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A series of new 6-substituted-4-(3-bromophenylamino)quinazoline derivatives that may function as irreversible inhibitors of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor (HER-2) tyrosine kinases have been prepared. These inhibitors have, at the C-6 position, butynamide, crotonamide, and methacrylamide Michael acceptors bearing water-solublilizing substituents. These compounds were prepared by acylation of 6-amino-4-(3-bromophenylamino)quinazoline with unsaturated acid chlorides or mixed anhydrides. We show that attaching a basic functional group onto the Michael acceptor results in greater reactivity, due to intramolecular catalysis of the Michael addition and/or an inductive effect of the protonated basic group. This, along with improved water solubility, results in compounds with enhanced biological properties. We present molecular modeling and experimental evidence that these inhibitors interact covalently with the target enzymes. One compound, 16a, was shown to have excellent oral activity in a human epidermoid carcinoma (A431) xenograft model in nude mice.

A series of of 6,7-disubstituted-4-anilinoquinoline-3-carbonitrile derivatives that function as irreversible inhibitors of EGFR and HER-2 kinases have been prepared. These inhibitors have, at the 6-position, butynamide, crotonamide, and methacrylamide Michael acceptors bearing water-solublilizing substituents. These compounds were prepared by acylation of 6-amino-4-(arylamino)quinoline-3-carbonitriles with unsaturated acid chlorides or mixed anhydrides. We performed competitive reactivity studies showing that attaching a dialkylamino group onto the end of the Michael acceptor results in compounds with greater reactivity due to intramolecular catalysis of the Michael addition. This, along with improved water-solubility results in compounds with enhanced biological properties. We present molecular modeling results consistent with the proposed mechanism of inhibition. One compound, 5 (EKB-569), which shows excellent oral in vivo activity, was selected for further studies and is currently in phase I clinical trials for the treatment of cancer.

A series of new 6,7-disubstituted-4-(arylamino)quinoline-3-carbonitrile derivatives that function as irreversible inhibitors of human epidermal growth factor receptor-2 (HER-2) and epidermal growth factor receptor (EGFR) kinases have been prepared. These compounds demonstrated enhanced activities for inhibiting HER-2 kinase and the growth of HER-2 positive cells compared to our EGFR kinase inhibitor 86 (EKB-569). Three synthetic routes were used to prepare these compounds. They were prepared mostly by acylation of 6-amino-4-(arylamino)quinoline-3-carbonitriles with unsaturated acid chlorides or by amination of 4-chloro-6-(crotonamido)quinoline-3-carbonitriles with monocyclic or bicyclic anilines. The third route was developed to prepare a key intermediate, 6-acetamido-4-chloroquinoline-3-carbonitrile, that involved a safer cyclization step. We show that attaching a large lipophilic group at the para position of the 4-(arylamino) ring results in improved potency for inhibiting HER-2 kinase. We also show the importance of a basic dialkylamino group at the end of the Michael acceptor for activity, due to intramolecular catalysis of the Michael addition. This, along with improved water solubility, resulted in compounds with enhanced biological properties. We present molecular modeling results consistent with the proposed mechanism of inhibition. Binding studies of one compound, 25o (C-14 radiolabeled), showed that it binds irreversibly to HER-2 protein in BT474 cells. Furthermore, it demonstrated excellent oral activity, especially in HER-2 overexpressing xenografts. Compound 25o (HKI-272) was selected for further studies and is currently in phase I clinical trials for the treatment of cancer.

