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Novel conformationally constrained BET bromodomain inhibitors have been developed. These inhibitors were optimized in two similar, yet distinct chemical series, the 6-methyl-1H-pyrrolo[2,3-c]pyridin-7(6H)-ones (A) and the 1-methyl-1H-pyrrolo[2,3-c]pyridin-7(6H)-ones (B). Each series demonstrated excellent activity in binding and cellular assays, and lead compounds from each series demonstrated significant efficacy in in vivo tumor xenograft models., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

An NMR fragment screen for binders to the bromodomains of BRD4 identified 2-methyl-3-ketopyrroles 1 and 2. Elaboration of these fragments guided by structure-based design provided lead molecules with significant activity in a mouse tumor model. Further modifications to the methylpyrrole core provided compounds with improved properties and enhanced activity in a mouse model of multiple myeloma., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

We report the synthesis and biological evaluation of 5-substituted indazoles as kinase inhibitors. The compounds were synthesized in a parallel synthesis fashion from readily available starting materials employing heterocycle forming and multicomponent reactions and were evaluated against a panel of kinase assays. Potent inhibitors were identified for Gsk3β, Rock2, and Egfr., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

We report the synthesis and biological evaluation of 5-substituted indazoles and amino indazoles as kinase inhibitors. The compounds were synthesized in a parallel synthesis fashion from readily available starting materials employing [2+3] cycloaddition reactions and were evaluated against a panel of kinase assays. Potent inhibitors were identified for numerous kinases such as Rock2, Gsk3β, Aurora2 and Jak2., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

This Letter describes the lead discovery, optimization, and biological characterization of a series of substituted 4-amino-1H-pyrazolo[3,4-d]pyrimidines as potent inhibitors of IGF1R, EGFR, and ErbB2. The leading compound 11 showed an IGF1R IC(50) of 12 nM, an EGFR (L858R) IC(50) of 31 nM, and an ErbB2 IC(50) of 11 nM, potent activity in cellular functional and anti-proliferation assays, as well as activity in an in vivo pharmacodynamic assay., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The design and enzyme activities of a novel class of imidazo[2,1-b]thiazoles is presented., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Emerging clinical and pre-clinical data indicate that both insulin-like growth factor receptor (IGF-IR) and members of the epidermal growth factor (EGF) family of receptor tyrosine kinases (RTKs) exhibit significant cross-talk in human cancers. Therefore, a small molecule that successfully inhibits the signaling of both classes of oncogenic kinases might provide an attractive agent for chemotherapeutic use. Herein, we disclose the structure activity relationships that led to the synthesis and biological characterization of 14, a novel small molecule inhibitor of both IGF-IR and members of the epidermal growth factor family of RTKs.

The synthesis and structure-activity relationships (SAR) of Chk1 inhibitors based on a 5,10-dihydro-dibenzo[b,e][1,4]diazepin-11-one core are described. Specifically, an exploration of the 7 and 8 positions on this previously disclosed core afforded compounds with improved enzymatic and cellular potency.

A variety of macrocyclic urea compounds were prepared as potent Chk1 inhibitors by modifying the C5 position of the benzene ring of the macrocyclic urea with ether moieties, aliphatic carbon chains, amide and halides. Enzymatic activity less than 20nM was observed in 29 of 40 compounds. Compounds 14, 46d, and 48j provided the best overall results in the cellular assays as they abrogated doxorubicin-induced cell cycle arrest (IC(50)=3.31, 3.08, and 3.13microM) and enhanced doxorubicin cytotoxicity (IC(50)=0.54, 1.27, and 0.96microM) while displaying no single agent activity, respectively.

A new series of potent macrocyclic urea-based Chk1 inhibitors are described. A detailed SAR study on the 4-position of the phenyl ring of the 14-member macrocyclic ureas 1a and d led to the identification of the potent Chk1 inhibitors 2, 5-7, 10, 13, 14, 19-21, 25, 27, and 31-34. These compounds significantly sensitize tumor cells to the DNA-damaging antitumor agent doxorubicin in a cell-based assay and efficiently abrogate the doxorubicin-induced G2/M and camptothecin-induced S checkpoints, indicating that the potent biological activities of these compounds are mechanism-based through Chk1 inhibition. Kinome profiling analysis of a representative macrocyclic urea 25 against a panel of 120 kinases indicates that these novel macrocyclic ureas are highly selective Chk1 inhibitors. Preliminary PK studies of 1a and b suggest that the 14-member macrocyclic inhibitors may possess better PK properties than their 15-member counterparts. An improved synthesis of 2 and 20 by using 2-(trimethylsilyl)ethoxycarbonyl (Teoc) to protect the amino group not only readily provided the desired compounds in pure form but also facilitated the scale up of potent compounds for various biological studies.

