Discovery of potent and cell-active allosteric dual Akt 1 and 2 inhibitors

This paper describes the improvement of cell potency in a class of allosteric Akt 1 and 2 inhibitors. Key discoveries include identifying the solvent exposed region of the molecule and appending basic amines to enhance the physiochemical properties of the molecules. Findings from the structure–activity relationships are discussed.     

Discovery of EBI-1051: A novel and orally efficacious MEK inhibitor with benzofuran scaffold

A novel series of benzodihydrofuran derivatives was developed as potent MEK inhibitors through scaffold hopping based on known clinical compounds. Further SAR exploration and optimization led to another benzofuran series with good oral bioavailability in rats. One of the compounds EBI-1051 (28d) demonstrated excellent in vivo efficacy in colo-205 tumor xenograft models in mouse and is suitable for pre-clinical development studies for the treatment of melanoma and MEK associated cancers. Compared to AZD6244, EBI-1051 showed superior potency in some cancer cell lines such as colon-205, A549 and MDA-MB-231.     

Design and synthesis of novel allosteric MEK inhibitor CH4987655 as an orally available anticancer agent

The MAP kinase pathway is one of the most important pathways involved in cell proliferation and differentiation, and its components are promising targets for antitumor drugs. Design and synthesis of a novel MEK inhibitor, based on the 3D-structural information of the target enzyme, and then multidimensional optimization including metabolic stability, physicochemical properties and safety profiles were effectively performed and led to the identification of a clinical candidate for an orally available potent MEK inhibitor, CH4987655, possessing a unique 3-oxo-oxazinane ring structure at the 5-position of the benzamide core structure. CH4987655 exhibits slow dissociation from the MEK enzyme, remarkable in vivo antitumor efficacy both in mono- and combination therapy, desirable metabolic stability, and insignificant MEK inhibition in mouse brain, implying few CNS-related side effects in human. An excellent PK profile and clear target inhibition in PBMC were demonstrated in a healthy volunteer clinical study.     

Identification of coumarin derivatives as a novel class of allosteric MEK1 inhibitors

A homogenous TR-FRET-based in vitro coupling assay for the MAP3Ks–MEK1–ERK2 kinase cascade was established and was used to screen for inhibitors of the ERK/MAPK pathway. A series of coumarin derivatives were identified from the screen. These compounds potently inhibit the activation of the unactivated human MEK1 by upstream MAP3Ks (including BRAF and COT), but do not inhibit the activity of the activated MEK1. In addition, the potency of these compounds in inhibiting MEK1 activation is not affected by varying the ATP concentration, suggesting that these inhibitors are not competitive with ATP. As expected, the coumarin compounds potently inhibit LPS-induced TNF production and ERK phosphorylation in THP-1 cells, with the most potent compound having an IC₅₀ of 90 nM. Molecular modeling studies suggest that these coumarins bind to an allosteric site in the inactive conformation of MEK1. This site has been shown to be utilized by the biarylamine series of MEK inhibitors such as PD318088. Very interestingly, the identified coumarin derivatives are almost identical to a series of inhibitors recently reported that block LPS-induced TNF production. Our findings have therefore raised the possibility that other naturally occurring or synthetic coumarins with anti-cancer and anti-inflammatory activities might exert their biological function through the inhibition of MEK1.     

Discovery,design and synthesis of a selective S1P3 receptor allosteric agonist

Potent and selective S1P₃ receptor (S1P₃-R) agonists may represent important proof-of-principle tools used to clarify the receptor biological function and assess the therapeutic potential of the S1P₃-R in cardiovascular, inflammatory and pulmonary diseases. N,N-Dicyclohexyl-5-propylisoxazole-3-carboxamide was identified by a high-throughput screening of MLSMR library as a promising S1P₃-R agonist. Rational chemical modifications of the hit allowed the identification of N,N-dicyclohexyl-5-cyclopropylisoxazole-3-carboxamide, a S1P₃-R agonist endowed with submicromolar activity and exquisite selectivity over the remaining S1P_1,2,4,5-R family members. A combination of ligand competition, site-directed mutagenesis and molecular modeling studies showed that the N,N-dicyclohexyl-5-cyclopropylisoxazole-3-carboxamide is an allosteric agonist and binds to the S1P₃-R in a manner that does not disrupt the S1P₃-R–S1P binding. The lead molecule herein disclosed constitutes a valuable pharmacological tool to explore the molecular basis of the receptor function, and provides the bases for further rational design of more potent and drug-like S1P₃-R allosteric agonists.     

