Highly potent and selective 3-N-methylquinazoline-4(3H)-one based inhibitors of B-Raf(V600E) kinase.

Herein we describe the design of a novel series of ATP competitive B-Raf inhibitors via structure-based methods. These 3-N-methylquinazoline-4(3H)-one based inhibitors exhibit both excellent cellular potency and striking B-Raf selectivity. Optimization led to the identification of compound 16, a potent, selective and orally available agent with excellent pharmacokinetic properties and robust tumor growth inhibition in xenograft studies. Our work also demonstrates that by replacing an aryl amide with an aryl sulfonamide, a multikinase inhibitor such as AZ-628, can be converted to a selective B-Raf inhibitor, a finding that should have broad application in kinase drug discovery.

Pyrazolopyridine inhibitors of B-Raf(V600E). Part 4: rational design and kinase selectivity profile of cell potent type II inhibitors.

Cell potent inhibitors of B-Raf(V600E) that bind to the kinase in the DFG-out conformation are reported. These compounds utilize the hinge-binding group and lipophilic linker from a previously disclosed series of B-Raf(V600E) inhibitors that bind to the kinase in an atypical DFG-in, αC-helix-out conformation. This new series demonstrates that DFG-out kinase inhibitors can be rationally designed from related inhibitors which utilize an unconventional binding mode. Kinase selectivity profiles are compared. The pattern of kinase selectivity was found to be determined by the feature of the inhibitor which extends into the back pocket of the kinase and leads to the kinase conformation, rather than by the hinge-binding group or other minor modifications.

The discovery of potent and selective pyridopyrimidin-7-one based inhibitors of B-RafV600E kinase.

Herein we describe the discovery of a novel series of ATP competitive B-Raf inhibitors via structure based drug design (SBDD). These pyridopyrimidin-7-one based inhibitors exhibit both excellent cellular potency and striking B-Raf selectivity. Optimization led to the identification of compound 17, a potent, selective and orally available agent with excellent pharmacokinetic properties and robust tumor growth inhibition in xenograft studies.

Pyrazolopyridine inhibitors of B-RafV600E. Part 2: structure-activity relationships.

Structure-activity relationships around a novel series of B-Raf(V600E) inhibitors are reported. The enzymatic and cellular potencies of inhibitors derived from two related hinge-binding groups were compared and3-methoxypyrazolopyridine proved to be superior. The 3-alkoxy group of lead B-Raf(V600E) inhibitor 1 was extended and minimally affected potency. The propyl sulfonamide tail of compound 1, which occupies the small lipophilic pocket formed by an outward shift of the αC-helix, was expanded to a series of arylsulfonamides. X-ray crystallography revealed that this lipophilic pocket unexpectedly enlarges to accommodate the bulkier aryl group.

Discovery of 2-pyridylureas as glucokinase activators.

Glucokinase (GK) is the rate-limiting step for insulin release from the pancreas in response to high levels of glucose. Flux through GK also contributes to reducing hepatic glucose output. Since many individuals with type 2 diabetes appear to have an inadequacy or defect in one or both of these processes, identifying compounds that can allosterically activate GK may address this issue. Herein we report the identification and initial optimization of a novel series of glucokinase activators (GKAs). Optimization led to the identification of 33 as a compound that displayed activity in an oral glucose tolerance test (OGTT) in normal and diabetic mice.

Pyrazolopyridine Inhibitors of B-Raf(V600E). Part 1: The Development of Selective, Orally Bioavailable, and Efficacious Inhibitors.

The V600E mutation of B-Raf kinase results in constitutive activation of the MAPK signaling pathway and is present in approximately 7% of all cancers. Using structure-based design, a novel series of pyrazolopyridine inhibitors of B-Raf(V600E) was developed. Optimization led to the identification of 3-methoxy pyrazolopyridines 17 and 19, potent, selective, and orally bioavailable agents that inhibited tumor growth in a mouse xenograft model driven by B-Raf(V600E) with no effect on body weight. On the basis of their in vivo efficacy and preliminary safety profiles, 17 and 19 were selected for further preclinical evaluation.

Crystal structure of human AKT1 with an allosteric inhibitor reveals a new mode of kinase inhibition.

AKT1 (NP_005154.2) is a member of the serine/threonine AGC protein kinase family involved in cellular metabolism, growth, proliferation and survival. The three human AKT isozymes are highly homologous multi-domain proteins with both overlapping and distinct cellular functions. Dysregulation of the AKT pathway has been identified in multiple human cancers. Several clinical trials are in progress to test the efficacy of AKT pathway inhibitors in treating cancer. Recently, a series of AKT isozyme-selective allosteric inhibitors have been reported. They require the presence of both the pleckstrin-homology (PH) and kinase domains of AKT, but their binding mode has not yet been elucidated. We present here a 2.7 Å resolution co-crystal structure of human AKT1 containing both the PH and kinase domains with a selective allosteric inhibitor bound in the interface. The structure reveals the interactions between the PH and kinase domains, as well as the critical amino residues that mediate binding of the inhibitor to AKT1. Our work also reveals an intricate balance in the enzymatic regulation of AKT, where the PH domain appears to lock the kinase in an inactive conformation and the kinase domain disrupts the phospholipid binding site of the PH domain. This information advances our knowledge in AKT1 structure and regulation, thereby providing a structural foundation for interpreting the effects of different classes of AKT inhibitors and designing selective ones.