Aminofurazans as potent inhibitors of AKT kinase

AKT inhibitors containing an imidazopyridine aminofurazan scaffold have been optimized. We have previously disclosed identification of the AKT inhibitor GSK690693, which has been evaluated in clinical trials in cancer patients. Herein we describe recent efforts focusing on investigating a distinct region of this scaffold that have afforded compounds (30 and 32) with comparable activity profiles to that of GSK690693.     

2-Aminobenzimidazoles as potent Aurora kinase inhibitors

This Letter describes the discovery and key structure–activity relationship (SAR) of a series of 2-aminobenzimidazoles as potent Aurora kinase inhibitors. 2-Aminobenzimidazole serves as a bioisostere of the biaryl urea residue of SNS-314 (1c), which is a potent Aurora kinase inhibitor and entered clinical testing in patients with solid tumors. Compared to SNS-314, this series of compounds offers better aqueous solubility while retaining comparable in vitro potency in biochemical and cell-based assays; in particular, 6m has also demonstrated a comparable mouse iv PK profile to SNS-314.     

Highly potent aminopyridines as Syk kinase inhibitors

A novel class of potent Syk inhibitors has been developed from rational design. Highly potent aminopyridine derivatives bearing a 4-trifluoromethyl-2-pyridyl motif and represented by compound 13b IC(50): 0.6nM were identified. Substitution by a 2-pyrazinyl motif and SAR expansion in position 4 of the central core provided diverse potent non-cytotoxic Syk inhibitors showing nanomolar activity inhibiting human mast cell line LAD2 degranulation.     

1-substituted apomorphines as potent dopamine agonists

A novel set of 1-substituted apomorphines as dopaminergic agonists were synthesized according to our new strategy employing the acid-catalyzed rearrangement of diversely functionalized 5β-substituted-6-demethoxythebaines. The activities of new compounds for dopamine receptors subtypes were evaluated using HEK293 based stable cell lines expressing D₁, D_2L or D₃ receptor subtypes. All studied compounds had affinities in nanomolar range for D_2L and D₃ receptors and the change of the nature of substituent in position 1 had only moderate effect. D₁ receptors were sensitive to the introduction of the 4-OH-benzyl function resulting in an increased affinity. The small hydrophilic group (hydroxymethyl) highly reduced the agonist affinity and potency thereby increasing subtype selectivity. This strategy for selective modulation of affinities and potencies of 1-substituted apomorphines gives essential hints for future design of subtype selective dopaminergic ligands.     

Neutral 5-substituted 4-indazolylaminoquinazolines as potent, orally active inhibitors of erbB2 receptor tyrosine kinase

We have identified a new series of C-5 substituted indazolylaminoquinazolines as potent erbB2 kinase inhibitors. The lead compound 22 showed excellent in vitro potency, good physical properties, acceptable oral pharmacokinetics in rat and dog, and low human in vitro clearance. It showed at least equivalent activity dose for dose compared to lapatinib in various erbB2- or EGFR-driven xenograft models after chronic oral administration.     

Neutral 5-substituted 4-anilinoquinazolines as potent, orally active inhibitors of erbB2 receptor tyrosine kinase

Neutral 5-substituted 4-anilinoquinazolines addressed high in vivo clearance and phospholipidosis associated with previous basic compounds. A representative compound 8a inhibited tumor growth in a mouse xenograft model when co-administered with the cytochrome P450 inhibitor 1-aminobenzotriazole (ABT), and data are consistent with pharmacology primarily reflecting inhibition of erbB2 receptor tyrosine kinase.     

3-(Indol-2-yl)indazoles as Chek1 kinase inhibitors: Optimization of potency and selectivity via substitution at C6

The development of 3-(indol-2-yl)indazoles as inhibitors of Chek1 kinase is described. Introduction of amides and heteroaryl groups at the C6 position of the indazole ring system provided sufficient Chek1 potency and selectivity over Cdk7 to permit escape from DNA damage-induced arrest in a cellular assay. Enzyme potency against Chek1 was optimized by the incorporation of a hydroxymethyl triazole moiety in compound 21 (Chek1 IC₅₀ = 0.30 nM) that was shown by X-ray crystallography to displace one of three highly conserved water molecules in the HI region of the ATP-binding cleft.     

Discovery of 6-substituted 4-anilinoquinazolines with dioxygenated rings as novel EGFR tyrosine kinase inhibitors

It had been reported that some dioxygenated rings fusing with the quinazoline scaffold could lead to new EGFR inhibitors. Based on this, several kinds of oxygenated alkane quinazoline derivatives were synthetized and evaluated as EGFR inhibitors. Their antiproliferative activities were tested against four cancer cell lines: A431, MCF-7, A549, and B16-F10. Most derivatives could counteract EGF-induced EGFR phosphorylation, and their potency was comparable to the reference compound Erlotinib. The size of the fused dioxygenated ring was crucial for the biological activity and the heptatomic ring derivative 19 showed potent in vitro inhibitory activity in the enzymatic assay as well as in the cellular assay.     

Development of pyridopyrimidines as potent Akt1/2 inhibitors

This communication reports a new synthetic route of pyridopyrimidines to facilitate their structural optimization in a library fashion and describes the development of pyridopyrimidines that have excellent enzymatic and cell potency against Akt1 and Akt2. This series also shows a high level of selectivity over other closely related kinases and significantly improved caspase-3 activity with the more optimized compounds.     

Chroman-3-amides as potent Rho kinase inhibitors

Inhibition of Rho kinase (ROCK) is an attractive strategy for the treatment of diseases such as hypertension, glaucoma, and cancer. Here we report chroman-3-amides as highly potent ROCK inhibitors with sufficient kinase selectivity, excellent cell activity, good microsomal stability, and desirable pharmacokinetic properties for study as potential therapeutic agents.     

