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Buijs SM, van Dorst DCH, Kruip MJHA, van den Akker RFP, Cheung KL, Porrazzo R, Oomen-de Hoop E, Jager A, Koolen SLW, Versmissen J, Jan Danser AH, Versteeg HH, Bos MHA, Mathijssen RHJ. The interplay between tamoxifen and endoxifen plasma concentrations and coagulation parameters in patients with primary breast cancer. Biomed Pharmacother 2024; 170:115969. [PMID: 38042112 DOI: 10.1016/j.biopha.2023.115969] [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] [Received: 08/29/2023] [Revised: 11/17/2023] [Accepted: 11/27/2023] [Indexed: 12/04/2023] Open
Abstract
BACKGROUND Tamoxifen is an effective treatment for primary breast cancer but increases the risk for venous thromboembolism. Tamoxifen decreases anticoagulant proteins, including antithrombin (AT), protein C (PC) and tissue factor (TF) pathway inhibitor, and enhances thrombin generation (TG). However, the relation between plasma concentrations of both tamoxifen and its active metabolite endoxifen and coagulation remains unknown. METHODS Tamoxifen and endoxifen were measured in 141 patients from the prospective open-label intervention TOTAM-study after 3 months (m) and 6 m of tamoxifen treatment. Levels of AT and PC, the procoagulant TF, and TG parameters were determined at both timepoints if samples were available (n = 53-135 per analysis). Levels of coagulation proteins and TG parameters were correlated and compared between: 1) quartiles of tamoxifen and endoxifen levels, and 2) 3 m and 6 m of treatment. RESULTS At 3 m, levels of AT, PC, TF and TG parameters were not associated with tamoxifen nor endoxifen levels. At 6 m, median TF levels were lower in patients in the 3rd (56.6 [33] pg/mL), and 4th (50.1 [19] pg/mL) endoxifen quartiles compared to the 1st (lowest) quartile (76 [69] pg/mL) (P=0.027 and P=0.018, respectively), but no differences in anticoagulant proteins or TG parameters were observed. An increase in circulating TF levels (3 m: 46.0 [15] versus 6 m: 54.4 [39] pg/mL, P < 0.001) and TG parameters was observed at the 6 m treatment timepoint, while AT and PC levels remained stable. CONCLUSIONS Our results indicate that higher tamoxifen and endoxifen levels are not correlated with an increased procoagulant state, suggesting tamoxifen dose escalation does not further promote hypercoagulability.
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Affiliation(s)
- Sanne M Buijs
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
| | - Daan C H van Dorst
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands; Department of Internal Medicine, Division of Pharmacology and Vascular Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Marieke J H A Kruip
- Department of Hematology, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Rob F P van den Akker
- Department of Internal Medicine, Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Ka L Cheung
- Department of Internal Medicine, Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Robert Porrazzo
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
| | - Esther Oomen-de Hoop
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
| | - Agnes Jager
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
| | - Stijn L W Koolen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands; Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Jorie Versmissen
- Department of Internal Medicine, Division of Pharmacology and Vascular Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Hospital Pharmacy, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - A H Jan Danser
- Department of Internal Medicine, Division of Pharmacology and Vascular Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Henri H Versteeg
- Department of Internal Medicine, Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Mettine H A Bos
- Department of Internal Medicine, Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Ron H J Mathijssen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
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2
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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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3
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Souwer ETD, Sanchez-Spitman A, Moes DJAR, Gelderblom H, Swen JJ, Portielje JEA, Guchelaar HJ, van Gelder T. Tamoxifen pharmacokinetics and pharmacodynamics in older patients with non-metastatic breast cancer. Breast Cancer Res Treat 2023; 199:471-478. [PMID: 37067610 PMCID: PMC10175413 DOI: 10.1007/s10549-023-06925-z] [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: 12/12/2022] [Accepted: 03/16/2023] [Indexed: 04/18/2023]
Abstract
BACKGROUND We aimed to study the pharmacokinetics and -dynamics of tamoxifen in older women with non-metastatic breast cancer. METHODS Data for this analysis were derived from the CYPTAM study (NTR1509) database. Patients were stratified by age (age groups < 65 and 65 and older). Steady-state trough concentrations were measured of tamoxifen, N-desmethyltamoxifen, 4-hydroxy-tamoxifen, and endoxifen. CYP2D6 and CYP3A4 phenotypes were assessed for all patients by genotyping. Multiple linear regression models were used to analyze tamoxifen and endoxifen variability. Outcome data included recurrence-free survival at time of tamoxifen discontinuation (RFSt) and overall survival (OS). RESULTS 668 patients were included, 141 (21%) were 65 and older. Demographics and treatment duration were similar across age groups. Older patients had significantly higher concentrations of tamoxifen 129.4 ng/ml (SD 53.7) versus 112.2 ng/ml (SD 42.0) and endoxifen 12.1 ng/ml (SD 6.6) versus 10.7 ng/ml (SD 5.7, p all < 0.05), independently of CYP2D6 and CYP3A4 gene polymorphisms. Age independently explained 5% of the variability of tamoxifen (b = 0.95, p < 0.001, R2 = 0.051) and 0.1% of the variability in endoxifen concentrations (b = 0.45, p = 0.12, R2 = 0.007). Older patients had worse RFSt (5.8 versus 7.3 years, p = 0.01) and worse OS (7.8 years versus 8.7 years, p = 0.01). This was not related to differences in endoxifen concentration (HR 1.0, 95% CI 0.96-1.04, p = 0.84) or CYP polymorphisms. CONCLUSION Serum concentrations of tamoxifen and its demethylated metabolites are higher in older patients, independent of CYP2D6 or CYP3A4 gene polymorphisms. A higher bioavailability of tamoxifen in older patients may explain the observed differences. However, clinical relevance of these findings is limited and should not lead to a different tamoxifen dose in older patients.
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Affiliation(s)
- E T D Souwer
- Department of Medical Oncology, Leiden University Medical Center, Albinusdreef 2, P.O. Box 9600, 2300 RC, Leiden, The Netherlands.
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands.
| | - A Sanchez-Spitman
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - D J A R Moes
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - H Gelderblom
- Department of Medical Oncology, Leiden University Medical Center, Albinusdreef 2, P.O. Box 9600, 2300 RC, Leiden, The Netherlands
| | - J J Swen
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - J E A Portielje
- Department of Medical Oncology, Leiden University Medical Center, Albinusdreef 2, P.O. Box 9600, 2300 RC, Leiden, The Netherlands
| | - H J Guchelaar
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - T van Gelder
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
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4
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Sanchez-Spitman A, Guchelaar HJ. Personalizing tamoxifen therapy in adjuvant therapy: a brief summary of the ongoing discussion. Expert Rev Clin Pharmacol 2023; 16:93-95. [PMID: 36461813 DOI: 10.1080/17512433.2023.2154652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Affiliation(s)
- Anabel Sanchez-Spitman
- Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - Henk-Jan Guchelaar
- Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, The Netherlands
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Pharmacokinetics of Tamoxifen and Its Major Metabolites and the Effect of the African Ancestry Specific CYP2D6*17 Variant on the Formation of the Active Metabolite, Endoxifen. J Pers Med 2023; 13:jpm13020272. [PMID: 36836506 PMCID: PMC9961245 DOI: 10.3390/jpm13020272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/13/2023] [Accepted: 01/25/2023] [Indexed: 02/05/2023] Open
Abstract
Tamoxifen (TAM) is widely used in the treatment of hormone receptor-positive breast cancer. TAM is metabolized into the active secondary metabolite endoxifen (ENDO), primarily by CYP2D6. We aimed to investigate the effects of an African-specific CYP2D6 variant allele, CYP2D6*17, on the pharmacokinetics (PK) of TAM and its active metabolites in 42 healthy black Zimbabweans. Subjects were grouped based on CYP2D6 genotypes as CYP2D6*1/*1 or *1/*2 or *2/*2 (CYP2D6*1 or *2), CYP2D6*1/*17 or 2*/*17, and CYP2D6*17/*17. PK parameters for TAM and three metabolites were determined. The pharmacokinetics of ENDO showed statistically significant differences among the three groups. The mean ENDO AUC0-∞ in CYP2D6*17/*17 subjects was 452.01 (196.94) h·*ng/mL, and the AUC0-∞ in CYP2D6*1/*17 subjects was 889.74 h·ng/mL, which was 5-fold and 2.8-fold lower than in CYP2D6*1 or *2 subjects, respectively. Individuals who were heterozygous or homozygous for CYP2D6*17 alleles showed a 2- and 5-fold decrease in Cmax, respectively, compared to the CYP2D6*1 or *2 genotype. CYP2D6*17 gene carriers have significantly lower ENDO exposure levels than CYP2D6*1 or *2 gene carriers. Pharmacokinetic parameters of TAM and the two primary metabolites, N-desmethyl tamoxifen (NDT) and 4-hydroxy tamoxifen (4OHT), did not show any significant difference in the three genotype groups. The African-specific CYP2D6*17 variant had effects on ENDO exposure levels that could potentially have clinical implications for patients homozygous for this variant.
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6
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Braal CL, Kleijburg A, Jager A, Koolen SLW, Mathijssen RHJ, Corro Ramos I, Wetzelaer P, Uyl-de Groot CA. Therapeutic Drug Monitoring-Guided Adjuvant Tamoxifen Dosing in Patients with Early Breast Cancer: A Cost-Effectiveness Analysis from the Prospective TOTAM Trial. Clin Drug Investig 2022; 42:163-175. [PMID: 35020170 PMCID: PMC8844136 DOI: 10.1007/s40261-021-01114-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2021] [Indexed: 11/24/2022]
Abstract
Background and Objectives Endoxifen is the active metabolite of tamoxifen, and a minimal plasma concentration of 16 nM has been suggested as a threshold above which it is effective in reducing the risk of breast cancer recurrence. The aim of the current analysis was to investigate the cost-effectiveness of therapeutic drug monitoring (TDM)-guided tamoxifen dosing. Methods A cost-effectiveness analysis was performed from a Dutch healthcare perspective, using a partitioned survival model and a lifetime horizon. The reduction in subtherapeutic treatment following TDM is modelled as improved rates of recurrence-free survival (RFS) and overall survival (OS) in comparison to standard tamoxifen treatment. A probabilistic sensitivity analysis (PSA) and a series of scenario analyses were performed to assess the robustness of the results. Results Base-case results estimated a total increase in life years and quality-adjusted life years (QALYs) for TDM of 0.40 and 0.53, respectively. Total costs for TDM and standard tamoxifen treatment are €32,893 and €39,524, respectively. The TDM intervention results in both more QALYs and less healthcare costs, indicating a dominating effect for TDM. The PSA results indicate that the probability of TDM being cost-effective is 92% when using a willingness-to-pay threshold of €20,000. Conclusions TDM-guided dose optimization of tamoxifen is estimated to save costs and increase QALYs for early breast cancer patients.
