ABSTRACT
The four members of the Janus family of nonreceptor tyrosine kinases play a significant role in immune function. The JAK family kinase inhibitor, tofacitinib 1, has been approved in the United States for use in rheumatoid arthritis (RA) patients. A number of JAK inhibitors with a variety of JAK family selectivity profiles are currently in clinical trials. Our goal was to identify inhibitors that were functionally selective for JAK1 and JAK3. Compound 22 was prepared with the desired functional selectivity profile, but it suffered from poor absorption related to physical properties. Use of the phosphate prodrug 32 enabled progression to a murine collagen induced arthritis (CIA) model. The demonstration of a robust efficacy in the CIA model suggests that use of phosphate prodrugs may resolve issues with progressing this chemotype for the treatment of autoimmune diseases such as RA.
ABSTRACT
PI3Kδ plays an important role controlling immune cell function and has therefore been identified as a potential target for the treatment of immunological disorders. This article highlights our work toward the identification of a potent, selective, and efficacious PI3Kδ inhibitor. Through careful SAR, the successful replacement of a polar pyrazole group by a simple chloro or trifluoromethyl group led to improved Caco-2 permeability, reduced Caco-2 efflux, reduced hERG PC activity, and increased selectivity profile while maintaining potency in the CD69 hWB assay. The optimization of the aryl substitution then identified a 4'-CN group that improved the human/rodent correlation in microsomal metabolic stability. Our lead molecule is very potent in PK/PD assays and highly efficacious in a mouse collagen-induced arthritis model.
Subject(s)
Arthritis, Experimental/drug therapy , Drug Evaluation, Preclinical/methods , Enzyme Inhibitors/pharmacology , Phosphoinositide-3 Kinase Inhibitors , Structure-Activity Relationship , Animals , Antigens, CD/metabolism , Antigens, Differentiation, T-Lymphocyte/metabolism , Caco-2 Cells/drug effects , Caco-2 Cells/immunology , Dogs , ERG1 Potassium Channel/metabolism , Enzyme Inhibitors/chemistry , Female , Humans , Immune System Diseases/drug therapy , Isoenzymes/antagonists & inhibitors , Isoenzymes/metabolism , Lectins, C-Type/metabolism , Male , Mice, Inbred BALB C , Pyrazoles/chemistry , Pyrazoles/metabolism , Pyrazoles/pharmacology , RabbitsABSTRACT
A series of potent dual JAK1/3 inhibitors have been developed from a moderately selective JAK3 inhibitor. Substitution at the C6 position of the pyrrolopyridazine core with aryl groups provided exceptional biochemical potency against JAK1 and JAK3 while maintaining good selectivity against JAK2 and Tyk2. Translation to in vivo efficacy was observed in a murine model of chronic inflammation. X-ray co-crystal structure determination confirmed the presumed inhibitor binding orientation in JAK3. Efforts to reduce hERG channel inhibition will be described.
Subject(s)
Janus Kinase 1/antagonists & inhibitors , Janus Kinase 3/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Pyridazines/chemistry , Pyrroles/chemistry , Animals , Binding Sites , Catalytic Domain , Cell Line , Crystallography, X-Ray , Disease Models, Animal , Drug Evaluation, Preclinical , Half-Life , Humans , Inflammation/prevention & control , Inhibitory Concentration 50 , Janus Kinase 1/metabolism , Janus Kinase 2/antagonists & inhibitors , Janus Kinase 2/metabolism , Janus Kinase 3/metabolism , Mice , Mice, Inbred BALB C , Molecular Conformation , Molecular Dynamics Simulation , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Pyridazines/chemical synthesis , Pyridazines/pharmacokinetics , Pyrroles/chemical synthesis , Pyrroles/pharmacokinetics , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship , TYK2 Kinase/antagonists & inhibitors , TYK2 Kinase/metabolismABSTRACT
Oral agents targeting Janus-associated kinases (JAKs) are promising new agents in clinical development. To better understand the relationship between JAK inhibition and biological outcome, compounds targeting JAKs were evaluated in peripheral human whole blood. To date, these analyses are low throughput and costly. Here, we developed a robust 384-well, high-throughput flow-based assay approach to screen small molecules for JAK/STAT signaling inhibition in human whole blood. This assay platform provides a highly sensitive analysis of signaling events in blood and facilitates measurement of target engagement. Further, the automation technologies and process optimizations developed here overcame sample integrity, handling, and multiparametric data analysis bottlenecks without affecting assay performance. Together these efforts dramatically increased sample throughput compared to conventional manual flow cytometric approaches and enabled development of novel JAK/STAT inhibitors.
