[Irinotecan pharmacogenetics in Japanese cancer patients: roles of UGT1A1*6 and *28].

Recent progress in pharmacogenetic research has made "personalized medicine" a reality, where a suitable drug at the appropriate dosage is prescribed based on individual genetic factors. Irinotecan, an anticancer drug, is one of the models for personalized medicine, and a number of clinical studies have revealed significant associations between UGT1A1(*)28 and irinotecan toxicity. Based on the cumulative evidence, clinical tests for the UGT1A1(*)28 marker have started in the United States since 2005. However, the appropriate criteria for irinotecan dose adjustments have not yet been fully established. Since there are considerable differences in genetic polymorphisms among different ethnic groups and in approved irinotecan-containing regimens between countries, the criteria for the choice of suitable genetic markers and dose adjustments should be standardized in each country. This mini-review outlines our recent studies on irinotecan pharmacogenetics and discusses the clinical significance of UGT1A1(*)6 and (*)28 markers for personalized irinotecan therapy in Japanese cancer patients.