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Affiliation(s)
- C Louwrens Braal
- Department of Medical Oncology, Erasmus University MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
| | - Anne Kleijburg
- Erasmus School of Health Policy and Management, Erasmus University Rotterdam, Rotterdam, The Netherlands.,CAPHRI School of Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands.,Centre of Economic Evaluation and Machine Learning, Trimbos Institute, Netherlands Institute of Mental Health and Addiction, Utrecht, The Netherlands
| | - Agnes Jager
- Department of Medical Oncology, Erasmus University MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Stijn L W Koolen
- Department of Medical Oncology, Erasmus University 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
| | - Ron H J Mathijssen
- Department of Medical Oncology, Erasmus University MC Cancer Institute, Dr. Molewaterplein 40, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Isaac Corro Ramos
- Institute for Medical Technology Assessment, Erasmus University Rotterdam, Rotterdam, The Netherlands
| | - Pim Wetzelaer
- Erasmus School of Health Policy and Management, Erasmus University Rotterdam, Rotterdam, The Netherlands
| | - Carin A Uyl-de Groot
- Erasmus School of Health Policy and Management, Erasmus University Rotterdam, Rotterdam, The Netherlands.,Institute for Medical Technology Assessment, Erasmus University Rotterdam, Rotterdam, The Netherlands
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7
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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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8
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van der Lee M, Allard WG, Vossen RHAM, Baak-Pablo RF, Menafra R, Deiman BALM, Deenen MJ, Neven P, Johansson I, Gastaldello S, Ingelman-Sundberg M, Guchelaar HJ, Swen JJ, Anvar SY. Toward predicting CYP2D6-mediated variable drug response from CYP2D6 gene sequencing data. Sci Transl Med 2021; 13:13/603/eabf3637. [PMID: 34290055 DOI: 10.1126/scitranslmed.abf3637] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 01/11/2021] [Accepted: 06/14/2021] [Indexed: 12/14/2022]
Abstract
Pharmacogenomics is a key component of personalized medicine that promises safer and more effective drug treatment by individualizing drug choice and dose based on genetic profiles. In clinical practice, genetic biomarkers are used to categorize patients into *-alleles to predict CYP450 enzyme activity and adjust drug dosages accordingly. However, this approach leaves a large part of variability in drug response unexplained. Here, we present a proof-of-concept approach that uses continuous-scale (instead of categorical) assignments to predict enzyme activity. We used full CYP2D6 gene sequences obtained with long-read amplicon-based sequencing and cytochrome P450 (CYP) 2D6-mediated tamoxifen metabolism data from a prospective study of 561 patients with breast cancer to train a neural network. The model explained 79% of interindividual variability in CYP2D6 activity compared to 54% with the conventional *-allele approach, assigned enzyme activities to known alleles with previously reported effects, and predicted the activity of previously uncharacterized combinations of variants. The results were replicated in an independent cohort of tamoxifen-treated patients (model R 2 adjusted = 0.66 versus *-allele R 2 adjusted = 0.35) and a cohort of patients treated with the CYP2D6 substrate venlafaxine (model R 2 adjusted = 0.64 versus *-allele R 2 adjusted = 0.55). Human embryonic kidney cells were used to confirm the effect of five genetic variants on metabolism of the CYP2D6 substrate bufuralol in vitro. These results demonstrate the advantage of a continuous scale and a completely phased genotype for prediction of CYP2D6 enzyme activity and could potentially enable more accurate prediction of individual drug response.
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Affiliation(s)
- Maaike van der Lee
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, 2333 ZA Leiden, Netherlands.,Leiden Network for Personalised Therapeutics, 2333 ZA Leiden, Netherlands
| | - William G Allard
- Department of Human Genetics, Leiden University Medical Center, 2333 ZA Leiden, Netherlands.,Leiden Genome Technology Center, Leiden University Medical Center, 2333 ZA Leiden, Netherlands
| | - Rolf H A M Vossen
- Department of Human Genetics, Leiden University Medical Center, 2333 ZA Leiden, Netherlands.,Leiden Genome Technology Center, Leiden University Medical Center, 2333 ZA Leiden, Netherlands
| | - Renée F Baak-Pablo
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, 2333 ZA Leiden, Netherlands
| | - Roberta Menafra
- Department of Human Genetics, Leiden University Medical Center, 2333 ZA Leiden, Netherlands.,Leiden Genome Technology Center, Leiden University Medical Center, 2333 ZA Leiden, Netherlands
| | - Birgit A L M Deiman
- Clinical Laboratory, Catharina Hospital Eindhoven, 5623 EJ Eindhoven, Netherlands
| | - Maarten J Deenen
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, 2333 ZA Leiden, Netherlands.,Department of Clinical Pharmacy, Catharina Hospital Eindhoven, 5623 EJ Eindhoven, Netherlands
| | | | - Inger Johansson
- Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum 5B, 171 77 Solna, Sweden
| | - Stefano Gastaldello
- Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum 5B, 171 77 Solna, Sweden
| | - Magnus Ingelman-Sundberg
- Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum 5B, 171 77 Solna, Sweden
| | - Henk-Jan Guchelaar
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, 2333 ZA Leiden, Netherlands.,Leiden Network for Personalised Therapeutics, 2333 ZA Leiden, Netherlands
| | - Jesse J Swen
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, 2333 ZA Leiden, Netherlands. .,Leiden Network for Personalised Therapeutics, 2333 ZA Leiden, Netherlands
| | - Seyed Yahya Anvar
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, 2333 ZA Leiden, Netherlands. .,Leiden Network for Personalised Therapeutics, 2333 ZA Leiden, Netherlands.,Department of Human Genetics, Leiden University Medical Center, 2333 ZA Leiden, Netherlands.,Leiden Genome Technology Center, Leiden University Medical Center, 2333 ZA Leiden, Netherlands
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9
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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: 112] [Impact Index Per Article: 37.3] [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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10
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Jones CJ, Subramaniam M, Emch MJ, Bruinsma ES, Ingle JN, Goetz MP, Hawse JR. Development and Characterization of Novel Endoxifen-Resistant Breast Cancer Cell Lines Highlight Numerous Differences from Tamoxifen-Resistant Models. Mol Cancer Res 2021; 19:1026-1039. [PMID: 33627502 DOI: 10.1158/1541-7786.mcr-20-0872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/25/2021] [Accepted: 02/19/2021] [Indexed: 12/24/2022]
Abstract
Despite the availability of drugs that target ERα-positive breast cancer, resistance commonly occurs, resulting in relapse, metastasis, and death. Tamoxifen remains the most commonly-prescribed endocrine therapy worldwide, and "tamoxifen resistance" has been extensively studied. However, little consideration has been given to the role of endoxifen, the most abundant active tamoxifen metabolite detected in patients, in driving resistance mechanisms. Endoxifen functions differently from the parent drug and other primary metabolites, including 4-hydroxy-tamoxifen (4HT). Many studies have shown that patients who extensively metabolize tamoxifen into endoxifen have superior outcomes relative to patients who do not, supporting a primary role for endoxifen in driving tamoxifen responses. Therefore, "tamoxifen resistance" may be better modeled by "endoxifen resistance" for some patients. Here, we report the development of novel endoxifen-resistant breast cancer cell lines and have extensively compared these models to 4HT and fulvestrant (ICI)-resistant models. Endoxifen-resistant cells were phenotypically and molecularly distinct from 4HT-resistant cells and more closely resembled ICI-resistant cells overall. Specifically, endoxifen resistance was associated with ERα and PR loss, estrogen insensitivity, unique gene signatures, and striking resistance to most FDA-approved second- and third-line therapies. Given these findings, and the importance of endoxifen in the efficacy of tamoxifen therapy, our data indicate that endoxifen-resistant models may be more clinically relevant than existing models and suggest that a better understanding of endoxifen resistance could substantially improve patient care. IMPLICATIONS: Here we report on the development and characterization of the first endoxifen-resistant models and demonstrate that endoxifen resistance may better model tamoxifen resistance in a subset of patients.
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Affiliation(s)
- Calley J Jones
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | | | - Michael J Emch
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Elizabeth S Bruinsma
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - James N Ingle
- Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - John R Hawse
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota.
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11
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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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12
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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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13
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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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14
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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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15
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Gusella M, Pasini F, Corso B, Bertolaso L, De Rosa G, Falci C, Modena Y, Barile C, Da Corte Z D, Fraccon A, Toso S, Cretella E, Brunello A, Modonesi C, Segati R, Oliani C, Minicuci N, Padrini R. Predicting steady-state endoxifen plasma concentrations in breast cancer patients by CYP2D6 genotyping or phenotyping. Which approach is more reliable? Pharmacol Res Perspect 2020; 8:e00646. [PMID: 32813313 PMCID: PMC7437348 DOI: 10.1002/prp2.646] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 07/10/2020] [Accepted: 07/16/2020] [Indexed: 12/24/2022] Open
Abstract
In previous studies, steady-state Z-endoxifen plasma concentrations (ENDOss) correlated with relapse-free survival in women on tamoxifen (TAM) treatment for breast cancer. ENDOss also correlated significantly with CYP2D6 genotype (activity score) and CYP2D6 phenotype (dextromethorphan test). Our aim was to ascertain which method for assessing CYP2D6 activity is more reliable in predicting ENDOss. The study concerned 203 Caucasian women on tamoxifen-adjuvant therapy (20 mg q.d.). Before starting treatment, CYP2D6 was genotyped (and activity scores computed), and the urinary log(dextromethorphan/dextrorphan) ratio [log(DM/DX)] was calculated after 15 mg of oral dextromethorphan. Plasma concentrations of TAM, N-desmethyl-tamoxifen (ND-TAM), Z-4OH-tamoxifen (4OH-TAM) and ENDO were assayed 1, 4, and 8 months after first administering TAM. Multivariable regression analysis was used to identify the clinical and laboratory variables predicting log-transformed ENDOss (log-ENDOss). Genotype-derived CYP2D6 phenotypes (PM, IM, NM, EM) and log(DM/DX) correlated independently with log-ENDOss. Genotype-phenotype concordance was almost complete only for poor metabolizers, whereas it emerged that 34% of intermediate, normal, and ultrarapid metabolizers were classified differently based on log(DM/DX). Multivariable regression analysis selected log(DM/DX) as the best predictor, with patients' age, weak inhibitor use, and CYP2D6 phenotype decreasingly important: log-ENDOss = 0.162 - log(DM/DX) × 0.170 + age × 0.0063 - weak inhibitor use × 0.250 + IM × 0.105 + (NM + UM) × 0.210; (R2 = 0.51). In conclusion, log(DM/DX) seems superior to genotype-derived CYP2D6 phenotype in predicting ENDOss.
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Affiliation(s)
| | - Felice Pasini
- Oncology UnitCasa di Cura PederzoliPeschiera del GardaItaly
| | - Barbara Corso
- National Research CouncilNeuroscience InstitutePadovaItaly
| | | | - Giovanni De Rosa
- Clinical Pharmacology Unit of the Department of Medicine (DIMED)University of PadovaPadovaItaly
| | - Cristina Falci
- Oncology Unit 2Istituto Oncologico Veneto (IOV)IRCCS PadovaPadovaItaly
| | | | | | | | | | | | | | | | | | | | | | - Nadia Minicuci
- National Research CouncilNeuroscience InstitutePadovaItaly
| | - Roberto Padrini
- Clinical Pharmacology Unit of the Department of Medicine (DIMED)University of PadovaPadovaItaly
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16
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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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17
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Jorge-Aarón RM, Rodrigo RC, Esther MPR. Endoxifen levels and metabolic phenotype-associated factors in Mexican Mestizo patients under tamoxifen treatment. Pharmacogenomics 2020; 21:929-943. [PMID: 32808577 DOI: 10.2217/pgs-2020-0061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: To evaluate plasma endoxifen levels and metabolic phenotype-associated factors in Mexican Mestizo patients under tamoxifen treatment. Patients & methods: A total of 138 breast cancer patients under tamoxifen treatment were cross-sectionally evaluated and side effects (SE) were recorded. CYP2D6 genetic phenotypes (GP) and metabolic phenotypes (MP) were assessed (metabolic poor [mPM], intermediate [mIM], normal [mNM], and ultrarapid [mUM] metabolizer). Associations were tested in uni-multivariate models for endoxifen >5.9 ng/ml and for mNM + mUM MP. Results: The main SE was hot flashes (62%). Distribution of the CYP2D6 MP was 4.3% mPM; 14.5% mIM; 75.4% mNM; and 5.8% mUM. Endoxifen >5.9 ng/ml was partially associated with SE (p = 0.06); the mNM + mUM MP was associated with treatment time (p = 0.03). Conclusion: The endoxifen-associated factors in Mexican Mestizo patients remain inconclusive, although treatment time was associated with MP.