Subject(s)
Flow Cytometry/methods , High-Throughput Screening Assays/methods , Protein Kinase Inhibitors/isolation & purification , Signal Transduction/drug effects , Humans , Janus Kinases/antagonists & inhibitors , Janus Kinases/genetics , Phosphorylation , Protein Kinase Inhibitors/chemistry , STAT Transcription Factors/antagonists & inhibitors , STAT Transcription Factors/genetics , Small Molecule Libraries/chemistryABSTRACT
A new class of Janus kinase (JAK) inhibitors was discovered using a rationally designed pyrrolo[1,2-b]pyridazine-3-carboxamide scaffold. Preliminary studies identified (R)-(2,2-dimethylcyclopentyl)amine as a preferred C4 substituent on the pyrrolopyridazine core (3b). Incorporation of amino group to 3-position of the cyclopentane ring resulted in a series of JAK3 inhibitors (4g-4j) that potently inhibited IFNγ production in an IL2-induced whole blood assay and displayed high functional selectivity for JAK3-JAK1 pathway relative to JAK2. Further modifications led to the discovery of an orally bioavailable (2-fluoro-2-methylcyclopentyl)amino analogue 5g which is a nanomolar inhibitor of both JAK3 and TYK2, functionally selective for the JAK3-JAK1 pathway versus JAK2, and active in a human whole blood assay.
Subject(s)
Drug Discovery , Janus Kinase 1/antagonists & inhibitors , Janus Kinase 2/antagonists & inhibitors , Janus Kinase 3/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Pyridazines/chemistry , Pyrroles/chemistry , Administration, Oral , Animals , Enzyme-Linked Immunosorbent Assay , Humans , Interferon-gamma/metabolism , Mice , Mice, Inbred BALB C , Models, Molecular , Molecular Structure , Protein Conformation/drug effects , Protein Kinase Inhibitors/administration & dosage , Protein Kinase Inhibitors/pharmacokinetics , Structure-Activity Relationship , Tissue DistributionABSTRACT
A novel series of p38 MAP kinase inhibitors with high selectivity for the p38α isoform over the other family members including the highly homologous p38ß isoform has been identified. X-ray co-crystallographic studies have revealed an unprecedented kinase binding mode in p38α for representative analogs, 5c and 9d, in which a Leu108/Met109 peptide flip occurs within the p38α hinge region. Based on these findings, a general strategy for the rational design of additional promising p38α isoform selective inhibitors by targeting this novel binding mode is proposed.
Subject(s)
Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Binding Sites , Crystallography, X-Ray , Humans , Hydrogen Bonding , Mitogen-Activated Protein Kinase 14/metabolism , Molecular Dynamics Simulation , Protein Binding , Protein Isoforms/antagonists & inhibitors , Protein Isoforms/metabolism , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/metabolism , Protein Structure, Tertiary , Structure-Activity RelationshipABSTRACT
Pyrrolo[2,1-f][1,2,4]triazine based inhibitors of p38α have been prepared exploring functional group modifications at the C6 position. Incorporation of aryl and heteroaryl ketones at this position led to potent inhibitors with efficacy in in vivo models of acute and chronic inflammation.
