus sTAC showed comparable efficacy and safety with significantly better renal function, particularly in patients with normal/mildly decreased renal function (CKD stage 1/2) at randomization and a trend toward lower HCC recurrence in patients transplanted with HCC beyond Milan at month 24. Further long-term data would be required to confirm these results.

Combination of atmospheric and room temperature plasma (ARTP) mutagenesis, genome shuffling and dimethyl sulfoxide (DMSO) feeding to improve FK506 production in Streptomyces tsukubaensis

FK506 is a clinically important macrocyclic polyketide with immunosuppressive activity produced by Streptomyces tsukubaensis. However, the production capacity of the strain is very low. To improve production, atmospheric and room temperature plasma (ARTP) mutagenesis was adopted to get the initial strains used in genome shuffling (GS). After three rounds of GS, S. tsukubaensis R3-C4 was the most productive strain, resulting in a FK506 concentration of 335 μg/mL, 2.6 times than that of the original wild-type strain. Moreover, exogenous DMSO 4% (v/v) addition could induce efflux of FK506 and increased FK506 production by 27.9% to 429 μg/mL. Finally, analyses of the differences in morphology, fermentation characteristics and specific gene expression levels between S. tsukubaensis R3-C4 and the wild-type strain revealed that R3-C4 strain: has hampered spore differentiation, thicker mycelia and more red pigment, which are likely related to the downregulation of bldD and cdgB expression. In addition, the expression levels of fkbO, fkbP, dahp, pccB and prpE all showed up-regulation at diverse degrees compared to the wild-type S. tsukubaensis. Overall, these results show that a combined approach involving classical random mutation and exogenous feeding can be applied to increase FK506 biosynthesis and may be applied also to the improvement of other important secondary metabolites.

Exploring the Complexity of Death-Censored Kidney Allograft Failure

BACKGROUND

Few studies have thoroughly investigated the causes of kidney graft loss (GL), despite its importance.

METHODS

A novel approach assigns each persistent and relevant decline in renal function over the lifetime of a renal allograft to a standardized category, hypothesizing that singular or multiple events finally lead to GL. An adjudication committee of three physicians retrospectively evaluated indication biopsies, laboratory testing, and medical history of all 303 GLs among all 1642 recipients of transplants between January 1, 1997 and December 31, 2017 at a large university hospital to assign primary and/or secondary causes of GL.

RESULTS

In 51.2% of the patients, more than one cause contributed to GL. The most frequent primary or secondary causes leading to graft failure were intercurrent medical events in 36.3% of graft failures followed by T cell-mediated rejection (TCMR) in 34% and antibody-mediated rejection (ABMR) in 30.7%. In 77.9%, a primary cause could be attributed to GL, of which ABMR was most frequent (21.5%). Many causes for GL were identified, and predominant causes for GL varied over time.

CONCLUSIONS

GL is often multifactorial and more complex than previously thought.

Immunosuppression trends in solid organ transplantation: The future of individualization, monitoring, and management

Immunosuppression regimens used in solid organ transplant have evolved significantly over the past 70 years in the United States. Early immunosuppression and targets for allograft success were measured by incidence and severity of allograft rejection and 1-year patient survival. The limited number of agents, infancy of human leukocyte antigen (HLA) matching techniques and lack of understanding of immunoreactivity limited the early development of effective regimens. The 1980s and 1990s saw incredible advancements in these areas, with acute rejection rates halving in a short span of time. However, the constant struggle to achieve the optimal balance between under- and overimmunosuppression is weaved throughout the history of transplant immunosuppression. The aim of this paper is to discuss the different eras of immunosuppression and highlight the important milestones that were achieved while also discussing this in the context of rational agent selection and regimen design. This discussion sets the stage for how we can achieve optimal long-term outcomes during the next era of immunosuppression, which will move from universal protocols to patient-specific optimization.