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Affiliation(s)
- Rangel-Méndez Jorge-Aarón
- Unidad de Investigación Biomédica, Unidad Médica de Alta Especialidad, Hospital de Especialidades del Centro Médico Nacional "Ignacio García Téllez", Instituto Mexicano del Seguro Social, Calle 41 No. 439, Col. Industrial, Mérida, Yucatán, 97150, México
| | - Rubi-Castellanos Rodrigo
- Centro de Investigaciones Regionales "Dr. Hideyo Noguchi" Calle 96 S/N, Avenida Jacinto Canek y calle 47, Paseo de las Fuentes, Merida, Yucatan, 97225, Mexico
| | - Moo-Puc Rosa Esther
- Unidad de Investigación Biomédica, Unidad Médica de Alta Especialidad, Hospital de Especialidades del Centro Médico Nacional "Ignacio García Téllez", Instituto Mexicano del Seguro Social, Calle 41 No. 439, Col. Industrial, Mérida, Yucatán, 97150, México
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18
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Thorén L, Lindh JD, Ackehed G, Kringen MK, Hall P, Bergh J, Molden E, Margolin S, Eliasson E. Impairment of endoxifen formation in tamoxifen-treated premenopausal breast cancer patients carrying reduced-function CYP2D6 alleles. Br J Clin Pharmacol 2020; 87:1243-1252. [PMID: 32713032 PMCID: PMC9328423 DOI: 10.1111/bcp.14500] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 07/12/2020] [Accepted: 07/13/2020] [Indexed: 12/18/2022] Open
Abstract
Aims Tamoxifen is bioactivated to endoxifen by polymorphic CYP2D6‐dependent metabolism. Here, endoxifen levels were compared to CYP2D6 diplotypes, tentative target concentrations and side effects. Methods In total, 118 Swedish premenopausal breast cancer patients diagnosed 2006–2014, with on‐going postoperative tamoxifen treatment January 2017, were included. Biobanked DNA from peripheral blood was used for CYP2D6 genotyping by TaqMan real‐time polymerase chain reaction (CYP2D6*1, *3, *4, *5, *6, *9, *10, *41, *1xN). Plasma levels of tamoxifen and 3 major metabolites were quantified by liquid chromatography–tandem mass spectrometry. Clinical information on treatment and side effects was retrospectively obtained from medical records. Results In the final analysis of 114 patients, a clear relationship between CYP2D6 genotype and plasma endoxifen levels was evident. Low endoxifen (1.6–5.2 ng/mL), i.e. below the suggested threshold for clinical efficacy, was found in all patients with 2 reduced‐function alleles, 2 null‐alleles, or a null/reduced‐function combination. CYP2D6*41 was the most common reduced‐function allele (82%) and 17 of 21 CYP2D6*41‐carriers exhibited a lower CYP2D6 activity than predicted from published guidelines. No difference in endoxifen levels was observed between carriers of 2 null‐alleles vs patients homozygous for CYP2D6*41 or the corresponding heterozygous combination (P = .338). In patients with endoxifen levels <5.9 ng/mL (36/114), side effects were either mild or absent. At higher endoxifen levels moderate‐to‐severe side effects were reported in a concentration‐dependent manner. Conclusion Significantly reduced endoxifen levels were observed not only in all homozygous carriers of CYP2D6 null‐alleles, but also in carriers of 2 reduced‐function alleles. This finding may be highly relevant for future, genotype‐based dose considerations.
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Affiliation(s)
- Linda Thorén
- Department of Clinical Science and Education at Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.,Department of Oncology, South General Hospital, Stockholm, Sweden
| | - Jonatan D Lindh
- Department of Laboratory Medicine, Clinical Pharmacology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Gerd Ackehed
- Department of Laboratory Medicine, Clinical Pharmacology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Marianne Kristiansen Kringen
- Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway.,Department of Life Sciences and Health, Oslo Metropolitan University, Oslo, Norway
| | - Per Hall
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Jonas Bergh
- Department of Oncology-Pathology, Karolinska Institutet and Breast Cancer Center, Cancer Theme, Karolinska University Hospital, Stockholm, Sweden
| | - Espen Molden
- Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway.,Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Sara Margolin
- Department of Clinical Science and Education at Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.,Department of Oncology, South General Hospital, Stockholm, Sweden
| | - Erik Eliasson
- Department of Laboratory Medicine, Clinical Pharmacology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
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19
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Rangel-Méndez JA, Rubi-Castellanos R, Ascencio-Montiel IDJ, Moo-Puc RE. CYP2D6 does not impact on breast cancer-free survival in Southeast Mexican patients under tamoxifen treatment. Per Med 2020; 17:261-270. [DOI: 10.2217/pme-2019-0135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Aim: We conducted a retrospective analysis in 71 Mexican Mestizo patients to evaluate the breast cancer-free survival (BCFS) among the inferred genetic phenotypes (GP) of CYP2D6. Patients & methods: CYP2D6 was genotyped through Taqman-probe analysis; GP were inferred according to international guidelines. The BCFS was estimated through Kaplan–Meier method and analyzed with a log-rank test; hazard ratios were calculated with 95% CI and p < 0.05. Results: The BCFS did not differ among CYP2D6 GP (p = 0.45) and recurrence risk was similar between gNM + gUM and gPM + gIM groups (hazard ratio: 1.54, 95% CI: 0.37–6.38; p = 0.55). Conclusion: The findings do not support any impact of CYP2D6 on BCFS. Evaluation of other genetic/nongenetic biomarkers is needed in Mexican Mestizo patients under tamoxifen treatment.
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Affiliation(s)
- Jorge-Aarón Rangel-Méndez
- Unidad de Investigación Médica Yucatán, Unidad Médica de Alta Especialidad, Hospital de Especialidades del Centro Médico Nacional ‘Ignacio García Téllez’, Instituto Mexicano del Seguro Social, Calle 41 No. 439, Col. Industrial, 97150 Mérida, Yucatán, México
| | - Rodrigo Rubi-Castellanos
- Centro de Investigaciones Regionales ‘Dr Hideyo Noguchi’ Calle 96 S/N, Avenida Jacinto Canek y calle 47, Paseo de las Fuentes, 97225 Mérida, Yucatán, México
| | - Iván de Jesús Ascencio-Montiel
- División Vigilancia Epidemiológica de Enfermedades No Transmisibles, Instituto Mexicano del Seguro Social, Mier y Pesado 120, Col. Del Valle, Benito Juárez, 03100 Ciudad de México, México
| | - Rosa Esther Moo-Puc
- Unidad de Investigación Médica Yucatán, Unidad Médica de Alta Especialidad, Hospital de Especialidades del Centro Médico Nacional ‘Ignacio García Téllez’, Instituto Mexicano del Seguro Social, Calle 41 No. 439, Col. Industrial, 97150 Mérida, Yucatán, México
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20
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Sanchez-Spitman AB, Moes DJAR, Swen JJ, Dezentjé VO, Lambrechts D, Neven P, Gelderblom H, Guchelaar HJ. Exposure-response analysis of endoxifen serum concentrations in early-breast cancer. Cancer Chemother Pharmacol 2020; 85:1141-1152. [PMID: 32468081 PMCID: PMC7305085 DOI: 10.1007/s00280-020-04089-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/19/2020] [Indexed: 12/14/2022]
Abstract
Purpose
Tamoxifen is part of endocrine therapy in breast cancer treatment. Studies have indicated the use of endoxifen concentrations, tamoxifen active metabolite, to guide tamoxifen efficacy. Three endoxifen thresholds have been suggested (5.9 ng/ml, 5.2 ng/ml and 3.3 ng/ml) for therapeutic drug monitoring (TDM). Our aim was to validate these thresholds and to examine endoxifen exposure with clinical outcome in early-breast cancer patients using tamoxifen. Methods Data from 667 patients from the CYPTAM study (NTR1509) were available. Patients were stratified (above or below), according to the endoxifen threshold values for tamoxifen efficacy and tested by Cox regression. Logistic regressions to estimate the probability of relapse and tamoxifen discontinuation were performed. Results None of the thresholds showed a statistically significant difference in relapse-free survival: 5.2 ng/ml threshold: hazard ratio (HR): 2.545, 95% confidence interval (CI) 0.912–7.096, p value: 0.074; 3.3 ng/ml threshold: HR: 0.728; 95% CI 0.421–1.258, p value: 0.255. Logistic regression did not show a statistically significant association between the risk of relapse (odds ratio (OR): 0.971 (95% CI 0.923–1.021, p value: 0.248) and the risk for tamoxifen discontinuation (OR: 1.006 95% CI 0.961–1.053, p value: 0.798) with endoxifen concentrations. Conclusion Our findings do not confirm the endoxifen threshold values for TDM nor does it allow definition of a novel threshold. These findings indicate a limited value of TDM to guide tamoxifen efficacy.
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Affiliation(s)
- Anabel Beatriz Sanchez-Spitman
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Albinusdreef 2, 2300 RC, Leiden, The Netherlands.,Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands
| | - Dirk-Jan A R Moes
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Albinusdreef 2, 2300 RC, Leiden, The Netherlands.,Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands
| | - Jesse J Swen
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Albinusdreef 2, 2300 RC, Leiden, The Netherlands.,Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands
| | - Vincent O Dezentjé
- Department of Medical Oncology, Netherlands Cancer Institute/Antoni van Leeuwenhoek, Amsterdam, The Netherlands
| | - Diether Lambrechts
- Center for Cancer Biology, VIB, Leuven, Belgium.,Laboratory for Translational Genetics, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Patrick Neven
- Department of Medical Oncology, University Hospital Leuven, Leuven, Belgium
| | - Hans Gelderblom
- Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands.,Department of Medical Oncology, Leiden University Medical Center, Leiden, The Netherlands
| | - Henk-Jan Guchelaar
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Albinusdreef 2, 2300 RC, Leiden, The Netherlands. .,Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands.
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21
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Klopp-Schulze L, Mueller-Schoell A, Neven P, Koolen SLW, Mathijssen RHJ, Joerger M, Kloft C. Integrated Data Analysis of Six Clinical Studies Points Toward Model-Informed Precision Dosing of Tamoxifen. Front Pharmacol 2020; 11:283. [PMID: 32296331 PMCID: PMC7136483 DOI: 10.3389/fphar.2020.00283] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/27/2020] [Indexed: 12/16/2022] Open
Abstract
Introduction At tamoxifen standard dosing, ∼20% of breast cancer patients do not reach proposed target endoxifen concentrations >5.97 ng/mL. Thus, better understanding the large interindividual variability in tamoxifen pharmacokinetics (PK) is crucial. By applying non-linear mixed-effects (NLME) modeling to a pooled ‘real-world’ clinical PK database, we aimed to (i) dissect several levels of variability and identify factors predictive for endoxifen exposure and (ii) assess different tamoxifen dosing strategies for their potential to increase the number of patients reaching target endoxifen concentrations. Methods Tamoxifen and endoxifen concentrations with genetic and demographic data of 468 breast cancer patients from six reported studies were used to develop a NLME parent-metabolite PK model. Different levels of variability on model parameters or measurements were investigated and the impact of covariates thereupon explored. The model was subsequently applied in a simulation-based comparison of three dosing strategies with increasing degree of dose individualization for a large virtual breast cancer population. Interindividual variability of endoxifen concentrations and the fraction of patients at risk for not reaching target concentrations were assessed for each dosing strategy. Results and Conclusions The integrated NLME model enabled to differentiate and quantify four levels of variability (interstudy, interindividual, interoccasion, and intraindividual). Strong influential factors, i.e., CYP2D6 activity score, drug–drug interactions with CYP3A and CYP2D6 inducers/inhibitors and age, were reliably identified, reducing interoccasion variability to <20% CV. Yet, unexplained interindividual variability in endoxifen formation remained large (47.2% CV). Hence, therapeutic drug monitoring seems promising for achieving endoxifen target concentrations. Three tamoxifen dosing strategies [standard dosing (20 mg QD), CYP2D6-guided dosing (20, 40, and 60 mg QD) and individual model-informed precision dosing (MIPD)] using three therapeutic drug monitoring samples (5–120 mg QD) were compared, leveraging the model. The proportion of patients at risk for not reaching target concentrations was 22.2% in standard dosing, 16.0% in CYP2D6-guided dosing and 7.19% in MIPD. While in CYP2D6-guided- and standard dosing interindividual variability in endoxifen concentrations was high (64.0% CV and 68.1% CV, respectively), it was considerably reduced in MIPD (24.0% CV). Hence, MIPD demonstrated to be the most promising strategy for achieving target endoxifen concentrations.
