ABSTRACT
BACKGROUND: GS-9256 is an inhibitor of HCV NS3 protease with a macrocyclic structure and novel phosphinic acid pharmacophore. METHODS: Key preclinical properties of GS-9256 including in vitro antiviral activity, cross-resistance and pharmacokinetic properties were investigated in non-human species. RESULTS: In genotype (GT) 1b Huh-luc cells with a replicon encoding luciferase, GS-9256 had a mean 50% effective concentration (EC50) value of 20.0 nM, with minimal cytotoxicity. Antiviral activity was similar in a number of additional GT1b and GT1a replicon cell lines. Similar potency was observed in chimeric replicons encoding the NS3 protease of GT1 clinical isolates. GS-9256 was less active in GT2a replicon cells (14.2-fold increase in EC50). Additive to synergistic in vitro antiviral activity was observed when GS-9256 was combined with other agents including interferon-α, ribavirin, NS5B polymerase inhibitors GS-6620 and tegobuvir, as well as the NS5A inhibitor ledipasvir. GS-9256 retained wild-type activity against all tested NS5B and NS5A inhibitor resistance mutations. GS-9256 was metabolically stable in microsomes and hepatocytes of tested species, including rodents, dogs and humans. GS-9256 had high bioavailability in mice (near 100%) and moderate bioavailability in rats (14%), dogs (21%) and monkeys (14%). Elimination half-lives were approximately 2 h in mice, 0.6 h in rats, 5 h in dogs and 4 h in monkey. A study in bile duct-cannulated rats indicated that the major route of elimination is through biliary excretion of unmetabolized GS-9256. CONCLUSIONS: GS-9256 showed a favourable preclinical profile supportive of clinical development for the treatment of chronic HCV infection in GT1 patients.
Subject(s)
Antiviral Agents/pharmacology , Hepacivirus/drug effects , Peptides, Cyclic/pharmacology , Phosphinic Acids/pharmacology , Protease Inhibitors/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/chemistry , Antiviral Agents/pharmacokinetics , Biological Availability , Cell Line , Cells, Cultured , Dogs , Drug Evaluation, Preclinical , Drug Resistance, Viral , Hepacivirus/enzymology , Hepatitis C/drug therapy , Hepatitis C/virology , Humans , Macaca fascicularis , Mice , Peptides, Cyclic/chemistry , Peptides, Cyclic/pharmacokinetics , Phosphinic Acids/chemistry , Phosphinic Acids/pharmacokinetics , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacokinetics , Rats , Virus Replication/drug effectsABSTRACT
A sulfonamide replacement of the P2-P3 amide bond in the context of macrocyclic HCV NS3 protease inhibitors was investigated. These analogs displayed good inhibitory potency in the absence of any P3 capping group. The synthesis and preliminary SAR are described.
Subject(s)
Hepacivirus/drug effects , Sulfonamides/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Enzyme Activation/drug effects , Humans , Inhibitory Concentration 50 , Molecular Structure , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , Structure-Activity Relationship , Sulfonamides/pharmacologyABSTRACT
GS-9451 is a selective hepatitis C virus (HCV) NS3 protease inhibitor in development for the treatment of genotype 1 (GT1) HCV infection. Key preclinical properties of GS-9451, including in vitro antiviral activity, selectivity, cross-resistance, and combination activity, as well as pharmacokinetic properties, were determined. In multiple GT1a and GT1b replicon cell lines, GS-9451 had mean 50% effective concentrations (EC50s) of 13 and 5.4 nM, respectively, with minimal cytotoxicity; similar potency was observed in chimeric replicons encoding the NS3 protease gene of GT1 clinical isolates. GS-9451 was less active in GT2a replicon cells (EC50 = 316 nM). Additive to synergistic in vitro antiviral activity was observed when GS-9451 was combined with other agents, including alpha interferon, ribavirin, and the polymerase inhibitors GS-6620 and tegobuvir (GS-9190), as well as the NS5A inhibitor ledipasvir (GS-5885). GS-9451 retained wild-type activity against multiple classes of NS5B and NS5A inhibitor resistance mutations. GS-9451 was stable in hepatic microsomes and hepatocytes from human and three other tested species. Systemic clearance was low in dogs and monkeys but high in rats. GS-9451 showed good oral bioavailability in all three species tested. In rats, GS-9451 levels were â¼40-fold higher in liver than plasma after intravenous dosing, and elimination of GS-9451 was primarily through biliary excretion. Together, these results are consistent with the antiviral activity observed in a recent phase 1b study. The results of in vitro cross-resistance and combination antiviral assays support the ongoing development of GS-9451 in combination with other agents for the treatment of chronic HCV infection.