The synthesis and SAR of a series of 4-anilino-6, 7-dialkoxyquinoline-3-carbonitrile inhibitors of epidermal growth factor receptor (EGF-R) kinase are described. Condensation of 3, 4-dialkoxyanilines with ethyl (ethoxymethylene)cyanoacetate followed by thermal cyclization gave, regiospecifically, 6,7-dialkoxy-4-oxo-1, 4-dihydroquinoline-3-carbonitriles. Chlorination (POCl(3)) followed by the reaction with substituted anilines furnished the 4-anilino-6, 7-dialkoxyquinoline-3-carbonitrile inhibitors of EGF-R kinase. An alternate synthesis of these compounds starts with a methyl 3, 4-dialkoxybenzoate. Nitration followed by reduction (Fe, NH(4)Cl, MeOH-H(2)O) gave a methyl 2-amino-4,5-dialkoxybenzoate. Amidine formation using DMF-acetal followed by cyclization using LiCH(2)CN furnished a 6,7-dialkoxy-4-oxo-1,4-dihydroquinoline-3-carbonitrile, which was transformed as before. Compounds containing acid, ester, amide, carbinol, and aldehyde groups at the 3-position of the quinoline ring were also prepared for comparison, as were several 1-anilino-6,7-dimethoxyisoquinoline-4-carbonitriles. The compounds were evaluated for their ability to inhibit the autophosphorylation of the catalytic domain of EGF-R. The SAR of these inhibitors with respect to the nature of the 6,7-alkoxy groups, the aniline substituents, and the substituent at the 3-position was studied. The compounds were further evaluated for their ability to inhibit the growth of cell lines that overexpress EGF-R or HER-2. It was found that 4-anilinoquinoline-3-carbonitriles are effective inhibitors of EGF-R kinase with activity comparable to the 4-anilinoquinazoline-based inhibitors. A new homology model of EGF-R kinase was constructed based on the X-ray structures of Hck and FGF receptor-1 kinase. The model suggests that with the quinazoline-based inhibitors, the N3 atom is hydrogen-bonded to a water molecule which, in turn, interacts with Thr 830. It is proposed that the quinoline-3-carbonitriles bind in a similar manner where the water molecule is displaced by the cyano group which interacts with the same Thr residue.

The cyclin-dependent kinases (CDKs), as complexes with their respective partners, the cyclins, are critical regulators of cell cycle progression. Because aberrant regulations of CDK4/cyclin D1 lead to uncontrolled cell proliferation, a hallmark of cancer, small-molecule inhibitors of CDK4/cyclin D1 are attractive as prospective antitumor agents. The series of 4-(phenylaminomethylene)isoquinoline-1,3(2H,4H)-dione derivatives reported here represents a novel class of potent inhibitors that selectively inhibit CDK4 over CDK2 and CDK1 activities. In the headpiece of the 4-(phenylaminomethylene)isoquinoline-1,3(2H,4H)-dione, a basic amine substituent is required on the aniline ring for the CDK4 inhibitory activity. The inhibitory activity is further enhanced when an aryl or heteroaryl substituent is introduced at the C-6 position of the isoquinoline-1,3(2H,4H)-dione core. We present here SAR data and a CDK4 mimic model that explains the binding, potency, and selectivity of our CDK4 selective inhibitors.

No abstract

The series of 4-(benzylaminomethylene)isoquinoline-1,3-(2H,4H)-dione and 4-[(pyridylmethyl)aminomethylene]isoquinoline-1,3-(2H,4H)-dione derivatives reported here represents a novel class of potential antitumor agents, which potently and selectively inhibit CDK4 over CDK2 and CDK1. In the benzylamino headpiece, a 3-OH substituent is required on the phenyl ring for CDK4 inhibitory activity, which is further enhanced when an iodo, aryl, heteroaryl, t-butyl, or cyclopentyl substituent is introduced at the C-6 position of the isoquinoline-1,3-dione core. To circumvent the metabolic liability associated with the phenolic OH group on the 4-substituted 3-OH phenyl headpiece, we take two approaches: first, introduce a nitrogen o- or p- to the 3-OH group in the phenyl ring; second, replace the phenyl headpiece with N-substituted 2-pyridones. We present here the synthesis, SAR data, metabolic stability data, and a CDK4 mimic model that explains the binding, potency, and selectivity of our CDK4 selective inhibitors.