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Centanni M, Reijnhout N, Thijs A, Karlsson MO, Friberg LE. Pharmacogenetic Testing or Therapeutic Drug Monitoring: A Quantitative Framework. Clin Pharmacokinet 2024; 63:871-884. [PMID: 38842789 PMCID: PMC11222190 DOI: 10.1007/s40262-024-01382-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2024] [Indexed: 06/07/2024]
Abstract
BACKGROUND Pharmacogenetic profiling and therapeutic drug monitoring (TDM) have both been proposed to manage inter-individual variability (IIV) in drug exposure. However, determining the most effective approach for estimating exposure for a particular drug remains a challenge. This study aimed to quantitatively assess the circumstances in which pharmacogenetic profiling may outperform TDM in estimating drug exposure, under three sources of variability (IIV, inter-occasion variability [IOV], and residual unexplained variability [RUV]). METHODS Pharmacokinetic models were selected from the literature corresponding to drugs for which pharmacogenetic profiling and TDM are both clinically considered approaches for dose individualization. The models were used to simulate relevant drug exposures (trough concentration or area under the curve [AUC]) under varying degrees of IIV, IOV, and RUV. RESULTS Six drug cases were selected from the literature. Model-based simulations demonstrated that the percentage of patients for whom pharmacogenetic exposure prediction is superior to TDM differs for each drug case: tacrolimus (11.0%), tamoxifen (12.7%), efavirenz (49.2%), vincristine (49.6%), risperidone (48.1%), and 5-fluorouracil (5-FU) (100%). Generally, in the presence of higher unexplained IIV in combination with lower RUV and IOV, exposure was best estimated by TDM, whereas, under lower unexplained IIV in combination with higher IOV or RUV, pharmacogenetic profiling was preferred. CONCLUSIONS For the drugs with relatively low RUV and IOV (e.g., tamoxifen and tacrolimus), TDM estimated true exposure the best. Conversely, for drugs with similar or lower unexplained IIV (e.g., efavirenz or 5-FU, respectively) combined with relatively high RUV, pharmacogenetic profiling provided the most accurate estimate for most patients. However, genotype prevalence and the relative influence of genotypes on the PK, as well as the ability of TDM to accurately estimate AUC with a limited number of samples, had an impact. The results could be used to support clinical decision making when considering other factors, such as the probability for severe side effects.
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Affiliation(s)
- Maddalena Centanni
- Department of Pharmacy, Uppsala University, Box 580, 751 23, Uppsala, Sweden
| | - Niels Reijnhout
- Department of Pharmacy, Uppsala University, Box 580, 751 23, Uppsala, Sweden
| | - Abel Thijs
- Department of Internal Medicine, Amsterdam UMC, Location VU University, Amsterdam, The Netherlands
| | - Mats O Karlsson
- Department of Pharmacy, Uppsala University, Box 580, 751 23, Uppsala, Sweden
| | - Lena E Friberg
- Department of Pharmacy, Uppsala University, Box 580, 751 23, Uppsala, Sweden.
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Mc Laughlin AM, Helland T, Klima F, Koolen SLW, van Schaik RHN, Mathijssen RHJ, Neven P, Swen JJ, Guchelaar HJ, Dalenc F, White-Koning M, Michelet R, Mikus G, Schroth W, Mürdter T, Brauch H, Schwab M, Søiland H, Mellgren G, Thomas F, Kloft C, Hertz DL. Nonlinear Mixed-Effects Model of Z-Endoxifen Concentrations in Tamoxifen-Treated Patients from the CEPAM Cohort. Clin Pharmacol Ther 2024. [PMID: 38494911 DOI: 10.1002/cpt.3238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 02/08/2024] [Indexed: 03/19/2024]
Abstract
Tamoxifen is widely used in patients with hormone receptor-positive breast cancer. The polymorphic enzyme CYP2D6 is primarily responsible for metabolic activation of tamoxifen, resulting in substantial interindividual variability of plasma concentrations of its most important metabolite, Z-endoxifen. The Z-endoxifen concentration thresholds below which tamoxifen treatment is less efficacious have been proposed but not validated, and prospective trials of individualized tamoxifen treatment to achieve Z-endoxifen concentration thresholds are considered infeasible. Therefore, we aim to validate the association between Z-endoxifen concentration and tamoxifen treatment outcomes, and identify a Z-endoxifen concentration threshold of tamoxifen efficacy, using pharmacometric modeling and simulation. As a first step, the CYP2D6 Endoxifen Percentage Activity Model (CEPAM) cohort was created by pooling data from 28 clinical studies (> 7,000 patients) with measured endoxifen plasma concentrations. After cleaning, data from 6,083 patients were used to develop a nonlinear mixed-effect (NLME) model for tamoxifen and Z-endoxifen pharmacokinetics that includes a conversion factor to allow inclusion of studies that measured total endoxifen but not Z-endoxifen. The final parent-metabolite NLME model confirmed the primary role of CYP2D6, and contributions from body weight, CYP2C9 phenotype, and co-medication with CYP2D6 inhibitors, on Z-endoxifen pharmacokinetics. Future work will use the model to simulate Z-endoxifen concentrations in patients receiving single agent tamoxifen treatment within large prospective clinical trials with long-term survival to identify the Z-endoxifen concentration threshold below which tamoxifen is less efficacious. Identification of this concentration threshold would allow personalized tamoxifen treatment to improve outcomes in patients with hormone receptor-positive breast cancer.
