Structure-based design of potent inhibitors of EGF-receptor tyrosine kinase as anti-cancer agents.

Abstract

In a systematic effort to design inhibitors of the epidermal growth factor receptor (EGFR) family protein tyrosine kinases (PTK) as anti-cancer agents, we have constructed a three-dimensional homology model of the EGFR kinase domain and used molecular modeling methods for the structure-based design of analogs of the active metabolite of leflunomide (LFM) with potent and specific inhibitory activity against EGFR. These docking studies identified alpha-cyano-beta-hydroxy-beta-methyl-N-[4-(trifluoromethoxy)phenyl]-p ropenamide (LFM-A12) as our lead compound, which was predicted to bind to the EGFR catalytic site in a planar conformation. LFM-A12 inhibited the proliferation (IC50 = 26.3 microM) and in vitro invasiveness (IC50 = 28.4 microM) of EGFR positive human breast cancer cells in a concentration-dependent fashion. Similarly, the model of the EGFR binding pocket was used in combination with docking procedures to predict the favorable placement of chemical groups with defined sizes at multiple modification sites on another class of EGFR inhibitors, the 4-anilinoquinazoline. This approach has led to the successful design of a dibromo quinazoline derivative, WHI-P97, which had an estimated Ki value of 0.09 microM from modeling studies and a measured IC50 value of 2.5 microM in EGFR kinase inhibition assays. WHI-P97 effectively inhibited the in vitro invasiveness of EGFR-positive human cancer cells in a concentration-dependent manner. However, unlike LFM-A12, the quinazoline compounds are not specific for EGFR.