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

Removing the physician from the equation: Patient-controlled, home-based therapeutic drug self-monitoring of tacrolimus

The dosing of tacrolimus, which forms the backbone of immunosuppressive therapy after kidney transplantation, is complex. This is due to its variable pharmacokinetics (both between and within individual patients), narrow therapeutic index, and the severe consequences of over- and underexposure, which may cause toxicity and rejection, respectively. Tacrolimus is, therefore, routinely dosed by means of therapeutic drug monitoring (TDM). TDM is performed for as long as the transplant functions and frequent and often lifelong sampling is therefore the rule. This puts a significant burden on patients and transplant professionals and is associated with high healthcare-associated costs. Furthermore, by its very nature, TDM is reactive and has no predictive power. Finally, the current practice of TDM does not foresee in an active role for patients themselves. Rather, the physician or pharmacist prescribes the next tacrolimus dose after obtaining the concentration measurement test results. In this article, we propose a strategy of patient-controlled, home-based, self-TDM of the immunosuppressant tacrolimus after transplantation. We argue that with the combined use of population tacrolimus pharmacokinetic models, home-based sampling by means of dried blood spotting and implementation of telemedicine, this may become a feasible approach in the near future.

Global research on the utilization of population pharmacokinetic model: a bibliometric analysis from 2000 to 2024

Objective

Population pharmacokinetic (PPK) model is capable of identifying the factors that influence the variability of pharmacokinetic (PK) profiles and the degree of their influence, effectively reduces unexplained variability, and demonstrates excellent predictive ability. PPK model has been successfully constructed in several populations for a variety of drugs. However, no study has yet conducted a bibliometric analysis of publications related to the PPK model. This study aims to provide a comprehensive overview of the research progress and hotspots in the field of PPK model research through bibliometric methods.

Methods

A systematic search of the Web of Science database was conducted to collect articles and reviews related to the PPK model between 2000 and 2024. We then analyzed the data using Bibliometrix R package, Microsoft Office Excel, CiteSpace and VOSviewers.

Results

Between 2000 and 2024, we identified a total of 6,125 papers and 128,856 citations. The average annual growth rate of the relevant publications was 10.35%, showing continued growth momentum. These research outputs are concentrated in North America, Western Europe, and East Asia, with USA leading the way with 2,340 publications and having the highest H-index (93) and total citations (54,965). Uppsala University and British Journal of Clinical Pharmacology are the institutions with the highest publication output and the most influential journals, respectively. Most of the funding agencies are from the USA and the subject categories for most publications are Pharmacology Pharmacy. In terms of author contributions, professor Karlsson MO is the leader in the field with 149 publications. In addition, wo found that "critically ill patients," "tacrolimus," "machine learning," "external evaluation," "polymyxin b," "voriconazole," "extracorporeal membrane oxygenation," "dose optimization" and "model-informed precision dosing" are current research hotspots and future research trends.

Conclusion

This study is the first comprehensive overview of the development of PPK model and research hotspots using bibliometric methods. Our findings provide researchers, especially beginners, with insights into the application area of PPK model, helping them to grasp key information in the field.

Using validated model informed precision dosing for dose adjustment: superior evidence needed for efficacy and safety

INTRODUCTION

Modelinformed precision dosing (MIPD) allows determining the optimal dosage regimen and its correction based on the target plasma/serum concentrations of the drug. MIPD software must go through a validation and clinical study of its effectiveness and safety before being used in clinical practice.

AREAS COVERED

This narrative literature review provides insight into what is known to date about efficacy and safety trials of MIPD concept. Relevant publications were searched for in the PubMed database, without time or language constraints.

EXPERT OPINION

The application of MIPD in clinical practice logically and theoretically has great potential to improve the treatment of patients by leading to optimal exposure of target tissues to drugs, while achieving full effect and minimizing toxicity. Greater implementation of MIPD in clinical practice is hindered by the fact that the beneficial effects of MIPD on treatment outcomes and reduction of drug toxicity have been proven through clinical studies only for a small number of drugs. It is necessary to conduct well-designed clinical studies of the effects of MIPD, with sufficient statistical power, to prove the benefits of MIPD administration and to justify the costs of implementation in clinical practice.

