Pharmacogenetics of irinotecan: a promoter polymorphism of UGT1A1 gene and severe adverse reactions to irinotecan

Invest New Drugs. 2005 Dec;23(6):539-45. doi: 10.1007/s10637-005-4022-6.


This review focuses on a pharmacogenetic association between genetic polymorphism of UGT1A1 gene and severe adverse reactions to irinotecan. Although many studies used pharmacokinetic parameters as surrogate measures for predicting clinical outcomes of irinotecan chemotherapy, they have not produced consistent evidence. On the other hand, genotyping results of UGT1A1 gene appear to predict severe adverse reactions more straightforward than the pharmacokinetic parameters or the phenotypes of the enzymatic activity. A case-control study of Japanese cancer patients revealed that those with the variant UGT1A1 alleles were at significantly higher risk of severe adverse reactions to irinotecan, suggesting that the genotyping strategy would be clinically useful. Nevertheless, clinical importance of the pharmacogenetic testing should differ for different patient groups and for different clinical situations. We need to keep this issue in mind in applying the pharmacogenetic evidence in clinical practice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents, Phytogenic / adverse effects*
  • Antineoplastic Agents, Phytogenic / pharmacokinetics
  • Antineoplastic Agents, Phytogenic / therapeutic use
  • Camptothecin / adverse effects
  • Camptothecin / analogs & derivatives*
  • Camptothecin / pharmacokinetics
  • Camptothecin / therapeutic use
  • Diarrhea / chemically induced
  • Enzyme Inhibitors / adverse effects*
  • Enzyme Inhibitors / pharmacokinetics
  • Enzyme Inhibitors / therapeutic use
  • Genotype
  • Glucuronosyltransferase / genetics*
  • Glucuronosyltransferase / metabolism
  • Humans
  • Irinotecan
  • Leukopenia / chemically induced
  • Pharmacogenetics
  • Polymorphism, Genetic
  • Prodrugs / adverse effects*
  • Prodrugs / pharmacokinetics
  • Prodrugs / therapeutic use
  • Promoter Regions, Genetic
  • Topoisomerase I Inhibitors


  • Antineoplastic Agents, Phytogenic
  • Enzyme Inhibitors
  • Prodrugs
  • Topoisomerase I Inhibitors
  • Irinotecan
  • UGT1A1 enzyme
  • Glucuronosyltransferase
  • Camptothecin