Subject(s)
Anti-Inflammatory Agents/chemistry , Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Pyrroles/chemistry , Triazines/chemistry , Administration, Oral , Animals , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/therapeutic use , Arthritis/drug therapy , Binding Sites , Crystallography, X-Ray , Disease Models, Animal , Drug Evaluation, Preclinical , Female , Mice , Mitogen-Activated Protein Kinase 14/metabolism , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , Protein Structure, Tertiary , Rats , Structure-Activity Relationship , Triazines/pharmacology , Triazines/therapeutic useABSTRACT
The synthesis and structure-activity relationships (SAR) of p38α MAP kinase inhibitors based on a 5-amino-pyrazole scaffold are described. These studies led to the identification of compound 2j as a potent and selective inhibitor of p38α MAP kinase with excellent cellular potency toward the inhibition of TNFα production. Compound 2j was highly efficacious in vivo in inhibiting TNFα production in an acute murine model of TNFα production. X-ray co-crystallography of a 5-amino-pyrazole analog 2f bound to unphosphorylated p38α is also disclosed.
Subject(s)
Mitogen-Activated Protein Kinase 14/chemistry , Protein Kinase Inhibitors/chemical synthesis , Pyrazoles/pharmacology , Animals , Crystallography, X-Ray , Mice , Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Protein Binding , Protein Conformation , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Pyrazoles/chemical synthesis , Pyrazoles/chemistry , Structure-Activity Relationship , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Tumor Necrosis Factor-alpha/biosynthesisABSTRACT
The discovery and characterization of 7k (BMS-582949), a highly selective p38α MAP kinase inhibitor that is currently in phase II clinical trials for the treatment of rheumatoid arthritis, is described. A key to the discovery was the rational substitution of N-cyclopropyl for N-methoxy in 1a, a previously reported clinical candidate p38α inhibitor. Unlike alkyl and other cycloalkyls, the sp(2) character of the cyclopropyl group can confer improved H-bonding characteristics to the directly substituted amide NH. Inhibitor 7k is slightly less active than 1a in the p38α enzymatic assay but displays a superior pharmacokinetic profile and, as such, was more effective in both the acute murine model of inflammation and pseudoestablished rat AA model. The binding mode of 7k with p38α was confirmed by X-ray crystallographic analysis.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Pyrroles/chemical synthesis , Triazines/chemical synthesis , Animals , Anti-Inflammatory Agents, Non-Steroidal/pharmacokinetics , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Arthritis, Experimental/drug therapy , Arthritis, Rheumatoid/drug therapy , Biological Availability , Caco-2 Cells , Crystallography, X-Ray , Female , Humans , Hydrogen Bonding , In Vitro Techniques , Inflammation/drug therapy , Inflammation/metabolism , Lipopolysaccharides/pharmacology , Male , Mice , Mice, Inbred BALB C , Microsomes, Liver/metabolism , Mitogen-Activated Protein Kinase 14/chemistry , Models, Molecular , Molecular Conformation , Protein Binding , Pyrroles/pharmacokinetics , Pyrroles/pharmacology , Rats , Rats, Inbred Lew , Rats, Sprague-Dawley , Stereoisomerism , Structure-Activity Relationship , Triazines/pharmacokinetics , Triazines/pharmacology , Tumor Necrosis Factor-alpha/biosynthesisABSTRACT
The design, synthesis, and structure-activity relationships (SAR) of a series of 2-aminothiazol-5-yl-pyrimidines as novel p38α MAP kinase inhibitors are described. These efforts led to the identification of 41 as a potent p38α inhibitor that utilizes a unique nitrogen-sulfur intramolecular nonbonding interaction to stabilize the conformation required for binding to the p38α active site. X-ray crystallographic studies that confirm the proposed binding mode of this class of inhibitors in p38 α and provide evidence for the proposed intramolecular nitrogen-sulfur interaction are discussed.