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Affiliation(s)
- Anna M Mc Laughlin
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
- PharMetrX Graduate Research Training Program, Berlin/Potsdam, Germany
| | - Thomas Helland
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, Michigan, USA
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Fenja Klima
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
- PharMetrX Graduate Research Training Program, Berlin/Potsdam, Germany
| | - Stijn L W Koolen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ron H N van Schaik
- Department of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ron H J Mathijssen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Patrick Neven
- Department of Gynecological Oncology and Multidisciplinary Breast Center, University Hospitals Leuven, Leuven, Belgium
| | - Jesse J Swen
- Department Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, the Netherlands
| | - Henk-Jan Guchelaar
- Department Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, the Netherlands
| | - Florence Dalenc
- Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France
| | - Melanie White-Koning
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France
| | - Robin Michelet
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
| | - Gerd Mikus
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Werner Schroth
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
- University Tübingen, Tübingen, Germany
| | - Thomas Mürdter
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
- University Tübingen, Tübingen, Germany
| | - Hiltrud Brauch
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
- University Tübingen, Tübingen, Germany
- iFIT Cluster of Excellence, University of Tübingen, Tübingen, Germany
- German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Partner Site Tübingen, Tübingen, Germany
| | - Matthias Schwab
- University Tübingen, Tübingen, Germany
- iFIT Cluster of Excellence, University of Tübingen, Tübingen, Germany
- German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Partner Site Tübingen, Tübingen, Germany
- Departments of Clinical Pharmacology, and of Biochemistry and Pharmacy, University of Tübingen, Tübingen, Germany
| | - Håvard Søiland
- Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Research, Stavanger University Hospital, Stavanger, Norway
| | - Gunnar Mellgren
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Fabienne Thomas
- Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France
| | - Charlotte Kloft
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
| | - Daniel L Hertz
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, Michigan, USA
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Ojara FW, Henrich A, Frances N, Nassar YM, Huisinga W, Hartung N, Geiger K, Holdenrieder S, Joerger M, Kloft C. A prognostic baseline blood biomarker and tumor growth kinetics integrated model in paclitaxel/platinum treated advanced non-small cell lung cancer patients. CPT Pharmacometrics Syst Pharmacol 2023; 12:1714-1725. [PMID: 36782356 PMCID: PMC10681433 DOI: 10.1002/psp4.12937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 01/11/2023] [Indexed: 02/15/2023] Open
Abstract
Paclitaxel/platinum chemotherapy, the backbone of standard first-line treatment of advanced non-small cell lung cancer (NSCLC), exhibits high interpatient variability in treatment response and high toxicity burden. Baseline blood biomarker concentrations and tumor size (sum of diameters) at week 8 relative to baseline (RS8) are widely investigated prognostic factors. However, joint analysis of data on demographic/clinical characteristics, blood biomarker levels, and chemotherapy exposure-driven early tumor response for improved prediction of overall survival (OS) is clinically not established. We developed a Weibull time-to-event model to predict OS, leveraging data from 365 patients receiving paclitaxel/platinum combination chemotherapy once every three weeks for ≤six cycles. A developed tumor growth inhibition model, combining linear tumor growth and first-order paclitaxel area under the concentration-time curve-induced tumor decay, was used to derive individual RS8. The median model-derived RS8 in all patients was a 20.0% tumor size reduction (range from -78% to +15%). Whereas baseline carcinoembryonic antigen, cytokeratin fragments, and thyroid stimulating hormone levels were not significantly associated with OS in a subset of 221 patients, and lactate dehydrogenase, interleukin-6 and neutrophil-to-lymphocyte ratio levels were significant only in univariate analyses (p value < 0.05); C-reactive protein (CRP) in combination with RS8 most significantly affected OS (p value < 0.01). Compared to the median population OS of 11.3 months, OS was 128% longer at the 5th percentile levels of both covariates and 60% shorter at their 95th percentiles levels. The combined paclitaxel exposure-driven RS8 and baseline blood CRP concentrations enables early individual prognostic predictions for different paclitaxel dosing regimens, forming the basis for treatment decision and optimizing paclitaxel/platinum-based advanced NSCLC chemotherapy.
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Affiliation(s)
- Francis Williams Ojara
- Department of Clinical Pharmacy and Biochemistry, Institute of PharmacyFreie Universitaet BerlinBerlinGermany
- Graduate Research Training Program PharMetrXBerlin/PotsdamGermany
| | - Andrea Henrich
- Department of Clinical Pharmacy and Biochemistry, Institute of PharmacyFreie Universitaet BerlinBerlinGermany
- Graduate Research Training Program PharMetrXBerlin/PotsdamGermany
| | - Nicolas Frances
- Department of Translational Modeling and Simulation, Roche Pharma Research and Early Development, Roche Innovation Center BaselF. Hoffmann‐La Roche LtdBaselSwitzerland
| | - Yomna M. Nassar
- Department of Clinical Pharmacy and Biochemistry, Institute of PharmacyFreie Universitaet BerlinBerlinGermany
- Graduate Research Training Program PharMetrXBerlin/PotsdamGermany
| | | | - Niklas Hartung
- Institute of MathematicsUniversity of PotsdamPotsdamGermany
| | - Kimberly Geiger
- Munich Biomarker Research Center, Institute of Laboratory Medicine, German Heart CenterTechnical University of MunichMunichGermany
| | - Stefan Holdenrieder
- Munich Biomarker Research Center, Institute of Laboratory Medicine, German Heart CenterTechnical University of MunichMunichGermany
| | - Markus Joerger
- Department of Oncology and HematologyCantonal Hospital St. GallenSt. GallenSwitzerland
| | - Charlotte Kloft
- Department of Clinical Pharmacy and Biochemistry, Institute of PharmacyFreie Universitaet BerlinBerlinGermany
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El Desoky ES, Taha AF, Mousa HS, Ibrahim A, Saleh MA, Abdelrady MA, Hareedy MS. Value of therapeutic drug monitoring of endoxifen in Egyptian premenopausal patients with breast cancer given tamoxifen adjuvant therapy: A pilot study. J Oncol Pharm Pract 2023; 29:1673-1686. [PMID: 36567618 DOI: 10.1177/10781552221146531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND The complex metabolic profile of tamoxifen anticancer drug and polymorphism in its metabolizing enzymes particularly CYP2D6 contribute to the high-observed inter-individual variability in its main active metabolite endoxifen. Therapeutic drug monitoring of endoxifen may play a key role in optimizing tamoxifen therapy, and control of both adverse effects and cancer recurrence. This pilot study aims to assess the clinical benefits of applying endoxifen measurement during tamoxifen therapy in patients with breast cancer. METHODS Adult premenopausal breast cancer patients ≥ 18 years who received tamoxifen at a fixed dose of 20 mg daily were included. The primary endpoint was to identify the inter-subject variability in serum concentration of the drug and its metabolites especially endoxifen, through fixation of the tamoxifen dose. The secondary endpoint was to check the correlation between endoxifen metabolite concentration and the development of tamoxifen's adverse effects and cancer recurrence. RESULTS Sixty patients were included in the study with a mean age of 38.4 ± 0.6 years (range: 26-50). The mean concentration of tamoxifen and endoxifen was 181 ± 9.6 ng/mL and 31.49 ng/mL, respectively. The inter-individual variability in concentrations for the drug and its active metabolite as estimated by the coefficient of variation percentage was in 41% and 31%, respectively. Cancer recurrence was observed in a group of patients (n = 16) with an average endoxifen level of 24.48 ng/mL. Another group of patients (n = 25) developed different tamoxifen adverse effects including hot flashes, vaginal bleeding, endometrial thickness, and ovarian cysts with the average endoxifen level of 38.61 ng/mL. The rest of the patients (n = 19) who responded smoothly to the drug with no complications had an average endoxifen level of 31.37 ng/mL. Analysis of variance test showed a significant difference in endoxifen levels between the three groups (p = 0.002). CONCLUSION The measurement of the endoxifen active metabolite of tamoxifen in breast cancer patients can help dose optimization in light of the observed wide inter-individual variability in drug fixed-dose related concentration of the metabolite. Monitoring of serum concentration of endoxifen can help to reveal, reduce and control tamoxifen's adverse effects and cancer recurrence.
