Investigation of biaryl heterocycles as inhibitors of Wee1 kinase.

In continuation of our previous research towards the discovery of potent, selective and drug-like Wee1 inhibitors, 2 novel series of biaryl heterocycles were designed, synthesized and evaluated. The new biaryl cores were designed to enable structure-activity exploration of substituents at C-8 or N-8 which were used for tuning compound properties and to improve compound profiles. The lead molecule 33 demonstrated a desirable pharmacokinetic profile and potentiated the anti-proliferative activity of irinotecan in vivo when dosed orally in the human breast MX-1 xenograft model.

Novel Modes of Inhibition of Wild-Type Isocitrate Dehydrogenase 1 (IDH1): Direct Covalent Modification of His315.

IDH1 plays a critical role in a number of metabolic processes and serves as a key source of cytosolic NADPH under conditions of cellular stress. However, few inhibitors of wild-type IDH1 have been reported. Here we present the discovery and biochemical characterization of two novel inhibitors of wild-type IDH1.

The Histone Methyltransferase Inhibitor A-366 Uncovers a Role for G9a/GLP in the Epigenetics of Leukemia.

Histone methyltransferases are epigenetic regulators that modify key lysine and arginine residues on histones and are believed to play an important role in cancer development and maintenance. These epigenetic modifications are potentially reversible and as a result this class of enzymes has drawn great interest as potential therapeutic targets of small molecule inhibitors. Previous studies have suggested that the histone lysine methyltransferase G9a (EHMT2) is required to perpetuate malignant phenotypes through multiple mechanisms in a variety of cancer types.

Pyrimidine-based tricyclic molecules as potent and orally efficacious inhibitors of wee1 kinase.

Aided by molecular modeling, compounds with a pyrimidine-based tricyclic scaffold were designed and confirmed to inhibit Wee1 kinase. Structure-activity studies identified key pharmacophores at the aminoaryl and halo-benzene regions responsible for binding affinity with sub-nM K i values. The potent inhibitors demonstrated sub-μM activities in both functional and mechanism-based cellular assays and also possessed desirable pharmacokinetic profiles.

Azaindole-Based Inhibitors of Cdc7 Kinase: Impact of the Pre-DFG Residue, Val 195.

To investigate the role played by the unique pre-DFG residue Val 195 of Cdc7 kinase on the potency of azaindole-chloropyridines (1), a series of novel analogues with various chloro replacements were synthesized and evaluated for their inhibitory activity against Cdc7. X-ray cocrystallization using a surrogate protein, GSK3β, and modeling studies confirmed the azaindole motif as the hinge binder. Weaker hydrophobic interactions with Met 134 and Val 195 by certain chloro replacements (e.

Hit to Lead optimization of a novel class of squarate-containing polo-like kinases inhibitors.

A high throughput screening (HTS) hit, 1 (Plk1 K(i)=2.2 μM) was optimized and evaluated for the enzymatic inhibition of Plk-1 kinase. Molecular modeling suggested the importance of adding a hydrophobic aromatic amine side chain in order to improve the potency by a classic kinase H-donor-acceptor binding mode.

Discovery and SAR of orally efficacious tetrahydropyridopyridazinone PARP inhibitors for the treatment of cancer.

PARP-1, the most abundant member of the PARP superfamily of nuclear enzymes, has emerged as a promising molecular target in the past decade particularly for the treatment of cancer. A number of PARP-1 inhibitors, including veliparab discovered at Abbott, have advanced into different stages of clinical trials. Herein we describe the development of a new tetrahydropyridopyridazinone series of PARP-1 inhibitors.

Aminopyrimidinone cdc7 kinase inhibitors.

We have investigated the SAR of a series of pyrimidinone-containing Cdc7 kinase inhibitors. A wide range of amine substitutions give potent compounds with activities (K(i)) less than 1nM. Kinase selectivity is reasonable and cytotoxicity corresponds to inhibition of MCM2 phosphorylation.