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Affiliation(s)
- Lena Klopp-Schulze
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Free University of Berlin, Berlin, Germany
| | - Anna Mueller-Schoell
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Free University of Berlin, Berlin, Germany.,Graduate Research Training Program PharMetrX, Berlin, Germany
| | - Patrick Neven
- Vesalius Research Center, University Hospitals Leuven, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Stijn L W Koolen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, Netherlands
| | - Ron H J Mathijssen
- Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, Netherlands
| | - Markus Joerger
- Department of Medical Oncology and Hematology, Cantonal Hospital, St., Gallen, Switzerland
| | - Charlotte Kloft
- Department of Clinical Pharmacy and Biochemistry, Institute of Pharmacy, Free University of Berlin, Berlin, Germany
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22
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van der Lee M, Allard WG, Bollen S, Santen GWE, Ruivenkamp CAL, Hoffer MJV, Kriek M, Guchelaar HJ, Anvar SY, Swen JJ. Repurposing of Diagnostic Whole Exome Sequencing Data of 1,583 Individuals for Clinical Pharmacogenetics. Clin Pharmacol Ther 2019; 107:617-627. [PMID: 31594036 PMCID: PMC7027978 DOI: 10.1002/cpt.1665] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/12/2019] [Indexed: 12/14/2022]
Abstract
For ~ 80 drugs, widely recognized pharmacogenetics dosing guidelines are available. However, the use of these guidelines in clinical practice remains limited as only a fraction of patients is subjected to pharmacogenetic screening. We investigated the feasibility of repurposing whole exome sequencing (WES) data for a panel of 42 variants in 11 pharmacogenes to provide a pharmacogenomic profile. Existing diagnostic WES‐data from child‐parent trios totaling 1,583 individuals were used. Results were successfully extracted for 39 variants. No information could be extracted for three variants, located in CYP2C19, UGT1A1, and CYP3A5, and for CYP2D6 copy number. At least one actionable phenotype was present in 86% of the individuals. Haplotype phasing proved relevant for CYP2B6 assignments as 1.5% of the phenotypes were corrected after phasing. In conclusion, repurposing WES‐data can yield meaningful pharmacogenetic profiles for 7 of 11 important pharmacogenes, which can be used to guide drug treatment.
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Affiliation(s)
- Maaike van der Lee
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands.,Leiden Network for Personalized Therapeutics, Leiden, The Netherlands
| | - William G Allard
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Sander Bollen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Gijs W E Santen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Claudia A L Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Mariëtte J V Hoffer
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marjolein Kriek
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Henk-Jan Guchelaar
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands.,Leiden Network for Personalized Therapeutics, Leiden, The Netherlands
| | - Seyed Y Anvar
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands.,Leiden Network for Personalized Therapeutics, Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Jesse J Swen
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands.,Leiden Network for Personalized Therapeutics, Leiden, The Netherlands
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23
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Hennig EE, Piątkowska M, Goryca K, Pośpiech E, Paziewska A, Karczmarski J, Kluska A, Brewczyńska E, Ostrowski J. Non- CYP2D6 Variants Selected by a GWAS Improve the Prediction of Impaired Tamoxifen Metabolism in Patients with Breast Cancer. J Clin Med 2019; 8:jcm8081087. [PMID: 31344832 PMCID: PMC6722498 DOI: 10.3390/jcm8081087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/28/2019] [Accepted: 07/10/2019] [Indexed: 12/25/2022] Open
Abstract
A certain minimum plasma concentration of (Z)-endoxifen is presumably required for breast cancer patients to benefit from tamoxifen therapy. In this study, we searched for DNA variants that could aid in the prediction of risk for insufficient (Z)-endoxifen exposure. A metabolic ratio (MR) corresponding to the (Z)-endoxifen efficacy threshold level was adopted as a cutoff value for a genome-wide association study comprised of 287 breast cancer patients. Multivariate regression was used to preselect variables exhibiting an independent impact on the MR and develop models to predict below-threshold MR values. In total, 15 single-nucleotide polymorphisms (SNPs) were significantly associated with below-threshold MR values. The strongest association was with rs8138080 (WBP2NL). Two alternative models for MR prediction were developed. The predictive accuracy of Model 1, including rs7245, rs6950784, rs1320308, and the CYP2D6 genotype, was considerably higher than that of the CYP2D6 genotype alone (AUC 0.879 vs 0.758). Model 2, which was developed using the same three SNPs as for Model 1 plus rs8138080, appeared as an interesting alternative to the full CYP2D6 genotype testing. In conclusion, the four novel SNPs, tested alone or in combination with the CYP2D6 genotype, improved the prediction of impaired tamoxifen-to-endoxifen metabolism, potentially allowing for treatment optimization.
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Affiliation(s)
- Ewa E Hennig
- Department of Gastroenterology, Hepatology and Clinical Oncology, Centre of Postgraduate Medical Education, 01-813 Warsaw, Poland.
- Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland.
| | - Magdalena Piątkowska
- Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland
| | - Krzysztof Goryca
- Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland
| | - Ewelina Pośpiech
- Malopolska Centre of Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Agnieszka Paziewska
- Department of Gastroenterology, Hepatology and Clinical Oncology, Centre of Postgraduate Medical Education, 01-813 Warsaw, Poland
| | - Jakub Karczmarski
- Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland
| | - Anna Kluska
- Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland
| | - Elżbieta Brewczyńska
- Department of Breast Cancer and Reconstructive Surgery, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland
| | - Jerzy Ostrowski
- Department of Gastroenterology, Hepatology and Clinical Oncology, Centre of Postgraduate Medical Education, 01-813 Warsaw, Poland
- Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland
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24
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A pilot study of the implementation of pharmacogenomic pharmacist initiated pre-emptive testing in primary care. Eur J Hum Genet 2019; 27:1532-1541. [PMID: 31227807 DOI: 10.1038/s41431-019-0454-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/17/2019] [Accepted: 05/22/2019] [Indexed: 12/23/2022] Open
Abstract
Despite the nationwide availability of pharmacogenomic (PGx) guidelines in electronic medication surveillance systems in The Netherlands, PGx guided prescribing is still uncommon in primary care. We set out to investigate the adoption of pharmacist initiated PGx testing in primary care. Community pharmacists were offered a free PGx test covering 40 variants in 8 genes to test patients receiving an incident prescription (IRx) of a selection of 10 drugs. Results of the PGx test along with predicted phenotypes and a therapeutic recommendation based on the Dutch Pharmacogenetics Working Group (DPWG) guidelines were transferred to the pharmacist and physician. Adoption was defined as the percentage of eligible patients that received genotyping. From November 2014-July 2016, 200 patients were included with an adoption of 18.0%. Of the included patients 57.5% received an IRx for atorvastatin, 14.5% started with simvastatin and 28.0% received an IRx for amitriptyline, (es)citalopram, nortriptyline, or venlafaxine. 90% of the patients carried at least one actionable PGx test result in the selected PGx-panel. In 31.0% of the incident prescriptions a combination between a drug with a known gene-drug interaction and an actionable genotype was present and a therapeutic recommendation was provided. The provided recommendations were accepted by the clinicians in 88.7% of the patients. Pharmacist initiated implementation of PGx in primary care is feasible, and the frequency of actionable gene-drug interactions for the selected drugs is high.
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25
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Tamoxifen citrate/Coenzyme Q10 as smart nanocarriers Bitherapy for Breast Cancer: Cytotoxicity, genotoxicity, and antioxidant activity. J Drug Deliv Sci Technol 2019. [DOI: 10.1016/j.jddst.2019.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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26
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Khalaj Z, Baratieh Z, Nikpour P, Schwab M, Schaeffeler E, Mokarian F, Khanahmad H, Salehi R, Mürdter TE, Salehi M. Clinical Trial: CYP2D6 Related Dose Escalation of Tamoxifen in Breast Cancer Patients With Iranian Ethnic Background Resulted in Increased Concentrations of Tamoxifen and Its Metabolites. Front Pharmacol 2019; 10:530. [PMID: 31178724 PMCID: PMC6543868 DOI: 10.3389/fphar.2019.00530] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 04/26/2019] [Indexed: 12/30/2022] Open
Abstract
Introduction: The polymorphic enzyme cytochrome P450 2D6 (CYP2D6) catalyzes a major step in the bioactivation of tamoxifen. Genotyping of clinically relevant CYP2D6 alleles and subsequent dose adjustment is a promising approach to individualize breast cancer therapy. The aim of this study was to investigate the relationship between the plasma levels of tamoxifen and its metabolites and different CYP2D6 genotypes under standard (20 mg/day) and dose-adjusted therapy (Registration ID in Iranian Registry of Clinical Trials: IRCT2015082323734N1). Materials and Methods: Using TaqMan® assays common alleles of CYP2D6 (∗1, ∗2, ∗4, ∗5, ∗6, ∗10, ∗17, and ∗41) and gene duplication were identified in 134 breast cancer patients. Based on CYP2D6 genotypes patients with an activity score 1 (n = 15) and 0-0.5 (n = 2) were treated with tamoxifen adjusted dosage of 30 and 40 mg/day, respectively. The concentration of tamoxifen and its metabolites before and after 4 and 8 months of dose adjustment were measured using LC-MS/MS technology. Results: At baseline, (Z)-endoxifen plasma concentrations (33 ± 15.5, 28.1 ± 14, 26.6 ± 23.4, 14.3 ± 8.6, and 10.7 ± 5.5 nmol/l for EM/EM, EM/IM, EM/PM, IM/IM and PM/PM, respectively) and the metabolic ratio (Z)-Endoxifen/N-desmethyltamoxifen (0.0558 ± 0.02, 0.0396 ± 0.0111, 0.0332 ± 0.0222, 0.0149 ± 0.0026, and 0.0169 ± 0.0177 for EM/EM, EM/IM, EM/PM, IM/IM, and PM/PM, respectively) correlated with CYP2D6 genotype (Kruskal-Wallis p = 0.013 and p < 0.0001, respectively). Dose escalation to 30 and 40 mg/day in patients with a CYP2D6 activity score of 1 (n = 15) and 0-0.5 (n = 2) resulted in a significant increase in (Z)-endoxifen plasma levels (22.17 ± 24.42, 34.43 ± 26.54, and 35.77 ± 28.89 nmol/l at baseline, after 4 and 8 months, respectively, Friedman p = 0.0388) along with the plasma concentrations of tamoxifen and its other metabolites. No severe side effects were recorded during dose escalation. Conclusion: For the first time, we show the feasibility of dose escalation of tamoxifen in breast cancer patients with compromised CYP2D6 activity and Iranian ethnic background to increase the plasma concentrations of (Z)-endoxifen.