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Affiliation(s)
- Ehab S El Desoky
- Department of Pharmacology, Faculty of Medicine, Assiut University, Egypt
| | - Amira F Taha
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Assiut University, Egypt
| | - Heba Salah Mousa
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, South Valley University, Qena, Egypt
| | - Abeer Ibrahim
- Department of Medical Oncology and Hematological Malignancy, South Egypt Cancer Institute, Assiut University, Egypt
| | - Medhat A Saleh
- Department of Public Health and Community Medicine, Faculty of Medicine, Assiut University, Egypt
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Agema BC, Buijs SM, Sassen SDT, Mürdter TE, Schwab M, Koch BCP, Jager A, van Schaik RHN, Mathijssen RHJ, Koolen SLW. Toward model-informed precision dosing for tamoxifen: A population-pharmacokinetic model with a continuous CYP2D6 activity scale. Biomed Pharmacother 2023; 160:114369. [PMID: 36753957 DOI: 10.1016/j.biopha.2023.114369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
BACKGROUND Tamoxifen is important in the adjuvant treatment of breast cancer. A plasma concentration of the active metabolite endoxifen of > 16 nM is associated with a lower risk of breast cancer-recurrence. Since inter-individual variability is high and > 20 % of patients do not reach endoxifen levels > 16 nM with the standard dose tamoxifen, therapeutic drug monitoring is advised. However, ideally, the correct tamoxifen dose should be known prior to start of therapy. Our aim is to develop a population pharmacokinetic (POP-PK) model incorporating a continuous CYP2D6 activity scale to support model informed precision dosing (MIPD) of tamoxifen to determine the optimal tamoxifen starting dose. METHODS Data from eight different clinical studies were pooled (539 patients, 3661 samples) and used to develop a POP-PK model. In this model, CYP2D6 activity per allele was estimated on a continuous scale. After inclusion of covariates, the model was subsequently validated using an independent external dataset (378 patients). Thereafter, dosing cut-off values for MIPD were determined. RESULTS A joint tamoxifen/endoxifen POP-PK model was developed describing the endoxifen formation rate. Using a continuous CYP2D6 activity scale, variability in predicting endoxifen levels was decreased by 37 % compared to using standard CYP2D6 genotype predicted phenotyping. After external validation and determination of dosing cut-off points, MIPD could reduce the proportion of patients with subtherapeutic endoxifen levels at from 22.1 % toward 4.8 %. CONCLUSION Implementing MIPD from the start of tamoxifen treatment with this POP-PK model can reduce the proportion of patients with subtherapeutic endoxifen levels at steady-state to less than 5 %.
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Affiliation(s)
- Bram C Agema
- Dept. of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center; Rotterdam, the Netherlands; Dept. of Clinical Pharmacy, Erasmus University Medical Center; Rotterdam, the Netherlands.
| | - Sanne M Buijs
- Dept. of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center; Rotterdam, the Netherlands
| | - Sebastiaan D T Sassen
- Dept. of Clinical Pharmacy, Erasmus University Medical Center; Rotterdam, the Netherlands; Rotterdam Clinical Pharmacometrics Group; Rotterdam, the Netherlands
| | - Thomas E Mürdter
- Margarete Fischer-Bosch-Institute of Clinical Pharmacology; Stuttgart, Germany; University of Tübingen; Tübingen, Germany
| | - Mathias Schwab
- Margarete Fischer-Bosch-Institute of Clinical Pharmacology; Stuttgart, Germany; Dept. of Clinical Pharmacology, University Hospital Tübingen; Tübingen, Germany; iFIT Cluster of Excellence (EXC2180) "Image Guided and Functionally Instructed Tumor Therapies", University of Tübingen, Tübingen, Germany
| | - Birgit C P Koch
- Dept. of Clinical Pharmacy, Erasmus University Medical Center; Rotterdam, the Netherlands; Rotterdam Clinical Pharmacometrics Group; Rotterdam, the Netherlands
| | - Agnes Jager
- Dept. of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center; Rotterdam, the Netherlands
| | - Ron H N van Schaik
- Dept. of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Ron H J Mathijssen
- Dept. of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center; Rotterdam, the Netherlands
| | - Stijn L W Koolen
- Dept. of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center; Rotterdam, the Netherlands; Dept. of Clinical Pharmacy, Erasmus University Medical Center; Rotterdam, the Netherlands
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Dilli Batcha JS, Raju AP, Matcha S, Raj S. EA, Udupa KS, Gota V, Mallayasamy S. Factors Influencing Pharmacokinetics of Tamoxifen in Breast Cancer Patients: A Systematic Review of Population Pharmacokinetic Models. BIOLOGY 2022; 12:biology12010051. [PMID: 36671744 PMCID: PMC9855885 DOI: 10.3390/biology12010051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/21/2022] [Accepted: 12/25/2022] [Indexed: 12/29/2022]
Abstract
BACKGROUND Tamoxifen is useful in managing breast cancer and it is reported to have significant variability in its pharmacokinetics. This review aimed to summarize reported population pharmacokinetics studies of tamoxifen and to identify the factors affecting the pharmacokinetics of tamoxifen in adult breast cancer patients. METHOD A systematic search was undertaken in Scopus, Web of Science, and PubMed for papers published in the English language from inception to 20 August 2022. Studies were included in the review if the population pharmacokinetic modeling was based on non-linear mixed-effects modeling with a parametric approach for tamoxifen in breast cancer patients. RESULTS After initial selection, 671 records were taken for screening. A total of five studies were selected from Scopus, Web of Science, PubMed, and by manual searching. The majority of the studies were two-compartment models with first-order absorption and elimination to describe tamoxifen and its metabolites' disposition. The CYP2D6 phenotype and CYP3A4 genotype were the main covariates that affected the metabolism of tamoxifen and its metabolites. Other factors influencing the drug's pharmacokinetics included age, co-medication, BMI, medication adherence, CYP2B6, and CYP2C19 genotype. CONCLUSION The disposition of tamoxifen and its metabolites varies primarily due to the CYP2D6 phenotype and CYP3A4 genotype. However, other factors, such as anthropometric characteristics and menopausal status, should also be addressed when accounting for this variability. All these studies should be externally evaluated to assess their applicability in different populations and to use model-informed dosing in the clinical setting.
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Affiliation(s)
- Jaya Shree Dilli Batcha
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
| | - Arun Prasath Raju
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
| | - Saikumar Matcha
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
| | - Elstin Anbu Raj S.
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
- Public Health Evidence South Asia, Department of Health Information, Prasanna School of Public Health, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
| | - Karthik S. Udupa
- Department of Medical Oncology, Kasturba Medical College, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
| | - Vikram Gota
- Department of Clinical Pharmacology, ACTREC, Tata Memorial Centre, Mumbai 410 210, Maharashtra, India
| | - Surulivelrajan Mallayasamy
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
- Center for Pharmacometrics, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
- Correspondence:
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Groenland SL, van Eerden RAG, Westerdijk K, Meertens M, Koolen SLW, Moes DJAR, de Vries N, Rosing H, Otten H, Vulink AJE, Desar IME, Imholz ALT, Gelderblom H, van Erp NP, Beijnen JH, Mathijssen RHJ, Huitema ADR, Steeghs N. Therapeutic drug monitoring-based precision dosing of oral targeted therapies in oncology: a prospective multicenter study. Ann Oncol 2022; 33:1071-1082. [PMID: 35777707 DOI: 10.1016/j.annonc.2022.06.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 04/08/2022] [Accepted: 06/20/2022] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Oral targeted therapies show a high pharmacokinetic (PK) interpatient variability. Even though exposure has been positively correlated with efficacy for many of these drugs, these are still dosed using a one-size-fits-all approach. Consequently, individuals have a high probability to be either underexposed or overexposed, potentially leading to suboptimal outcomes. Therapeutic drug monitoring, which is personalized dosing based on measured systemic drug concentrations, could address these problems. PATIENTS AND METHODS Patients were enrolled in this prospective multicenter study (www.trialregister.nl; NL6695) if they started treatment with one of the 24 participating oral targeted therapies. Primary outcome was to halve the proportion of underexposed patients, compared with historical data. PK sampling was carried out after 4, 8 and 12 weeks, and every 12 weeks thereafter. In case of Cmin below the predefined target and manageable toxicity, a pharmacokinetically guided intervention was proposed (i.e. checking compliance and drug-drug interactions, concomitant intake with food, splitting intake moments or dose increments). RESULTS In total, 600 patients were included of whom 426 patients are assessable for the primary outcome and 552 patients had ≥1 PK sample(s) available and were therefore assessable for the overall analyses. Pharmacokinetically guided dosing reduced the proportion of underexposed patients at the third PK measurement by 39.0% (95% confidence interval 28.0% to 49.0%) compared with historical data. At the third PK measurement, 110 out of 426 patients (25.8%) had a low exposure. In total, 294 patients (53.3%) had ≥1 PK sample(s) below the preset target at a certain time point during treatment. In 166 of these patients (56.5%), pharmacokinetically guided interventions were carried out, which were successful in 113 out of 152 assessable patients (74.3%). CONCLUSIONS Pharmacokinetically guided dose optimization of oral targeted therapies was feasible in clinical practice and reduced the proportion of underexposed patients considerably.