Exploring the comprehensive factors influencing tacrolimus pharmacokinetics in early renal transplant recipients: A population pharmacokinetic analysis

PURPOSE

To establish a population pharmacokinetic (PopPK) model of tacrolimus in the early stages after renal transplantation and evaluate the model's predictive performance with external data.

METHODS

Intravenous and oral tacrolimus were administered to 302 renal transplant recipients in the early posttransplantation stages. Related data were obtained from the electronic medical records. Single nucleotide polymorphisms in genes associated with tacrolimus pharmacokinetics were tested. The data were analyzed by NONMEM. The external data from 153 patients were subsequently used to evaluate model extrapolation.

RESULTS

A one-compartment model was used to determine tacrolimus pharmacokinetics. The estimated clearance (CL), volume of distribution (V) and bioavailability (F) of tacrolimus were 4.91 L/h, 77 L and 26.5%, respectively. CL and V decreased with increasing hematocrit. CL and F decreased with increasing operation time. Diltiazem and Wuzhi capsule resulted in 28.4% and 43.9% decreases in the CL, respectively. Omeprazole or esomeprazole resulted in a 9% increase in F. The value of F for patients expressing CYP3A5 was 36.6% lower than that for the patients who did not express CYP3A5. The evaluation of external data revealed that the proportion of individual prediction error within 20% of the observed tacrolimus concentration was greater than 77.3%.

CONCLUSIONS

A PopPK model for tacrolimus was established for early renal transplantation. CYP3A5 was a significant covariate for F. Fat-free mass was the best predictor of the influence of body size on CL and V. The model could be extrapolated to stable renal transplant recipients.

Calcineurin Inhibitor Associated Nephrotoxicity in Kidney Transplantation-A Transplant Nephrologist's Perspective

AIM

Calcineurin inhibitors (CNIs) have revolutionized transplant medicine, improving allograft survival but posing challenges like calcineurin inhibitor-induced nephrotoxicity (CNT). Acute CNT, often dose-dependent, leads to vasoconstriction and acute kidney injury, with treatment focusing on CNI exposure reduction. Chronic CNT manifests as progressive allograft function decline, with challenges in distinguishing it from nonspecific allograft nephropathy.

METHODS

This narrative review provides a concise overview of the clinical management of CNT, covering acute and chronic CNT. We reviewed original articles, landmark papers, and meta-analyses on CNT mitigation strategies, including CNI-sparing approaches.

RESULTS

Preventive measures include co-medications, CNI exposure monitoring, and CNI sparing strategies, such as reducing target trough levels and converting to mTOR inhibitors (mTORi) or belatacept. Despite improvements in graft function, challenges persist in demonstrating significant differences in allograft survival with CNI-sparing regimens. The paradigm shift from chronic CNT as the main cause of chronic allograft nephropathy toward rather immunologic triggered injuries and/or comorbidities as relevant contributors to allograft deterioration over time must be kept in mind.

CONCLUSION

CNIs have significantly improved kidney transplant outcomes, but their associated nephrotoxicity necessitates mitigation strategies. The decision to implement such regimens is always an individual choice balancing against the risk of immunologic injuries. Further long-term studies are needed to optimize immunosuppressive approaches and refine CNT management.

Microdose Cocktail Study Reveals the Activity and Key Influencing Factors of OATP1B, P-Gp, BCRP, and CYP3A in End-Stage Renal Disease Patients

OATP1B, P-gp, BCRP, and CYP3A are the most contributing drug-metabolizing enzymes or transporters (DMETs) for commonly prescribed medication. Their activities may change in end-stage renal disease (ESRD) patients with large inter-individual variabilities (IIVs), leading to altered substrate drug exposure and ultimately elevated safety risk. However, the changing extent and indictive influencing factors are not quantified so far. Here, a microdose cocktail regimen containing five sensitive substrate drugs (pitavastatin, dabigatran etexilate, rosuvastatin, midazolam, and atorvastatin) for these DMETs was administrated to Chinese healthy volunteers and ESRD patients. Drug pharmacokinetics profiles were determined, together with physiological, pharmacogenetic, and gut microbiome signature. Population pharmacokinetic and machine learning model were established to identify key influencing factors and quantify their contribution to drug exposure change. The exposure of pitavastatin, dabigatran, rosuvastatin, and atorvastatin increased to 1.8-, 3.1-, 1.1-, and 1.3-fold, respectively, whereas midazolam exposure decreased by 72% in ESRD patients. Notably, in addition to disease state, the relative abundance of genus Veillonella and Clostridium_XIVb were firstly identified as significant influencing factors for PTV and RSV apparent clearance, respectively, suggesting their indicative role for OATP and BCRP activity evaluation. Moreover, several genera were found to strongly associate with drug clearance and reduce unexplained IIVs. Accordingly, it was estimated that OATP1B and intestine P-gp activity decreased by 35-75% and 29-44%, respectively, whereas BCRP and CYP3A4 activity may upregulate to some extent. Our study provides a quantitative and mechanistic understanding of individual DMET activity and could support precision medicine of substrate drugs in ESRD patients.