Distinct peripheral blood molecular signature emerges with successful tacrolimus withdrawal in kidney transplant recipients

Tacrolimus (Tac) is an effective anti-rejection agent in kidney transplantation, but its off-target effects make withdrawal desirable. Although studies indicate that Tac can be safely withdrawn in a subset of kidney transplant recipients, immune mechanisms that underlie successful vs unsuccessful Tac removal are unknown. We performed microarray analyses of peripheral blood mononuclear cells (PBMC) RNA from subjects enrolled in the Clinical Trials in Organ Transplantation-09 study in which we randomized stable kidney transplant recipients to Tac withdrawal or maintenance of standard immunosuppression beginning 6 months after transplant. Eight of 14 subjects attempted but failed withdrawal, while six developed stable graft function for ≥2 years on mycophenolate mofetil plus prednisone. Whereas failed withdrawal upregulated immune activation genes, successful Tac withdrawal was associated with a downregulatory and proapoptotic gene program enriched within T cells. Functional analyses suggested stronger donor-reactive immunity in subjects who failed withdrawal without evidence of regulatory T cell dysfunction. Together, our data from a small, but unique, patient cohort support the conclusion that successful Tac withdrawal is not simply due to absence of donor-reactive immunity but rather is associated with an active immunological process.

Induction immunosuppression and the risk of incident malignancies among older and younger kidney transplant recipients: A prospective cohort study

BACKGROUND

Older (≥65) KT recipients differ from their younger counterparts in their immune response to immunosuppression (IS) and may have a different risk of malignancy after receiving induction.

METHODS

We identified 66 700 adult KT recipients treated with anti-thymocyte globulin (ATG) (n = 40 443) or interleukin-2 receptor antagonist (IL-2RA) (n = 26 327) induction (1/1/1999-12/31/2014) using USRDS/Medicare data. We estimated the risk of first-diagnosed post-KT malignancy associated with induction (ATG vs. IL-2RA) using Cox proportional hazard models. We then tested whether these risks differed between older and younger recipients (Wald test for interaction). Models incorporated inverse probability of treatment weights to adjust for confounders.

RESULTS

The 3-year cumulative incidences of any diagnosed malignancy were 11.5%. ATG was associated with a higher malignancy risk (HR = 1.12, 95%CI:1.06-1.18). This association differed (p_interaction  = 0.04) between younger (HR = 1.12, 95%CI:1.06-1.18) and older recipients (HR = 1.03, 95%CI:0.96-1.09). ATG was also associated with higher risk of skin (HR = 1.18, 95%CI:1.08-1.29), lung (HR = 1.24, 95%CI:1.05-1.47), and ovary malignancies (HR = 1.94, 95%CI:1.08-3.48). However, only the association of ATG with post-KT skin malignancy differed (p_interaction  = 0.01) between younger (HR = 1.18; 95%CI:1.08-1.29) and older (HR = 1.01; 95%CI:0.93-1.09) recipients.

CONCLUSIONS

Compared with IL-2RA induction, ATG was associated with elevated post-KT malignancy risk but only among younger recipients. Transplant centers may need to tailor induction IS for younger recipients to mitigate malignancy risk.

Profiling circulating T follicular helper cells and their effects on B cells in post-cardiac transplant recipients

Background

To evaluate circulating T follicular helper (cTfh) cells and characterize their function in chronic-phase recipients after heart transplantation.

Methods

Participants were divided into healthy control (HC, n=40), preoperative (Pre, n=40), and post-transplantation chronic-phase recipient (1-year, n=40) groups. The percentages of cTfh cell subsets and CD19⁺ B cell subsets were measured using flow cytometry. In vitro co-culture experiments were performed using cTfh cells and B cells isolated by fluorescence-activated cell sorting. Plasma concentrations of IL-21, chemokine ligand 13 (CXCL13), immunoglobulin G1 (IgG1), and immunoglobulin G3 (IgG3) were quantified using enzyme-linked immunosorbent assays (ELISA).

