title: Pharmacogenetic screening of CYP3A and ABCB1 in relation to population pharmacokinetics of docetaxel.
abstract: OBJECTIVE
  Despite the extensive clinical experience with docetaxel, unpredictable interindividual variability in efficacy and toxicity remain important limitations associated with the use of this anticancer drug. Large interindividual pharmacokinetic variability has been associated with variation in toxicity profiles. Genetic polymorphisms in drug-metabolizing enzymes and drug transporters could possibly explain the observed pharmacokinetic variability. The aim of this study was therefore to investigate the influence of polymorphisms in the CYP3A and ABCB1 genes on the population pharmacokinetics of docetaxel.
  
  
  METHODS
  Whole blood samples were obtained from patients with solid tumors and treated with docetaxel to quantify the exposure to docetaxel. DNA was collected to determine polymorphisms in the CYP3A and ABCB1 genes with DNA sequencing. A population pharmacokinetic analysis of docetaxel was done using nonlinear mixed-effect modeling.
  
  
  RESULTS
  In total, 92 patients were assessable for pharmacokinetic analysis of docetaxel. A three-compartmental model adequately described the pharmacokinetics of docetaxel. Several polymorphisms in the CYP3A and ABCB1 genes were found, with allele frequencies of 0.54% to 48.4%. The homozygous C1236T polymorphism in the ABCB1 gene (ABCB1*8) was significantly correlated with a decreased docetaxel clearance (-25%; P = 0.0039). No other relationships between polymorphisms and pharmacokinetic variables reached statistical significance. Furthermore, no relationship between haplotypes of CYP3A and ABCB1 and the pharmacokinetics could be identified.
  
  
  CONCLUSIONS
  The polymorphism C1236T in the ABCB1 gene was significantly related to docetaxel clearance. Our current finding may provide a meaningful tool to explain interindividual differences in docetaxel treatment in daily practice.
authors.affiliation: Department of Pharmacy and Pharmacology, The Netherlands Cancer Institute/Slotervaart Hospital, Louwesweg 6, 1066 EC Amsterdam, the Netherlands. aptbo@slz.nl
authors.forename: Tessa M
authors.initials: TM
authors.lastname: Bosch
authors.forename: Alwin D R
authors.initials: AD
authors.lastname: Huitema
authors.forename: Valerie D
authors.initials: VD
authors.lastname: Doodeman
authors.forename: Robert
authors.initials: R
authors.lastname: Jansen
authors.forename: Els
authors.initials: E
authors.lastname: Witteveen
authors.forename: Wim M
authors.initials: WM
authors.lastname: Smit
authors.forename: Rob L
authors.initials: RL
authors.lastname: Jansen
authors.forename: Carla M
authors.initials: CM
authors.lastname: van Herpen
authors.forename: Marcel
authors.initials: M
authors.lastname: Soesan
authors.forename: Jos H
authors.initials: JH
authors.lastname: Beijnen
authors.forename: Jan H M
authors.initials: JH
authors.lastname: Schellens
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000972:Antineoplastic Agents, Phytogenic / Q000493:pharmacokinetics*; D051544:Cytochrome P-450 CYP3A / Q000235:genetics* / Q000378:metabolism; D000077143:Docetaxel; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009369:Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000235:genetics*; D027361:Organic Anion Transporters / Q000235:genetics* / Q000378:metabolism; D010597:Pharmacogenetics; D011110:Polymorphism, Genetic; D043823:Taxoids / Q000493:pharmacokinetics*
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; D027361:Organic Anion Transporters; D043823:Taxoids; D000077143:Docetaxel; D051544:Cytochrome P-450 CYP3A