Personalized Nanomedicine-Mediated immune regulation for Anti-Rejection in organ transplantation

The advent of personalized medicine and nanomedicine has led to significant advancements in organ transplantation. Personalized medicine leverages individual patient profiles, including genetic, epigenetic, and immune characteristics, to tailor treatment regimens. Nanomedicine, involving the use of nanoparticles and nanotechnology, offers precise drug delivery and innovative diagnostic tools. The integration of personalized nanomedicine into these fields has the potential to revolutionize transplantation by enhancing graft survival, minimizing adverse effects, and achieving immune tolerance. This review explores the current landscape of personalized nanomedicine for organ transplantation, focusing on immune modulation and therapeutic strategies tailored to individual patient profiles. We also discuss future research directions, including large-scale clinical trials, and regulatory considerations. This review concludes by examining the potential of personalized nanomedicine in improving long-term transplant outcomes and enhancing patient quality of life.

RGD-HSA-TAC nanoparticles targeted delivery of tacrolimus and attenuation of podocyte injury in diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is a prevalent and severe complication of diabetes and plays a pivotal role in the pathogenesis and progression of DKD. However, the current clinical application of the treatment methods does not yield effective results. Tacrolimus has been utilized in the management of immune-mediated and genetic-mediated nephropathy, with an emphasis on the restoration of podocyte cytoskeletal integrity and inhibition of apoptosis. The clinical management of diabetic nephropathy with tacrolimus remains challenging because of the risk of worsening hyperglycemia and infection.

RESULTS

We developed two RGD-HSA-TAC nanoparticles designed for targeted delivery of tacrolimus to podocytes. Administration of SANPs and CNPs resulted in elevated levels of tacrolimus in podocytes, leading to a reduction in podocyte damage and albuminuria in diabetic nephropathy mice. Furthermore, the use of SANPs and CNPs resulted in a decrease in tacrolimus accumulation in the pancreas, lymph nodes, and thymus, thereby reducing the potential to exacerbate hyperglycemia and infection. Importantly, compared to tacrolimus alone, both SANPs and CNPs demonstrated superior therapeutic efficacy, with CNPs exhibiting a greater advantage over SANPs.

CONCLUSIONS

Compared to tacrolimus, SANPs and CNPs demonstrated superior therapeutic efficacy and a reduced incidence of adverse effects in the treatment of diabetic nephropathy.

Customizing Tacrolimus Dosing in Kidney Transplantation: Focus on Pharmacogenetics

ABSTRACT

Different polymorphisms in genes encoding metabolizing enzymes and drug transporters have been associated with tacrolimus pharmacokinetics. In particular, studies on CYP3A4 and CYP3A5, and their combined cluster have demonstrated their significance in adjusting tacrolimus dosing to minimize under- and overexposure thereby increasing the proportion of patients who achieve tacrolimus therapeutic target. Many factors influence the pharmacokinetics of tacrolimus, contributing to inter-patient variability affecting individual dosing requirements. On the other hand, the growing use of population pharmacokinetic models in solid organ transplantation, including different tacrolimus formulations, has facilitated the integration of pharmacogenetic data and other variables into algorithms to easier implement the personalized dose adjustment in transplant centers. The future of personalized medicine in transplantation lies in implementing these models in clinical practice, with pharmacogenetics as a key factor to account for the high inter-patient variability in tacrolimus exposure. To date, three clinical trials have validated the clinical application of these approaches. The aim of this review is to provide an overview of the current studies regarding the different population pharmacokinetic including pharmacogenetics and those translated to the clinical practice for individualizing tacrolimus dose adjustment in kidney transplantation.