Results

cTfh and programmed cell death protein 1-positive (PD-1⁺) cTfh cells, the cTfh17/cTfh ratio, and class-switched memory B cells in peripheral blood were significantly increased in the 1-year group versus the HC and Pre groups (P<0.01), whereas the cTfh1/cTfh ratio and number of naïve B cells were significantly decreased in the 1-year group. Co-culture experiments showed that cTfh cells promoted B cell differentiation to plasmablasts. In the 1-year group, cTfh and PD-1⁺ cTfh cell numbers were positively correlated with plasmablasts in CD19⁺ B cells (P<0.01). The cTfh17/cTfh ratio was positively correlated with IgG3 concentrations in plasma (P<0.01). The plasma concentrations of interleukin-21 (IL-21) and CXCL13 in the 1-year group were increased compared to the HC and Pre groups (P<0.05). Chronic-phase recipients had increased proportions of CD4⁺CXCR5⁺ and CD4⁺CXCR5⁺PD-1⁺ cTfh cells, with a cTfh1-to-cTfh17 subtype conversion. An increased number of cTfh cells was positively correlated with B cell differentiation to plasmablasts, class-switched memory B cells, and greater IgG production.

Conclusions

During the chronic phase, the proportion of cTfh cells increased and enhanced B cell responses. The cTfh-related soluble factors CXCL13 and IL-21 may regulate the immunopathogenesis of chronic immune injury. Thus, cTfh cells may drive long-term immune rejection in chronic-phase recipients after heart transplantation.

Randomized trial of 3 maintenance regimens (TAC/SRL vs. TAC/MMF vs. CSA/SRL) with low-dose corticosteroids in primary kidney transplantation: 18-year results

A randomized trial of 150 primary kidney transplant recipients, initiated in May 2000, compared tacrolimus (TAC)/sirolimus (SRL) vs. TAC/mycophenolate mofetil (MMF) vs. cyclosporine microemulsion (CSA)/SRL (N = 50/group). All patients received daclizumab induction and maintenance corticosteroids. With current median follow-up of 18 years post-transplant, biopsy-proven acute rejection (BPAR) occurred less often in TAC/MMF (26% (13/50)), vs. the TAC/SRL (36% (18/50)) and CSA/SRL (34% (17/50)) arms combined (p = .23), with statistical significance favoring TAC/MMF (p = .05) after controlling for the multivariable (Cox model) effects of recipient age, recipient race/ethnicity, and donor age. First BPAR rate was clearly more favorable for TAC/MMF after stratifying patients by having 0-1 (N = 72) vs. 2-3 (N = 78) unfavorable baseline characteristics (recipient age <50 years, African American or Hispanic recipient, and donor age ≥50 years) (p = .02). Mean estimated glomerular filtration rate (eGFR), using the CKD-EPI formula, was consistently higher for TAC/MMF, particularly after controlling for the multivariable effect of donor age, throughout the first 96 months post-transplant (p ≤ .008). These differences were translated into an observed more favorable graft failure due to immunologic cause (CAI/TG) rate for TAC/MMF (p = .06), although no significant differences in overall death-uncensored graft loss were observed. Previously reported significantly higher study drug discontinuation and requirement for antilipid therapy rates in the SRL-assigned arms were maintained over time. Overall, these results at 18 years post-transplant more definitively show that TAC/MMF should be the gold standard for achieving optimal, long-term maintenance immunosuppression in kidney transplantation.

Interactions of FK506 and Rapamycin With FK506 Binding Protein 12 in Opportunistic Human Fungal Pathogens

Over the past few decades advances in modern medicine have resulted in a global increase in the prevalence of fungal infections. Particularly people undergoing organ transplants or cancer treatments with a compromised immune system are at an elevated risk for lethal fungal infections such as invasive candidiasis, aspergillosis, cryptococcosis, etc. The emergence of drug resistance in fungal pathogens poses a serious threat to mankind and it is critical to identify new targets for the development of antifungals. Calcineurin and TOR proteins are conserved across eukaryotes including pathogenic fungi. Two small molecules FK506 and rapamycin bind to FKBP12 immunophilin and the resulting complexes (FK506-FKBP12 and rapamycin-FKBP12) target calcineurin and TOR, respectively in both humans and fungi. However, due to their immunosuppressive nature these drugs in the current form cannot be used as an antifungal. To overcome this, it is important to identify key differences between human and fungal FKBP12, calcineurin, and TOR proteins which will facilitate the development of new small molecules with higher affinity toward fungal components. The current review highlights FK506/rapamycin-FKBP12 interactions with calcineurin/TOR kinase in human and fungi, and development of non-immunosuppressive analogs of FK506, rapamycin, and novel small molecules in inhibition of fungal calcineurin and TOR kinase.