Discovery of a cobalt complex with high MEK1 binding affinity

A series of Schiff base ligands (L¹–L⁵) and their cobalt(II) complexes (1–5) were designed and synthesized for MEK1 binding experiment. The biological evaluation results showed that Bis(N,N′-disalicylidene)-3,4-phenylenediamine-cobalt(II) 1 and Bis(N,N′-disalicylidene)-1,2-cyclohexanediamine-cobalt(II) 2 are much more effective than the parent Schiff bases (L¹ and L²). Importantly, 2 exhibited MEK1 binding affinity with IC₅₀71 nM, which is so far the best result for metal complexes and more potent than U0126 (7.02 μM) and AZD6244 (2.20 μM). Docking study was used to elucidate the binding modes of complex 2 with MEK1. Thus cobalt(II) complex 2 may be further developed as a novel MEK1 inhibitor.     

Discovery of GSK143, a highly potent, selective and orally efficacious spleen tyrosine kinase inhibitor

The lead optimisation of the diaminopyrimidine carboxamide series of spleen tyrosine kinase inhibitors is described. The medicinal chemistry strategy was focused on optimising the human whole blood activity whilst achieving a sufficient margin over liability kinases and hERG activity. GSK143 is a potent and highly selective SYK inhibitor showing good efficacy in the rat Arthus model.     

The design and synthesis of potent and cell-active allosteric dual Akt 1 and 2 inhibitors devoid of hERG activity

This letter details the attenuation of hERG in a class of Akt inhibitors through heteroatom insertions into aromatic rings. The development of a cell-active dual Akt 1 and 2 inhibitors devoid of hERG activity is discussed using structure–activity relationships.     

Discovery of PH-797804, a highly selective and potent inhibitor of p38 MAP kinase

The synthesis and SAR studies of a novel N-aryl pyridinone class of p38 kinase inhibitors are described. Systematic structural modifications to the HTS lead, 5, led to the identification of (−)-4a as a clinical candidate for the treatment of inflammatory diseases. Additionally, the chiral synthesis and properties of (−)-4a are described.     

Structure-based design and synthesis of bicyclic fused-pyridines as MEK inhibitors

The MAPK pathway is identified as one of the most important pathways involved in cell proliferation and differentiation. A key kinase in the pathway, the Mitogen-activated protein kinase kinase (MEK) is recognized as a promising target for antitumor drugs. Structure-based design and optimization of known MEK inhibitors resulted in identification of compound 10a as a potent non-ATP competitive MEK inhibitor in both in vitro and in vivo tests.     

Discovery of a potent and selective c-Kit inhibitor for the treatment of inflammatory diseases

A potent and selective c-Kit inhibitor 20 was identified through a structure–activity relationship study. In an in vivo mouse model of mast cell activation, 20 blocked the SCF-induced histamine release with an EC₅₀ of 26 nM.     

Discovery of triazine-benzimidazoles as selective inhibitors of mTOR

mTOR is part of the PI3K/AKT pathway and is a central regulator of cell growth and survival. Since many cancers display mutations linked to the mTOR signaling pathway, mTOR has emerged as an important target for oncology therapy. Herein, we report the discovery of triazine benzimidazole inhibitors that inhibit mTOR kinase activity with up to 200-fold selectivity over the structurally homologous kinase PI3Kα. When tested in a panel of cancer cell lines displaying various mutations, a selective inhibitor from this series inhibited cellular proliferation with a mean IC₅₀ of 0.41 μM. Lead compound 42 demonstrated up to 83% inhibition of mTOR substrate phosphorylation in a murine pharmacodynamic model.     

Discovery of a potent and selective aurora kinase inhibitor

This communication describes the discovery of a novel series of Aurora kinase inhibitors. Key SAR and critical binding elements are discussed. Some of the more advanced analogues potently inhibit cellular proliferation and induce phenotypes consistent with Aurora kinase inhibition. In particular, compound 21 (SNS-314) is a potent and selective Aurora kinase inhibitor that exhibits significant activity in pre-clinical in vivo tumor models.     

