ABSTRACT
In the search for novel influenza inhibitors we evaluated 7-fluoro-substituted indoles as bioisosteric replacements for the 7-azaindole scaffold of Pimodivir, a PB2 (polymerase basic protein 2) inhibitor currently in clinical development. Specifically, a 5,7-difluoroindole derivative 11a was identified as a potent and metabolically stable influenza inhibitor. 11a demonstrated a favorable oral pharmacokinetic profile and in vivo efficacy in mice. In addition, it was found that 11a was not at risk of metabolism via aldehyde oxidase, an advantage over previously described inhibitors of this class. The crystal structure of 11a bound to influenza A PB2 cap region is disclosed here and deposited to the PDB.
Subject(s)
Antiviral Agents/chemical synthesis , Antiviral Agents/pharmacology , Drug Design , Indoles/chemical synthesis , Indoles/pharmacology , Viral Proteins/drug effects , A549 Cells , Animals , Antiviral Agents/chemistry , Antiviral Agents/pharmacokinetics , Crystallography, X-Ray , Dogs , Humans , Indoles/chemistry , Indoles/pharmacokinetics , Influenza A Virus, H1N1 Subtype/drug effects , Influenza A Virus, H3N2 Subtype/drug effects , Madin Darby Canine Kidney Cells , Microbial Sensitivity Tests , Molecular StructureABSTRACT
A novel series of 2,4-diaminoquinazolines was identified as potent dual Toll-like receptor (TLR) 7 and 8 agonists with reduced off-target activity. The stereochemistry of the amino alcohol was found to influence the TLR7/8 selectivity with the ( R) isomer resulting in selective TLR8 agonism. Lead optimization toward a dual agonist afforded ( S)-3-((2-amino-8-fluoroquinazolin-4-yl)amino)hexanol 31 as a potent analog, being structurally different from previously described dual agonists ( McGowan J. Med. Chem. 2016 , 59 , 7936 ). Pharmacokinetic and pharmacodynamic (PK/PD) studies revealed the desired high first pass profile aimed at limiting systemic cytokine activation. In vivo pharmacodynamic studies with lead compound 31 demonstrated production of cytokines consistent with TLR7/8 activation in mice and cynomolgus monkeys and ex vivo inhibition of hepatitis B virus (HBV).
Subject(s)
Antiviral Agents/pharmacology , Hepatitis B virus/drug effects , Quinazolines/pharmacology , Toll-Like Receptor 7/metabolism , Toll-Like Receptor 8/metabolism , Animals , Antiviral Agents/chemistry , Antiviral Agents/metabolism , HEK293 Cells , Humans , Male , Mice , Molecular Docking Simulation , Protein Conformation , Quinazolines/chemistry , Quinazolines/metabolism , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship , Toll-Like Receptor 7/chemistry , Toll-Like Receptor 8/chemistryABSTRACT
The discovery of a novel series of highly potent quinazoline TLR 7/8 agonists is described. The synthesis and structure-activity relationship is presented. Structural requirements and optimization of this series toward TLR 7 selectivity afforded the potent agonist 48. Pharmacokinetic and pharmacodynamic studies highlighted 48 as an orally available endogenous interferon (IFN-α) inducer in mice.
Subject(s)
Membrane Glycoproteins/agonists , Quinazolines/pharmacology , Toll-Like Receptor 7/agonists , Animals , Cytochrome P-450 Enzyme Inhibitors/chemical synthesis , Cytochrome P-450 Enzyme Inhibitors/chemistry , Cytochrome P-450 Enzyme Inhibitors/pharmacokinetics , Cytochrome P-450 Enzyme Inhibitors/pharmacology , HEK293 Cells , Half-Life , Humans , Interferon-alpha/metabolism , Male , Mice, Inbred C57BL , Microsomes, Liver/metabolism , Molecular Docking Simulation , Molecular Structure , Quinazolines/chemical synthesis , Quinazolines/chemistry , Quinazolines/pharmacokinetics , Rats, Sprague-Dawley , Structure-Activity Relationship , Toll-Like Receptor 8/agonistsABSTRACT
Pyrrolo[3,2-d]pyrimidines were identified as a new series of potent and selective TLR7 agonists. Compounds were optimized for their activity and selectivity over TLR8. This presents an advantage over recently described scaffolds that have residual TLR8 activity, which may be detrimental to the tolerability of the candidate drug. Oral administration of the lead compound 54 effectively induced a transient interferon stimulated gene (ISG) response in mice and cynomolgus monkeys. We aimed for a high first pass effect, limiting cytokine induction systemically, and demonstrated the potential for the immunotherapy of viral hepatitis.