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Affiliation(s)
- S L Groenland
- Department of Clinical Pharmacology, Division of Medical Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
| | - R A G van Eerden
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands
| | - K Westerdijk
- Department of Medical Oncology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - M Meertens
- Department of Pharmacy & Pharmacology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - S L W Koolen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands; Department of Pharmacy, Erasmus Medical Center, Rotterdam, The Netherlands
| | - D J A R Moes
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - N de Vries
- Department of Pharmacy & Pharmacology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - H Rosing
- Department of Pharmacy & Pharmacology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - H Otten
- Department of Medical Oncology, Meander Medical Center, Amersfoort, The Netherlands
| | - A J E Vulink
- Department of Medical Oncology, Reinier de Graaf Hospital, Delft, The Netherlands
| | - I M E Desar
- Department of Medical Oncology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - A L T Imholz
- Department of Medical Oncology, Deventer Hospital, Deventer, The Netherlands
| | - H Gelderblom
- Department of Medical Oncology, Leiden University Medical Center, Leiden, The Netherlands
| | - N P van Erp
- Department of Pharmacy, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - J H Beijnen
- Department of Pharmacy & Pharmacology, The Netherlands Cancer Institute, Amsterdam, The Netherlands; Department of Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - R H J Mathijssen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands
| | - A D R Huitema
- Department of Pharmacy & Pharmacology, The Netherlands Cancer Institute, Amsterdam, The Netherlands; Department of Clinical Pharmacy, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands; Department of Pharmacology, Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - N Steeghs
- Department of Clinical Pharmacology, Division of Medical Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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Developing a Nationwide Infrastructure for Therapeutic Drug Monitoring of Targeted Oral Anticancer Drugs: The ON-TARGET Study Protocol. Cancers (Basel) 2021; 13:cancers13246281. [PMID: 34944899 PMCID: PMC8699239 DOI: 10.3390/cancers13246281] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/10/2021] [Accepted: 12/12/2021] [Indexed: 12/28/2022] Open
Abstract
Simple Summary Relationships between drug concentrations in blood and efficacy and/or toxicity have been reported for up to 80% of oral anticancer drugs (OADs). Most OADs exhibit highly variable drug concentrations at the approved dose. This may result in a significant proportion of patients with suboptimal drug concentrations. Therapeutic Drug Monitoring (TDM), which is dose optimization based on measured drug concentrations, can be used to personalize drug dosing with the overall goal to improve the benefit-risk ratio of anticancer drug treatment. The ON-TARGET study aims to investigate the feasibility of TDM in patients receiving either axitinib or cabozantinib for the treatment of renal-cell carcinoma with the main objective to improve severe tyrosine kinase inhibitor associated toxicity. Additionally, the feasibility of volumetric absorptive microsampling (VAMS), a novel minimally invasive and easy to handle blood sampling technique, for TDM sample collection is investigated. Abstract Exposure-efficacy and/or exposure-toxicity relationships have been identified for up to 80% of oral anticancer drugs (OADs). Usually, OADs are administered at fixed doses despite their high interindividual pharmacokinetic variability resulting in large differences in drug exposure. Consequently, a substantial proportion of patients receive a suboptimal dose. Therapeutic Drug Monitoring (TDM), i.e., dosing based on measured drug concentrations, may be used to improve treatment outcomes. The prospective, multicenter, non-interventional ON-TARGET study (DRKS00025325) aims to investigate the potential of routine TDM to reduce adverse drug reactions in renal cell carcinoma patients receiving axitinib or cabozantinib. Furthermore, the feasibility of using volumetric absorptive microsampling (VAMS), a minimally invasive and easy to handle blood sampling technique, for sample collection is examined. During routine visits, blood samples are collected and sent to bioanalytical laboratories. Venous and VAMS blood samples are collected in the first study phase to facilitate home-based capillary blood sampling in the second study phase. Within one week, the drug plasma concentrations are measured, interpreted, and reported back to the physician. Patients report their drug intake and toxicity using PRO-CTCAE-based questionnaires in dedicated diaries. Ultimately, the ON-TARGET study aims to develop a nationwide infrastructure for TDM for oral anticancer drugs.
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9
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Braal CL, Jager A, Hoop EOD, Westenberg JD, Lommen KMWT, de Bruijn P, Vastbinder MB, van Rossum-Schornagel QC, Thijs-Visser MF, van Alphen RJ, Struik LEM, Zuetenhorst HJM, Mathijssen RHJ, Koolen SLW. Therapeutic Drug Monitoring of Endoxifen for Tamoxifen Precision Dosing: Feasible in Patients with Hormone-Sensitive Breast Cancer. Clin Pharmacokinet 2021; 61:527-537. [PMID: 34786650 PMCID: PMC8975771 DOI: 10.1007/s40262-021-01077-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2021] [Indexed: 02/08/2023]
Abstract
Background Endoxifen is the most important active metabolite of tamoxifen. Several retrospective studies have suggested a minimal or threshold endoxifen systemic concentration of 14–16 nM is required for a lower recurrence rate. The aim of this study was to investigate the feasibility of reaching a predefined endoxifen level of ≥ 16 nM (5.97 ng/mL) over time using therapeutic drug monitoring (TDM). Methods This prospective open-label intervention study enrolled patients who started treatment with a standard dose of tamoxifen 20 mg once daily for early breast cancer. An outpatient visit was combined with a TDM sample at 3, 4.5, and 6 months after initiation of the tamoxifen treatment. The tamoxifen dose was escalated to a maximum of 40 mg if patients had an endoxifen concentration < 16 nM. The primary endpoint of the study was the percentage of patients with an endoxifen level ≥ 16 nM at 6 months after the start of therapy compared with historical data, in other words, 80% of patients with endoxifen levels ≥ 16 nM with standard therapy. Results In total, 145 patients were included. After 6 months, 89% of the patients had endoxifen levels ≥ 16 nM, compared with a literature-based 80% of patients with endoxifen levels ≥ 16 nM at baseline (95% confidence interval 82–94; P = 0.007). In patients with an affected CYP2D6 allele, it was not always feasible to reach the predefined endoxifen level of ≥ 16 nM. No increase in tamoxifen-related adverse events was reported after dose escalation. Conclusion This study demonstrated that it is feasible to increase the percentage of patients with endoxifen levels ≥ 16 nM using TDM. TDM is a safe strategy that offers the possibility of nearly halving the number of patients with endoxifen levels < 16 nM.