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Affiliation(s)
- Zahra Khalaj
- Department of Genetics and Molecular Biology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Zohreh Baratieh
- Department of Genetics and Molecular Biology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Parvaneh Nikpour
- Department of Genetics and Molecular Biology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.,Child Growth and Development Research Center, Research Institute for Primordial Prevention of Non-communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany.,Department of Clinical Pharmacology, University Hospital Tübingen, Tübingen, Germany.,Department of Pharmacy and Biochemistry, University Hospital Tübingen, Tübingen, Germany
| | - Elke Schaeffeler
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany.,University of Tübingen, Tübingen, Germany
| | - Fariborz Mokarian
- Cancer Prevention Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Hossein Khanahmad
- Department of Genetics and Molecular Biology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Rasoul Salehi
- Department of Genetics and Molecular Biology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.,Child Growth and Development Research Center, Research Institute for Primordial Prevention of Non-communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Thomas E Mürdter
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany.,University of Tübingen, Tübingen, Germany
| | - Mansoor Salehi
- Department of Genetics and Molecular Biology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.,Child Growth and Development Research Center, Research Institute for Primordial Prevention of Non-communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran.,Cellular, Molecular and Genetics Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
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Exploiting Pharmacokinetic Models of Tamoxifen and Endoxifen to Identify Factors Causing Subtherapeutic Concentrations in Breast Cancer Patients. Clin Pharmacokinet 2019; 57:229-242. [PMID: 28540639 DOI: 10.1007/s40262-017-0555-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND AND OBJECTIVES A better understanding of the highly variable pharmacokinetics (PK) of tamoxifen and its active metabolite endoxifen in breast cancer patients is crucial to support individualised treatment. This study used a modelling and simulation approach to quantitatively assess the influence of cytochrome P450 (CYP) 2D6 activity and other relevant factors on tamoxifen and endoxifen PK to identify subgroups at risk for subtherapeutic endoxifen concentrations. METHODS Simulations were performed using two previously published PK models jointly describing tamoxifen and endoxifen with CYP2D6 and CYP3A4/5 enzyme activities implemented as covariates. Steady-state predictions were compared between models and with the literature values. Factors potentially causing between-model discrepancies were explored. A previously published threshold (6 ng/mL) was used to identify patients with subtherapeutic endoxifen concentrations and to perform a dose adaptation study. RESULTS Steady-state predictions of tamoxifen and endoxifen were considerably different between the models. The factors, differences in sampling time, adherence and bioavailability, were not able to fully capture between-model variability. Endoxifen steady-state fluctuations within a dosing interval were minimal (<6%). Poor (97%) and intermediate (54%) CYP2D6 metabolisers failed to achieve therapeutic endoxifen concentrations, suggesting adapted doses of tamoxifen 80 and 40 mg, respectively, achieving therapeutic endoxifen concentrations in 89.7% of patients (standard dosing 45.2%). However, interindividual variability remained. CONCLUSIONS To achieve therapeutic endoxifen concentrations early in treatment, it is advisable to initiate treatment by CYP2D6 genotype/phenotype-guided dosing, followed by therapeutic drug monitoring at steady-state. We strongly advocate to adequately measure, report and prospectively investigate influential factors (i.e. adherence, bioavailability, time to PK steady-state) in clinical trials.
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Sanchez-Spitman A, Swen J, Dezentje V, Moes D, Gelderblom H, Guchelaar H. Clinical pharmacokinetics and pharmacogenetics of tamoxifen and endoxifen. Expert Rev Clin Pharmacol 2019; 12:523-536. [DOI: 10.1080/17512433.2019.1610390] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- A.B. Sanchez-Spitman
- Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - J.J. Swen
- Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - V.O. Dezentje
- Department of Medical Oncology, Netherlands Cancer Institute/Antoni van Leeuwenhoek, Amsterdam, The Netherlands
| | - D.J.A.R. Moes
- Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - H. Gelderblom
- Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands
- Department of Medical Oncology, Leiden University Medical Center, Leiden, The Netherlands
| | - H.J. Guchelaar
- Leiden Network for Personalised Therapeutics, Leiden University Medical Center, Leiden, The Netherlands
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
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29
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Sanchez-Spitman A, Dezentjé V, Swen J, Moes DJA, Böhringer S, Batman E, van Druten E, Smorenburg C, van Bochove A, Zeillemaker A, Jongen L, Los M, Neven P, Gelderblom H, Guchelaar HJ. Tamoxifen Pharmacogenetics and Metabolism: Results From the Prospective CYPTAM Study. J Clin Oncol 2019; 37:636-646. [DOI: 10.1200/jco.18.00307] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Tamoxifen is widely prescribed as adjuvant therapy in patients with early-stage breast cancer. It has been postulated that concentrations of endoxifen, the active metabolite of tamoxifen, are a better predictor of tamoxifen efficacy than CYP2D6 genotypes. Although in a retrospective study, an endoxifen threshold of 5.9 ng/mL for efficacy was described, confirmation based on prospective studies is lacking. The objective of the prospective CYPTAM (The Netherlands National Trial Register: NTR1509) study was to associate endoxifen concentrations and CYP2D6 genotypes with clinical outcome in patients with early-stage breast cancer receiving tamoxifen. PATIENTS AND METHODS From February 2008 to December 2010, patients with breast cancer treated with adjuvant tamoxifen were included. Patients could be enrolled up to a maximum of 12 months after tamoxifen initiation. Blood samples were retrieved for CYP2D6 genotyping and endoxifen measurements by Amplichip (Roche Diagnostics, Indianapolis, IN) and high-performance liquid chromatography–tandem mass spectrometry, respectively. Endoxifen concentrations were analyzed as a continuous variable, classifying patients into quartiles and using an endoxifen threshold of 5.9 ng/mL. Endoxifen concentrations and CYP2D6 genotypes were associated with relapse-free survival (censored at the time of tamoxifen discontinuation; RFSt) by Cox regression analysis. RESULTS A total of 667 pre- and postmenopausal patients were enrolled and had received tamoxifen for a median time of 0.37 years (range, 0.23 to 0.6 years) before study entry. No association was found between endoxifen concentrations and RFSt (adjusted hazard ratio, 0.991; 95% CI, 0.946 to 1.038; P = .691). Also, neither categorizing endoxifen concentrations into quartiles nor using 5.9 ng/mL as threshold altered these results. In addition, no association was found between CYP2D6 genotype and RFSt (adjusted hazard ratio, 0.929; 95% CI, 0.525 to 1.642; P = .799). CONCLUSION This prospective clinical study shows no association between endoxifen concentrations or CYP2D6 genotypes and clinical outcome in patients with early-stage breast cancer receiving adjuvant tamoxifen.
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Affiliation(s)
| | - Vincent Dezentjé
- Netherlands Cancer Institute/Antoni van Leeuwenhoek, Amsterdam, the Netherlands
| | - Jesse Swen
- Leiden University Medical Center, Leiden, the Netherlands
| | | | | | | | | | - Carolien Smorenburg
- Netherlands Cancer Institute/Antoni van Leeuwenhoek, Amsterdam, the Netherlands
- Medical Center Alkmaar, Alkmaar, the Netherlands
| | | | | | - Lynn Jongen
- Katholieke Universiteit Leuven, Leuven, Belgium
| | - Maartje Los
- St Antonius Ziekenhuis, Nieuwegein, the Netherlands
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30
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Ariza Márquez YV, Briceño I, Aristizábal F, Niño LF, Yosa Reyes J. Dynamic Effects of CYP2D6 Genetic Variants in a Set of Poor Metaboliser Patients with Infiltrating Ductal Cancer Under Treatment with Tamoxifen. Sci Rep 2019; 9:2521. [PMID: 30792473 PMCID: PMC6385267 DOI: 10.1038/s41598-018-38340-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 12/19/2018] [Indexed: 12/28/2022] Open
Abstract
Breast cancer is a group of multigenic diseases. It is the most common cancer diagnosed among women worldwide and is often treated with tamoxifen. Tamoxifen is catalysed by cytochrome P450 2D6 (CYP2D6), and inter-individual variations in the enzyme due to single nucleotide polymorphisms (SNPs) could alter enzyme activity. We evaluated SNPs in patients from Colombia in South America who were receiving tamoxifen treatment for breast cancer. Allelic diversity in the CYP2D6 gene was found in the studied population, with two patients displaying the poor-metaboliser phenotype. Molecular dynamics and trajectory analyses were performed for CYP2D6 from these two patients, comparing it with the common allelic form (CYP2D6*1). Although we found no significant structural change in the protein, its dynamics differ significantly from those of CYP2D6*1, the effect of such differential dynamics resulting in an inefficient enzyme with serious implications for tamoxifen-treated patients, increasing the risk of disease relapse and ineffective treatment.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antineoplastic Agents, Hormonal/administration & dosage
- Antineoplastic Agents, Hormonal/metabolism
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma, Ductal/drug therapy
- Carcinoma, Ductal/genetics
- Carcinoma, Ductal/metabolism
- Carcinoma, Ductal/pathology
- Chemotherapy, Adjuvant
- Cytochrome P-450 CYP2D6/genetics
- Cytochrome P-450 CYP2D6/metabolism
- Female
- Genotype
- Humans
- Inactivation, Metabolic/genetics
- Middle Aged
- Pharmacogenomic Variants/genetics
- Phenotype
- Polymorphism, Single Nucleotide/genetics
- Tamoxifen/administration & dosage
- Tamoxifen/adverse effects
- Tamoxifen/metabolism
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Affiliation(s)
- Yeimy Viviana Ariza Márquez
- Universidad Nacional de Colombia, Instituto de Biotecnología IBUN, Departamento de Farmacia, Bogota, 111321, Colombia
| | - Ignacio Briceño
- Universidad de la Sabana, Facultad de Medicina, Bogota, 140013, Colombia
- Pontificia Universidad Javeriana, Facultad de Medicina, Instituto de Genética Humana IGH, Bogota, 110231, Colombia
| | - Fabio Aristizábal
- Universidad Nacional de Colombia, Instituto de Biotecnología IBUN, Departamento de Farmacia, Bogota, 111321, Colombia
| | - Luis Fernando Niño
- Universidad Nacional de Colombia, Facultad de Ingeniería, Departamento de Ingeniería de Sistemas e Industrial, Bogota, 111321, Colombia
| | - Juvenal Yosa Reyes
- Universidad Simón Bolivar, Facultad de Ciencias Básicas y Biomédicas, Laboratorio de Simulación Molecular y Bioinformática, Barranquilla, 080002, Colombia.
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Weissenstein U, Kunz M, Oufir M, Wang JT, Hamburger M, Urech K, Regueiro U, Baumgartner S. Absence of herb-drug interactions of mistletoe with the tamoxifen metabolite (E/Z)-endoxifen and cytochrome P450 3A4/5 and 2D6 in vitro. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2019; 19:23. [PMID: 30658716 PMCID: PMC6339413 DOI: 10.1186/s12906-019-2439-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 01/14/2019] [Indexed: 01/16/2023]
Abstract
Background Women diagnosed with breast cancer frequently seek complementary and alternative (CAM) treatment options that can help to cope with their disease and the side effects of conventional cancer therapy. Especially in Europe, breast cancer patients use herbal products containing mistletoe (Viscum album L.). The oldest and one of the most prescribed conventional drugs for the treatment of estrogen receptor positive breast cancer is tamoxifen. Aside from positive clinical experience with the combination of tamoxifen and mistletoe, little is known about possible herb-drug interactions (HDIs) between the two products. In the present in vitro study, we investigated the effect of standardized commercial mistletoe preparations on the activity of endoxifen, the major active metabolite of tamoxifen. Methods The estrogen receptor positive human breast carcinoma cell line MCF-7 was treated with (E/Z)-endoxifen hydrochloride in the presence and absence of a defined estradiol concentration. Each concentration of the drug was combined with fermented Viscum album L. extracts (VAE) at clinically relevant doses, and proliferation, apoptosis and cell cycle were analyzed. In parallel, possible inhibition of CYP3A4/5 and CYP2D6 was investigated using 50-donor mixed gender pooled human liver microsomes (HLMs). Results VAE did not inhibit endoxifen induced cytostasis and cytotoxicity. At higher concentrations, VAE showed an additive inhibitory effect. VAE preparations did not cause inhibition of CYP3A4/5 and CYP2D6 catalyzed tamoxifen metabolism. Conclusions The in vitro results suggest that mistletoe preparations can be used in combination with tamoxifen without the risk of HDIs. Electronic supplementary material The online version of this article (10.1186/s12906-019-2439-2) contains supplementary material, which is available to authorized users.