Population dynamics analysis of the interaction between tacrolimus and voriconazole in renal transplant recipients

Background

The concurrent administration of tacrolimus and voriconazole in kidney transplant recipients can lead to drug interactions, potentially resulting in severe adverse reactions. This study aimed to establish a robust population pharmacokinetic model to explore the interaction between tacrolimus and voriconazole in greater depth.

Methods

Tacrolimus blood samples and laboratory data were prospectively collected from eligible patients enrolled between April 2023 and April 2024, following predefined inclusion and exclusion criteria. Using Phoenix (version 8.1), a pharmacokinetic prediction model was developed. Model performance was assessed using model fitting plots, bootstrap analysis, and visual predictive checks (VPC).

Results

This study ultimately included 51 eligible patients, with a total of 281 blood samples collected. Analysis revealed a significant negative correlation between voriconazole concentration (Cvrc) and tacrolimus volume of clearance rate (CL), a significant positive correlation between platelets (PLT) and tacrolimus clearance (CL), and a significant negative correlation between blood cells (RBC) and tacrolimus clearance (CL).

Conclusion

This study successfully established a population pharmacokinetic model for renal transplant patients concurrently receiving tacrolimus and voriconazole. The model demonstrated good predictive performance and offers valuable insights to clinicians for optimizing tacrolimus dosing in this patient population.

Model-informed precision dosing: State of the art and future perspectives

Model-informed precision dosing (MIPD) stands as a significant development in personalized medicine to tailor drug dosing to individual patient characteristics. MIPD moves beyond traditional therapeutic drug monitoring (TDM) by integrating mathematical predictions of dosing and considering patient-specific factors (patient characteristics, drug measurements) as well as different sources of variability. For this purpose, rigorous model qualification is required for the application of MIPD in patients. This review delves into new methods in model selection and validation, also highlighting the role of machine learning in improving MIPD, the utilization of biosensors for real-time monitoring, as well as the potential of models integrating biomarkers for efficacy or toxicity for precision dosing. The clinical evidence of TDM and MIPD is discussed for various medical fields including infection medicine, oncology, transplant medicine, and inflammatory bowel diseases, thereby underscoring the role of pharmacokinetics/pharmacodynamics and specific biomarkers. Further research, particularly randomized clinical trials, is warranted to corroborate the value of MIPD in enhancing patient outcomes and advancing personalized medicine.

Factors and interventions affecting tacrolimus intrapatient variability: A systematic review and meta-analysis

BACKGROUNDS

Tacrolimus is a cornerstone of posttransplantation immunosuppressive regimens. Despite routine monitoring, the efficacy of its trough concentrations in reflecting drug concentration fluctuations is limited. Intrapatient variability (IPV) emerges as a novel monitoring marker for predicting clinical outcomes. However, understanding the factors affecting IPV and assessing interventions to address it remain enigmatic, posing a conundrum in clinical management.

OBJECTIVES

This systematic review aimed to investigate a spectrum of factors affecting IPV and assess the effect of strategic interventions, thereby charting a course for enhanced clinical stewardship.

METHODS

We electronically searched of PubMed, Embase, and the Cochrane Library databases for studies investigating factors and interventions affecting IPV up to October 2023. Two reviewers independently screened literature, extracted data, and assessed quality, using RevMan 5.4.1 software for meta-analysis.

RESULTS

A total of 15 randomized controlled trials (RCTs), 34 cohort studies, and 20 self-controlled studies were included. The results indicated that IPV was significantly higher in cytochrome P450 3A5 (CYP3A5) expressers, nonadherent patients, patients taking proton pump inhibitors or statins, and Black or African American recipients, whereas recipients consuming extended-release formulation exhibited lower IPV. Additionally, the participation of pharmacists had a positive effect on improving IPV.

CONCLUSIONS

Factors affecting IPV encompassed genotype, formulation, adherence, drug combinations, and ethnicity, with each factor exerting varying degrees of effect. Identifying these factors was crucial for developing targeted intervention strategies. While the participation of pharmacists held a promise in improving IPV, further investigation of interventions such as mobile technology, educational measures to enhance adherence, and personalized dosing regimens was warranted.