Medical care of liver transplant patients

INTRODUCTION

Liver transplantation is a life-changing event for patients and survival following transplantation has improved significantly since the first transplantation in 1967. Following liver transplantation, patients face a unique set of healthcare management decisions including transplantation-specific complications, recurrence of primary liver disease, as well as metabolic and malignancy concerns related to immunosuppression. As more patients with liver disease receive transplantation and live longer, understanding and managing these patients will require not only transplant specialist but also local subspecialist and primary care physicians.

AREAS COVERED

This review covers common issues related to the management of patients following liver transplantation including immunosuppression, liver allograft dysfunction, metabolic complications, as well as routine health maintenance such as immunizations and cancer screening.

EXPERT OPINION

Optimizing medical care for patients following liver transplant will benefit from ensuring all providers, not just transplant specialist, have a basic understanding of the common issues encountered in the post-transplant patient. This review provides an overview of common healthcare concerns and management options for patients following liver transplantation.

Cross-Reactive Donor-Specific CD8+ Tregs Efficiently Prevent Transplant Rejection

To reduce the use of non-specific immunosuppressive drugs detrimental to transplant patient health, therapies in development aim to achieve antigen-specific tolerance by promoting antigen-specific regulatory T cells (Tregs). However, identification of the natural antigens recognized by Tregs and the contribution of their dominance in transplantation has been challenging. We identify epitopes derived from distinct major histocompatibility complex (MHC) class II molecules, sharing a 7-amino acid consensus sequence positioned in a central mobile section in complex with MHC class I, recognized by cross-reactive CD8⁺ Tregs, enriched in the graft. Antigen-specific CD8⁺ Tregs can be induced in vivo with a 16-amino acid-long peptide to trigger transplant tolerance. Peptides derived from human HLA class II molecules, harboring the rat consensus sequence, also activate and expand human CD8⁺ Tregs, suggesting its potential in human transplantation. Altogether, this work should facilitate the development of therapies with peptide epitopes for transplantation and improve our understanding of CD8⁺ Treg recognition.

IL-34 Actions on FOXP3+ Tregs and CD14+ Monocytes Control Human Graft Rejection

Cytokines are major players regulating immune responses toward inflammatory and tolerogenic results. In organ and bone marrow transplantation, new reagents are needed to inhibit tissue destructive mechanisms and eventually induce immune tolerance without overall immunosuppression. IL-34 is a cytokine with no significant homology with any other cytokine but that acts preferentially through CSF-1R, as CSF-1 does, and through PTPζ and CD138. Although IL-34 and CSF-1 share actions, a detailed analysis of their effects on immune cells needs further research. We previously showed that both CD4⁺ and CD8⁺ FOXP3⁺ Tregs suppress effector T cells through the production of IL-34, but not CSF-1, and that this action was mediated through antigen-presenting cells. We showed here by single-cell RNAseq and cytofluorimetry that different subsets of human monocytes expressed different levels of CSF-1R, CD138, and PTPζ and that both CD4⁺ and CD8⁺ FOXP3⁺ Tregs expressed higher levels of CSF-1R than conventional T cells. The effects of IL-34 differed in the survival of these different subpopulations of monocytes and RNAseq analysis showed several genes differentially expressed between IL-34, CSF-1, M0, M1, and also M2 macrophages. Acute graft-vs.-host disease (aGVHD) in immunodeficient NSG mice injected with human PBMCs was decreased when treated with IL-34 in combination with an anti-CD45RC mAb that depleted conventional T cells. When IL-34-differentiated monocytes were used to expand Tregs in vitro, both CD4⁺ and CD8⁺ FOXP3⁺ Tregs were highly enriched and this effect was superior to the one obtained with CSF-1. Human CD8⁺ Tregs expanded in vitro with IL-34-differentiated allogeneic monocytes suppressed human immune responses in an NSG mouse aGVHD model humanized with hPBMCs. Overall, we showed that IL-34 induced the differentiation of human monocytes with a particular transcriptional profile and these cells favored the development of potent suppressor FOXP3⁺ Tregs.