An extensive structure-activity relationship study of the 3-position of a series of tricyclic pyrazole-based Chk1 inhibitors is described. As a result, 4'-(1,4-dihydro-indeno[1,2-c]pyrazol-3-yl)-benzonitriles (4) and 4'-(1,4-dihydro-indeno[1,2-c]pyrazol-3-yl)-pyridine-2'-carbonitriles (29) emerged as new lead series. Compared with the original lead compound 2, these new leads fully retain the biological activity in both enzymatic inhibition and cell-based assays. More importantly, the new leads 4 and 29 exhibit favorable physicochemical properties such as lower molecular weight, lower Clog P, and the absence of a hydroxyl group. Furthermore, structure-activity relationship studies were performed at the 6- and 7-positions of 4, which led to the identification of ideal Chk1 inhibitors 49, 50, 51, and 55. These compounds not only potently inhibit Chk1 in an enzymatic assay but also significantly potentiate the cytotoxicity of DNA-damaging agents in cell-based assays while they show little single agent activity. A cell cycle analysis by FACS confirmed that these Chk1 inhibitors efficiently abrogate the G2/M and S checkpoints induced by DNA-damaging agent. The current work paved the way to the identification of several potent Chk1 inhibitors with good pharmacokinetics that are suitable for in vivo study with oral dosing.

A series of 1,4-dihydroindeno[1,2-c]pyrazole compounds with a cyanopyridine moiety at the 3-position of the tricyclic pyrazole core was explored as potent CHK-1 inhibitors. The impact of substitutions at the 6 and/or 7-position of the core on pharmacokinetic properties was studied in detail. Compounds carrying a side chain with an ether linker at the 7-position and a terminal morpholino group, such as 29 and 30, exhibited much-improved oral biovailability in mice as compared to earlier generation inhibitors. These compounds also possessed desirable cellular activity in potentiating doxorubicin and will serve as valuable tool compounds for in vivo evaluation of CHK-1 inhibitors to sensitize DNA-damaging agents.

A high throughput screen of Abbott's compound repository revealed that the pyrazolo[3,4-d]pyrimidine class of kinase inhibitors possessed moderate potency for IGF-IR, a promising target for cancer chemotherapy. The synthesis and subsequent optimization of this class of compounds led to the discovery of 14, a compound that possesses in vivo IGF-IR inhibitory activity.

A new series of potent tricyclic pyrazole-based Chk1 inhibitors are described. Analogues disubstituted on the 6- and 7-positions show improved Chk1 inhibition potency compared with analogues with a single substituent on either the 6- or 7-position. Based on the lead compound 4'-(6,7-dimethoxy-2,4-dihydro-indeno[1,2-c]pyrazol-3-yl)-biphenyl-4-ol (2), detailed SAR studies on the 6- and 7-positions were performed. 3'-morpholin-4'-yl-propoxy, pyridin-4'-ylmethoxy, pyridin-3'-ylmethoxy, 2'-(5''-ethyl-pyridin-2''-yl)-ethoxy, pyridin-2'-ylethoxy, (6'-methyl-pyridin-2'-yl)-propoxyethoxy, 2',3'-dihydroxyl-1'-yl-propoxy, and tetrahydro-furan-3'-yloxy have been identified as the best groups on the 6-position when the 7-position is substituted with methoxyl group. Pyridin-2'-ylmethoxy and pyridin-3'-ylmethoxy have been identified as the best substituents at the 7-position while the 6-position bearing methoxyl group. These compounds significantly potentiate the cytotoxicity of DNA-damaging antitumor agents in a cell-based assay and efficiently abrogate the doxorubicin-induced G2/M and the camptothecin-induced S checkpoints, suggesting that their potent biological activities are mechanism-based through Chk1 inhibition.

A study on substitutions at the four open positions on the phenyl ring of the 1,4-dihydroindeno[1,2-c]pyrazoles as potent CHK-1 inhibitors is described. Bis-substitution at both the 6- and 7-positions led to inhibitors with IC(50) values below 0.3nM. The compound with the best overall activities (36) was able to potentiate the anti-proliferative effect of doxorubicin in HeLa cells by at least 47-fold. Physicochemical, metabolic, and pharmacokinetic properties of selected inhibitors are also disclosed.

