Discovery of 6-Fluoro-5-{4-[(5-fluoro-2-methyl-3-oxo-3,4-dihydroquinoxalin-6-yl)methyl]piperazin-1-yl}--methylpyridine-2-carboxamide (AZD9574): A CNS-Penetrant, PARP1-Selective Inhibitor.

PARP inhibitors have attracted considerable interest in drug discovery due to the clinical success of first-generation agents such as olaparib, niraparib, rucaparib, and talazoparib. Their success lies in their ability to trap PARP to DNA; however, first-generation PARP inhibitors were not strictly optimized for trapping nor for selectivity among the PARP enzyme family. Previously we described the discovery of the second-generation PARP inhibitor AZD5305, a selective PARP1-DNA trapper.

Discovery of a Series of 7-Azaindoles as Potent and Highly Selective CDK9 Inhibitors for Transient Target Engagement.

Optimization of a series of azabenzimidazoles identified from screening hit and the information gained from a co-crystal structure of the azabenzimidazole-based lead bound to CDK9 led to the discovery of azaindoles as highly potent and selective CDK9 inhibitors. With the goal of discovering a highly selective and potent CDK9 inhibitor administrated intravenously that would enable transient target engagement of CDK9 for the treatment of hematological malignancies, further optimization focusing on physicochemical and pharmacokinetic properties led to azaindoles and . These compounds are highly potent and selective CDK9 inhibitors having short half-lives in rodents, suitable physical properties for intravenous administration, and the potential to achieve profound but transient inhibition of CDK9 .

Discovery of 5-{4-[(7-Ethyl-6-oxo-5,6-dihydro-1,5-naphthyridin-3-yl)methyl]piperazin-1-yl}--methylpyridine-2-carboxamide (AZD5305): A PARP1-DNA Trapper with High Selectivity for PARP1 over PARP2 and Other PARPs.

Poly-ADP-ribose-polymerase (PARP) inhibitors have achieved regulatory approval in oncology for homologous recombination repair deficient tumors including BRCA mutation. However, some have failed in combination with first-line chemotherapies, usually due to overlapping hematological toxicities. Currently approved PARP inhibitors lack selectivity for PARP1 over PARP2 and some other 16 PARP family members, and we hypothesized that this could contribute to toxicity.

Addition of Fluorine and a Late-Stage Functionalization (LSF) of the Oral SERD AZD9833.

Herein we describe our efforts using a late stage functionalization together with more traditional synthetic approaches to generate fluorinated analogues of the clinical candidate AZD9833. The effects of the addition of fluorine on the lipophilicity, permeability, and metabolism are discussed. Many of these changes were tolerated in terms of pharmacology and resulted in high quality molecules which reached advanced stages of profiling in the testing cascade.

Discovery of AZD4573, a Potent and Selective Inhibitor of CDK9 That Enables Short Duration of Target Engagement for the Treatment of Hematological Malignancies.

A CDK9 inhibitor having short target engagement would enable a reduction of Mcl-1 activity, resulting in apoptosis in cancer cells dependent on Mcl-1 for survival. We report the optimization of a series of amidopyridines (from compound ), focusing on properties suitable for achieving short target engagement after intravenous administration. By increasing potency and human metabolic clearance, we identified compound , a potent and selective CDK9 inhibitor with suitable predicted human pharmacokinetic properties to deliver transient inhibition of CDK9.

Bicyclo((aryl)methyl)benzamides as inhibitors of GlyT1.

A series of isoquinuclidine benzamides as glycine uptake inhibitors for the treatment of schizophrenia are described. Potency, lipophilicity, and intrinsic human microsomal clearance were parameters for optimization. Potency correlated with the nature of the ortho substituents of the benzamide ring, and reductions in lipophilicity could be achieved through heteroatom incorporation in the benzamide and pendant phenyl moieties.

Structure-Based Design of Selective Noncovalent CDK12 Inhibitors.