Subject(s)
Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Nitrogen/chemistry , Protein Kinase Inhibitors/chemical synthesis , Pyrimidines/chemistry , Sulfur/chemistry , Thiazoles/chemistry , Binding Sites , Crystallography, X-Ray , Drug Design , Mitogen-Activated Protein Kinase 14/metabolism , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Protein Structure, Tertiary , Pyrimidines/chemical synthesis , Pyrimidines/pharmacology , Structure-Activity Relationship , Thiazoles/chemical synthesis , Thiazoles/pharmacologyABSTRACT
A novel structural class of p38alpha MAP kinase inhibitors has been identified via iterative SAR studies of a focused deck screen hit. Optimization of the lead series generated 6e, BMS-640994, a potent and selective p38alpha inhibitor that is orally efficacious in rodent models of acute and chronic inflammation.
Subject(s)
Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Thiazoles/pharmacology , Animals , Arthritis/drug therapy , Caco-2 Cells , Cell Membrane Permeability/drug effects , Cells, Cultured , Crystallography, X-Ray , Cytochrome P-450 Enzyme Inhibitors , Cytochrome P-450 Enzyme System/metabolism , Ether-A-Go-Go Potassium Channels/antagonists & inhibitors , Humans , Lipopolysaccharides/pharmacology , Male , Mice , Microsomes, Liver/drug effects , Mitogen-Activated Protein Kinase 14/metabolism , Molecular Structure , Monocytes/cytology , Monocytes/drug effects , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Rats , Rats, Inbred Lew , Structure-Activity Relationship , Thiazoles/chemical synthesis , Thiazoles/pharmacokinetics , Tumor Necrosis Factor-alpha/metabolismABSTRACT
The synthesis and structure-activity relationships (SAR) of p38 alpha MAP kinase inhibitors based on a pyrazolo-pyrimidine scaffold are described. These studies led to the identification of compound 2x as a potent and selective inhibitor of p38 alpha MAP kinase with excellent cellular potency toward the inhibition of TNFalpha production. Compound 2x was highly efficacious in vivo in inhibiting TNFalpha production in an acute murine model of TNFalpha production. X-ray co-crystallography of a pyrazolo-pyrimidine analog 2b bound to unphosphorylated p38 alpha is also disclosed.
Subject(s)
Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Pyrazoles/chemistry , Pyrimidines/chemical synthesis , Pyrimidines/pharmacology , p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors , p38 Mitogen-Activated Protein Kinases/metabolism , Crystallography, X-Ray , Humans , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemistry , Pyrimidines/chemistry , Structure-Activity Relationship , p38 Mitogen-Activated Protein Kinases/chemistryABSTRACT
A novel series of compounds based on the pyrrolo[2,1-f][1,2,4]triazine ring system have been identified as potent p38 alpha MAP kinase inhibitors. The synthesis, structure-activity relationships (SAR), and in vivo activity of selected analogs from this class of inhibitors are reported. Additional studies based on X-ray co-crystallography have revealed that one of the potent inhibitors from this series binds to the DFG-out conformation of the p38 alpha enzyme.
Subject(s)
Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Mitogen-Activated Protein Kinase 14/metabolism , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Pyrroles/chemistry , Triazines/chemical synthesis , Triazines/pharmacology , Amides/chemistry , Animals , Crystallography, X-Ray , Female , Mice , Mice, Inbred BALB C , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemistry , Structure-Activity Relationship , Triazines/chemistry , Tumor Necrosis Factor-alpha/biosynthesisABSTRACT
Rational design, synthesis, and SAR studies of a novel class of benzothiazole based inhibitors of p38alpha MAP kinase are described. The issue of metabolic instability associated with vicinal phenyl, benzo[d]thiazol-6-yl oxazoles/imidazoles was addressed by the replacement of the central oxazole or imidazole ring with an aminopyrazole system. The proposed binding mode of this new class of p38alpha inhibitors was confirmed by X-ray crystallographic studies of a representative inhibitor (6a) bound to the p38alpha enzyme.
