Irinogenetics: What Is the Right Star?

The response of patients to drug therapy is variable and un-predictable. The current focus of pharmacogenetics is to find com-mon genetic variants that are predictors of clinical phenotypes associated with drug therapy. This goal is usually pursued by geno-typing patients for a particular polymorphism (a genetic variant occurring in 1 % of the population), a set of polymorphisms in the same gene, or different polymorphisms in different genes. The genes of interest in pharmacogenetics are those involved in the mechanism of action and/or disposition of a certain drug. For the classic cytotoxic agents commonly used in oncology, the eluci-dation of potential genetic predispositions of patients to severe toxicity has been of interest with a goal of improving their thera-peutic index. The pharmacogenetics of irinotecan (irinogenetics)1 indicate that a common polymorphism in the uridine diphosphate-