Design,synthesis and evaluation of acridine derivatives as multi-target Src and MEK kinase inhibitors for anti-tumor treatment

Clinical studies have shown enhanced anticancer effects of combined inhibition of Src and MEK kinases. Development of multi-target drugs against Src and MEK is of potential therapeutic advantage against cancers. As a follow-up of our previous studies, and by using molecular docking method, we designed and synthesized a new series of 9-anilinoacridines containing phenyl-urea moieties as potential novel dual Src and MEK inhibitors. The anti-proliferative assays against K562 and HepG-2 tumor cells showed that most of the derivatives displayed good cytotoxicity in vitro. In particular, kinase inhibition assays showed that compound 8m inhibited Src (59.67%) and MEK (43.23%) at 10 μM, and displayed moderate inhibitory activity against ERK and AKT, the downstream effectors of both Src and MEK. Moreover, compound 8m was found to induce K562 cells apoptosis. Structure–activity relationships of these derivatives were analyzed. Our study suggested that acridine scaffold, particularly compound 8m, is of potential interest for developing novel multi-target Src and MEK kinase inhibitors.     

The sulfamide moiety affords higher inhibitory activity and oral bioavailability to a series of coumarin dual selective RAF/MEK inhibitors

Introducing a sulfamide moiety to our coumarin derivatives afforded enhanced Raf/MEK inhibitory activity concomitantly with an acceptable PK profile. Novel sulfamide 17 showed potent HCT116 cell growth inhibition (IC₅₀ = 8 nM) and good PK profile (bioavailability of 51% in mouse), resulting in high in vivo antitumor efficacy in the HCT116 xenograft (ED₅₀ = 4.8 mg/kg). We confirmed the sulfamide moiety showed no negative impact on tests run on the compound to evaluate DMPK (PK profiles in three animal species, CYP inhibition and CYP induction) and the safety profile (hERG and AMES tests). Sulfamide 17 had favorable properties that warranted further preclinical assessment     

Rational discovery of a highly novel and selective mTOR inhibitor

Aided by Structure Based Drug Discovery (SBDD), we rapidly designed a highly novel and selective series of mTOR inhibitors. This chemotype conveys exquisite kinase selectivity, excellent in vitro and in vivo potencies and ADME safety profiles. These compounds could serve as good tools to explore the potential of TORC inhibition in various human diseases.     

Discovery of novel 3,5-disubstituted indole derivatives as potent inhibitors of Pim-1, Pim-2, and Pim-3 protein kinases

A series of novel 3,5-disubstituted indole derivatives as potent and selective inhibitors of all three members of the Pim kinase family is described. High throughput screen identified a pan-Pim kinase inhibitor with a promiscuous scaffold. Guided by structure-based drug design, SAR of the series afforded a highly selective indole chemotype that was further developed into a potent set of compounds against Pim-1, 2, and 3 (Pim-1 and Pim-3: IC(50)≤2nM and Pim-2: IC(50)≤100nM).     

Discovery of potent and selective spiroindolinone MDM2 inhibitor,RO8994, for cancer therapy

The field of small-molecule inhibitors of protein–protein interactions is rapidly advancing and the specific area of inhibitors of the p53/MDM2 interaction is a prime example. Several groups have published on this topic and multiple compounds are in various stages of clinical development. Building on the strength of the discovery of RG7112, a Nutlin imidazoline-based compound, and RG7388, a pyrrolidine-based compound, we have developed additional scaffolds that provide opportunities for future development. Here, we report the discovery and optimization of a highly potent and selective series of spiroindolinone small-molecule MDM2 inhibitors, culminating in RO8994.     

Discovery of potent and selective Spleen Tyrosine Kinase inhibitors for the topical treatment of inflammatory skin disease

The discovery and lead optimisation of a novel series of SYK inhibitors is described. These were optimised for SYK potency and selectivity against Aurora B. Compounds were profiled in a human skin penetration study to identify a suitable candidate molecule for pre-clinical development. Compound 44 (GSK2646264) was selected for progression and is currently in Phase I clinical trials.     

Discovery of XL413, a potent and selective CDC7 inhibitor

CDC7 is a serine/threonine kinase that has been shown to be required for the initiation and maintenance of DNA replication. Up-regulation of CDC7 is detected in multiple tumor cell lines, with inhibition of CDC7 resulting in cell cycle arrest. In this paper, we disclose the discovery of a potent and selective CDC7 inhibitor, XL413 (14), which was advanced into Phase 1 clinical trials. Starting from advanced lead 3, described in a preceding communication, we optimized the CDC7 potency and selectivity to demonstrate in vitro CDC7 dependent cell cycle arrest and in vivo tumor growth inhibition in a Colo-205 xenograft model.