ABSTRACT
Herein we describe the discovery of IDX21437 35b, a novel RPd-aminoacid-based phosphoramidate prodrug of 2'-α-chloro-2'-ß-C-methyluridine monophosphate. Its corresponding triphosphate 6 is a potent inhibitor of the HCV NS5B RNA-dependent RNA polymerase (RdRp). Despite showing very weak activity in the in vitro Huh-7 cell based HCV replicon assay, 35b demonstrated high levels of active triphosphate 6 in mouse liver and human hepatocytes. A biochemical study revealed that the metabolism of 35b was mainly attributed to carboxyesterase 1 (CES1), an enzyme which is underexpressed in HCV Huh-7-derived replicon cells. Furthermore, due to its metabolic activation, 35b was efficiently processed in liver cells compared to other cell types, including human cardiomyocytes. The selected RP diastereoisomeric configuration of 35b was assigned by X-ray structural determination. 35b is currently in Phase II clinical trials for the treatment of HCV infection.
Subject(s)
Antiviral Agents/pharmacology , DNA-Directed RNA Polymerases/antagonists & inhibitors , Drug Discovery , Enzyme Inhibitors/pharmacology , Hepacivirus/drug effects , Uridine Monophosphate/analogs & derivatives , Uridine/pharmacology , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , DNA-Directed RNA Polymerases/metabolism , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Hepacivirus/enzymology , Hepatocytes/drug effects , Hepatocytes/virology , Humans , Liver/drug effects , Liver/virology , Mice , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , Uridine/chemical synthesis , Uridine/chemistry , Uridine Monophosphate/chemical synthesis , Uridine Monophosphate/chemistry , Uridine Monophosphate/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/metabolismABSTRACT
Hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase (RdRp) plays a central role in virus replication. NS5B has no functional equivalent in mammalian cells, and as a consequence is an attractive target for selective inhibition. This paper describes the discovery of a novel family of HCV NS5B non-nucleoside inhibitors inspired by the bioisosterism between sulfonamide and phosphonamide. Systematic structural optimization in this new series led to the identification of IDX375, a potent non-nucleoside inhibitor that is selective for genotypes 1a and 1b. The structure and binding domain of IDX375 were confirmed by X-ray co-crystalisation study.
Subject(s)
Antiviral Agents/chemistry , Hepacivirus/enzymology , Lactams/chemistry , Organophosphorus Compounds/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Allosteric Regulation , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/metabolism , Antiviral Agents/pharmacology , Binding Sites , Crystallography, X-Ray , Genotype , Half-Life , Haplorhini , Hepacivirus/genetics , Hepacivirus/physiology , Humans , Lactams/pharmacology , Mice , Molecular Dynamics Simulation , Organophosphorus Compounds/pharmacology , Protein Structure, Tertiary , Rats , Structure-Activity Relationship , Sulfonamides/chemistry , Viral Nonstructural Proteins/metabolism , Virus Replication/drug effectsABSTRACT
The hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase (RdRp) plays a central role in virus replication. NS5B has no functional equivalent in mammalian cells and, as a consequence, is an attractive target for selective inhibition. This Letter describes the discovery of a new family of HCV NS5B non-nucleoside inhibitors, based on the bioisosterism between amide and phosphonamidate functions. As part of this program, SAR in this new series led to the identification of IDX17119, a potent non-nucleoside inhibitor, active on the genotypes 1b, 2a, 3a and 4a. The structure and binding domain of IDX17119 were confirmed by X-ray co-crystallization study.
Subject(s)
Antiviral Agents/pharmacology , Genotype , Hepacivirus/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors , Allosteric Site , Antiviral Agents/chemistry , Antiviral Agents/metabolism , Crystallography, X-Ray , Structure-Activity Relationship , Viral Nonstructural Proteins/metabolismABSTRACT
BACKGROUND: Ribonucleoside analogs possessing a ß-methyl substituent at the 2'-position of the d-ribose moiety have been previously discovered to be potent and selective inhibitors of hepatitis C virus (HCV) replication, their triphosphates acting as alternative substrate inhibitors of the HCV RdRp NS5B. Results/methodology: In this article, the authors detail the synthesis, anti-HCV evaluation in cell-based replicon assays and structure-activity relationships of several phosphoramidate diester derivatives of 2'-C-methylguanosine (2'-MeG). CONCLUSION: The most promising compound, namely the O-[S-(hydroxyl)pivaloyl-2-thioethyl]{abbreviated as O-[(HO)tBuSATE)]} N-benzylamine phosphoramidate diester derivative (IDX184), was selected for further in vivo studies, and was the first clinical pronucleotide evaluated for the treatment of chronic hepatitis C up to Phase II trials.