Subject(s)
Benzothiazoles/chemistry , Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Animals , Cells, Cultured/drug effects , Cells, Cultured/enzymology , Crystallography, X-Ray , Humans , Lipopolysaccharides/pharmacology , Mice , Microsomes/drug effects , Microsomes/enzymology , Mitogen-Activated Protein Kinase 14/metabolism , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Rats , Structure-Activity Relationship , Tumor Necrosis Factor-alpha/metabolismABSTRACT
A novel structural class of p38 mitogen-activated protein (MAP) kinase inhibitors consisting of substituted 4-(phenylamino)-pyrrolo[2,1- f][1,2,4]triazines has been discovered. An initial subdeck screen revealed that the oxindole-pyrrolo[2,1- f][1,2,4]triazine lead 2a displayed potent enzyme inhibition (IC 50 60 nM) and was active in a cell-based TNFalpha biosynthesis inhibition assay (IC 50 210 nM). Replacement of the C4 oxindole with 2-methyl-5- N-methoxybenzamide aniline 9 gave a compound with superior p38 kinase inhibition (IC 50 10 nM) and moderately improved functional inhibition in THP-1 cells. Further replacement of the C6 ester of the pyrrolo[2,1- f][1,2,4]triazine with amides afforded compounds with increased potency, excellent oral bioavailability, and robust efficacy in a murine model of acute inflammation (murine LPS-TNFalpha). In rodent disease models of chronic inflammation, multiple compounds demonstrated significant inhibition of disease progression leading to the advancement of 2 compounds 11b and 11j into further preclinical and toxicological studies.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Pyrroles/chemical synthesis , Triazines/chemical synthesis , Administration, Oral , Animals , Anti-Inflammatory Agents, Non-Steroidal/pharmacokinetics , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Arthritis, Experimental/drug therapy , Binding Sites , Crystallography, X-Ray , Drug Design , Female , Humans , In Vitro Techniques , Leukocytes, Mononuclear/drug effects , Leukocytes, Mononuclear/metabolism , Lipopolysaccharides/pharmacology , Male , Mice , Mice, Inbred BALB C , Microsomes, Liver/metabolism , Mitogen-Activated Protein Kinase 14/chemistry , Models, Molecular , Pyrroles/pharmacokinetics , Pyrroles/pharmacology , Rats , Rats, Inbred Lew , Structure-Activity Relationship , Triazines/pharmacokinetics , Triazines/pharmacology , Tumor Necrosis Factor-alpha/biosynthesis , Tumor Necrosis Factor-alpha/bloodABSTRACT
Dasatinib is an oral small molecule inhibitor of Abl and Src family tyrosine kinases (SFK), including p56(Lck) (Lck). Given the central importance of Lck in transmitting signals from the T-cell receptor (TCR) signaling complex and the potent ability of dasatinib to inhibit Lck activity, we hypothesized this agent could provide a novel route of immunomodulation via targeted inhibition of antigen-induced signaling. Herein, we show that dasatinib inhibits TCR-mediated signal transduction, cellular proliferation, cytokine production, and in vivo T-cell responses. However, dasatinib-mediated inhibition does not induce apoptosis because the effect is reversible or may be overcome by signals bypassing the TCR, such as phorbol ester. Signal transduction and proliferative responses via IL-2 remain essentially unperturbed, suggesting that dasatinib displays specificity for TCR signaling. In addition, dasatinib combined with cyclosporine A or rapamycin led to a much more potent inhibition of T-cell activation, suggesting that targeted inhibition of Lck could be a useful adjunct for enhanced immunomodulation. In combination with currently available immunomodulatory agents, SFK inhibition could potentially increase immunomodulatory efficacy while minimizing toxicity of individual agents.
