The effect of rs5758550 on CYP2D6*2 phenotype and formation of endoxifen in breast cancer patients using tamoxifen. (August 2017)

• Record Type: Journal Article
• Authors: Sanchez-Spitman, Anabel B; Moes, Dirk-Jan AR; Gelderblom, Hans; Dezentjé, Vincent O; Swen, Jesse J; Guchelaar, Henk-Jan
• Is Part Of: Pharmacogenomics. Volume 18:Number 12(2017)
• Page Start: 1125
• Page End: 1132
• Publication Date: 2017-08
• Subjects: CYP2D6*2 -- endoxifen -- enhancer -- rs5758550 -- tamoxifen; Pharmacogenomics -- Periodicals; 615.1
• DOI: 10.2217/pgs-2017-0080
• Languages: English
• ISSNs: 1462-2416

Abstract

Aim: CYP2D6*2 is considered fully active, but it has been suggested that it only happens in the presence of rs5758550. This study aims to elucidate the impact of this enhancer.Materials & methods: DNA and blood samples from women enrolled in the CYPTAM study (NTR1509) were analyzed. Fourteen CYP2D6*2 carriers without the enhancer were reclassified. The relationship of CYP2D6 phenotypes and drug levels was studied.Results: After correction for the absence of the enhancer, the correlation between CYP2D6 phenotypes and endoxifen did not improve (R 2 : 0.290 vs 0.279). No difference was observed in mean concentrations between CYP2D6*2 individuals with and without the enhancer.Conclusion: The rs5758550 enhancer does not lead to improved prediction of endoxifen levels in breast cancer patients.