Iniparib nonselectively modifies cysteine-containing proteins in tumor cells and is not a bona fide PARP inhibitor.

Purpose: PARP inhibitors are being developed as therapeutic agents for cancer. More than six compounds have entered clinical trials. The majority of these compounds are β-nicotinamide adenine dinucleotide (NAD(+))-competitive inhibitors.

The Bcl-2/Bcl-X(L)/Bcl-w inhibitor, navitoclax, enhances the activity of chemotherapeutic agents in vitro and in vivo.

The ability of a cancer cell to avoid apoptosis is crucial to tumorigenesis and can also contribute to chemoresistance. The Bcl-2 family of prosurvival proteins (Bcl-2, Bcl-X(L), Bcl-w, Mcl-1, and A1) plays a key role in these processes. We previously reported the discovery of ABT-263 (navitoclax), a potent small-molecule inhibitor of Bcl-2, Bcl-X(L), and Bcl-w.

Ubiquitin-specific cysteine protease 2a (USP2a) regulates the stability of Aurora-A.

The ubiquitin/proteasome pathway plays critical roles in virtually all aspects of cell biology. Enzymes of the ubiquitin pathway add (ligases) or remove (deubiquitinases) ubiquitin tags to or from their target proteins in a selective fashion. USP2a is a member of a subfamily of deubiquitinases, called ubiquitin-specific cysteine proteases (USPs).

The Bcl-2 inhibitor ABT-263 enhances the response of multiple chemotherapeutic regimens in hematologic tumors in vivo.

Purpose: This study was designed to test the ability of the Bcl-2 family inhibitor ABT-263 to potentiate commonly used chemotherapeutic agents and regimens in hematologic tumor models.

Methods: Models of B-cell lymphoma and multiple myeloma were tested in vitro and in vivo with ABT-263 in combination with standard chemotherapeutic regimens, including VAP, CHOP and R-CHOP, as well as single cytotoxic agents including etoposide, rituximab, bortezomib and cyclophosphamide. Alterations in Bcl-2 family member expression patterns were analyzed to define mechanisms of potentiation.

Acquired resistance to combination treatment with temozolomide and ABT-888 is mediated by both base excision repair and homologous recombination DNA repair pathways.

Many established cancer therapies involve DNA-damaging chemotherapy or radiotherapy. Gain of DNA repair capacity of the tumor represents a common mechanism used by cancer cells to survive DNA-damaging therapy. Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme that is activated by DNA damage and plays a critical role in base excision repair.

Discovery of an orally bioavailable small molecule inhibitor of prosurvival B-cell lymphoma 2 proteins.

Overexpression of prosurvival proteins such as Bcl-2 and Bcl-X L has been correlated with tumorigenesis and resistance to chemotherapy, and thus, the development of antagonists of these proteins may provide a novel means for the treatment of cancer. We recently described the discovery of 1 (ABT-737), which binds Bcl-2, Bcl-X L, and Bcl-w with high affinity, shows robust antitumor activity in murine tumor xenograft models, but is not orally bioavailable. Herein, we report that targeted modifications at three key positions of 1 resulted in a 20-fold improvement in the pharmacokinetic/pharmacodynamic relationship (PK/PD) between oral exposure (AUC) and in vitro efficacy in human tumor cell lines (EC 50).

ABT-263: a potent and orally bioavailable Bcl-2 family inhibitor.

Overexpression of the prosurvival Bcl-2 family members (Bcl-2, Bcl-xL, and Mcl-1) is commonly associated with tumor maintenance, progression, and chemoresistance. We previously reported the discovery of ABT-737, a potent, small-molecule Bcl-2 family protein inhibitor. A major limitation of ABT-737 is that it is not orally bioavailable, which would limit chronic single agent therapy and flexibility to dose in combination regimens.

Studies leading to potent, dual inhibitors of Bcl-2 and Bcl-xL.

