Tyrosine kinase inhibitors. 18. 6-substituted 4-anilinoquinazolines and 4-anilinopyrido [3,4-d]pyrimidines as soluble, irreversible inhibitors of theepidermal growth factor receptor

4-Anilinoquinazoline- and 4-anilinopyrido[3,4-d]pyrimidine-6-acrylamides ar e potent pan-erbB tyrosine kinase inactivators, and one example (CI-1033) i s in clinical trial. A series of analogues with a variety of Michael accept or units at the 6-position were prepared to define the structural requireme nts for irreversible inhibition. A particular goal was to determine whether additional functions to increase solubility could be appended to the Micha el acceptor. Substituted acrylamides were prepared by direct acylation of t he corresponding 6-amines with the requisite acid or acid chloride. Vinylsu lfonamide derivatives were obtained by acylation of the amines with chloroe thylsulfonyl chloride followed by base-promoted elimination. Vinylsulfone a nd vinylsulfine derivatives were prepared by oxidation and base elimination of a hydroxyethylthio intermediate. The compounds were evaluated for their inhibition of phosphorylation of the isolated EGFR enzyme and for inhibiti on of EGF-stimulated autophosphorylation of EGFR in A431 cells and of hereg ulin-stimulated autophosphorylation of erbB2 in MDA-MB 453 cells. Substitut ion at the nitrogen of the acrylamide was tolerated only with a methyl grou p; larger substituents were dystherapeutic, and no substitution at all was tolerated at the acrylamide ex-carbon. In contrast, while electron-donating groups at the acrylamide P-carbon were not useful, even quite large electr on-withdrawing groups (which increase its electrophilicity) were tolerated. A series of derivatives with solubility-enhancing substituents linked to t he acrylamide P-carbon via amides were potent irreversible inhibitors of is olated EGFR (IC(50)s = 0.4-1.1 nM), with weakly basic morpholine and imidaz ole derivatives being the best. Vinylsulfonamides were also potent and irre versible inhibitors, but vinylsulfones and vinylsulfines were reversible an d only poorly active. Two compounds were evaluated against A431, H125, and MCF-7 xenografts in nude mice but were inferior in these assays to the clin ical trial compound CI-1033.