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CYP2D6 as a treatment decision aid for ER-positive non-metastatic breast cancer patients: a systematic review with accompanying clinical practice guidelines. Breast Cancer Res Treat 2018; 173:521-532. [PMID: 30411242 DOI: 10.1007/s10549-018-5027-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Accepted: 10/21/2018] [Indexed: 12/11/2022]
Abstract
PURPOSE Tamoxifen is one of the principal treatments for estrogen receptor (ER)-positive breast cancer. Unfortunately, between 30 and 50% of patients receiving this hormonal therapy relapse. Since CYP2D6 genetic variants have been reported to play an important role in survival outcomes after treatment with tamoxifen, this study sought to summarize and critically appraise the available scientific evidence on this topic. METHODS A systematic literature review was conducted to identify studies investigating associations between CYP2D6 genetic variation and survival outcomes after tamoxifen treatment. Critical appraisal of the retrieved scientific evidence was performed, and recommendations were developed for CYP2D6 genetic testing in the context of tamoxifen therapy. RESULTS Although conflicting literature exists, the majority of the current evidence points toward CYP2D6 genetic variation affecting survival outcomes after tamoxifen treatment. Of note, review of the CYP2D6 genotyping assays used in each of the studies revealed the importance of comprehensive genotyping strategies to accurately predict CYP2D6 metabolizer phenotypes. CONCLUSIONS AND RECOMMENDATIONS Critical appraisal of the literature provided evidence for the value of comprehensive CYP2D6 genotyping panels in guiding treatment decisions for non-metastatic ER-positive breast cancer patients. Based on this information, it is recommended that alternatives to standard tamoxifen treatments may be considered in CYP2D6 poor or intermediate metabolizers.
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33
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van Nuland M, Vreman RA, Ten Ham RMT, de Vries Schultink AHM, Rosing H, Schellens JHM, Beijnen JH, Hövels AM. Cost-effectiveness of monitoring endoxifen levels in breast cancer patients adjuvantly treated with tamoxifen. Breast Cancer Res Treat 2018; 172:143-150. [PMID: 30006796 PMCID: PMC6208915 DOI: 10.1007/s10549-018-4886-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 07/10/2018] [Indexed: 01/13/2023]
Abstract
PURPOSE Breast cancer is the most common malignancy in women worldwide. Recurrence rates in breast cancer are considered to be dependent on the serum concentration of endoxifen, the active metabolite of tamoxifen. The goal of this study is to investigate the cost-effectiveness of periodically monitoring serum concentrations of endoxifen in adjuvant estrogen receptor alfa (ERα) positive breast cancer patients treated with tamoxifen in the Netherlands. METHODS A Markov model with disease-free survival (DFS), recurrent disease (RD), and death states was constructed. The benefit of drug monitoring was modeled via a difference in the fraction of patients achieving adequate serum concentrations. Robustness of results to changes in model assumptions were tested through deterministic and probabilistic sensitivity analyses. RESULTS Monitoring of endoxifen added 0.0115 quality-adjusted life-years (QALYs) and saved € 1564 per patient in the base case scenario. Deterministic sensitivity analysis demonstrated a large effect on the incremental cost-effectiveness ratio (ICER) of the differences in costs and utilities between the DFS and RD states. Probabilistic sensitivity analysis showed that the probability of cost-effectiveness at a willingness to pay of € 0 per quality-adjusted life-year (QALY) was 89.8%. CONCLUSIONS Based on this model, monitoring of endoxifen in adjuvant ERα + breast cancer patients treated with tamoxifen is likely to add QALYs and save costs from a healthcare payer perspective. We advise clinicians to consider integrating serum endoxifen concentration monitoring into standard adjuvant tamoxifen treatment of ERα + breast cancer patients.
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Affiliation(s)
- M van Nuland
- Department of Pharmacy and Pharmacology, The Netherlands Cancer Institute and MC Slotervaart, Amsterdam, The Netherlands. .,Division of Pharmacology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. .,Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
| | - R A Vreman
- Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - R M T Ten Ham
- Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - A H M de Vries Schultink
- Department of Pharmacy and Pharmacology, The Netherlands Cancer Institute and MC Slotervaart, Amsterdam, The Netherlands.,Division of Pharmacology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - H Rosing
- Department of Pharmacy and Pharmacology, The Netherlands Cancer Institute and MC Slotervaart, Amsterdam, The Netherlands
| | - J H M Schellens
- Division of Pharmacology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.,Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.,Division of Clinical Pharmacology, Department of Medical Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - J H Beijnen
- Department of Pharmacy and Pharmacology, The Netherlands Cancer Institute and MC Slotervaart, Amsterdam, The Netherlands.,Division of Pharmacology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.,Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - A M Hövels
- Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
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34
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Cronin-Fenton DP, Damkier P. Tamoxifen and CYP2D6: A Controversy in Pharmacogenetics. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2018; 83:65-91. [PMID: 29801584 DOI: 10.1016/bs.apha.2018.03.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Tamoxifen reduces the rate of breast cancer recurrence by about one-half. It is converted to more active metabolites by enzymes encoded by polymorphic genes, including cytochrome P450 2D6 (CYP2D6) and transported by ATP-binding cassette transporters. Genetic polymorphisms that confer reduced CYP2D6 activity or concurrent use of CYP2D6-inhibiting drugs may reduce the clinical efficacy of tamoxifen. The issue of the clinical utility of CYP2D6 genotype testing is subject to considerable and ongoing academic and clinical controversy. In this chapter, we outline tamoxifen's clinical pharmacology and give an overview of the research to date on the association between CYP2D6 inhibition and tamoxifen effectiveness. Based on the evidence to date, the impact of drug-induced and/or gene-induced inhibition of CYP2D6 activity is likely to be null or small, or at most moderate in subjects carrying two reduced function alleles. Future research should examine the effect of polymorphisms in genes encoding enzymes in tamoxifen's complete metabolic pathway, should comprehensively evaluate other biomarkers that affect tamoxifen effectiveness, such as the transport enzymes, and focus on subgroups of patients, such as premenopausal breast cancer patients, for whom tamoxifen is the only guideline approved endocrine therapy.
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Affiliation(s)
| | - Per Damkier
- Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark; Department of Clinical Research, University of Southern Denmark, Odense, Denmark
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35
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Khan BA, Robinson R, Fohner AE, Muzquiz LI, Schilling BD, Beans JA, Olnes MJ, Trawicki L, Frydenlund H, Laukes C, Beatty P, Phillips B, Nickerson D, Howlett K, Dillard DA, Thornton TA, Thummel KE, Woodahl EL. Cytochrome P450 Genetic Variation Associated with Tamoxifen Biotransformation in American Indian and Alaska Native People. Clin Transl Sci 2018; 11:312-321. [PMID: 29436156 PMCID: PMC5944577 DOI: 10.1111/cts.12542] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/12/2017] [Accepted: 01/15/2017] [Indexed: 01/24/2023] Open
Abstract
Despite evidence that pharmacogenetics can improve tamoxifen pharmacotherapy, there are few studies with American Indian and Alaska Native (AIAN) people. We examined variation in cytochrome P450 (CYP) genes (CYP2D6, CYP3A4, CYP3A5, and CYP2C9) and tamoxifen biotransformation in AIAN patients with breast cancer (n = 42) from the Southcentral Foundation in Alaska and the Confederated Salish and Kootenai Tribes in Montana. We tested for associations between CYP diplotypes and plasma concentrations of tamoxifen and metabolites. Only the CYP2D6 variation was significantly associated with concentrations of endoxifen (P = 0.0008) and 4-hydroxytamoxifen (P = 0.0074), tamoxifen's principal active metabolites, as well as key metabolic ratios. The CYP2D6 was also the most significant predictor of active metabolites and metabolic ratios in a multivariate regression model, including all four genes as predictors, with minor roles for other CYP genes. In AIAN populations, CYP2D6 is the largest contributor to tamoxifen bioactivation, illustrating the importance of validating pharmacogenetic testing for therapy optimization in an understudied population.
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Affiliation(s)
- Burhan A. Khan
- Department of Biomedical and Pharmaceutical SciencesUniversity of MontanaMissoulaMontanaUSA
- Southcentral FoundationAnchorageAlaskaUSA
| | | | - Alison E. Fohner
- Institute for Public Health GeneticsUniversity of WashingtonSeattleWashingtonUSA
| | - LeeAnna I. Muzquiz
- Tribal Health DepartmentConfederated Salish and Kootenai TribesMontanaUSA
| | | | | | | | - Laura Trawicki
- Alaska Native Tribal Health ConsortiumAnchorageAlaskaUSA
| | | | - Cindi Laukes
- Department of Biomedical and Pharmaceutical SciencesUniversity of MontanaMissoulaMontanaUSA
- Montana Cancer Institute FoundationMissoulaMontanaUSA
| | - Patrick Beatty
- Montana Cancer Institute FoundationMissoulaMontanaUSA
- Montana Cancer SpecialistsMissoulaMontanaUSA
| | - Brian Phillips
- Department of PharmaceuticsUniversity of WashingtonSeattleWashingtonUSA
| | - Deborah Nickerson
- Department of Genome SciencesUniversity of WashingtonSeattleWashingtonUSA
| | - Kevin Howlett
- Tribal Health DepartmentConfederated Salish and Kootenai TribesMontanaUSA
| | | | | | | | - Erica L. Woodahl
- Department of Biomedical and Pharmaceutical SciencesUniversity of MontanaMissoulaMontanaUSA
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Haviari S, You B, Tod M. In Silico Evaluation of Pharmacokinetic Optimization for Antimitogram-Based Clinical Trials. Cancer Res 2018; 78:1873-1882. [PMID: 29317432 DOI: 10.1158/0008-5472.can-17-1710] [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: 06/16/2017] [Revised: 10/30/2017] [Accepted: 01/05/2018] [Indexed: 11/16/2022]
Abstract
Antimitograms are prototype in vitro tests for evaluating chemotherapeutic efficacy using patient-derived primary cancer cells. These tests might help optimize treatment from a pharmacodynamic standpoint by guiding treatment selection. However, they are technically challenging and require refinements and trials to demonstrate benefit to be widely used. In this study, we performed simulations aimed at exploring how to validate antimitograms and how to complement them by pharmacokinetic optimization. A generic model of advanced cancer, including pharmacokinetic-pharmacodynamic monitoring, was used to link dosing schedules with progression-free survival (PFS), as built from previously validated modules. This model was used to explore different possible situations in terms of pharmacokinetic variability, pharmacodynamic variability, and antimitogram performance. The model recapitulated tumor dynamics and standalone therapeutic drug monitoring efficacy consistent with published clinical results. Simulations showed that combining pharmacokinetic and pharmacodynamic optimization should increase PFS in a synergistic fashion. Simulated data were then used to compute required clinical trial sizes, which were 30% to 90% smaller when pharmacokinetic optimization was added to pharmacodynamic optimization. This improvement was observed even when pharmacokinetic optimization alone exhibited only modest benefit. Overall, our work illustrates the synergy derived from combining antimitograms with therapeutic drug monitoring, permitting a disproportionate reduction of the trial size required to prove a benefit on PFS. Accordingly, we suggest that strategies with benefits too small for standalone clinical trials could be validated in combination in a similar manner.Significance: This work offers a method to reduce the number of patients needed for a clinical trial to prove the hypothesized benefit of a drug to progression-free survival, possibly easing opportunities to evaluate combinations. Cancer Res; 78(7); 1873-82. ©2018 AACR.