Development of video-based educational materials for kidney-transplant patients

INTRODUCTION

Treatment adherence has been evaluated as a major predictor of long-term outcome, and education has been suggested to improve adherence. Considering the characteristics of adult learners, it is necessary to implement educational programs that meet the needs of transplant patients. Multimedia education may be well-suited for this. This study aims to develop video education materials in accordance with transplant patients' self-care needs.

METHODS

This study includes a literature review and patient interviews aimed at developing video education materials for the self-care needs of patients who underwent renal transplant surgery at a university hospital in Seoul. Ten patients were interviewed about the desired educational content, accessibility, and other preferences. After verifying the validity of the data, the video scenarios were produced and satisfaction surveys were conducted.

RESULTS

Eleven self-care education items were identified through interviews with 10 kidney transplant patients. The expert validation of video-based educational content result was high (mean CVI = 0.94). The mean score of the patients' satisfaction evaluation of the completed 7-minute video instructional materials was also high (4.55 on a 5-point Likert scale).

CONCLUSION

Findings indicate that the video education materials will meet the needs of adult learners and mitigate the limitations of the existing education programs by increasing interest and motivation and may contribute to increased treatment adherence and ultimately, positively effect self-care for new transplant patients.

Effect of Concentration/Dose Ratio in De Novo Kidney Transplant Recipients Receiving LCP-Tacrolimus or Immediate-Release Tacrolimus: Post Hoc Analysis of a Phase 3 Clinical Trial

Background

A previous phase 3 clinical trial in de novo adult kidney transplant recipients (NCT01187953) compared the efficacy and safety of once-daily LCP-tacrolimus (LCPT) and twice-daily immediate-release tacrolimus (IR-Tac). However, whether the rate of tacrolimus metabolism affects outcomes between LCPT and IR-Tac was not examined.

Material/Methods

Patients were initiated on 0.17 mg/kg/day LCPT or 0.1 mg/kg/day IR-Tac, with doses adjusted over time to maintain target therapeutic trough concentrations. This post hoc analysis examined dosing trends, relative efficacy, and safety of LCPT (n=247) and IR-Tac (n=249) in slow, intermediate, and rapid metabolizers as defined by concentration/dose ratios at day 30.

Results

For all metabolizer subgroups, minimum target tacrolimus trough concentrations were obtained more rapidly with LCPT than with IR-Tac. Slow metabolizers were more likely to exceed target trough concentrations with LCPT, while rapid metabolizers were more likely to fall below target trough concentrations with IR-Tac. Regardless of metabolizer status, significant differences were not detected between LCPT and IR-Tac for treatment failure, death, graft failure, biopsy-proven acute rejection, estimated glomerular filtration rate, or other clinical outcomes.

Conclusions

Although within metabolizer subgroups, attainment of target trough concentrations in the first week differed between LCPT and IR-Tac, these results suggest that, regardless of metabolizer phenotype, clinical outcomes do not differ between these formulations when dose adjustments are made.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT01187953

Relationship between rabbit anti-thymocyte globulin and development of PTLD and its aggressive form in renal transplant population

Introduction

The aim of our study is to explore the relationship of rabbit anti-thymocyte globulin (R-ATG) on development of post-transplant lymphoproliferative disease (PTLD) and its aggressive forms (monomorphic PTLD and Hodgkin lymphoma) in renal transplant recipients.

Methodology

All patients diagnosed with PTLD post-renal transplant in the United States’ Organ Procurement and Transplantation Network from 2003 till 2013 and followed up till 2017 were retrospectively reviewed. Multi-variable logistic regression analysis assessed association of R-ATG to development of PTLD and its aggressive form.

