Implementation of a Physiologically Based Pharmacokinetic Modeling Approach to Guide Optimal Dosing Regimens for Imatinib and Potential Drug Interactions in Paediatrics (original) (raw)
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Population Pharmacokinetics and Pharmacogenetics of Imatinib in Children and Adults
Clinical Cancer Research, 2008
Purpose: The aim of this study was to explore the effect of several demographic, biological, and pharmacogenetic covariates on the disposition of imatinib and its main metabolite (CGP74588) in both adults and children. Experimental Design: Thirty-three children with solid malignancies included in a phase II exploratory study and 34 adults with gastrointestinal stromal tumors received 340 mg/m2 and 400 mg imatinib, respectively. Plasma imatinib and CGP74588 concentrations observed on day 1 and at steady-state were analyzed by a population pharmacokinetic method (NONMEM) to evaluate the effect of age, body weight, age, sex, albuminemia, plasma α1-acid glycoprotein (AGP), and eight polymorphisms corresponding to ABCB1, ABCG2, CYP3A4, CYP3A5, and AGP (pharmacogenetic data available for 46 of 67 patients). Results: Analysis of the whole data set in 67 patients showed that apparent clearance (CL/F) of imatinib was positively correlated with body weight and albuminemia and negatively with ...
Influence of CYP3A4 Inhibition on the Steady-State Pharmacokinetics of Imatinib
Clinical Cancer Research, 2007
In the recent years, eight tyrosine kinase inhibitors (TKIs) have been approved for cancer treatment and numerous are under investigation. These drugs are rationally designed to target specific tyrosine kinases that are mutated and/or over-expressed in cancer tissues. Post marketing study commitments have been made upon (accelerated) approval such as additional pharmacokinetic studies in patients with renal-or hepatic impairment, in children, additional interactions studies and studies on the relative or absolute bioavailability. Therefore, much information will emerge on the pharmacokinetic behavior of these drugs after their approval. In the present manuscript, the pharmacokinetic characteristics; absorption, distribution, metabolism and excretion (ADME), of the available TKIs are reviewed. Results from additional studies on the effect of drug transporters and drug-drug interactions have been incorporated. In general, TKIs reach their maximum plasma levels relatively fast; have an unknown absolute bioavailability, are extensively distributed and highly protein bound. The drugs are primarily metabolized by cytochrome P450 (CYP) 3A4 with other CYPenzymes playing a secondare role. They are predominantly excreted with the feces and only a minor fraction is eliminated with the urine. All TKIs appear to be transported by the efflux ATP binding cassette transports (ABC) B1 and G2. Additionally these drugs can inhibit some of their own metabolizing enzymes and transporters making steady-state metabolism and drug-drug interactions both complex and unpredictable. By understanding the pharmacokinetic profile of these drugs and their similarities, factors that influence drug exposure will be better recognized and this knowledge may be used to limit sub-or supra-therapeutic drug exposure.
European Journal of Clinical Pharmacology, 2010
Purpose To illustrate the interface of pharmacogenetics and therapeutic drug monitoring and to estimate target blood level for imatinib in the treatment of chronic myelogenous leukemia Methods A literature review to provide the evidence and necessary data to support the case for the interface, and quantitative analysis of the data to estimate the target blood level for imatinib using receiver operating curve (ROC; signal detection theory) analysis. Results and discussion One study estimated the optimum target level of imatinib in chronic myelogenous leukaemia as 1002 ng/mL (1.70 µM) through ROC analysis. Using individual-patient level data reported in another study and the same methodology, we estimated the target level as 0.95 µM. This is consistent with the results of other observational studies where dose-response was not the primary research objective. The available evidence suggests considerable inter-individual variability in dose-blood level response. In addition to the pharmacogenetics of metabolic enzymes and transporters, genetic mutations in genes participating in the signalling pathways may also account for the wide inter-individual variability in dose-blood level and dose-clinical response relationships. Conclusion A single-dose regimen for all pharmacogenetically eligible patients is not the optimum strategy for prescribing imatinib to patients with chronic myelogenous leukaemia. We suggest that therapeutic drug monitoring aimed at ensuring a trough target level of 1 µM would reduce the incidence of pseudo-resistance and hence personalize treatment and optimise response to imatinib. Persistent resistance can then be probed further for other causes.
Pharmaceutics
Ethical regulations and limited paediatric participants are key challenges that contribute to a median delay of 6 years in paediatric mAb approval. To overcome these barriers, modelling and simulation methodologies have been adopted to design optimized paediatric clinical studies and reduce patient burden. The classical modelling approach in paediatric pharmacokinetic studies for regulatory submissions is to apply body weight-based or body surface area-based allometric scaling to adult PK parameters derived from a popPK model to inform the paediatric dosing regimen. However, this approach is limited in its ability to account for the rapidly changing physiology in paediatrics, especially in younger infants. To overcome this limitation, PBPK modelling, which accounts for the ontogeny of key physiological processes in paediatrics, is emerging as an alternative modelling strategy. While only a few mAb PBPK models have been published, PBPK modelling shows great promise demonstrating a si...
Physiologically based pharmacokinetic modeling and simulation in pediatric drug development
CPT: pharmacometrics & systems pharmacology, 2014
Increased regulatory demands for pediatric drug development research have fostered interest in the use of modeling and simulation among industry and academia. Physiologically based pharmacokinetic (PBPK) modeling offers a unique modality to incorporate multiple levels of information to estimate age-specific pharmacokinetics. This tutorial will serve to provide the reader with a basic understanding of the procedural steps to developing a pediatric PBPK model and facilitate a discussion of the advantages and limitations of this modeling technique.
Advances in clinical and experimental medicine : official organ Wroclaw Medical University, 2018
Chronic myeloid leukemia (CML) constitutes only 2-3% of all leukemias in pediatric patients. Philapelphia chromosome and BCR-ABL fusion are genetic hallmarks of CML, and their presence is crucial for targeted molecular therapy with tyrosine kinase inhibitors (TKIs), which replaced hematopoietic stem cell transplantation (HSCT) as a standard first-line therapy. The disease in pediatric population is rare, and despite molecular and clinical similarities to CML in adults, different approach is needed, due to the long lifetime expectancy and distinct developmental characteristics of affected children. The objective of this study is to evaluate treatment with imatinib in Polish pediatric patients with CML. We analyzed the results of treatment with imatinib in 57 pediatric patients (June 2006 - January 2016) from 14 Polish pediatric hematology and oncology centers. In the study group, 40 patients continued imatinib (median follow-up: 23.4 months), while in 17 the treatment was terminated ...