Cyclin-dependent kinase (CDK) 12 knockdown via siRNA decreases the transcription of DNA-damage-response genes and sensitizes BRCA wild-type cells to poly(ADP-ribose) polymerase (PARP) inhibition. To recapitulate this effect with a small molecule, we sought a potent, selective CDK12 inhibitor. Crystal structures and modeling informed hybridization between dinaciclib and SR-3029, resulting in lead compound 5 [(S)-2-(1-(6-(((6,7-difluoro-1H-benzo[d]imidazol-2-yl)methyl)amino)-9-ethyl-9H-purin-2-yl)piperidin-2-yl)ethan-1-ol].

Optimization of Highly Kinase Selective Bis-anilino Pyrimidine PAK1 Inhibitors.

Group I p21-activated kinase (PAK) inhibitors are indicated as important in cancer progression, but achieving high kinase selectivity has been challenging. A bis-anilino pyrimidine PAK1 inhibitor was identified and optimized through structure-based drug design to improve PAK1 potency and achieve high kinase selectivity, giving probe compound (). Reduction of lipophilicity to lower clearance afforded () as an probe compound with oral exposure in mouse.

Fragment-assisted hit investigation involving integrated HTS and fragment screening: Application to the identification of phosphodiesterase 10A (PDE10A) inhibitors.

Fragment-based drug design (FBDD) relies on direct elaboration of fragment hits and typically requires high resolution structural information to guide optimization. In fragment-assisted drug discovery (FADD), fragments provide information to guide selection and design but do not serve as starting points for elaboration. We describe FADD and high-throughput screening (HTS) campaign strategies conducted in parallel against PDE10A where fragment hit co-crystallography was not available.

Towards the next generation of dual Bcl-2/Bcl-xL inhibitors.

Structural modifications of the left-hand side of compound 1 were identified which retained or improved potent binding to Bcl-2 and Bcl-xL in in vitro biochemical assays and had strong activity in an RS4;11 apoptotic cellular assay. For example, sulfoxide diastereomer 13 maintained good binding affinity and comparable cellular potency to 1 while improving aqueous solubility. The corresponding diastereomer (14) was significantly less potent in the cell, and docking studies suggest that this is due to a stereochemical preference for the RS versus SS sulfoxide.

Discovery of novel positive allosteric modulators of the metabotropic glutamate receptor 5 (mGlu5).

Novel in vitro mGlu(5) positive allosteric modulators with good potency, solubility, and low lipophilicity are described. Compounds were identified which did not rely on the phenylacetylene and carbonyl functionalities previously observed to be required for in vitro activity. Investigation of the allosteric binding requirements of a series of dihydroquinolinone analogs led to phenylacetylene azachromanone 4 (EC(50) 11.

Identification of N-(2-(azepan-1-yl)-2-phenylethyl)-benzenesulfonamides as novel inhibitors of GlyT1.

A novel series of glycine transporter 1 (GlyT1) inhibitors is described. Scoping of the heterocycle moiety of hit 4-chlorobenzenesulfonamide 1 led to replacement of the piperidine with an azepane for a modest increase in potency. Phenyl sulfonamides proved superior to alkyl and non-phenyl aromatic sulfonamides, while subsequent ortho substitution of the 2-(azepan-1-yl)-2-phenylethanamine aromatic ring yielded 39 (IC(50) 37 nM, solubility 14 microM), the most potent GlyT1 inhibitor in this series.

Position 5.46 of the serotonin 5-HT2A receptor contributes to a species-dependent variation for the 5-HT2C agonist (R)-9-ethyl-1,3,4,10b-tetrahydro-7-trifluoromethylpyrazino[2,1-a]isoindol-6(2H)-one: impact on selectivity and toxicological evaluation.

Successful development of 5-HT(2C) agonists requires selectivity versus the highly homologous 5-HT(2A) receptor, because agonism at this receptor can result in significant adverse events. (R)-9-Ethyl-1,3,4,10b-tetrahydro-7-trifluoromethylpyrazino[2,1-a]isoindol-6(2H)-one (compound 1) is a potent 5-HT(2C) agonist exhibiting selectivity over the human 5-HT(2A) receptor. Evaluation of the compound at the rat 5-HT(2A) receptor, however, revealed potent binding and agonist functional activity.