The discovery of potent cRaf1 kinase inhibitors

A series of benzylidene-1H-indol-2-one (oxindole) derivatives was synthesized and evaluated as cRaf-1 kinase inhibitors. The key features of the molecules were the donor/acceptor motif common to kinase inhibitors and a critical acidic phenol flanked by two substitutions. Diverse 5-position substitutions provided compounds with low nanomolar kinase enzyme inhibition and inhibited the intracellular MAPK pathway.     

4-Anilino-7-alkenylquinoline-3-carbonitriles as potent MEK1 kinase inhibitors

A series of substituted 7-alkenyl 4[3-chloro-4-(1-methyl-1H-imidazol-2-ylsulfanyl)]anilino-3-quinolinecarbonitrile analogs were synthesized and evaluated as MEK1 kinase inhibitors. The synthetic details, structure-activity relationships, biological activity, and selected oral exposure studies of these analogs are described. From these studies, compound 5m was chosen as a strong candidate for further evaluation. The selectivity of 5m was ascertained against a panel of 17 kinases, where activity was observed against EGFR, Src, Lyn, and IR kinases. Western blot studies in WM-266 cells demonstrated that 5m inhibited phosphorylation of ERK, while additional kinase pathways tested showed no inhibition at up to 10 microM of 5 m. PK studies, as well as a xenograft and in vivo biomarker studies are described for 5m.     

2-Amino-7-substituted benzoxazole analogs as potent RSK2 inhibitors

2-Amino-7-substituted benzoxazole analogs were identified by HTS as inhibitors of RSK2. Molecular modeling and medicinal chemistry techniques were employed to explore the SAR for this series with a focus of improving in vitro and target modulation potency and physicochemical properties.     

4-substituted cyclohexyl sulfones as potent, orally active gamma-secretase inhibitors

The protease gamma-secretase plays a pivotal role in the synthesis of pathogenic amyloid-beta in Alzheimer's disease (AD). Here, we report a further extension to a series of cyclohexyl sulfone-based gamma-secretase inhibitors which has allowed the preparation of highly potent compounds which also demonstrate robust Abeta(40) lowering in vivo (e.g., compound 32, MED 1mg/kg p.o. in APP-YAC mice).     

Structure-activity studies of 5-substituted pyridopyrimidines as adenosine kinase inhibitors

The synthesis and SAR of a novel series of non-nucleoside pyridopyrimidine inhibitors of the enzyme adenosine kinase (AK) are described. It was found that pyridopyrimidines with a broad range of medium and large non-polar substituents at the 5-position potently inhibited AK activity. A narrower range of analogues was capable of potently inhibiting adenosine phosphorylation in intact cells indicating an enhanced ability of these analogues to penetrate cell membranes. Potent AK inhibitors were found to effectively reduce nociception in animal models of thermal hyperalgesia and persistent pain.     

Synthesis and evaluation of substituted benzoisoquinolinones as potent inhibitors of Chk1 kinase

From HTS lead 1, a novel benzoisoquinolinone class of ATP-competitive Chk1 inhibitors was devised and synthesized via a photochemical route. Using X-ray crystallography as a guide, potency was rapidly enhanced through the installation of a tethered basic amine designed to interact with an acidic residue (Glu91) in the enzyme pocket. Further SAR was explored at the solvent front and near to the H1 pocket and resulted in the discovery of low MW, sub-nanomolar inhibitors of Chk1.     

N-substituted azaindoles as potent inhibitors of Cdc7 kinase

Cdc7 kinase is responsible for the initiation and regulation of DNA replication and has been proposed as a target for cancer therapy. We have identified a class of Cdc7 inhibitors based on a substituted indole core. Synthesis of focused indole and azaindole analogs yielded potent and selective 5-azaindole Cdc7 inhibitors with improved intrinsic metabolic stability (ie 36). In parallel, quantum mechanical conformational analysis helped to rationalize SAR observations, led to a proposal of the preferred binding conformation in the absence of co-crystallography data, and allowed the design of 7-azaindole 37 as a second lead in this series.     

Synthesis and activity of quinolinyl-methylene-thiazolinones as potent and selective cyclin-dependent kinase 1 inhibitors

A novel series of quinolinyl-methylene-thiazolinones has been identified as potent and selective cyclin-dependent kinase 1 (CDK1) inhibitors. Their synthesis and structure activity relationships (SAR) are described. Representative compounds from this class reversibly inhibit CDK1 activity in vitro, and block cell cycle progression in human tumor cell lines, suggesting a potential use as antitumor agents.     

Novel azulene-based derivatives as potent multi-receptor tyrosine kinase inhibitors

A series of azulene-based derivatives were synthesized as potent inhibitors for receptor tyrosine kinases such as FMS-like tyrosine kinase 3 (FLT-3). Systematic side chain modification of prototype 1a was carried out through SAR studies. Analogue 22 was identified from this series and found to be one of the most potent FLT-3 inhibitors, with good pharmaceutical properties, superior efficacy, and tolerability in a tumor xenograft model.     

Novel N1-substituted 1,3-dihydro-2H-benzimidazol-2-ones as potent non-nucleoside reverse transcriptase inhibitors

Several N(1)-substituted 1,3-dihydro-2H-benzimidazol-2-ones were synthesized and evaluated as anti-HIV agents. Some of them proved to be highly effective in inhibiting HIV-1 replication at nanomolar concentration as potent non-nucleoside HIV-1 RT inhibitors (NNRTIs) with low cytotoxicity. SAR studies highlighted that the nature of the substituents at N(1) and on the benzene ring of benzimidazolone moiety significantly influenced the anti-HIV activity of this class of potent antiretroviral agents.