Results

Risk of developing PTLD post renal transplant is 1.35%. In comparison to interleukin-2 blocker induction therapy, R-ATG is associated with increased risk of development of PTLD (Odds Ratio = 1.48, confidence interval ranges from 1.04 to 2.11, p = .02) and is associated with higher risk of development of aggressive PTLD (Odds Ratio = 1.83, confidence interval ranges from 1.001 to 3.34, p = .04).

Conclusion

We conclude that R-ATG induction is associated with a higher risk of PTLD and its aggressive form (monomorphic PTLD and Hodgkin lymphoma). Careful monitoring for development of PTLD in renal transplant recipients receiving R-ATG induction therapy is advised.

Propofol Infusion Syndrome in the Postoperative Period of a Kidney Transplant

Sedation during medical procedures poses a risk to any patient, and the use of specific anesthetic agents should be carefully considered to avoid adverse outcomes. We report on a patient with propofol infusion syndrome diagnosed during the post-operative period of a renal transplant. A 58-year-old female on chronic hemodialysis due to end stage kidney disease secondary to microscopic polyangiitis underwent kidney transplant from a deceased donor. Anesthetic induction was performed with fentanyl, propofol, and cisatracurium, and maintained with continuous propofol infusion. In the recovery room, the patient developed somnolence, tachypnea, and thoracoabdominal dissociation secondary to residual neuromuscular block. An arterial-blood gas test indicated acidemia, high pCO₂, low HCO₃, and mildly increased serum lactate. The patient remained hemodynamically stable, on volume-controlled ventilation, with sedation by continuous propofol infusion. Blood gas tests revealed persistent acidemia without tissue hypoperfusion. Doppler ultrasound of the renal graft reported adequate blood flow and serum triglycerides were elevated. A diagnosis of propofol infusion syndrome was made, and infusion ceased. A decrease in serum lactate levels was observed, with normalization 4 h later. This case highlights the importance of considering adverse effects of anesthetic agents as the cause of post-operative complications when prolonged sedation is required.

Determining the conversion ratios for oral versus sublingual administration of tacrolimus in solid organ transplant recipients

Tacrolimus is utilized as maintenance immunosuppression in solid organ transplant (SOT). Current literature has reported conflicting conversion ratios when transitioning between oral and sublingual tacrolimus, and the exact conversion ratio has not been fully established in SOT. The purpose of this study was to determine the conversion ratios between oral and sublingual tacrolimus needed to achieve equivalent whole blood concentrations in heart, kidney, liver, and lung transplant recipients. A retrospective, single-center analysis was conducted at Mayo Clinic in Florida. One hundred and eighteen hospitalized SOT recipients who received oral and sublingual tacrolimus during the same inpatient admission from June 1, 2012, through June 1, 2017, were reviewed. The median conversion ratio of sublingual to oral tacrolimus was 1.34 (IQR: 1.03-1.93) in all SOT, 1.25 (IQR: 1.08-1.64) in heart transplant, 1.23 (IQR: 1.1-2.06) in kidney transplant, 1.64 (IQR: 1.27-2.29) in liver transplant, and 1.34 (IQR: 0.94-1.93) in lung transplant. A slightly higher dose of oral tacrolimus is needed in the majority of solid organ recipients in our population when converting between sublingual to oral tacrolimus administration.

Immunologic Risk Assessment and Approach to Immunosuppression Regimen in Kidney Transplantation

The outcomes of kidney transplantation show a steady improvement with an increasing number of transplantations and decreasing incidence of acute rejection episodes. Successful transplantation begins with a comprehensive immunologic risk assessment and judicious choice of therapeutic agents. In this review, we discuss the trends in transplant immunosuppression practices and outcomes in the United States. We discuss practical testing algorithms for clinical decision making in induction therapy and fine-tuning maintenance immunosuppression. We introduce assessment tools for immune monitoring after transplantation and speculate on future directions in management.