Evaluating the evidence for genotype-informed Bayesian dosing of tacrolimus in children undergoing solid organ transplantation: A systematic literature review

Tacrolimus, a calcineurin inhibitor, is a highly effective immunosuppressant used in solid organ transplantation (SOT). However, it is characterized by a narrow therapeutic range and high inter-patient variability in pharmacokinetics. Standard weight-based dosing followed by empiric dose titration is suboptimal in controlling drug concentrations, increasing risk of rejection or toxicity, particularly in the initial months post transplantation. This review explores the potential of combined pre-transplant genotyping and pharmacokinetic (PK) modelling to improve tacrolimus dosing in paediatric SOT recipients. A systematic search of Medline, Embase and Cochrane databases identified studies published between March 2013 and March 2023 that investigated genotype- and PK model-informed tacrolimus dosing in children post-SOT. The Newcastle-Ottawa Scale assessed study quality. Seven studies encompassing paediatric kidney, heart, liver and lung transplants reported using genotype and model-informed dosing. A combination of clinical and genetic factors significantly impacts tacrolimus clearance and thus initial dose recommendation. Body size, transplant organ and co-medications were consistently important, while either time post-transplant or haematocrit emerged in some studies. Several models were identified, however, with limitations evident in some and with absence of evidence for their effectiveness in optimizing initial and subsequent dosing. This review highlights the development of PK models in paediatric SOT that integrate genotype and clinical covariates to personalize early tacrolimus dosing. While promising, prospective studies are needed to validate and confirm their effectiveness in improving time to therapeutic concentrations and reducing under- or overexposure. This approach has the potential to optimize tacrolimus therapy in paediatric SOT, thereby improving outcomes.

Early CYP3A5 Genotype-Based Adjustment of Tacrolimus Dosage Reduces Risk of De Novo Donor-Specific HLA Antibodies and Rejection among CYP3A5-Expressing Renal Transplant Patients

BACKGROUND/OBJECTIVES

Our previous retrospective single-center cohort study found, at 3-year follow-up, a trend toward low tacrolimus trough levels and an increased risk of de novo donor-specific anti-HLA antibodies (DSAs) and of antibody-mediated rejection (ABMR) in CYP3A5-expressing patients. Determining CYP3A5-expression status immediately after renal transplant would allow early genotype-based dosage adjustment of tacrolimus and might prevent the occurrence of de novo DSAs and ABMR, improving transplant outcome.

METHODS

160 renal allograft recipients who underwent renal transplant at the University Hospital Essen between May 2019 and May 2022 were genotyped for the CYP3A5 rs776746 polymorphism within the first two weeks after transplant, and genotype-based dose adjustment of tacrolimus was performed for the follow-up of 2 years.

RESULTS

CYP3A5 expression was detected in 33 (21%) of the 160 patients. Tacrolimus trough levels were similar in CYP3A5 expressers and nonexpressers over the entire 2-year follow-up period. However, we observed a trend toward slightly higher tacrolimus trough levels in CYP3A5 expressers, who, as expected, required tacrolimus dosages twice as high as did nonexpressers during follow-up. Calcineurin inhibitor (CNI) nephrotoxicity-free survival rates were comparable between CYP3A5 expressers and nonexpressers (p = 0.49). Rejection-free survival rates (p = 0.89), de novo anti-HLA antibody-free survival rates (p = 0.57) and de novo DSA-free survival rates (p = 0.61) did not differ between the two groups.

CONCLUSIONS

Early detection of CYP3A5-expression status and resultant genotype-based adjustment of tacrolimus dosage after renal transplant protected patients from transplant rejection and de novo DSA formation and was not associated with increased incidence of CNI toxicity among CYP3A5 expressers.

Model-Informed Precision Dosing of Tacrolimus: A Systematic Review of Population Pharmacokinetic Models and a Benchmark Study of Software Tools

BACKGROUND AND OBJECTIVE

Tacrolimus is an immunosuppressant commonly administered after solid organ transplantation. It is characterized by a narrow therapeutic window and high variability in exposure, demanding personalized dosing. In recent years, population pharmacokinetic models have been suggested to guide model-informed precision dosing of tacrolimus. We aimed to provide a comprehensive overview of population pharmacokinetic models and model-informed precision dosing software modules of tacrolimus in all solid organ transplant settings, including a simulation-based investigation of the impact of covariates on exposure and target attainment.