Subject(s)
Antiviral Agents/pharmacology , Hepacivirus/drug effects , Hepatitis C, Chronic/drug therapy , Protease Inhibitors/pharmacology , Quinolines/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/pharmacokinetics , Benzimidazoles/pharmacology , Dogs , Drug Evaluation, Preclinical , Drug Resistance, Viral/drug effects , Drug Resistance, Viral/genetics , Drug Synergism , Drug Therapy, Combination , Fluorenes/pharmacology , Haplorhini , Hepacivirus/physiology , Hepatitis C, Chronic/pathology , Hepatitis C, Chronic/virology , Hepatocytes/drug effects , Hepatocytes/virology , Humans , Inhibitory Concentration 50 , Interferon-alpha/pharmacology , Protease Inhibitors/pharmacokinetics , Purines/pharmacology , Pyridazines/pharmacology , Quinolines/pharmacokinetics , Rats , Replicon/drug effects , Ribavirin/pharmacology , Viral Nonstructural Proteins/metabolismABSTRACT
The discovery of GS-9451 is reported. Modification of the P3 cap and P2 quinoline with a series of solubilizing groups led to the identification of potent HCV NS3 protease inhibitors with greatly improved pharmacokinetic properties in rats, dogs and monkeys.
Subject(s)
Antiviral Agents/chemical synthesis , Carboxylic Acids/chemical synthesis , Hepacivirus/drug effects , Quinolines/chemical synthesis , Serine Proteinase Inhibitors/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/pharmacokinetics , Antiviral Agents/pharmacology , Biological Availability , Caco-2 Cells , Carboxylic Acids/pharmacokinetics , Carboxylic Acids/pharmacology , Crystallography, X-Ray , Dogs , Hepacivirus/chemistry , Hepacivirus/enzymology , Hepatitis C/drug therapy , Hepatitis C/virology , Humans , Macaca fascicularis , Models, Molecular , Quinolines/pharmacokinetics , Quinolines/pharmacology , Rats , Serine Proteinase Inhibitors/pharmacokinetics , Serine Proteinase Inhibitors/pharmacology , Structure-Activity Relationship , Viral Nonstructural Proteins/chemistryABSTRACT
A potent and novel class of phosphinic acid derived product-like inhibitors of the HCV NS3/4A protease was discovered previously. Modification of the phosphinic acid and quinoline heterocycle led to GS-9256 with potent cell-based activity and favorable pharmacokinetic parameters. Based on these attributes, GS-9256 was advanced to human clinical trial as a treatment for chronic infection with genotype 1 HCV.
Subject(s)
Carrier Proteins/antagonists & inhibitors , Drug Discovery , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Hepacivirus/drug effects , Peptides, Cyclic/chemistry , Phosphinic Acids/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Dogs , Enzyme Inhibitors/chemical synthesis , Hepacivirus/enzymology , Humans , Inhibitory Concentration 50 , Intracellular Signaling Peptides and Proteins , Molecular Structure , Peptides, Cyclic/chemical synthesis , Peptides, Cyclic/pharmacology , Phosphinic Acids/chemical synthesis , Phosphinic Acids/pharmacology , SwineABSTRACT
A novel, potent, and orally bioavailable class of product-like inhibitors of the HCV NS3 protease was discovered by constraining the P2-P3 amide bond and the P3 hydrocarbon substituent to the protease-bound conformation. This preorganization was accomplished by incorporation of the P2-P3 amide into a six-membered ring attached to the P2-proline 5-position. Isothermal calorimetric characterization of the role of hydrocarbon substitution of this six-membered ring, upon binding the HCV NS3 protease, was found to be exclusively entropic in nature. The synthesis, preliminary SAR and pharmacokinetic profiling of this compact, indolizidinone-derived scaffold are described.
Subject(s)
Enzyme Inhibitors/pharmacology , Indolizines/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Administration, Oral , Biological Availability , Crystallography, X-Ray , Dose-Response Relationship, Drug , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/chemistry , Indolizines/administration & dosage , Indolizines/chemistry , Models, Molecular , Molecular Structure , Structure-Activity Relationship , Viral Nonstructural Proteins/metabolismABSTRACT
A potent and novel class of product-like inhibitors of the HCV NS3 protease was discovered by employing a phosphinic acid as a carboxylate isostere. The replicon activity and pharmacokinetic profile of this series of compounds was optimized by exploring the substitution of the phosphinic acid, as well as conformationally constraining these compounds through macrocyclization. The syntheses and preliminary biological evaluation of these phosphinic acids is described.
Subject(s)
Hepacivirus/drug effects , Hepacivirus/enzymology , Phosphinic Acids/chemical synthesis , Phosphinic Acids/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Administration, Oral , Cyclization , Humans , Inhibitory Concentration 50 , Molecular Structure , Phosphinic Acids/chemistryABSTRACT
A novel class of phosphonate derivatives was designed to mimic the interaction of product-like carboxylate based inhibitors of HCV NS3 protease. A phosphonic acid (compound 2) was demonstrated to be a potent HCV NS3 protease inhibitor, and a potential candidate for treating HCV infection. The syntheses and preliminary biological evaluation of this phosphonate class of inhibitor are described.
