Trial reportPharmacogenetics and genomics2015
Evaluation of CYP2D6 enzyme activity using a 13C-dextromethorphan breath test in women receiving adjuvant tamoxifen.
Trial report in Pharmacogenetics and genomics, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 8 papers, 2 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
8 citing papers in PubMed, 2 syntheses or guidelines pooled it, 11 citations in OpenAlex.
- European guideline on indications, performance and clinical impact ofUnited European gastroenterology journal · 2021Guideline
- Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2D6 and Tamoxifen Therapy.Clinical pharmacology and therapeutics · 2018Guideline
- A novel substrate for CYP3A4 phenotyping: in vitro biotransformation of hubamine into butanone.Analytical and bioanalytical chemistry · 2026Article
- Endoxifen, an Estrogen Receptor Targeted Therapy: From Bench to Bedside.Endocrinology · 2021Review
- Generating a Precision Endoxifen Prediction Algorithm to Advance Personalized Tamoxifen Treatment in Patients with Breast Cancer.Journal of personalized medicine · 2021Review
- Predicting steady-state endoxifen plasma concentrations in breast cancer patients by CYP2D6 genotyping or phenotyping. Which approach is more reliable?Pharmacology research & perspectives · 2020Article
- First-in-Human Phase I Study of the Tamoxifen Metabolite Z-Endoxifen in Women With Endocrine-Refractory Metastatic Breast Cancer.Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2017Article
- Stable isotope biomarker breath tests for human metabolic and infectious diseases: a review of recent patent literature.Expert opinion on therapeutic patents · 2016Review
Corrections and comments
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Authors and funding
13 authors at 3 institutions in 2 countries.
Funding
Abstract
backgroundIn tamoxifen-treated patients, breast cancer recurrence differs according to CYP2D6 genotype and endoxifen steady-state concentrations (Endx Css). The ¹³C-dextromethorphan breath test (DM-BT), labeled with ¹³C at the O-CH3 moiety, measures CYP2D6 enzyme activity. We sought to examine the ability of the DM-BT to identify known CYP2D6 genotypic poor metabolizers and examine the correlation between DM-BT and Endx Css.
methodsDM-BT and tamoxifen pharmacokinetics were obtained at baseline, 3, and 6 months following tamoxifen initiation. Potent CYP2D6 inhibitors were prohibited. The correlation between baseline DM-BT with CYP2D6 genotype and Endx Css was determined. The association between baseline DM-BT (where values ≤0.9 is an indicator of poor in vivo CYP2D6 metabolism) and Endx Css (using values≤11.2 known to be associated with poorer recurrence free survival) was explored.
resultsA total of 91 patients were enrolled and 77 were eligible. CYP2D6 genotype was positively correlated with baseline, 3, and 6 months DM-BT (r ranging from 0.457-0. 60; P<0.001). Both CYP2D6 genotype (r=0.47, 0.56, P<0.0001), and baseline DM-BT (r=0.60, 0.54, P<0.001) were associated with 3 and 6 months Endx Css, respectively. Seven (78%) of nine patients with low (≤11.2 nmol/l) 3 month Endx Css also had low DM-BT (≤0.9) including 2/2 CYP2D6 PM/PM and 5/5 IM/PM. In contrast, one (2%) of 48 patients with a low DM-BT had Endx Css more than 11.2 nmol/l.
conclusionIn patients not taking potent CYP2D6 inhibitors, DM-BT was associated with CYP2D6 genotype and 3 and 6 months Endx Css but did not provide better discrimination of Endx Css compared with CYP2D6 genotype alone. Further studies are needed to identify additional factors which alter Endx Css.
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