Subject(s)
Lymphocyte Activation/drug effects , Lymphocyte Activation/immunology , Protein Kinase Inhibitors/pharmacology , Protein-Tyrosine Kinases/antagonists & inhibitors , Pyrimidines/pharmacology , T-Lymphocytes/drug effects , T-Lymphocytes/immunology , Thiazoles/pharmacology , Animals , Biomarkers , CD28 Antigens/immunology , CD3 Complex/immunology , Cell Proliferation/drug effects , Cells, Cultured , Cyclosporine/pharmacology , Cytokines/biosynthesis , Dasatinib , Humans , Male , Mice , Protein Binding , Protein-Tyrosine Kinases/metabolism , Receptors, Antigen, T-Cell/immunology , Signal Transduction/drug effects , Signal Transduction/immunology , Sirolimus/pharmacology , T-Lymphocytes/enzymologyABSTRACT
A novel class of 5-cyanopyrimidine-based inhibitors of p38alpha MAP kinase has been investigated. Analogues optimized through SAR iterations display low nanomolar enzymatic and cellular activity. The in vivo efficacy of this class of p38 inhibitors was demonstrated by 3a and 3b (>50% reduction in TNF levels when orally dosed at 5 mg/kg, 5 h prior to LPS administration in an acute murine model of inflammation). For 3a and 3b, the previously identified N-methoxybenzamide moiety (1) was replaced with N-(isoxazol-3-yl)benzamide, thereby providing increased metabolic stability. Cyanopyrimidine 3a demonstrated 100% oral bioavailability in mouse. High p38 kinase selectivity versus over 20 kinases was observed for analogue 3b. Direct hydrogen bonding of the cyano nitrogen of the 5-cyanopyrimidine core to the backbone NH of Met109 was confirmed by X-ray crystallographic analysis of 3a bound to p38alpha.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Benzamides/chemical synthesis , Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Nitriles/chemical synthesis , Pyrimidines/chemical synthesis , Administration, Oral , Animals , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Benzamides/chemistry , Benzamides/pharmacology , Biological Availability , Cells, Cultured , Crystallography, X-Ray , Female , Humans , In Vitro Techniques , Leukocytes, Mononuclear/drug effects , Leukocytes, Mononuclear/metabolism , Lipopolysaccharides/pharmacology , Mice , Mice, Inbred BALB C , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Mitogen-Activated Protein Kinase 14/chemistry , Models, Molecular , Nitriles/chemistry , Nitriles/pharmacology , Pyrimidines/chemistry , Pyrimidines/pharmacology , Rats , Structure-Activity Relationship , Tumor Necrosis Factor-alpha/biosynthesisABSTRACT
A series of substituted 2-(aminoheteroaryl)-thiazole-5-carboxamide analogs have been synthesized as novel, potent inhibitors of the Src-family kinase p56Lck. Among them, compound 2 displayed superior in vitro potency and excellent in vivo efficacy.
Subject(s)
Amides/pharmacology , Anti-Inflammatory Agents/pharmacology , Enzyme Inhibitors/pharmacology , Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/antagonists & inhibitors , Thiazoles/pharmacology , src-Family Kinases/antagonists & inhibitors , Administration, Oral , Amides/chemical synthesis , Amides/pharmacokinetics , Animals , Anti-Inflammatory Agents/chemical synthesis , Anti-Inflammatory Agents/pharmacokinetics , Arthritis, Experimental/therapy , Disease Models, Animal , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacokinetics , Male , Models, Molecular , Molecular Structure , Rats , Structure-Activity Relationship , Thiazoles/chemical synthesis , Thiazoles/pharmacokineticsABSTRACT
A new structural class of triaminotriazine aniline amides possessing potent p38 enzyme activity has been discovered. The initial hit (compound 1a) was identified through screening the Pharmacopeia ECLiPS compound collection. SAR modification led to the identification of a short acting triaminotriazine aniline methoxyamide (compound 1m) possessing in vitro and in vivo oral activity in animal models of acute and chronic inflammatory disease. An X-ray crystal structure of compound 1m in this class, cocrystallized with unactivated p38 alpha protein, indicates that these compounds bind to the ATP binding pocket and possess key H-bonding interactions within a deeper cleft. Hydrogen bonding between one of the triazine nitrogens and the backbone NH of the Met109 residue occurs through a water molecule. The methoxyamide NH and carbonyl oxygen are within H-bonding distance of Glu71 and Asp168.