Implementation of model-informed precision dosing for tamoxifen therapy in patients with breast cancer: A prospective intervention study

Tamoxifen is an estrogen-receptor (ER) antagonist, used as adjuvant treatment of ER-positive breast cancer. It is converted by CYP2D6 into endoxifen, its most active metabolite. Patients with endoxifen plasma concentrations <16 nM face a higher risk of recurrence. The use of a priori model-inform...

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Main Authors: Ruben Y.M. van Nijnatten, Sanne M. Buijs, Bram C. Agema, Raphaël M.J. Fischer, Inge Ghobadi Moghaddam-Helmantel, Caroline M.E. Contant, Felix E. de Jongh, Auke M.T. Huijben, Manon Kop, Annemieke van der Padt-Pruijsten, Hanneke J.M. Zuetenhorst, Ron H.N. van Schaik, Birgit C.P. Koch, A. Jager, Stijn L.W. Koolen, Ron H.J. Mathijssen
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Language:English
Published: Elsevier 2025-02-01
Series:Breast
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Online Access:http://www.sciencedirect.com/science/article/pii/S0960977625000098
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author Ruben Y.M. van Nijnatten
Sanne M. Buijs
Bram C. Agema
Raphaël M.J. Fischer
Inge Ghobadi Moghaddam-Helmantel
Caroline M.E. Contant
Felix E. de Jongh
Auke M.T. Huijben
Manon Kop
Annemieke van der Padt-Pruijsten
Hanneke J.M. Zuetenhorst
Ron H.N. van Schaik
Birgit C.P. Koch
A. Jager
Stijn L.W. Koolen
Ron H.J. Mathijssen
author_facet Ruben Y.M. van Nijnatten
Sanne M. Buijs
Bram C. Agema
Raphaël M.J. Fischer
Inge Ghobadi Moghaddam-Helmantel
Caroline M.E. Contant
Felix E. de Jongh
Auke M.T. Huijben
Manon Kop
Annemieke van der Padt-Pruijsten
Hanneke J.M. Zuetenhorst
Ron H.N. van Schaik
Birgit C.P. Koch
A. Jager
Stijn L.W. Koolen
Ron H.J. Mathijssen
author_sort Ruben Y.M. van Nijnatten
collection DOAJ
description Tamoxifen is an estrogen-receptor (ER) antagonist, used as adjuvant treatment of ER-positive breast cancer. It is converted by CYP2D6 into endoxifen, its most active metabolite. Patients with endoxifen plasma concentrations <16 nM face a higher risk of recurrence. The use of a priori model-informed precision dosing (MIPD) may lead to faster target attainment and thus potentially improve patient outcomes.In total, 106 evaluable patients were prospectively included in this single-arm MIPD-intervention study. Patients received a model-predicted tamoxifen dose when starting tamoxifen-treatment (65.1 % of patients received 20 mg, 16.0 % received 30 mg and 18.9 % received 40 mg). Seventy-five percent of the 40 mg group was predicted to be unable to reach the threshold of 16 nM despite receiving the highest registered dose. After attaining steady-state, 84.0 % of patients reached endoxifen levels ≥16 nM, which was not significantly higher compared to a historical control cohort (77.9 %, p = 0.17). The model showed adequate performance and correctly identified patients requiring 40 mg tamoxifen. Endoxifen samples that were acquired 4–6 weeks after treatment initiation, are informative of steady-state endoxifen levels and can be used to inform MIPD and adjust tamoxifen dosing prior to steady-state attainment.In this first MIPD implementation study for patients treated with tamoxifen, MIPD did lead to more patients achieving endoxifen levels ≥16 nM as compared to the one-dose-fits-all strategy, albeit insignificant. This may partly be explained by a larger proportion of patients who were recommended to switch to an aromatase inhibitor (AI) in the intervention cohort. In conclusion, MIPD seems beneficial compared to one-size-fits-all-dosing, but TDM still remains an important addition.