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Affiliation(s)
- Skerdi Haviari
- EA3738 CTO, Faculté de Médecine Lyon-Sud, Université Lyon 1, Oullins, France.
- Hospices Civils de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
| | - Benoît You
- EA3738 CTO, Faculté de Médecine Lyon-Sud, Université Lyon 1, Oullins, France
- Université Claude Bernard Lyon 1, Lyon, France
- Service d'Oncologie Médicale, Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, Pierre-Bénite, France
| | - Michel Tod
- EA3738 CTO, Faculté de Médecine Lyon-Sud, Université Lyon 1, Oullins, France.
- Université Claude Bernard Lyon 1, Lyon, France
- Pharmacie, Hôpital de la Croix Rousse, Hospices civils de Lyon, Lyon, France
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Neven P, Jongen L, Lintermans A, Van Asten K, Blomme C, Lambrechts D, Poppe A, Wildiers H, Dieudonné AS, Brouckaert O, Decloedt J, Berteloot P, Verhoeven D, Joerger M, Vuylsteke P, Wynendaele W, Casteels M, Van Huffel S, Lybaert W, Van Ginderachter J, Paridaens R, Vergote I, Dezentjé VO, Van Calster B, Guchelaar HJ. Tamoxifen Metabolism and Efficacy in Breast Cancer: A Prospective Multicenter Trial. Clin Cancer Res 2018; 24:2312-2318. [PMID: 29459457 DOI: 10.1158/1078-0432.ccr-17-3028] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 12/21/2017] [Accepted: 02/13/2018] [Indexed: 01/20/2023]
Abstract
Purpose: Levels of endoxifen, the most active metabolite of tamoxifen, vary by the highly polymorphic cytochrome P450 (CYP) 2D6 enzyme. We prospectively investigated tamoxifen efficacy by serum endoxifen levels and the tamoxifen activity score (TAS).Experimental Design: A prospective observational multicenter study included postmenopausal women with an estrogen receptor-positive breast cancer receiving first-line tamoxifen, 20 mg daily in the neoadjuvant or metastatic setting, recruited between February 2009 and May 2014. The primary endpoint was the objective response rate (ORR) using RECIST criteria 1.0. Secondary endpoints were clinical benefit (CB), progression-free survival (PFS), and tolerability of tamoxifen. The main analysis used logistic regression to relate ORR to serum endoxifen levels after 3 months. Endpoints were also related to other tamoxifen metabolites and to TAS.Results: Endoxifen levels were available for 247 of all 297 patients (83%), of which 209 with target lesions (85%). Median follow-up time for PFS was 32.5 months, and 62% progressed. ORR and CB were 45% and 84%, respectively. ORR was not related to endoxifen, and the OR of ORR was 1.008 per μg/L increase in endoxifen (95% confidence interval, 0.971-1.046; P = 0.56). In general, none of the endpoints was associated with endoxifen levels, tamoxifen metabolites, or TAS.Conclusions: Under the prespecified assumptions, the results from this prospective clinical trial do not suggest therapeutic drug monitoring of endoxifen to be of clinical value in postmenopausal women treated with tamoxifen for breast cancer in the neoadjuvant or metastatic setting. Clin Cancer Res; 24(10); 2312-8. ©2018 AACR.
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Affiliation(s)
- Patrick Neven
- Department of Oncology, KU Leuven-University of Leuven, Leuven, Belgium. .,Department of Gynaecology and Obstetrics, University Hospitals Leuven, Leuven, Belgium
| | - Lynn Jongen
- Department of Oncology, KU Leuven-University of Leuven, Leuven, Belgium
| | | | | | - Chantal Blomme
- Department of Gynaecology and Obstetrics, University Hospitals Leuven, Leuven, Belgium
| | - Diether Lambrechts
- Department of Human Genetics, Laboratory for Translational Genetics, KU Leuven-University of Leuven, Leuven, Belgium; VIB Vesalius Research Centre, Laboratory for Translational Genetics, Leuven, Belgium
| | - An Poppe
- Department of Gynaecology and Obstetrics, University Hospitals Leuven, Leuven, Belgium
| | - Hans Wildiers
- Department of Oncology, KU Leuven-University of Leuven, Leuven, Belgium.,Department of Medical Oncology, University Hospitals Leuven, Leuven, Belgium
| | | | - Olivier Brouckaert
- Department of Gynaecology and Obstetrics, University Hospitals Leuven, Leuven, Belgium
| | - Jan Decloedt
- Department of Gynaecology and Obstetrics, Algemeen Ziekenhuis Sint-Blasius, Dendermonde, Belgium
| | - Patrick Berteloot
- Department of Gynaecology and Obstetrics, Algemeen Ziekenhuis Sint-Maarten, Duffel, Belgium
| | - Didier Verhoeven
- Department of Medical Oncology, Algemeen Ziekenhuis Klina, Brasschaat, Belgium
| | - Markus Joerger
- Department of Medical Oncology and Hematology, Cantonal Hospital, St. Gallen, Switzerland
| | - Peter Vuylsteke
- Department of Medical Oncology, Université catholique de Louvain, CHU UCL, Namur site Sainte-Elisabeth, Namur, Belgium
| | - Wim Wynendaele
- Department of Medical Oncology, Imelda Ziekenhuis, Bonheiden, Belgium
| | - Minne Casteels
- Department of Clinical Pharmacology and Pharmacotherapy, KU Leuven-University of Leuven, Leuven, Belgium
| | - Sabine Van Huffel
- Department of Electrical Engineering, KU Leuven-University of Leuven, Leuven, Belgium.,Imec, Leuven, Belgium
| | - Willem Lybaert
- Department of Medical Oncology, Algemeen Ziekenhuis Nikolaas, Sint-Niklaas, Belgium
| | - Johan Van Ginderachter
- Department of Gynaecology and Obstetrics, Algemeen Ziekenhuis Maria Middelares, Ghent, Belgium
| | - Robert Paridaens
- Department of Oncology, KU Leuven-University of Leuven, Leuven, Belgium.,Department of Medical Oncology, University Hospitals Leuven, Leuven, Belgium
| | - Ignace Vergote
- Department of Oncology, KU Leuven-University of Leuven, Leuven, Belgium.,Department of Gynaecology and Obstetrics, University Hospitals Leuven, Leuven, Belgium
| | - Vincent Olaf Dezentjé
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Centre, Leiden, the Netherlands.,Department of Medical Oncology, Netherlands Cancer Institute/Antoni van Leeuwenhoek, Amsterdam, The Netherlands
| | - Ben Van Calster
- Department of Development and Regeneration, KU Leuven-University of Leuven, Leuven, Belgium.,Department of Biomedical Data Sciences, Leiden University Medical Centre, Leiden, The Netherlands
| | - Henk-Jan Guchelaar
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Centre, Leiden, the Netherlands
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38
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Pharmacogenomics Guided-Personalization of Warfarin and Tamoxifen. J Pers Med 2017; 7:jpm7040020. [PMID: 29236081 PMCID: PMC5748632 DOI: 10.3390/jpm7040020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/23/2017] [Accepted: 12/07/2017] [Indexed: 02/07/2023] Open
Abstract
The use of pharmacogenomics to personalize drug therapy has been a long-sought goal for warfarin and tamoxifen. However, conflicting evidence has created reason for hesitation in recommending pharmacogenomics-guided care for both drugs. This review will provide a summary of the evidence to date on the association between cytochrome P450 enzymes and the clinical end points of warfarin and tamoxifen therapy. Further, highlighting the clinical experiences that we have gained over the past ten years of running a personalized medicine program, we will offer our perspectives on the utility and the limitations of pharmacogenomics-guided care for warfarin and tamoxifen therapy.
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39
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Marcath LA, Deal AM, Van Wieren E, Danko W, Walko CM, Ibrahim JG, Weck KE, Jones DR, Desta Z, McLeod HL, Carey LA, Irvin WJ, Hertz DL. Comprehensive assessment of cytochromes P450 and transporter genetics with endoxifen concentration during tamoxifen treatment. Pharmacogenet Genomics 2017; 27:402-409. [PMID: 28877533 PMCID: PMC5659294 DOI: 10.1097/fpc.0000000000000311] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVES Tamoxifen bioactivation to endoxifen is mediated primarily by CYP2D6; however, considerable variability remains unexplained. Our aim was to perform a comprehensive assessment of the effect of genetic variation in tamoxifen-relevant enzymes and transporters on steady-state endoxifen concentrations. PATIENTS AND METHODS Comprehensive genotyping of CYP enzymes and transporters was performed using the iPLEX ADME PGx Pro Panel in 302 tamoxifen-treated breast cancer patients. Predicted activity phenotype for 19 enzymes and transporters were analyzed for univariate association with endoxifen concentration, and then adjusted for CYP2D6 and clinical covariates. RESULTS In univariate analysis, higher activity of CYP2C8 (regression β=0.22, P=0.020) and CYP2C9 (β=0.20, P=0.04), lower body weight (β=-0.014, P<0.0001), and endoxifen measurement during winter (each β<-0.39, P=0.002) were associated with higher endoxifen concentrations. After adjustment for the CYP2D6 diplotype, weight, and season, CYP2C9 remained significantly associated with higher concentrations (P=0.02), but only increased the overall model R by 1.3%. CONCLUSION Our results further support a minor contribution of CYP2C9 genetic variability toward steady-state endoxifen concentrations. Integration of clinician and genetic variables into individualized tamoxifen dosing algorithms would marginally improve their accuracy and potentially enhance tamoxifen treatment outcomes.
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Affiliation(s)
- Lauren A Marcath
- aDepartment of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, Michigan bUNC Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina cDeBartolo Family Personalized Medicine Institute, Moffitt Cancer Center, Tampa, Florida dDepartment of Clinical Pharmacology, Indiana University, Indianapolis, Indiana eBon Secours Cancer Institute, Richmond, Virginia, USA
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40
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Schroth W, Winter S, Mürdter T, Schaeffeler E, Eccles D, Eccles B, Chowbay B, Khor CC, Tfayli A, Zgheib NK, Eichelbaum M, Schwab M, Brauch H. Improved Prediction of Endoxifen Metabolism by CYP2D6 Genotype in Breast Cancer Patients Treated with Tamoxifen. Front Pharmacol 2017; 8:582. [PMID: 28955222 PMCID: PMC5609540 DOI: 10.3389/fphar.2017.00582] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/11/2017] [Indexed: 12/13/2022] Open
Abstract
Purpose: Prediction of impaired tamoxifen (TAM) to endoxifen metabolism may be relevant to improve breast cancer treatment, e.g., via TAM dose increase. The polymorphic cytochrome P450 2D6 (CYP2D6) strongly determines an individual's capacity for endoxifen formation, however, CYP2D6 phenotype assignments inferred from genotype widely differ between studies. Thus, we modeled plasma endoxifen predictability depending on variable CYP2D6 genotype groupings. Methods: CYP2D6 diplotype and metabolite plasma concentrations were assessed in 908 pre- and post-menopausal estrogen receptor (ER)-positive, TAM treated early breast cancer patients of Caucasian (N = 678), Middle-Eastern Arab (N = 77), and Asian (N = 153) origin. Robust coefficients of determination (R2) were estimated for endoxifen (E) or metabolic ratio endoxifen/desmethyl-TAM (E/DMT) as dependent and different CYP2D6 phenotype assignments as independent variables. Allele activity scores (ASs) were modified with respect to a reduced ∗10 allele activity. Predictability of endoxifen plasma concentrations above the clinical threshold of 5.9 ng/mL was investigated by receiver operating characteristic (ROC) analysis. Results: CYP2D6 diplotypes (N = 898) were strongly associated with E and E/DMT independent of age (P < 10-15). Across all ethnicities, 68-82% inter-patient variability of E/DMT was explained by CYP2D6 diplotype, while plasma endoxifen was predictable by 39-58%. The previously used codeine specific phenotype classification showed worse prediction for both endpoints particularly in Asians (median R2< 20%; P < 10-9). Downgrading of ∗10 activity slightly improved the explanatory value of metabolizer phenotype (P < 0.002). Endoxifen plasma concentrations above the clinical threshold of 5.9 ng/mL were achieved in 82.3% of patients and were predictable (96% sensitivity, 57% specificity) by CYP2D6 diplotypes with AS > 0.5, i.e., omitting PM/PM and PM/IM patients. Conclusion: The CYP2D6 explanatory power for active drug level assessment is maximized by TAM-specific phenotype assignments while a genotype cutoff that separates PM/PM and PM/IM from the remaining patients may improve clinical benefit via increased endoxifen concentrations.
