Dual irreversible kinase inhibitors: quinazoline-based inhibitors incorporating two independent reactive centers with each targeting different cysteine residues in the kinase domains of EGFR and VEGFR-2.

A series of 4-dimethylamino-but-2-enoic acid [4-(3,6-dioxo-cyclohexa-1,4-dienylamino)-7-ethoxy-quinazolin-6-yl]-amide derivatives were prepared. These compounds have two independent reactive centers and were designed to function as dual irreversible inhibitors of the kinase domains of both Epidermal Growth Factor Receptor (EGFR) and Vascular Endothelial Growth Factor Receptor-2 (VEGFR-2) where each reactive center targets a different, non-conserved, cysteine residue located in the ATP binding pocket of these enzymes. The compounds contain a 6-(4-(dimethylamino) crotonamide) Michael acceptor group that targets Cys-773 in EGFR and a 4-(amino-[1,4]benzoquinone) moiety that targets Cys-1045 in VEGFR-2. In vitro studies indicated that most of these compounds are relatively potent inhibitors of each enzyme. These inhibitors were compared with reference compounds that lack one or both of the reactive centers. The relative dependence of the IC(50) values on the concentration of ATP used in the assays suggests that these compounds appear to function as irreversible inhibitors of each kinase.

2-(Quinazolin-4-ylamino)-[1,4]benzoquinones as covalent-binding, irreversible inhibitors of the kinase domain of vascular endothelial growth factor receptor-2.

A series of 2-(quinazolin-4-ylamino)-[1,4] benzoquinone derivatives that function as potent covalent-binding, irreversible inhibitors of the kinase domain of vascular endothelial growth factor receptor-2 (VEGFR-2) has been prepared by ceric ammonium nitrate oxidation of substituted (2,5-dimethoxyphenyl)(6,7-disubstituted-quinazolin-4-yl)amines and by displacement of the chlorine atom of substituted 2-chloro-5-(6,7-disubstituted-quinazolin-4-ylamino)-[1,4]benzoquinones with various amines, anilines, phenols, and alcohols. Enzyme studies were conducted in the absence and presence of glutathione and plasma. Several of the compounds inhibit VEGF-stimulated autophosphorylation in intact cells. Kinetic experiments were performed to study the reactivity of selected inhibitors toward glutathione. Reactivities correlated with LUMO energies calculated as averages of those of individual conformers weighted by the Boltzmann distribution. These results and molecular modeling were used to rationalize the biological observations. The compounds behave as non-ATP-competitive inhibitors. Unequivocal evidence, from mass spectral studies, indicates that these inhibitors form a covalent interaction with Cys-1045. One member of this series displays antitumor activity in an in vivo model.