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spelling doaj-art-bfcbbf555cb04ef1911b16aa0beb95a32025-02-12T05:30:40ZengElsevierBreast1532-30802025-02-0179103880Implementation of model-informed precision dosing for tamoxifen therapy in patients with breast cancer: A prospective intervention studyRuben Y.M. van Nijnatten0Sanne M. Buijs1Bram C. Agema2Raphaël M.J. Fischer3Inge Ghobadi Moghaddam-Helmantel4Caroline M.E. Contant5Felix E. de Jongh6Auke M.T. Huijben7Manon Kop8Annemieke van der Padt-Pruijsten9Hanneke J.M. Zuetenhorst10Ron H.N. van Schaik11Birgit C.P. Koch12A. Jager13Stijn L.W. Koolen14Ron H.J. Mathijssen15Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the NetherlandsDepartment of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands; Corresponding author. Department of Medical Oncology, Erasmus MC Cancer Institute Dr. Molewaterplein 40, PO Box 2040, CN, 3015, the Netherlands.Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the NetherlandsDepartment of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the NetherlandsDepartment of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the NetherlandsDepartment of Surgery, Maasstad Hospital, Rotterdam, the NetherlandsDepartment of Internal Medicine, Breast Cancer Center South Holland South, Ikazia Hospital, Rotterdam, the NetherlandsDepartment of Internal Medicine, Breast Cancer Center South Holland South, Maasstad Hospital, Rotterdam, the NetherlandsDepartment of Internal Medicine, IJsselland Hospital, Capelle aan den IJssel, the NetherlandsDepartment of Internal Medicine, Breast Cancer Center South Holland South, Spijkenisse Medical Center, Spijkenisse, the NetherlandsDepartment of Internal Medicine, Franciscus Gasthuis &amp; Vlietland, Schiedam, the NetherlandsDepartment of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, the NetherlandsDepartment of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, the NetherlandsDepartment of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the NetherlandsDepartment of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands; Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, the NetherlandsDepartment of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the NetherlandsTamoxifen is an estrogen-receptor (ER) antagonist, used as adjuvant treatment of ER-positive breast cancer. It is converted by CYP2D6 into endoxifen, its most active metabolite. Patients with endoxifen plasma concentrations <16 nM face a higher risk of recurrence. The use of a priori model-informed precision dosing (MIPD) may lead to faster target attainment and thus potentially improve patient outcomes.In total, 106 evaluable patients were prospectively included in this single-arm MIPD-intervention study. Patients received a model-predicted tamoxifen dose when starting tamoxifen-treatment (65.1 % of patients received 20 mg, 16.0 % received 30 mg and 18.9 % received 40 mg). Seventy-five percent of the 40 mg group was predicted to be unable to reach the threshold of 16 nM despite receiving the highest registered dose. After attaining steady-state, 84.0 % of patients reached endoxifen levels ≥16 nM, which was not significantly higher compared to a historical control cohort (77.9 %, p = 0.17). The model showed adequate performance and correctly identified patients requiring 40 mg tamoxifen. Endoxifen samples that were acquired 4–6 weeks after treatment initiation, are informative of steady-state endoxifen levels and can be used to inform MIPD and adjust tamoxifen dosing prior to steady-state attainment.In this first MIPD implementation study for patients treated with tamoxifen, MIPD did lead to more patients achieving endoxifen levels ≥16 nM as compared to the one-dose-fits-all strategy, albeit insignificant. This may partly be explained by a larger proportion of patients who were recommended to switch to an aromatase inhibitor (AI) in the intervention cohort. In conclusion, MIPD seems beneficial compared to one-size-fits-all-dosing, but TDM still remains an important addition.http://www.sciencedirect.com/science/article/pii/S0960977625000098Breast cancerEstrogen receptor positiveHormone therapyTamoxifenEndoxifenModel informed precision dosing
spellingShingle Ruben Y.M. van Nijnatten
Sanne M. Buijs
Bram C. Agema
Raphaël M.J. Fischer
Inge Ghobadi Moghaddam-Helmantel
Caroline M.E. Contant
Felix E. de Jongh
Auke M.T. Huijben
Manon Kop
Annemieke van der Padt-Pruijsten
Hanneke J.M. Zuetenhorst
Ron H.N. van Schaik
Birgit C.P. Koch
A. Jager
Stijn L.W. Koolen
Ron H.J. Mathijssen
Implementation of model-informed precision dosing for tamoxifen therapy in patients with breast cancer: A prospective intervention study
Breast
Breast cancer
Estrogen receptor positive
Hormone therapy
Tamoxifen
Endoxifen
Model informed precision dosing
title Implementation of model-informed precision dosing for tamoxifen therapy in patients with breast cancer: A prospective intervention study
title_full Implementation of model-informed precision dosing for tamoxifen therapy in patients with breast cancer: A prospective intervention study
title_fullStr Implementation of model-informed precision dosing for tamoxifen therapy in patients with breast cancer: A prospective intervention study
title_full_unstemmed Implementation of model-informed precision dosing for tamoxifen therapy in patients with breast cancer: A prospective intervention study
title_short Implementation of model-informed precision dosing for tamoxifen therapy in patients with breast cancer: A prospective intervention study
title_sort implementation of model informed precision dosing for tamoxifen therapy in patients with breast cancer a prospective intervention study
topic Breast cancer
Estrogen receptor positive
Hormone therapy
Tamoxifen
Endoxifen
Model informed precision dosing
url http://www.sciencedirect.com/science/article/pii/S0960977625000098
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