Subject(s)
Antiviral Agents/chemical synthesis , Hepatitis B/drug therapy , Pyrimidines/chemical synthesis , Pyrroles/chemical synthesis , Toll-Like Receptor 7/agonists , Administration, Oral , Animals , Antiviral Agents/pharmacokinetics , Antiviral Agents/pharmacology , Dendritic Cells/drug effects , Dendritic Cells/metabolism , Dogs , Female , Genes, Reporter , HEK293 Cells , Hepatitis B/immunology , Humans , Immunotherapy , Interferons/biosynthesis , Macaca fascicularis , Madin Darby Canine Kidney Cells , Mice, Inbred C57BL , Molecular Docking Simulation , Pyrimidines/pharmacokinetics , Pyrimidines/pharmacology , Pyrroles/pharmacokinetics , Pyrroles/pharmacology , Rats , Structure-Activity Relationship , Toll-Like Receptor 7/genetics , Toll-Like Receptor 8/agonists , Toll-Like Receptor 8/geneticsABSTRACT
Toll-like receptor (TLR) 7 and 8 agonists can potentially be used in the treatment of viral infections and are particularly promising for chronic hepatitis B virus (HBV) infection. An internal screening effort identified a pyrimidine Toll-like receptor 7 and 8 dual agonist. This provided a novel alternative over the previously reported adenine and pteridone type of agonists. Structure-activity relationship, lead optimization, in silico docking, pharmacokinetics, and demonstration of ex vivo and in vivo cytokine production of the lead compound are presented.
Subject(s)
Antiviral Agents/chemistry , Hepatitis B virus/drug effects , Pyrimidines/chemistry , Toll-Like Receptor 7/agonists , Toll-Like Receptor 8/agonists , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/pharmacokinetics , Antiviral Agents/pharmacology , Computer Simulation , Cytokines/biosynthesis , Dogs , Hepatitis B/drug therapy , Hepatitis B/virology , Hepatitis B virus/physiology , High-Throughput Screening Assays , Humans , Macaca fascicularis , Mice , Mice, Inbred C57BL , Molecular Docking Simulation , Pyrimidines/chemical synthesis , Pyrimidines/pharmacokinetics , Pyrimidines/pharmacology , Rats, Sprague-Dawley , Stereoisomerism , Structure-Activity Relationship , Virus Replication/drug effectsABSTRACT
The influx of leukocytes (eosinophils, lymphocytes, and monocytes) into the airways and their production of proinflammatory cytokines contribute to the severity of allergic asthma. We describe here the synthesis and pharmacological evaluation of a series of triazinylphenylalkylthiazolecarboxylic acid esters that were designed to act as lung-specific antedrugs and inhibitors of the production of interleukin (IL)-5, a primary eosinophil-activating and proinflammatory cytokine. Closer examination of the hydroxypropyl ester, 15, indicated its high metabolic stability (t(1/2) > 240 min) in human lung S9 fraction but rapid conversion (t(1/2) = 15 min) into the pharmacologically inactive carboxylic acid by human liver preparations. In stimulated human whole blood cultures, 15 reduced not only the production of IL-5 (IC(50) = 78 nM) but also the biosynthesis of the monocyte chemotactic proteins MCP-1 (IC(50) = 220 nM), MCP-2 (IC(50) = 580 nM), and MCP-3 (IC(50) = 80 nM). In vivo, intratracheal administration of 15 (6 mg/animal) to allergic sheep, either before (-4 h) or after (+1.5 h) the pulmonary allergen challenge, completely abrogated the late-phase airway response and reduced the bronchial hyperreactivity to inhaled carbachol.