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Affiliation(s)
- C Louwrens Braal
- Department of Medical Oncology, Erasmus MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Agnes Jager
- Department of Medical Oncology, Erasmus MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Esther Oomen-de Hoop
- Department of Medical Oncology, Erasmus MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Justin D Westenberg
- Department of Medical Oncology, Erasmus MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Koen M W T Lommen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Peter de Bruijn
- Department of Medical Oncology, Erasmus MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Mijntje B Vastbinder
- Department of Internal Medicine, IJsselland Hospital, Capelle aan den IJssel, The Netherlands
| | | | - Martine F Thijs-Visser
- Department of Internal Medicine, Ikazia Hospital, Rotterdam, The Netherlands.,Department of Internal Medicine, Spijkenisse MC, Spijkenisse, The Netherlands
| | - Robbert J van Alphen
- Department of Internal Medicine, Elisabeth Tweesteden Hospital, Tilburg, The Netherlands
| | - Liesbeth E M Struik
- Department of Internal Medicine, Ikazia Hospital, Rotterdam, The Netherlands
| | | | - Ron H J Mathijssen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Stijn L W Koolen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands. .,Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, The Netherlands.
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10
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Mueller-Schoell A, Michelet R, Klopp-Schulze L, van Dyk M, Mürdter TE, Schwab M, Joerger M, Huisinga W, Mikus G, Kloft C. Computational Treatment Simulations to Assess the Need for Personalized Tamoxifen Dosing in Breast Cancer Patients of Different Biogeographical Groups. Cancers (Basel) 2021; 13:cancers13102432. [PMID: 34069810 PMCID: PMC8157244 DOI: 10.3390/cancers13102432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/10/2021] [Accepted: 05/13/2021] [Indexed: 12/24/2022] Open
Abstract
Simple Summary Tamoxifen is a drug often used to treat the most common type of breast cancer. Its metabolite endoxifen is formed by the liver enzyme CYP2D6, whose activity is variable and depends on a patient’s genetic profile. The frequency of CYP2D6 variants with different functional enzymatic activity varies largely between populations. To ensure sufficient efficacy of tamoxifen, a certain target concentration of endoxifen is needed, and 20% of White breast cancer patients have been shown not to reach this target concentration. However, little is known about the risk of not attaining the endoxifen target amongst other ethnic populations. This study investigated the risk for suboptimal endoxifen concentration in nine different biogeographical populations based on their distinct CYP2D6 genetic profile. The variability between the populations was high (up to three-fold), and East Asian breast cancer patients were identified as the population with the highest need for personalized tamoxifen dosing. Abstract Tamoxifen is used worldwide to treat estrogen receptor-positive breast cancer. It is extensively metabolized, and minimum steady-state concentrations of its metabolite endoxifen (CSS,min ENDX) >5.97 ng/mL have been associated with favorable outcome. Endoxifen formation is mediated by the enzyme CYP2D6, and impaired CYP2D6 function has been associated with lower CSS,min ENDX. In the Women’s Healthy Eating and Living (WHEL) study proposing the target concentration, 20% of patients showed subtarget CSS,min ENDX at tamoxifen standard dosing. CYP2D6 allele frequencies vary largely between populations, and as 87% of the patients in the WHEL study were White, little is known about the risk for subtarget CSS,min ENDX in other populations. Applying pharmacokinetic simulations, this study investigated the risk for subtarget CSS,min ENDX at tamoxifen standard dosing and the need for dose individualization in nine different biogeographical groups with distinct CYP2D6 allele frequencies. The high variability in CYP2D6 allele frequencies amongst the biogeographical groups resulted in an up to three-fold difference in the percentages of patients with subtarget CSS,min ENDX. Based on their CYP2D6 allele frequencies, East Asian breast cancer patients were identified as the population for which personalized, model-informed precision dosing would be most beneficial (28% of patients with subtarget CSS,min ENDX).
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Affiliation(s)
- Anna Mueller-Schoell
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 12169 Berlin, Germany; (A.M.-S.); (R.M.); (L.K.-S.); (G.M.)
- Graduate Research Training Program PharMetrX, 12169 Berlin, Germany
| | - Robin Michelet
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 12169 Berlin, Germany; (A.M.-S.); (R.M.); (L.K.-S.); (G.M.)
| | - Lena Klopp-Schulze
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 12169 Berlin, Germany; (A.M.-S.); (R.M.); (L.K.-S.); (G.M.)
| | - Madelé van Dyk
- College of Medicine and Public Health, Flinders University, Adelaide, SA 5042, Australia;
| | - Thomas E. Mürdter
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, and University Tübingen, 70376 Tübingen, Germany;
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, 70376 Stuttgart, Germany;
- German Cancer Consortium (DKTK), Partner Site Tübingen, German Cancer Research, 69120 Heidelberg, Germany
- Departments of Clinical Pharmacology, Pharmacy and Biochemistry, University Tübingen, 72076 Tübingen, Germany
| | - Markus Joerger
- Department of Medical Oncology and Hematology, Cantonal Hospital, 9007 St. Gallen, Switzerland;
| | - Wilhelm Huisinga
- Institute of Mathematics, University of Potsdam, 14476 Potsdam, Germany;
| | - Gerd Mikus
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 12169 Berlin, Germany; (A.M.-S.); (R.M.); (L.K.-S.); (G.M.)
- Department of Clinical Pharmacology and Pharmacoepidemiology, University Hospital Heidelberg, 69120 Heidelberg, Germany
- Department of Clinical Pharmacy, Institute of Pharmacy, University of Bonn, 53113 Bonn, Germany
| | - Charlotte Kloft
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 12169 Berlin, Germany; (A.M.-S.); (R.M.); (L.K.-S.); (G.M.)
- Correspondence:
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11
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Mueller-Schoell A, Groenland SL, Scherf-Clavel O, van Dyk M, Huisinga W, Michelet R, Jaehde U, Steeghs N, Huitema ADR, Kloft C. Therapeutic drug monitoring of oral targeted antineoplastic drugs. Eur J Clin Pharmacol 2021; 77:441-464. [PMID: 33165648 PMCID: PMC7935845 DOI: 10.1007/s00228-020-03014-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/01/2020] [Indexed: 02/06/2023]
Abstract
PURPOSE This review provides an overview of the current challenges in oral targeted antineoplastic drug (OAD) dosing and outlines the unexploited value of therapeutic drug monitoring (TDM). Factors influencing the pharmacokinetic exposure in OAD therapy are depicted together with an overview of different TDM approaches. Finally, current evidence for TDM for all approved OADs is reviewed. METHODS A comprehensive literature search (covering literature published until April 2020), including primary and secondary scientific literature on pharmacokinetics and dose individualisation strategies for OADs, together with US FDA Clinical Pharmacology and Biopharmaceutics Reviews and the Committee for Medicinal Products for Human Use European Public Assessment Reports was conducted. RESULTS OADs are highly potent drugs, which have substantially changed treatment options for cancer patients. Nevertheless, high pharmacokinetic variability and low treatment adherence are risk factors for treatment failure. TDM is a powerful tool to individualise drug dosing, ensure drug concentrations within the therapeutic window and increase treatment success rates. After reviewing the literature for 71 approved OADs, we show that exposure-response and/or exposure-toxicity relationships have been established for the majority. Moreover, TDM has been proven to be feasible for individualised dosing of abiraterone, everolimus, imatinib, pazopanib, sunitinib and tamoxifen in prospective studies. There is a lack of experience in how to best implement TDM as part of clinical routine in OAD cancer therapy. CONCLUSION Sub-therapeutic concentrations and severe adverse events are current challenges in OAD treatment, which can both be addressed by the application of TDM-guided dosing, ensuring concentrations within the therapeutic window.
