CYP3A4 intron 6 C > T SNP (CYP3A4*22) encodes lower CYP3A4 activity in cancer patients, as measured with probes midazolam and erythromycin

Laure Elens, Annemieke Nieuweboer, SJ Clarke, KA Charles, Anne-joy Graan, V Haufroid, RHJ Mathijssen, Ron van Schaik

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Aim: The CYP3A4*22 allele was recently reported to be associated with reduced CYP3A4 activity. We investigated the impact of this allele on the metabolism of the CYP3A-phenotyping probes, midazolam (MDZ) and erythromycin. Patients & methods: Genomic DNA from 108 cancer patients receiving intravenous MDZ and 45 undergoing the erythromycin breath test was analyzed for CYP3A4*22 (rs35599367 C>T) and CYP3A5*3. Results: The MDZ metabolic ratio (1'-OH-MDZ:MDZ) was 20.7% (95% CI: -36.2 to -6.2) lower for CYP3A4*22 carriers compared with CYP3A4*1/*1 patients (p = 0.01). Combining CYP3A4*22 and CYP3A5*3 genotypes showed a 38.7% decrease (95% CI: -50.0 to -27.4; p < 0.001) in 1'-OH-MDZ:MDZ for poor (CYP3A4*22-CYP3A5*3/*3) and 28.0% (95% CI: -33.3 to -22.6; p < 0.001) for intermediate (CYP3A4*1/*1-CYP3A5*3/*3) metabolizers, compared with extensive (CYP3A4*1/*1-CYP3A5*1) CYP3A metabolizers. CYP3A4 erythromycin N-demethylation activity was 40% lower in CYP3A4*22 carriers compared with CYP3A4*1/*1 patients (p = 0.032). Conclusion: The CYP3A4*22 allele is associated with decreased CYP3A4-mediated metabolism, as verified by CYP3A-phenotyping probes.
Original languageUndefined/Unknown
Pages (from-to)137-149
Number of pages13
Issue number2
Publication statusPublished - 2013

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