Overexpression of the antiapototic proteins Bcl-2 and Bcl-xL provides a common mechanism through which cancer cells gain a survival advantage and become resistant to conventional chemotherapy. Inhibition of these prosurvival proteins is an attractive strategy for cancer therapy. We recently described the discovery of a selective Bcl-xL antagonist that potentiates the antitumor activity of chemotherapy and radiation.

Discovery and SAR of oxindole-pyridine-based protein kinase B/Akt inhibitors for treating cancers.

We describe a series of potent and selective oxindole-pyridine-based protein kinase B/Akt inhibitors. The most potent compound 11n in this series demonstrated an IC(50) of 0.17nM against Akt1 and more than 100-fold selectivity over other Akt isozymes.

Isoquinoline-pyridine-based protein kinase B/Akt antagonists: SAR and in vivo antitumor activity.

The structure-activity relationships of a series of isoquinoline-pyridine-based protein kinase B/Akt antagonists have been investigated in an effort to improve the major short-comings of the lead compound 3, including poor pharmacokinetic profiles in several species (e.g., mouse i.

Discovery and structure-activity relationship of antagonists of B-cell lymphoma 2 family proteins with chemopotentiation activity in vitro and in vivo.

Development of a rationally designed potentiator of cancer chemotherapy, via inhibition of Bcl-X(L) function, is described. Lead compounds generated by NMR screening and directed parallel synthesis displayed sub-microM binding but were strongly deactivated in the presence of serum. The dominant component of serum deactivation was identified as domain III of human serum albumin (HSA); NMR solution structures of inhibitors bound to both Bcl-X(L) and HSA domain III indicated two potential optimization sites for separation of affinities.

Optimal classes of chemotherapeutic agents sensitized by specific small-molecule inhibitors of akt in vitro and in vivo.

Akt is a serine/threonine kinase that transduces survival signals from survival/growth factors. Deregulation and signal imbalance in cancer cells make them prone to apoptosis. Upregulation or activation of Akt to aid the survival of cancer cells is a common theme in human malignancies.

Evaluating hypoxia-inducible factor-1alpha as a cancer therapeutic target via inducible RNA interference in vivo.

Validating potential targets is an important step in the drug discovery process. In this study, we tested the feasibility of using inducible RNA interference (RNAi) in vivo to obtain an unbiased evaluation on the efficacy of inhibiting hypoxia-inducible factor-1alpha (HIF-1alpha) in established tumors. We showed that HIF-1alpha inhibition resulted in transient tumor stasis or tumor regression, and inhibiting HIF-1alpha in early-stage tumors was found to be more efficacious than inhibiting HIF-1alpha in more established tumors.

Potent and selective inhibitors of Akt kinases slow the progress of tumors in vivo.

The Akt kinases are central nodes in signal transduction pathways that are important for cellular transformation and tumor progression. We report the development of a series of potent and selective indazole-pyridine based Akt inhibitors. These compounds, exemplified by A-443654 (K(i) = 160 pmol/L versus Akt1), inhibit Akt-dependent signal transduction in cells and in vivo in a dose-responsive manner.

An inhibitor of Bcl-2 family proteins induces regression of solid tumours.

Proteins in the Bcl-2 family are central regulators of programmed cell death, and members that inhibit apoptosis, such as Bcl-X(L) and Bcl-2, are overexpressed in many cancers and contribute to tumour initiation, progression and resistance to therapy. Bcl-X(L) expression correlates with chemo-resistance of tumour cell lines, and reductions in Bcl-2 increase sensitivity to anticancer drugs and enhance in vivo survival. The development of inhibitors of these proteins as potential anti-cancer therapeutics has been previously explored, but obtaining potent small-molecule inhibitors has proved difficult owing to the necessity of targeting a protein-protein interaction.

Rapamycin inhibits Akt-mediated oncogenic transformation and tumor growth.

Akt is a serine/threonine kinase that plays a critical role in cell survival and proliferation. Three isoforms of Akt have been identified and have been shown to be up-regulated in human malignancies. We examined the requirement of these pathways for Akt transformation.