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Affiliation(s)
- Anna Mueller-Schoell
- Dept. of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
- Graduate Research Training Program, PharMetrX, Berlin/Potsdam, Germany
| | - Stefanie L Groenland
- Department of Clinical Pharmacology, Division of Medical Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Oliver Scherf-Clavel
- Institute of Pharmacy and Food Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Madelé van Dyk
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Wilhelm Huisinga
- Institute of Mathematics, University of Potsdam, Potsdam, Germany
| | - Robin Michelet
- Dept. of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
| | - Ulrich Jaehde
- Department of Clinical Pharmacy, Institute of Pharmacy, University of Bonn, Bonn, Germany
| | - Neeltje Steeghs
- Department of Clinical Pharmacology, Division of Medical Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Alwin D R Huitema
- Department of Pharmacy & Pharmacology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek, Amsterdam, The Netherlands
- Department of Clinical Pharmacy, University Medical Center, Utrecht University, Utrecht, The Netherlands
| | - Charlotte Kloft
- Dept. of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany.
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12
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Helland T, Alsomairy S, Lin C, Søiland H, Mellgren G, Hertz DL. Generating a Precision Endoxifen Prediction Algorithm to Advance Personalized Tamoxifen Treatment in Patients with Breast Cancer. J Pers Med 2021; 11:jpm11030201. [PMID: 33805613 PMCID: PMC8000933 DOI: 10.3390/jpm11030201] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/05/2021] [Accepted: 03/09/2021] [Indexed: 02/06/2023] Open
Abstract
Tamoxifen is an endocrine treatment for hormone receptor positive breast cancer. The effectiveness of tamoxifen may be compromised in patients with metabolic resistance, who have insufficient metabolic generation of the active metabolites endoxifen and 4-hydroxy-tamoxifen. This has been challenging to validate due to the lack of measured metabolite concentrations in tamoxifen clinical trials. CYP2D6 activity is the primary determinant of endoxifen concentration. Inconclusive results from studies investigating whether CYP2D6 genotype is associated with tamoxifen efficacy may be due to the imprecision in using CYP2D6 genotype as a surrogate of endoxifen concentration without incorporating the influence of other genetic and clinical variables. This review summarizes the evidence that active metabolite concentrations determine tamoxifen efficacy. We then introduce a novel approach to validate this relationship by generating a precision endoxifen prediction algorithm and comprehensively review the factors that must be incorporated into the algorithm, including genetics of CYP2D6 and other pharmacogenes. A precision endoxifen algorithm could be used to validate metabolic resistance in existing tamoxifen clinical trial cohorts and could then be used to select personalized tamoxifen doses to ensure all patients achieve adequate endoxifen concentrations and maximum benefit from tamoxifen treatment.
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Affiliation(s)
- Thomas Helland
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI 48109, USA; (S.A.); (C.L.); (D.L.H.)
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway;
- Department of Clinical Science, University of Bergen, 5007 Bergen, Norway;
- Correspondence: ; Tel.: +47-92847793
| | - Sarah Alsomairy
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI 48109, USA; (S.A.); (C.L.); (D.L.H.)
| | - Chenchia Lin
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI 48109, USA; (S.A.); (C.L.); (D.L.H.)
| | - Håvard Søiland
- Department of Clinical Science, University of Bergen, 5007 Bergen, Norway;
| | - Gunnar Mellgren
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway;
- Department of Clinical Science, University of Bergen, 5007 Bergen, Norway;
| | - Daniel Louis Hertz
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI 48109, USA; (S.A.); (C.L.); (D.L.H.)
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13
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Mueller-Schoell A, Klopp-Schulze L, Michelet R, van Dyk M, Mürdter TE, Schwab M, Joerger M, Huisinga W, Mikus G, Kloft C. Simulation-Based Assessment of the Impact of Non-Adherence on Endoxifen Target Attainment in Different Tamoxifen Dosing Strategies. Pharmaceuticals (Basel) 2021; 14:ph14020115. [PMID: 33546125 PMCID: PMC7913149 DOI: 10.3390/ph14020115] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/22/2021] [Accepted: 01/29/2021] [Indexed: 12/12/2022] Open
Abstract
Tamoxifen is widely used in breast cancer treatment and minimum steady-state concentrations of its active metabolite endoxifen (CSS,min ENDX) above 5.97 ng/mL have been associated with favourable disease outcome. Yet, about 20% of patients do not reach target CSS,min ENDX applying conventional tamoxifen dosing. Moreover, 4-75% of patients are non-adherent, resulting in worse disease outcomes. Assuming complete adherence, we previously showed model-informed precision dosing (MIPD) to be superior to conventional and CYP2D6-guided dosing in minimising the proportion of patients with subtarget CSS,min ENDX. Given the high non-adherence rate in long-term tamoxifen therapy, this study investigated the impact of non-adherence on CSS,min ENDX target attainment in different dosing strategies. We show that MIPD allows to account for the expected level of non-adherence (here: up to 2 missed doses/week): increasing the MIPD target threshold from 5.97 ng/mL to 9 ng/mL (the lowest reported CSS,min ENDX in CYP2D6 normal metabolisers) as a safeguard resulted in the lowest interindividual variability and proportion of patients with subtarget CSS,min ENDX even in non-adherent patients. This is a significant improvement to conventional and CYP2D6-guided dosing. Adding a fixed increment to the originally selected dose is not recommended, since it inflates interindividual variability.
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Affiliation(s)
- Anna Mueller-Schoell
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 14163 Berlin, Germany; (A.M.-S.); (L.K.-S.); (R.M.); (G.M.)
