Structural insights into how irreversible inhibitors can overcome drug resistance in EGFR

Resistance to kinase- targeted cancer drugs has recently been linked to a single point mutation in the ATP binding site of the kinase. In EGFR, the crucial Thr790 gatekeeper residue is mutated to a Met and prevents reversible ATP competitive inhibitors from binding. Irreversible 4-(phenylamino) quinazolines have been shown to overcome this drug resistance and are currently in clinical trials. In order to obtain a detailed structural understanding of how irreversible inhibitors overcome drug resistance, we used Src kinase as a model system for drug resistant EGFR-T790M. We report the first crystal structure of a drug resistant kinase in complex with an irreversible inhibitor. This 4-(phenylamino) quinazoline inhibits wild type and drug resistant EGFR in vitro at low nM concentrations. The co-crystal structure of drug resistant cSrc-T338M kinase domain provides the structural basis of this activity. (C) 2008 Elsevier Ltd. All rights reserved.