Polymorphisms of the UDP-glucuronosyl transferase 1A genes are associated with adverse events in cancer patients receiving irinotecan-based chemotherapy

Tohoku J Exp Med. 2013 Feb;229(2):107-14. doi: 10.1620/tjem.229.107.


A prodrug, irinotecan (CPT-11), is a semisynthetic derivative of camptothecin. It inhibits topoisomerase I and is used for treatment of lung, stomach, and colon cancers in Japan. The active form of CPT-11, SN-38, causes the adverse events such as neutropenia and diarrhea. Since SN-38 is metabolized to non-toxic SN-38-glucuronide by hepatic uridine diphosphate glucuronosyl transferase (UGT) 1A enzymes, UGT1A enzyme activities may influence adverse events of CPT-11. UGT1A enzymes consist of three isozymes (1A1, 1A7, 1A9), and their genes are characterized by polymorphisms. Here, to identify the genetic factors that affect the adverse events of CPT-11, we determined the polymorphism in three UGT 1A isozyme genes in 45 inpatients with lung, colon, or stomach cancer. The univariate and multivariate analysis of patients' physiological and genetic factors revealed that one or more genotypes of UGT1A1*6/*28, UGT1A7*3/*3, and UGT1A9*1/*1 may enhance the adverse events. Each of the first two genotypes is expected to generate the enzyme with low catalytic activity. The UGT1A9*1 represents the wild-type allele, which however provides the lower catalytic activity, compared to the UGT1A9*22 variant that is common in this study population. Indeed, four (67%) out of six patients who carry one or more of the above-mentioned genotypes suffered from adverse events, leading to the discontinuation of chemotherapy or the decreased dose of CPT-11. By contrast, only six (15%) out of 39 patients with other genotypes suffered from adverse events. In conclusion, UGT1A1*6/*28, UGT1A7*3/*3, and UGT1A9*1/*1 should be taken into consideration as markers for preventing severe adverse events of CPT-11 administration.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents, Phytogenic / adverse effects*
  • Camptothecin / adverse effects
  • Camptothecin / analogs & derivatives*
  • Colonic Neoplasms / drug therapy
  • Colonic Neoplasms / genetics
  • Colonic Neoplasms / pathology
  • Diarrhea / chemically induced
  • Drug-Related Side Effects and Adverse Reactions / etiology
  • Drug-Related Side Effects and Adverse Reactions / genetics*
  • Female
  • Genetic Predisposition to Disease
  • Glucuronosyltransferase / genetics*
  • Humans
  • Irinotecan
  • Isoenzymes
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / genetics
  • Lung Neoplasms / pathology
  • Male
  • Middle Aged
  • Neoplasms / drug therapy*
  • Neoplasms / genetics*
  • Neoplasms / pathology
  • Neutropenia / chemically induced
  • Pharmacogenetics
  • Polymorphism, Genetic*
  • Stomach Neoplasms / drug therapy
  • Stomach Neoplasms / genetics
  • Stomach Neoplasms / pathology


  • Antineoplastic Agents, Phytogenic
  • Isoenzymes
  • Irinotecan
  • UGT1A1 enzyme
  • Glucuronosyltransferase
  • Camptothecin