Biochemical assay-based selectivity profiling of clinically relevant kinase inhibitors on mutant forms of EGF receptor.

Gefitinib and erlotinib are potent EGFR tyrosine kinase inhibitors (potentially) useful for the treatment of non-small-cell lung cancer (NSCLC). Clinical responses, however, in NSCLC patients have been linked to the presence of certain activating mutations of EGFR. We used an ELISA-based biochemical assay to confirm the selective inhibitory efficacy of gefitinib and erlotinib on the activated mutant receptor. Our results are in line with the clinical observations providing evidence for the predictive power of the kinase assay. Four additional compounds were also investigated: CI-1033 and EKB-569 had dramatic inhibitory effects on all EGFR forms, whereas PD153035 and AG1478 were active on wild-type and activating mutant protein. In docking simulations with wild-type EGFR, our inhibitory data are in good agreement with the binding scores. These data confirm that anilinoquinazolines are good starting structures for the next generation of selective drugs against mutant EGFR, whereas CI-1033 and EKB-569 may represent advances for patients with both wild-type and anilinoquinazoline-resistant mutant tumors.