Tacrolimus: Influence of the Posttransplant Concentration/Dose Ratio on Kidney Graft Function in a Two-Year Follow-Up

INTRODUCTION

Tacrolimus (TAC) metabolism rate has the potential to impact graft function after kidney transplantation (KTx). We aimed to analyze the relationship between the early post-KTx TAC C/D ratio (blood trough concentration normalized by total daily dose) and kidney graft function in a 2-year follow-up.

METHODS

We retrospectively analyzed data from 101 post-KTx patients at 3, 6, 12, and 24 months after KTx to identify the C/D ratio cutoff value optimal for dividing patients into fast and slow TAC metabolizers. We investigated the relationship between their TAC metabolism rate and graft function.

RESULTS

Patients were divided based on the TAC C/D ratio at 6 months after KTx of 1.47 ng/mL * 1 mg. Fast metabolizers (C/D ratio <1.47 ng/mL * 1 mg) presented with significantly worse graft function throughout the whole study period (p < 0.05 at each timepoint) and were significantly less likely to develop good graft function (estimated glomerular filtration rate ≥45 mL/min/1.73 m2) than slow metabolizers. Our model based on donor and recipient age, recipient sex and slow/fast metabolism status allowed for identification of patients with compromised graft function in 2-year follow-up with 66.7% sensitivity and 94.6% specificity.

CONCLUSION

Estimating TAC C/D ratio at 6 months post-KTx might help identify patients at risk of developing deteriorated graft function in a 2-year follow-up.

Identification of anti-flaviviral drugs with mosquitocidal and anti-Zika virus activity in Aedes aegypti

Zika virus (ZIKV), an emerging arbovirus belonging to the genus Flavivirus, is transmitted by Aedes mosquitoes. ZIKV infection can cause microcephaly of newborn babies and Guillain-Barré syndrome in adults. Because no licensed vaccine or specific antiviral treatment is available for ZIKV infection, the most commonly used approach to control the spread of ZIKV is suppression of the mosquito vector population. A novel proposed strategy to block arthropod virus (arbovirus) transmission is based on the chemical inhibition of virus infection in mosquitoes. However, only a few drugs and compounds have been tested with such properties. Here we present a comprehensive screen of 55 FDA-approved anti-flaviviral drugs for potential anti-ZIKV and mosquitocidal activity. Four drugs (auranofin, actinomycin D (Act-D), bortezomib and gemcitabine) were toxic to C6/36 cells, and two drugs (5-fluorouracil and mycophenolic acid (MPA)) significantly reduced ZIKV production in C6/36 cells at 2 μM and 0.5 μM, respectively. Three drugs (Act-D, cyclosporin A, ivermectin) exhibited a strong adulticidal activity, and six drugs (U18666A, retinoic acid p-hydroxyanilide (4-HPR), clotrimazole, bortezomib, MPA, imatinib mesylate) significantly suppressed ZIKV infection in mosquito midguts. Some of these FDA-approved drugs may have potential for use for the development of ZIKV transmission-blocking strategies.

A Population Pharmacokinetic Model to Predict the Individual Starting Dose of Tacrolimus Following Pediatric Renal Transplantation

Background

Multiple clinical, demographic, and genetic factors affect the pharmacokinetics of tacrolimus in children, yet in daily practice, a uniform body-weight based starting dose is used. It can take weeks to reach the target tacrolimus pre-dose concentration.

Objectives

The objectives of this study were to determine the pharmacokinetics of tacrolimus immediately after kidney transplantation and to find relevant parameters for dose individualization using a population pharmacokinetic analysis.

Methods

A total of 722 blood samples were collected from 46 children treated with tacrolimus over the first 6 weeks after renal transplantation. Non-linear mixed-effects modeling (NONMEM^®) was used to develop a population pharmacokinetic model and perform a covariate analysis. Simulations were performed to determine the optimal starting dose and to develop dosing guidelines.