Structure-activity relationship and pharmacokinetic profile of 5-ketopyrazole factor Xa inhibitors.

Efforts to further optimize the clinical candidate razaxaban have led to a new series of pyrazole-based factor Xa (fXa) inhibitors. Designed to prevent the potential formation of primary aniline metabolites in vivo, the nitrogen of the carboxamido linker between the pyrazole and proximal phenyl moiety of the razaxaban scaffold was replaced with a methylene group. The resulting ketones demonstrated excellent potency and selectivity for fXa but initially had poor oral bioavailability.

Design, structure-activity relationship, and pharmacokinetic profile of pyrazole-based indoline factor Xa inhibitors.

A new series of pyrazole-based factor Xa inhibitors have been identified as part of our ongoing efforts to optimize previously reported clinical candidate razaxaban. Concern over the possible formation of primary aniline metabolites via amide hydrolysis led to the replacement of the primary amide linker between the pyrazole and phenyl moieties with secondary amides. This was accomplished by replacing the aniline with a variety of heterobicycles, of which indolines were the most potent.

CC chemokine receptor-3 (CCR3) antagonists: improving the selectivity of DPC168 by reducing central ring lipophilicity.

DPC168, a benzylpiperidine-substituted aryl urea CCR3 antagonist evaluated in clinical trials, was a relatively potent inhibitor of the 2D6 isoform of cytochrome P-450 (CYP2D6). Replacement of the cyclohexyl central ring with saturated heterocycles provided potent CCR3 antagonists with improved selectivity against CYP2D6. The favorable preclinical profile of DPC168 was maintained in an acetylpiperidine derivative, BMS-570520.

Discovery of (R)-9-ethyl-1,3,4,10b-tetrahydro-7-trifluoromethylpyrazino[2,1-a]isoindol- 6(2H)-one, a selective, orally active agonist of the 5-HT(2C) receptor.

Robust pharmaceutical treatment of obesity has been limited by the undesirable side-effect profile of currently marketed therapies. This paper describes the synthesis and optimization of a new class of pyrazinoisoindolone-containing, selective 5-HT2C agonists as antiobesity agents. Key to optimization of the pyrazinoisoindolone core was the identification of the appropriate substitution pattern and functional groups which led to the discovery of (R)-9-ethyl-1,3,4,10b-tetrahydro-7-trifluoromethylpyrazino[2,1-a]isoindol-6(2H)-one (58), a 5-HT2C agonist with >300-fold functional selectivity over 5-HT2B and >70-fold functional selectivity over 5-HT2A.

Discovery of N-propylurea 3-benzylpiperidines as selective CC chemokine receptor-3 (CCR3) antagonists.

The discovery of novel and selective small molecule antagonists of the CC Chemokine Receptor-3 (CCR3) is presented. Simple conversion from a 4- to 3-benzylpiperidine gave improved selectivity for CCR3 over the serotonin 5HT(2A) receptor. Chiral resolution and exploration of mono- and disubstitution of the N-propylurea resulted in several 3-benzylpiperidine N-propylureas with CCR3 binding IC(50)s under 5 nM.

CCR3 antagonists: a potential new therapy for the treatment of asthma. Discovery and structure-activity relationships.

CCR3 antagonist leads with IC(50) values in the microM range were converted into low nM binding compounds that displayed in vitro inhibition of human eosinophil chemotaxis induced by human eotaxin. In particular, 4-benzylpiperidin-1-yl-n-propylureas and erythro-3-(4-benzyl-2-(alpha-hydroxyalkyl)piperidin-1-yl)-n-propylureas (obtained via Beak reaction of N-BOC-4-benzylpiperidine) exhibited single digit nanomolar IC(50) values for CCR3.