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Affiliation(s)
- Werner Schroth
- Dr. Margarete Fischer-Bosch-Institute of Clinical PharmacologyStuttgart, Germany
- Department of Clinical Pharmacology, University of TübingenTübingen, Germany
| | - Stefan Winter
- Dr. Margarete Fischer-Bosch-Institute of Clinical PharmacologyStuttgart, Germany
- Department of Clinical Pharmacology, University of TübingenTübingen, Germany
| | - Thomas Mürdter
- Dr. Margarete Fischer-Bosch-Institute of Clinical PharmacologyStuttgart, Germany
- Department of Clinical Pharmacology, University of TübingenTübingen, Germany
| | - Elke Schaeffeler
- Dr. Margarete Fischer-Bosch-Institute of Clinical PharmacologyStuttgart, Germany
- Department of Clinical Pharmacology, University of TübingenTübingen, Germany
| | - Diana Eccles
- Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of SouthamptonSouthampton, United Kingdom
| | | | - Balram Chowbay
- Laboratory of Clinical Pharmacology, Division of Medical Sciences, National Cancer CentreSingapore, Singapore
- Clinical Pharmacology, SingHealthSingapore, Singapore
- Office of Clinical Sciences, Duke-NUS Medical SchoolSingapore, Singapore
| | - Chiea C. Khor
- Division of Human Genetics, Genome Institute of SingaporeSingapore, Singapore
- Singapore Eye Research InstituteSingapore, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore
| | - Arafat Tfayli
- Hematology-Oncology Division, Department of Internal Medicine, Faculty of Medicine, American University of BeirutBeirut, Lebanon
| | - Nathalie K. Zgheib
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of BeirutBeirut, Lebanon
| | - Michel Eichelbaum
- Dr. Margarete Fischer-Bosch-Institute of Clinical PharmacologyStuttgart, Germany
- Department of Clinical Pharmacology, University of TübingenTübingen, Germany
- Discipline of Pharmacology, Adelaide Medical School, Faculty of Health and Medical Sciences, The University of Adelaide, AdelaideSA, Australia
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch-Institute of Clinical PharmacologyStuttgart, Germany
- Department of Clinical Pharmacology, Institute of Experimental and Clinical Pharmacology and Toxicology, University Hospital TübingenTübingen, Germany
- Department of Pharmacy and Biochemistry, University of TübingenTübingen, Germany
- German Cancer Consortium of German Cancer Research CenterHeidelberg, Germany
| | - Hiltrud Brauch
- Dr. Margarete Fischer-Bosch-Institute of Clinical PharmacologyStuttgart, Germany
- Department of Clinical Pharmacology, University of TübingenTübingen, Germany
- German Cancer Consortium of German Cancer Research CenterHeidelberg, Germany
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41
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Kim S, Yun YM, Chae HJ, Cho HJ, Ji M, Kim IS, Wee KA, Lee W, Song SH, Woo HI, Lee SY, Chun S. Clinical Pharmacogenetic Testing and Application: Laboratory Medicine Clinical Practice Guidelines. Ann Lab Med 2017; 37:180-193. [PMID: 28029011 PMCID: PMC5204002 DOI: 10.3343/alm.2017.37.2.180] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/07/2016] [Accepted: 12/11/2016] [Indexed: 12/15/2022] Open
Abstract
Pharmacogenetic testing for clinical applications is steadily increasing. Correct and adequate use of pharmacogenetic tests is important to reduce unnecessary medical costs and adverse patient outcomes. This document contains recommended pharmacogenetic testing guidelines for clinical application, interpretation, and result reporting through a literature review and evidence-based expert opinions for the clinical pharmacogenetic testing covered by public medical insurance in Korea. This document aims to improve the utility of pharmacogenetic testing in routine clinical settings.
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Affiliation(s)
- Sollip Kim
- Department of Laboratory Medicine, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea
| | - Yeo Min Yun
- Department of Laboratory Medicine, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea
| | - Hyo Jin Chae
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hyun Jung Cho
- Department of Laboratory Medicine, Konyang University Hospital, College of Medicine, Konyang University, Daejeon, Korea
| | - Misuk Ji
- Department of Laboratory Medicine, Veterans Health Service Medical Center, Seoul, Korea
| | - In Suk Kim
- Department of Laboratory Medicine, School of Medicine, Pusan National University, Busan, Korea
| | - Kyung A Wee
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Woochang Lee
- Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea
| | - Sang Hoon Song
- Department of Laboratory Medicine, Seoul National University Hospital and College of Medicine, Seoul, Korea
| | - Hye In Woo
- Department of Laboratory Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
| | - Soo Youn Lee
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
| | - Sail Chun
- Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
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42
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Buermans HPJ, Vossen RHAM, Anvar SY, Allard WG, Guchelaar HJ, White SJ, den Dunnen JT, Swen JJ, van der Straaten T. Flexible and Scalable Full-Length CYP2D6 Long Amplicon PacBio Sequencing. Hum Mutat 2017; 38:310-316. [PMID: 28044414 PMCID: PMC5324676 DOI: 10.1002/humu.23166] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 11/18/2016] [Accepted: 12/22/2016] [Indexed: 01/08/2023]
Abstract
Cytochrome P450 2D6 (CYP2D6) is among the most important genes involved in drug metabolism. Specific variants are associated with changes in the enzyme's amount and activity. Multiple technologies exist to determine these variants, like the AmpliChip CYP450 test, Taqman qPCR, or Second‐Generation Sequencing, however, sequence homology between cytochrome P450 genes and pseudogene CYP2D7 impairs reliable CYP2D6 genotyping, and variant phasing cannot accurately be determined using these assays. To circumvent this, we sequenced CYP2D6 using the Pacific Biosciences RSII and obtained high‐quality, full‐length, phased CYP2D6 sequences, enabling accurate variant calling and haplotyping of the entire gene‐locus including exonic, intronic, and upstream and downstream regions. Unphased diplotypes (Roche AmpliChip CYP450 test) were confirmed for 24 of the 25 samples, including gene duplications. Cases with gene deletions required additional specific assays to resolve. In total, 61 unique variants were detected, including variants that had not previously been associated with specific haplotypes. To further aid genomic analysis using standard reference sequences, we have established an LOVD‐powered CYP2D6 gene‐variant database, and added all reference haplotypes and data reported here. We conclude that our CYP2D6 genotyping approach produces reliable CYP2D6 diplotypes and reveals information about additional variants, including phasing and copy‐number variation.
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Affiliation(s)
- Henk P J Buermans
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, 2333ZC, The Netherlands
| | - Rolf H A M Vossen
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, 2333ZC, The Netherlands
| | - Seyed Yahya Anvar
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, 2333ZC, The Netherlands
| | - William G Allard
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, 2333ZC, The Netherlands
| | - Henk-Jan Guchelaar
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, 2333ZA, The Netherlands
| | - Stefan J White
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, 2333ZC, The Netherlands
| | - Johan T den Dunnen
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, 2333ZC, The Netherlands.,Department of Clinical Genetics, Leiden University Medical Center, Leiden, 2333ZC, The Netherlands
| | - Jesse J Swen
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, 2333ZA, The Netherlands
| | - Tahar van der Straaten
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, 2333ZA, The Netherlands
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43
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Hertz DL, Rae JM. One step at a time: CYP2D6 guided tamoxifen treatment awaits convincing evidence of clinical validity. Pharmacogenomics 2016; 17:823-6. [PMID: 27249031 DOI: 10.2217/pgs-2016-0059] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Daniel L Hertz
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI, USA
| | - James M Rae
- Division of Hematology/Oncology, University of Michigan Comprehensive Cancer Center, Ann Arbor, MI, USA
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44
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Del Re M, Citi V, Crucitta S, Rofi E, Belcari F, van Schaik RH, Danesi R. Pharmacogenetics of CYP2D6 and tamoxifen therapy: Light at the end of the tunnel? Pharmacol Res 2016; 107:398-406. [PMID: 27060675 DOI: 10.1016/j.phrs.2016.03.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 03/06/2016] [Accepted: 03/21/2016] [Indexed: 01/08/2023]
Abstract
The clinical usefulness of assessing the enzymatic activity of CYPD6 in patients taking tamoxifen had been longly debated. In favour of preemptive evaluation of phenotypic profile of patients is the strong pharmacologic rationale, being that the formation of endoxifen, the major and clinically most important metabolite of tamoxifen, is largely dependent on the activity of CYP2D6. This enzyme is highly polymorphic for which the activity is largely depending on genetics, but that can also be inhibited by a number of drugs, i.e. antidepressants, which are frequently used in patients with cancer. Unfortunately, the clinical trials that have been published in the last years are contradicting each other on the association between CYP2D6 and significant clinical endpoints, and for this reason CYP2D6 genotyping is at present not generally recommended. Despite this, the CYP2D6 genotyping test for tamoxifen is available in many laboratories and it may still be an appropriate test to use it in specific cases.
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Affiliation(s)
- M Del Re
- Clinical Pharmacology and Pharmacogenetics Unit, Department of Laboratory Medicine, University Hospital, Pisa, Italy.
| | - V Citi
- Clinical Pharmacology and Pharmacogenetics Unit, Department of Laboratory Medicine, University Hospital, Pisa, Italy
| | - S Crucitta
- Clinical Pharmacology and Pharmacogenetics Unit, Department of Laboratory Medicine, University Hospital, Pisa, Italy
| | - E Rofi
- Clinical Pharmacology and Pharmacogenetics Unit, Department of Laboratory Medicine, University Hospital, Pisa, Italy
| | - F Belcari
- Clinical Pharmacology and Pharmacogenetics Unit, Department of Laboratory Medicine, University Hospital, Pisa, Italy
| | - R H van Schaik
- Department of Clinical Chemistry, Erasmus MC, Rotterdam, The Netherlands
| | - R Danesi
- Clinical Pharmacology and Pharmacogenetics Unit, Department of Laboratory Medicine, University Hospital, Pisa, Italy
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45
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Hertz DL, Rae JM. Individualized Tamoxifen Dose Escalation: Confirmation of Feasibility, Question of Utility. Clin Cancer Res 2016; 22:3121-3. [PMID: 27012810 DOI: 10.1158/1078-0432.ccr-16-0370] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 02/29/2016] [Indexed: 01/13/2023]
Abstract
Tamoxifen may require metabolic activation to endoxifen for efficacy in treating hormone receptor-positive breast cancer. Dose escalation in patients with low endoxifen concentrations could enhance treatment efficacy. This approach is clinically feasible, and successfully increases endoxifen concentrations; however, it is unknown whether patients benefit from individualized tamoxifen dose escalation. Clin Cancer Res; 22(13); 3121-3. ©2016 AACRSee related article by Fox et al., p. 3164.
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Affiliation(s)
- Daniel L Hertz
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, Michigan.
| | - James M Rae
- Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
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