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Mbavha BT, Thelingwani RS, Chikwambi Z, Nyakabau AM, Masimirembwa C. Pharmacogenetics and pharmacokinetics of tamoxifen in a Zimbabwean breast cancer cohort. Br J Clin Pharmacol 2023; 89:3209-3216. [PMID: 37337448 PMCID: PMC10529681 DOI: 10.1111/bcp.15827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/21/2023] Open
Abstract
Tamoxifen is the most used hormonal therapy for oestrogen receptor-positive breast cancer. CYP2D6 is the main enzyme in the metabolic pathway of tamoxifen to endoxifen. Variations in endoxifen plasma concentrations are associated with CYP2D6 polymorphisms. This study aimed to determine the association between the CYP2D6 polymorphisms and endoxifen plasma concentrations in a cohort of Zimbabwean breast cancer patients (n = 40). TaqMan genotyping and copy number assays were done to determine CYP2D6 genotypes. Tamoxifen and metabolites were quantitated using LC-MS/MS. The population had high frequencies of the CYP2D6 reduced function alleles, *17 (15%) and *29 (18%). The median endoxifen concentration was 4.78 ng/mL, and in 55% of the patients, mostly intermediate metabolizers were below the endoxifen therapeutic threshold of 5.97 ng/mL. The CYP2D6 phenotypes and activity scores were significantly associated with endoxifen plasma concentrations (P = 0.0151) and with endoxifen to N-desmethyl-tamoxifen ratios (P = 0.0006).
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Affiliation(s)
- Bianza Tinotenda Mbavha
- Department of Genomic Medicine, African Institute of Biomedical Science and Technology (AiBST), 911 Boronia Township, Beatrice, Zimbabwe
- Department of Biotechnology, Chinhoyi University of Technology, Private Bag 7724, Chinhoyi, Zimbabwe
| | - Roslyn Stella Thelingwani
- Department of Genomic Medicine, African Institute of Biomedical Science and Technology (AiBST), 911 Boronia Township, Beatrice, Zimbabwe
| | - Zedias Chikwambi
- Department of Genomic Medicine, African Institute of Biomedical Science and Technology (AiBST), 911 Boronia Township, Beatrice, Zimbabwe
- Department of Biotechnology, Chinhoyi University of Technology, Private Bag 7724, Chinhoyi, Zimbabwe
| | - Anna Mary Nyakabau
- Parirenyatwa Hospital Radiotherapy and Oncology Center, Harare, Zimbabwe
| | - Collen Masimirembwa
- Department of Genomic Medicine, African Institute of Biomedical Science and Technology (AiBST), 911 Boronia Township, Beatrice, Zimbabwe
- Sydney Brenner Institute for Molecular Bioscience (SBIMB), University of the Witwatersrand, Johannesburg 2000, South Africa
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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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Mulder TAM, de With M, del Re M, Danesi R, Mathijssen RHJ, van Schaik RHN. Clinical CYP2D6 Genotyping to Personalize Adjuvant Tamoxifen Treatment in ER-Positive Breast Cancer Patients: Current Status of a Controversy. Cancers (Basel) 2021; 13:cancers13040771. [PMID: 33673305 PMCID: PMC7917604 DOI: 10.3390/cancers13040771] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 02/07/2023] Open
Abstract
Simple Summary Tamoxifen is an important adjuvant endocrine therapy in estrogen receptor (ER)-positive breast cancer patients. It is mainly catalyzed by the enzyme CYP2D6 into the most active metabolite endoxifen. Genetic variation in the CYP2D6 gene influences endoxifen formation and thereby potentially therapy outcome. However, the association between CYP2D6 genotype and clinical outcome on tamoxifen is still under debate, as contradictory outcomes have been published. This review describes the latest insights in both CYP2D6 genotype and endoxifen concentrations, as well CYP2D6 genotype and clinical outcome, from 2018 to 2020. Abstract Tamoxifen is a major option for adjuvant endocrine treatment in estrogen receptor (ER) positive breast cancer patients. The conversion of the prodrug tamoxifen into the most active metabolite endoxifen is mainly catalyzed by the enzyme cytochrome P450 2D6 (CYP2D6). Genetic variation in the CYP2D6 gene leads to altered enzyme activity, which influences endoxifen formation and thereby potentially therapy outcome. The association between genetically compromised CYP2D6 activity and low endoxifen plasma concentrations is generally accepted, and it was shown that tamoxifen dose increments in compromised patients resulted in higher endoxifen concentrations. However, the correlation between CYP2D6 genotype and clinical outcome is still under debate. This has led to genotype-based tamoxifen dosing recommendations by the Clinical Pharmacogenetic Implementation Consortium (CPIC) in 2018, whereas in 2019, the European Society of Medical Oncology (ESMO) discouraged the use of CYP2D6 genotyping in clinical practice for tamoxifen therapy. This paper describes the latest developments on CYP2D6 genotyping in relation to endoxifen plasma concentrations and tamoxifen-related clinical outcome. Therefore, we focused on Pharmacogenetic publications from 2018 (CPIC publication) to 2021 in order to shed a light on the current status of this debate.
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Affiliation(s)
- Tessa A. M. Mulder
- Department of Clinical Chemistry, Erasmus MC University Hospital, Wytemaweg 80, 3015CN Rotterdam, The Netherlands; (T.A.M.M.); (M.d.W.); (M.d.R.); (R.D.)
| | - Mirjam de With
- Department of Clinical Chemistry, Erasmus MC University Hospital, Wytemaweg 80, 3015CN Rotterdam, The Netherlands; (T.A.M.M.); (M.d.W.); (M.d.R.); (R.D.)
- Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus MC, Wytemaweg 80, 3015CN Rotterdam, The Netherlands;
| | - Marzia del Re
- Department of Clinical Chemistry, Erasmus MC University Hospital, Wytemaweg 80, 3015CN Rotterdam, The Netherlands; (T.A.M.M.); (M.d.W.); (M.d.R.); (R.D.)
- Clinical Pharmacology and Pharmacogenetics Unit, Department of Clinical and Experimental Medicine, University of Pisa, 55, Via Roma, 56126 Pisa, Italy
| | - Romano Danesi
- Department of Clinical Chemistry, Erasmus MC University Hospital, Wytemaweg 80, 3015CN Rotterdam, The Netherlands; (T.A.M.M.); (M.d.W.); (M.d.R.); (R.D.)
- Clinical Pharmacology and Pharmacogenetics Unit, Department of Clinical and Experimental Medicine, University of Pisa, 55, Via Roma, 56126 Pisa, Italy
| | - Ron H. J. Mathijssen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus MC, Wytemaweg 80, 3015CN Rotterdam, The Netherlands;
| | - Ron H. N. van Schaik
- Department of Clinical Chemistry, Erasmus MC University Hospital, Wytemaweg 80, 3015CN Rotterdam, The Netherlands; (T.A.M.M.); (M.d.W.); (M.d.R.); (R.D.)
- Correspondence: ; Tel.: +31-10-703-3119
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