title: Evaluating predictive pharmacogenetic signatures of adverse events in colorectal cancer patients treated with fluoropyrimidines.
abstract: The potential clinical utility of genetic markers associated with response to fluoropyrimidine treatment in colorectal cancer patients remains controversial despite extensive study. Our aim was to test the clinical validity of both novel and previously identified markers of adverse events in a broad clinical setting. We have conducted an observational pharmacogenetic study of early adverse events in a cohort study of 254 colorectal cancer patients treated with 5-fluorouracil or capecitabine. Sixteen variants of nine key folate (pharmacodynamic) and drug metabolising (pharmacokinetic) enzymes have been analysed as individual markers and/or signatures of markers. We found a significant association between TYMP S471L (rs11479) and early dose modifications and/or severe adverse events (adjusted OR = 2.02 [1.03; 4.00], p = 0.042, adjusted OR = 2.70 [1.23; 5.92], p = 0.01 respectively). There was also a significant association between these phenotypes and a signature of DPYD mutations (Adjusted OR = 3.96 [1.17; 13.33], p = 0.03, adjusted OR = 6.76 [1.99; 22.96], p = 0.002 respectively). We did not identify any significant associations between the individual candidate pharmacodynamic markers and toxicity. If a predictive test for early adverse events analysed the TYMP and DPYD variants as a signature, the sensitivity would be 45.5 %, with a positive predictive value of just 33.9 % and thus poor clinical validity. Most studies to date have been under-powered to consider multiple pharmacokinetic and pharmacodynamic variants simultaneously but this and similar individualised data sets could be pooled in meta-analyses to resolve uncertainties about the potential clinical utility of these markers.
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, United Kingdom.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Jennings
authors.forename: Yoon K
authors.initials: YK
authors.lastname: Loke
authors.forename: Jane
authors.initials: J
authors.lastname: Skinner
authors.forename: Melanie
authors.initials: M
authors.lastname: Keane
authors.forename: Gavin S
authors.initials: GS
authors.lastname: Chu
authors.forename: Richard
authors.initials: R
authors.lastname: Turner
authors.forename: Daniel
authors.initials: D
authors.lastname: Epurescu
authors.forename: Ann
authors.initials: A
authors.lastname: Barrett
authors.forename: Gavin
authors.initials: G
authors.lastname: Willis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010597:Pharmacogenetics; D011743:Pyrimidines / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D012189:Retrospective Studies
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D011743:Pyrimidines; C029269:5-fluoropyrimidine