- Graduate Research Training Program PharMetrX, 12169 Berlin, Germany
| | - Lena Klopp-Schulze
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 14163 Berlin, Germany; (A.M.-S.); (L.K.-S.); (R.M.); (G.M.)
| | - Robin Michelet
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 14163 Berlin, Germany; (A.M.-S.); (L.K.-S.); (R.M.); (G.M.)
| | - Madelé van Dyk
- College of Medicine and Public Health, Flinders University, Adelaide, SA 5042, Australia;
| | - Thomas E. Mürdter
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, and University Tübingen, 70376 Tübingen, Germany;
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, 70376 Stuttgart, Germany;
- German Cancer Consortium (DKTK), Partner Site Tübingen, German Cancer Research, 69120 Heidelberg, Germany
- Departments of Clinical Pharmacology, Pharmacy and Biochemistry, University Tübingen, 72076 Tübingen, Germany
| | - Markus Joerger
- Department of Medical Oncology and Hematology, Cantonal Hospital, 9007 St. Gallen, Switzerland;
| | - Wilhelm Huisinga
- Institute of Mathematics, University of Potsdam, 14476 Potsdam, Germany;
| | - Gerd Mikus
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 14163 Berlin, Germany; (A.M.-S.); (L.K.-S.); (R.M.); (G.M.)
| | - Charlotte Kloft
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, 14163 Berlin, Germany; (A.M.-S.); (L.K.-S.); (R.M.); (G.M.)
- Correspondence:
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14
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Abdulla A, Edwina EE, Flint RB, Allegaert K, Wildschut ED, Koch BCP, de Hoog M. Model-Informed Precision Dosing of Antibiotics in Pediatric Patients: A Narrative Review. Front Pediatr 2021; 9:624639. [PMID: 33708753 PMCID: PMC7940353 DOI: 10.3389/fped.2021.624639] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 02/03/2021] [Indexed: 12/17/2022] Open
Abstract
Optimal pharmacotherapy in pediatric patients with suspected infections requires understanding and integration of relevant data on the antibiotic, bacterial pathogen, and patient characteristics. Because of age-related physiological maturation and non-maturational covariates (e.g., disease state, inflammation, organ failure, co-morbidity, co-medication and extracorporeal systems), antibiotic pharmacokinetics is highly variable in pediatric patients and difficult to predict without using population pharmacokinetics models. The intra- and inter-individual variability can result in under- or overexposure in a significant proportion of patients. Therapeutic drug monitoring typically covers assessment of pharmacokinetics and pharmacodynamics, and concurrent dose adaptation after initial standard dosing and drug concentration analysis. Model-informed precision dosing (MIPD) captures drug, disease, and patient characteristics in modeling approaches and can be used to perform Bayesian forecasting and dose optimization. Incorporating MIPD in the electronic patient record system brings pharmacometrics to the bedside of the patient, with the aim of a consisted and optimal drug exposure. In this narrative review, we evaluated studies assessing optimization of antibiotic pharmacotherapy using MIPD in pediatric populations. Four eligible studies involving amikacin and vancomycin were identified from 418 records. Key articles, independent of year of publication, were also selected to highlight important attributes of MIPD. Although very little research has been conducted until this moment, the available data on vancomycin indicate that MIPD is superior compared to conventional dosing strategies with respect to target attainment. The utility of MIPD in pediatrics needs to be further confirmed in frequently used antibiotic classes, particularly aminoglycosides and beta-lactams.
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Affiliation(s)
- Alan Abdulla
- Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Elma E Edwina
- Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Robert B Flint
- Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, Netherlands.,Division of Neonatology, Department of Pediatrics, Sophia Children's Hospital, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Karel Allegaert
- Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, Netherlands.,Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.,Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Enno D Wildschut
- Department of Pediatric Intensive Care, Sophia Children's Hospital, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Birgit C P Koch
- Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Matthijs de Hoog
- Department of Pediatric Intensive Care, Sophia Children's Hospital, Erasmus University Medical Center, Rotterdam, Netherlands
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15
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Slanař O, Hronová K, Bartošová O, Šíma M. Recent advances in the personalized treatment of estrogen receptor-positive breast cancer with tamoxifen: a focus on pharmacogenomics. Expert Opin Drug Metab Toxicol 2020; 17:307-321. [PMID: 33320718 DOI: 10.1080/17425255.2021.1865310] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Introduction: Tamoxifen is still an important drug in hormone-dependent breast cancer therapy. Personalization of its clinical use beyond hormone receptor positivity could improve the substantial variability of the treatment response.Areas covered: The overview of the current evidence for the treatment personalization using therapeutic drug monitoring, or using genetic biomarkers including CYP2D6 is provided. Although many studies focused on the PK aspects or the impact of CYP2D6 variability the translation into clinical routine is not clearly defined due to the inconsistent clinical outcome data.Expert opinion: We believe that at least the main candidate factors, i.e. CYP2D6 polymorphism, CYP2D6 inhibition, endoxifen serum levels may become important predictors of clinical relevance for tamoxifen treatment personalization in the future. To achieve this aim, however, further research should take into consideration more precise characterization of the disease, epigenetic factors and also utilize an appropriately powered multifactorial approach instead of a single gene evaluating studies.
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Affiliation(s)
- Ondřej Slanař
- Department of Pharmacology, Charles University and General University Hospital, Prague, Czech Republic
| | - Karolína Hronová
- Department of Pharmacology, Charles University and General University Hospital, Prague, Czech Republic
| | - Olga Bartošová
- Department of Pharmacology, Charles University and General University Hospital, Prague, Czech Republic
| | - Martin Šíma
- Department of Pharmacology, Charles University and General University Hospital, Prague, Czech Republic
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16
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Puszkiel A, Arellano C, Vachoux C, Evrard A, Le Morvan V, Boyer JC, Robert J, Delmas C, Dalenc F, Debled M, Venat-Bouvet L, Jacot W, Dohollou N, Bernard-Marty C, Laharie-Mineur H, Filleron T, Roché H, Chatelut E, Thomas F, White-Koning M. Model-Based Quantification of Impact of Genetic Polymorphisms and Co-Medications on Pharmacokinetics of Tamoxifen and Six Metabolites in Breast Cancer. Clin Pharmacol Ther 2020; 109:1244-1255. [PMID: 33047329 DOI: 10.1002/cpt.2077] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/04/2020] [Indexed: 12/21/2022]
Abstract
Variations in clinical response to tamoxifen (TAM) may be related to polymorphic cytochromes P450 (CYPs) involved in forming its active metabolite endoxifen (ENDO). We developed a population pharmacokinetic (PopPK) model for tamoxifen and six metabolites to determine clinically relevant factors of ENDO exposure. Concentration-time data for TAM and 6 metabolites come from a prospective, multicenter, 3-year follow-up study of adjuvant TAM (20 mg/day) in patients with breast cancer, with plasma samples drawn every 6 months, and genotypes for 63 genetic polymorphisms (PHACS study, NCT01127295). Concentration data for TAM and 6 metabolites from 928 patients (n = 27,433 concentrations) were analyzed simultaneously with a 7-compartment PopPK model. CYP2D6 phenotype (poor metabolizer (PM), intermediate metabolizer (IM), normal metabolizer (NM), and ultra-rapid metabolizer (UM)), CYP3A4*22, CYP2C19*2, and CYP2B6*6 genotypes, concomitant CYP2D6 inhibitors, age, and body weight had a significant impact on TAM metabolism. Formation of ENDO from N-desmethyltamoxifen was decreased by 84% (relative standard error (RSE) = 14%) in PM patients and by 47% (RSE = 9%) in IM patients and increased in UM patients by 27% (RSE = 12%) compared with NM patients. Dose-adjustment simulations support an increase from 20 mg/day to 40 and 80 mg/day in IM patients and PM patients, respectively, to reach ENDO levels similar to those in NM patients. However, when considering Antiestrogenic Activity Score (AAS), a dose increase to 60 mg/day in PM patients seems sufficient. This PopPK model can be used as a tool to predict ENDO levels or AAS according to the patient's CYP2D6 phenotype for TAM dose adaptation.