Based on the X-ray crystallography of our lead compound 1-(5-chloro-2,4-dimethoxyphenyl)-3-(5-cyanopyrazin-2-yl)urea in the checkpoint kinase 1 (Chk1) enzyme, we modified R4, and to a lesser extent, R2, and R5 of the phenyl ring, and made a variety of N-aryl-N'-pyrazinylurea Chk1 inhibitors. Enzymatic activity less than 20 nM was observed in 15 of 41 compounds. Compound 8i provided the best overall results in the cellular assays as it abrogated doxorubicin-induced cell cycle arrest (IC50=1.7 microM) and enhanced doxorubicin cytotoxicity (IC50=0.44 microM) while displaying no single agent activity.

Chk1 inhibitors have emerged as a novel class of neoplastic agents for abrogating the G2 DNA damage checkpoint arrest. Analogs of the Chk1 inhibitor, 3-ethylidene-1,3-dihydro-indol-2-one, were synthesized and tested in vitro for their inhibitory activities. The most promising compound identified from this series is analog 28, which possesses potent enzymatic and cellular activities.

A series of indole containing oxazolines has been discovered as a result of structural modifications of the lead compound A-105972. The compounds exert their anticancer activity through inhibition of tubulin polymerization by binding at the colchicine site. A-289099 was identified as an orally active antimitotic agent active against various cancer cell lines including those that express the MDR phenotype. The anticancer activity, pharmacokinetics, and an efficient and enantioselective synthesis of A-289099 are described.

The synthesis and biological evaluation of novel sulfonate analogues of E-7010 are reported. Several of the compounds are potent inhibitors of cell proliferation and tubulin polymerization. Importantly, these compounds are also active against P-glycoprotein positive (+) cancer cells, which are resistant to many other antitumor agents.

Sulfonate analogues of combretastatin A-4 have been prepared. These compounds compete with colchicine and combretastatin A-4 for the colchicine binding site on tubulin and are potent inhibitors of tubulin polymerization and cell proliferation. Importantly, these compounds also inhibit the proliferation of P-glycoprotein positive (+) cancer cells, which are resistant to many other antitumor agents.

Farnesylation of Ras is required for its transforming activity in human cancer and the reaction is catalysed by the enzyme farnesyltransferase. Recently, we discovered a novel chemical series of potent farnesyl pyrophosphate (FPP) analogues which selectively inhibited farnesyltransferase. Our most potent compound to date in this series, A-176120, selectively inhibited farnesyltransferase activity (IC(50) 1.2+/-0.3 nM) over the closely related enzymes geranylgeranyltransferase I (GGTaseI) (IC(50) 423+/-1.8 nM), geranylgeranyltransferase II (GGTaseII) (IC(50) 3000 nM) and squalene synthase (SSase) (IC(50)>10000 nM). A-176120 inhibited ras processing in H-ras-transformed NIH3T3 cells and HCT116 K-ras-mutated cells (ED(50) 1.6 and 0.5 microM, respectively). The anti-angiogenic potential of A-176120 was demonstrated by a decrease in Ras processing, cell proliferation and capillary structure formation of human umbilical vein endothelial cells (HUVEC), and a decrease in the secretion of vascular endothelial growth factor (VEGF) from HCT116 cells. In vivo, A-176120 reduced H-ras NIH3T3 tumour growth and extended the lifespan of nude mice inoculated with H- or K-ras-transformed NIH3T3 cells. A-176120 also had an additive effect in combination with cyclophosphamide in nude mice inoculated with K-ras NIH3T3 transformed cells. Overall, our results demonstrate that A-176120 is a potent FPP mimetic with both antitumour and anti-angiogenic properties.

Potent and orally bioavailable nonthiol-containing inhibitors of protein farnesyltransferase are described. Oral bioavailability was achieved by replacement of the pyridyl ether moiety of 1 with a 2-substituted furan ether to give 4. Potency was regained with 2,5-disubstituted furan ethers while maintaining the bioavailability inherent in 4. p-Chlorophenylfuran ether 24 is 0.7 nM in vitro (FTase) and is 32% bioavailable in the mouse, 30% bioavailable in rats, and 21% bioavailable in dogs.

Synthesis and biological evaluation of heteroarenes as reduced cysteine replacements are described. Of the heteroaryl groups examined with respect to FT inhibitor FTI-276 (1), pyridyl was the replacement found to be most effective. Substitutions at C4 of the pyridyl moiety did not affect the in vitro activity. Compound 9a was found to have moderate in vivo bioavailability.