Potential clinical benefit of therapeutic drug monitoring of imatinib in oncology

Abstract

Imatinib mesylate is a competitive inhibitor of BCR/ ABL tyrosine kinase and inhibits also several receptor tyrosin kinases. Since its launch to the market, imatinib has proven to be very valuable in the treatment of Philadelphia chromosome (BCR/ ABL) - positive (Ph+) chronic myeloid leukemia and Kit (CD117) positive gastrointestinal stromal tumors. The drug is metabolized by cytochrome P450, and there are many clinically important pharmacokinetic drug-drug interactions described in the literature. Frequent polypharmacy in oncological patients increases probability of such interactions, and also adherence may play its role during longterm treatment. Fixed dosing therapeutic regimens fail to respect known interindividual variability in pharmacokinetics of the drug and thus, some patients may not achieve sufficient plasma concentrations. Based on current evidence, there seems to be a relationship between plasma concentration and clinical response to imatinib. Therefore, imatinib appears to be suitable candidate for therapeutic drug monitoring. Here, we present an overview of pharmacokinetics, drug-drug interactions and current knowledge and suggestions on therapeutic drug monitor-ing of imatinib, its potential benefits and limitations.