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Affiliation(s)
- Alicja Puszkiel
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France
| | - Cécile Arellano
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France
| | - Christelle Vachoux
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France
| | - Alexandre Evrard
- Laboratoire de Biochimie et Biologie Moléculaire, Centre Hospitalier Universitaire Nîmes-Carémeau, Nîmes, France.,IRCM, Inserm, Université de Montpellier, ICM, Montpellier, France
| | - Valérie Le Morvan
- Inserm U1218, Université de Bordeaux, Bordeaux, France.,Institut Bergonié, Bordeaux, France
| | - Jean-Christophe Boyer
- Laboratoire de Biochimie et Biologie Moléculaire, Centre Hospitalier Universitaire Nîmes-Carémeau, Nîmes, France
| | - Jacques Robert
- Inserm U1218, Université de Bordeaux, Bordeaux, France.,Institut Bergonié, Bordeaux, France
| | - Caroline Delmas
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France.,Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
| | - Florence Dalenc
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France.,Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
| | | | | | - William Jacot
- Institut du Cancer de Montpellier, Montpellier, France
| | | | | | | | - Thomas Filleron
- Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
| | - Henri Roché
- Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
| | - Etienne Chatelut
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France.,Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
| | - Fabienne Thomas
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France.,Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
| | - Melanie White-Koning
- Cancer Research Center of Toulouse (CRCT), Inserm U1037, Université Paul Sabatier, Toulouse, France
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Kluwe F, Michelet R, Mueller‐Schoell A, Maier C, Klopp‐Schulze L, Dyk M, Mikus G, Huisinga W, Kloft C. Perspectives on Model‐Informed Precision Dosing in the Digital Health Era: Challenges, Opportunities, and Recommendations. Clin Pharmacol Ther 2020; 109:29-36. [DOI: 10.1002/cpt.2049] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/09/2020] [Indexed: 12/20/2022]
Affiliation(s)
- Franziska Kluwe
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy Freie Universität Berlin Berlin Germany
- Graduate Research Training Program PharMetrX Freie Universität Berlin and Universitaet Potsdam Berlin Germany
| | - Robin Michelet
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy Freie Universität Berlin Berlin Germany
| | - Anna Mueller‐Schoell
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy Freie Universität Berlin Berlin Germany
- Graduate Research Training Program PharMetrX Freie Universität Berlin and Universitaet Potsdam Berlin Germany
| | - Corinna Maier
- Graduate Research Training Program PharMetrX Freie Universität Berlin and Universitaet Potsdam Berlin Germany
- Institute of Mathematics Universität Potsdam Potsdam Germany
| | - Lena Klopp‐Schulze
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy Freie Universität Berlin Berlin Germany
- Graduate Research Training Program PharMetrX Freie Universität Berlin and Universitaet Potsdam Berlin Germany
| | - Madelé Dyk
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health Flinders University Adelaide Australia
| | - Gerd Mikus
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy Freie Universität Berlin Berlin Germany
- Department of Clinical Pharmacology and Pharmacoepidemiology University Hospital Heidelberg Heidelberg Germany
| | | | - Charlotte Kloft
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy Freie Universität Berlin Berlin Germany
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18
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Mueller-Schoell A, Klopp-Schulze L, Schroth W, Mürdter T, Michelet R, Brauch H, Huisinga W, Joerger M, Neven P, Koolen SLW, Mathijssen RHJ, Copson E, Eccles D, Chen S, Chowbay B, Tfayli A, Zgheib NK, Schwab M, Kloft C. Obesity Alters Endoxifen Plasma Levels in Young Breast Cancer Patients: A Pharmacometric Simulation Approach. Clin Pharmacol Ther 2020; 108:661-670. [PMID: 32578187 DOI: 10.1002/cpt.1960] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 05/29/2020] [Indexed: 01/03/2023]
Abstract
Endoxifen is one of the most important metabolites of the prodrug tamoxifen. High interindividual variability in endoxifen steady-state concentrations (CSS,min ENDX ) is observed under tamoxifen standard dosing and patients with breast cancer who do not reach endoxifen concentrations above a proposed therapeutic threshold of 5.97 ng/mL may be at a 26% higher recurrence risk compared with patients with endoxifen concentrations exceeding this value. In this investigation, 10 clinical tamoxifen studies were pooled (1,388 patients) to investigate influential factors on CSS,min ENDX using nonlinear mixed-effects modeling. Age and body weight were found to significantly impact CSS,min ENDX in addition to CYP2D6 phenotype. Compared with postmenopausal patients, premenopausal patients had a 30% higher risk for subtarget CSS,min ENDX at tamoxifen 20 mg per day. In treatment simulations for distinct patient subpopulations, young overweight patients had a 3.1-13.8-fold higher risk for subtarget CSS,min ENDX compared with elderly low-weight patients. Considering ever-rising obesity rates and the clinical importance of tamoxifen for premenopausal patients, this subpopulation may benefit most from individualized tamoxifen dosing.
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Affiliation(s)
- Anna Mueller-Schoell
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
- Graduate Research Training Program PharMetrX, Berlin/Potsdam, Germany
| | - Lena Klopp-Schulze
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
| | - Werner Schroth
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
- University of Tübingen, Tübingen, Germany
| | - Thomas Mürdter
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
- University of Tübingen, Tübingen, Germany
| | - Robin Michelet
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
| | - Hiltrud Brauch
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
- University of Tübingen, Tübingen, Germany
- German Cancer Consortium (DKTK) and of German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Wilhelm Huisinga
- Institute of Mathematics, University of Potsdam, Potsdam, Germany
| | - Markus Joerger
- Department of Medical Oncology and Haematology, Cantonal Hospital, St. Gallen, Switzerland
| | - Patrick Neven
- Vesalius Research Center - VIB, University Hospitals Leuven, KU Leuven-University of Leuven, Leuven, Belgium
| | - Stijn L W Koolen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands
| | - Ron H J Mathijssen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands
| | - Ellen Copson
- Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton, Southampton, UK
- University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Diana Eccles
- Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton, Southampton, UK
- University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Sylvia Chen
- Clinical Pharmacology Laboratory, Division of Cellular & Molecular Research, Humphrey Oei Institute of Cancer Research, National Cancer Centre Singapore, Singapore
| | - Balram Chowbay
- Clinical Pharmacology Laboratory, Division of Cellular & Molecular Research, Humphrey Oei Institute of Cancer Research, National Cancer Centre Singapore, Singapore
- Center for Clinician-Scientist Development, Duke-NUS Medical School, Singapore
- SingHealth Clinical Pharmacology, SingHealth, Singapore
| | - Arafat Tfayli
- Hematology-Oncology Division, Department of Internal Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Nathalie K Zgheib
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
- German Cancer Consortium (DKTK) and of German Cancer Research Center (DKFZ), Heidelberg, Germany
- Departments of Clinical Pharmacology, Pharmacy and Biochemistry, University Tübingen, Tübingen, Germany
| | - Charlotte Kloft
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Freie Universitaet Berlin, Berlin, Germany
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