title: Pharmacogenetic effects of regulatory nuclear receptors (PXR, CAR, RXRα and HNF4α) on docetaxel disposition in Chinese nasopharyngeal cancer patients.
abstract: OBJECTIVE
  This exploratory study was aimed at elucidating the pharmacogenetics of regulatory nuclear receptors (PXR, CAR, RXRα and HNF4α) and their implications on docetaxel pharmacokinetics and pharmacodynamics in local Chinese nasopharyngeal cancer patients.
  
  
  METHODS
  A total of 59 single nucleotide polymorphisms (SNPs), including tag-SNPs and functionally relevant SNPs of the genes encoding these regulatory nuclear receptors (PXR/NR1I2, CAR/NR1I3, RXRα/NR2B1 and HNF4α/NR2A1), were profiled in the patients enrolled in our study by direct sequencing (N = 50). The generalized linear model was employed to estimate the haplotypic effects on the pharmacokinetics and pharmacodynamics of the patients.
  
  
  RESULTS
  The pharmacokinetic profiles of docetaxel in these patients were characterized by marked interindividual variability, with approximately four- to sixfold variations observed in Cmax, AUC0-∞ and CL. Individual SNP association tests revealed that polymorphisms in NR2B1 and NR2A1 were significantly correlated with altered docetaxel pharmacokinetics. Subsequent haplotype association analysis identified the NR2B1 LD block 2 AG haplotype [*+4458G>A(rs3132291) and *+4988A>G(rs4842198)] to be significantly associated with altered pharmacokinetics, in which patients carrying two copies of the AG haplotype had approximately a 20 % decreased Cmax and AUC0-∞ and a 21 % increased CL compared to those who carried only one copy or no copies of the haplotype. A number of SNPs in NR1I2, NR1I3, NR2B1 and NR2A1 were also associated with a significant decrease in blood counts from baseline. No haplotype was found to exert any effects on the pharmacodynamics parameters.
  
  
  CONCLUSIONS
  The present exploratory study identified several SNPs in the genes encoding regulatory nuclear receptors which may account for the interpatient variability in docetaxel pharmacokinetics and pharmacodynamics. These findings highlight the important role of regulatory nuclear receptors on the disposition of docetaxel.
authors.affiliation: Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore, Singapore, 117597.
authors.forename: Sin-Chi
authors.initials: SC
authors.lastname: Chew
authors.forename: Joanne
authors.initials: J
authors.lastname: Lim
authors.forename: Onkar
authors.initials: O
authors.lastname: Singh
authors.forename: Xiangai
authors.initials: X
authors.lastname: Chen
authors.forename: Eng-Huat
authors.initials: EH
authors.lastname: Tan
authors.forename: Edmund-J D
authors.initials: EJ
authors.lastname: Lee
authors.forename: Balram
authors.initials: B
authors.lastname: Chowbay
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D044466:Asian People / Q000235:genetics; D002277:Carcinoma; D000090702:Constitutive Androstane Receptor; D000077143:Docetaxel; D005260:Female; D006239:Haplotypes; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000235:genetics* / Q000378:metabolism*; D010976:Platelet Count; D020641:Polymorphism, Single Nucleotide; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*; D043823:Taxoids / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D000090702:Constitutive Androstane Receptor; D006454:Hemoglobins; C000716327:NR1I3 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D043823:Taxoids; D000077143:Docetaxel