Results

The data were accurately described by a two-compartment model with allometric scaling for bodyweight. Mean tacrolimus apparent clearance was 50.5 L/h, with an inter-patient variability of 25%. Higher bodyweight, lower estimated glomerular filtration rate, and higher hematocrit levels resulted in lower total tacrolimus clearance. Cytochrome P450 3A5 expressers and recipients who received a kidney from a deceased donor had a significantly higher tacrolimus clearance. The model was successfully externally validated. In total, these covariates explained 41% of the variability in clearance. From the significant covariates, the cytochrome P450 3A5 genotype, bodyweight, and donor type were useful to adjust the starting dose to reach the target pre-dose concentration. Dosing guidelines range from 0.27 to 1.33 mg/kg/day.

Conclusion

During the first 6 weeks after transplantation, the tacrolimus weight-normalized starting dose should be higher in pediatric kidney transplant recipients with a lower bodyweight, those who express the cytochrome P450 3A5 genotype, and those who receive a kidney from a deceased donor.

The hepatic protective effects of tacrolimus as a rinse solution in liver transplantation: A meta-analysis

BACKGROUND

Tacrolimus was used as a rinse solution against ischaemia-reperfusion injury (IRI) in liver transplantation for years but its protective effects remain controversies.

METHODS

We conducted literature retrieval in electronic databases including MEDLINE, EMBASE and Cochrane Central to identify relevant randomized controlled trials (RCTs) investigating the effects of tacrolimus as a rinse solution in liver transplantation. Postoperative liver function, including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL), at postoperative day (POD) 1, 2 and 7 was extracted for pooled estimation. Forest plots were generated to calculate the differences between the groups. The I2 index statistic was used to assess heterogeneity. Publication bias was evaluated using funnel plots and Egger's test.

RESULTS

Three RCTs including 70 liver transplants were evaluated in this study. Pooled estimation revealed that rinse with tacrolimus in liver transplantation did not provide hepatic protection with respect to postoperative ALT (Test Z = 1.36; P = .175), AST (Test Z = 1.70; P = .090) or TBIL (Test Z = 0.69; P = .490). Sensitivity analysis by excluding extended donor criteria (EDC) livers showed similar results. Funnel plots and Egger's test demonstrated that there was no substantial bias.

CONCLUSION

We may tentatively conclude that tacrolimus is ineffective for amelioration of postoperative liver function as a rinse solution in liver transplantation. Nevertheless, there is great space for future research in this area, and the potential clinical value of tacrolimus needs to be further addressed. We are expecting more evidence to support our speculations.

Prior Amiodarone Exposure Reduces Tacrolimus Dosing Requirements in Heart Transplant Recipients

Introduction:

Amiodarone use prior to heart transplant is independently associated with a higher rate of severe primary graft dysfunction and in-hospital mortality. Amiodarone may also alter the pharmacokinetics of medications metabolized via cytochrome P450. No data exist regarding the interaction between pretransplant amiodarone and tacrolimus concentrations.

Design:

Single-center retrospective study of transplant patients between January 1, 2014, and June 30, 2016. A therapeutic tacrolimus concentration was defined as a trough level between 8 and 15 ng/mL for 2 consecutive days. The primary outcome was the tacrolimus therapeutic weight-based dosing requirements (mg/kg/day) for patients receiving amiodarone prior to transplant when compared to those without prior receipt of amiodarone. Secondary outcomes include the incidence of cellular rejection and mortality within 6 months posttransplant.

Results:

Multi-organ transplant recipients (n = 3), retransplants (n = 9), those who died prior to a therapeutic level (n = 1), and those receiving amiodarone posttransplant (n = 7) were excluded from the analysis. Of the 80 patients included, 34 (42%) received amiodarone prior to transplant. Patient characteristics were similar, with the exception of primary graft dysfunction incidence (38% in amiodarone vs 8.5% in control, P = .001). The median therapeutic dose was 0.1 (interquartile range [IQR]: 0.07-0.12) versus 0.13 (IQR: 0.09-0.17) in the amiodarone and control groups, respectively, ( P < .01). No significant difference in mortality or rejection was noted.

Conclusion:

Patients receiving amiodarone prior to transplant require a lower weight-based dose of tacrolimus.