METHODS

We performed a systematic literature search to identify population pharmacokinetic models of tacrolimus in solid organ transplant recipients. We integrated selected population pharmacokinetic models into an interactive software tool that allows dosing simulations, Bayesian forecasting, and investigation of the impact of covariates on exposure and target attainment. We conducted a web survey amongst model-informed precision dosing software tool providers and benchmarked publicly available tools in terms of models, target populations, and clinical integration.

RESULTS

We identified 80 population pharmacokinetic models, including 44 one-compartment and 36 two-compartment models. The most frequently retained covariates on clearance and distribution parameters were cytochrome P450 3A5 polymorphisms and body weight, respectively. Our simulation tool, hosted at https://lpmx.shinyapps.io/tacrolimus/ , allows thorough investigation of the impact of covariates on exposure and target attainment. We identified 15 model-informed precision dosing software tool providers, of which ten offer a tacrolimus solution and nine completed the survey.

CONCLUSIONS

Our work provides a comprehensive overview of the landscape of available tacrolimus population pharmacokinetic models and model-informed precision dosing software modules. Our simulation tool allows an interactive thorough exploration of covariates on exposure and target attainment.

Genomics in the kidney transplant clinic: the future standard of care?

New evidence indicates potential benefit of genomics to illuminate nonkidney monogenic morbidity and mortality risk among kidney transplant recipients. This might be of direct relevance to an equivalent proportion of patients to those who harbor a monogenic kidney disease. Further evidence and replication are indicated, including a broadening potential range of monogenic and polygenic opportunities to improve clinical outcomes. Implementation will require such information, although it holds great promise.

Weight, CYP3A5 Genotype, and Voriconazole Co-administration Influence Tacrolimus Initial Dosage in Pediatric Lung Transplantation Recipients with Low Hematocrit based on a Simulation Model

OBJECTIVE

The method of administering the initial doses of tacrolimus in recipients of pediatric lung transplantation, especially in patients with low hematocrit, is not clear. The present study aims to explore whether weight, CYP3A5 genotype, and voriconazole co-administration influence tacrolimus initial dosage in recipients of pediatric lung transplantation with low hematocrit based on safety and efficacy using a simulation model.

METHODS

The present study utilized the tacrolimus population pharmacokinetic model, which was employed in lung transplantation recipients with low hematocrit.

RESULTS

For pediatric lung transplantation recipients not carrying CYP3A5*1 and without voriconazole, the recommended tacrolimus doses for weights of 10-13, 13-19, 19-22, 22-35, 35-38, and 38-40 kg are 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08 mg/kg/day, which are split into two doses, respectively. For pediatric lung transplantation recipients carrying CYP3A5*1 and without voriconazole, the recommended tacrolimus doses for weights of 10-18, 18-30, and 30-40 kg are 0.06, 0.08, 0.11 mg/kg/day, which are split into two doses, respectively. For pediatric lung transplantation recipients not carrying CYP3A5*1 and with voriconazole, the recommended tacrolimus doses for weights of 10-20 and 20-40 kg are 0.02 and 0.03 mg/kg/day, which are split into two doses, respectively. For pediatric lung transplantation recipients carrying CYP3A5*1 and with voriconazole, the recommended tacrolimus doses for weights of 10-20, 20-33, and 33-40 kg are 0.03, 0.04, and 0.05 mg/kg/day, which are split into two doses, respectively.

CONCLUSION

The present study is the first to recommend the initial dosages of tacrolimus in recipients of pediatric lung transplantation with low hematocrit using a simulation model.

A first small step toward personalized immunosuppression

Lloberas et al. provide further evidence for the benefits of an individualized tacrolimus dosing algorithm based on population pharmacokinetics and pharmacogenetics. Better tacrolimus dosing could prevent underexposure and overexposure and potentially save costs. Most important, this could be the start of precision medicine in kidney transplantation, incorporating improved immunologic and donor quality assessments, advanced biopsy readouts, innovative pharmacogenomics for drug safety, and novel diagnostic and outcome algorithms to guide a truly personalized therapy.