ABSTRACT
HCV NS5A inhibitors have shown impressive in vitro potency profiles in HCV replicon assays thus making them attractive components for inclusion in an all oral fixed dose combination regimen. Herein, we describe the discovery and characterization of silyl proline-containing HCV NS5A inhibitor MK-8325 with good pan-genotype activity and acceptable pharmacokinetic properties.
Subject(s)
Antiviral Agents/chemistry , Heterocyclic Compounds, 4 or More Rings/chemistry , Proline/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/pharmacokinetics , Antiviral Agents/pharmacology , Cytochrome P-450 Enzyme System/metabolism , Dogs , Genotype , Half-Life , Haplorhini , Hepacivirus/drug effects , Hepacivirus/genetics , Hepacivirus/physiology , Heterocyclic Compounds, 4 or More Rings/pharmacokinetics , Heterocyclic Compounds, 4 or More Rings/pharmacology , Humans , Rats , Viral Nonstructural Proteins/metabolism , Virus Replication/drug effectsABSTRACT
Herein we describe our research efforts around the aryl and heteroaryl substitutions at the aminal carbon of the tetracyclic indole-based HCV NS5A inhibitor MK-8742. A series of potent NS5A inhibitors are described, such as compounds 45-47, 54, 56, and 65, which showed improved potency against clinically relevant and resistance associated HCV variants. The improved potency profiles of these compounds demonstrated an SAR that can improve the potency against GT2b, GT1a Y93H, and GT1a L31V altogether, which was unprecedented in our previous efforts in NS5A inhibition.
Subject(s)
Antiviral Agents/pharmacology , Benzofurans/pharmacology , Hepacivirus/drug effects , Imidazoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Benzofurans/chemical synthesis , Benzofurans/chemistry , Dose-Response Relationship, Drug , Imidazoles/chemical synthesis , Imidazoles/chemistry , Male , Microbial Sensitivity Tests , Molecular Structure , Rats , Rats, Sprague-Dawley , Structure-Activity RelationshipABSTRACT
A matched and mixed capping SAR study was conducted on the tetracyclic indole class of HCV NS5A inhibitors to examine the influence of modifications of this region on the overall HCV virologic resistance profiles.
Subject(s)
Antiviral Agents/chemistry , Hepacivirus/metabolism , Indoles/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/metabolism , Antiviral Agents/pharmacology , Area Under Curve , Genotype , Half-Life , Hepacivirus/drug effects , Hepacivirus/genetics , Indoles/metabolism , Indoles/pharmacology , ROC Curve , Rats , Structure-Activity Relationship , Viral Nonstructural Proteins/metabolismABSTRACT
HCV NS5A inhibitors have demonstrated impressive in vitro potency profiles in HCV replicon assays and robust HCV RNA titer reduction in the clinic making them attractive components for inclusion in an all oral fixed dose combination regimen for the treatment of HCV infection. Herein we describe our continued research efforts around the alkyl "Z group" modification of the tetracyclic indole-based NS5A inhibitor MK-8742, which led to the discovery of a series of potent NS5A inhibitors. Compounds 10 and 19 are of particular interests since they are as potent as our previous leads and have much improved rat pharmacokinetic profiles.
Subject(s)
Antiviral Agents/pharmacology , Benzofurans/pharmacology , Hepacivirus/drug effects , Imidazoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Benzofurans/chemical synthesis , Benzofurans/chemistry , Dose-Response Relationship, Drug , Hepatitis C/drug therapy , Imidazoles/chemical synthesis , Imidazoles/chemistry , Male , Microbial Sensitivity Tests , Molecular Structure , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship , Virus Replication/drug effectsABSTRACT
HCV NS5A inhibitors have demonstrated impressive in vitro virologic profiles in HCV replicon assays and robust HCV RNA titer reduction in the clinic making them attractive components for inclusion in an all oral fixed-dose combination (FDC) regimen for the treatment of HCV infection. Merck's effort in this area identified MK-4882 and MK-8325 as early development leads. Herein, we describe the discovery of potent macrocyclic NS5A inhibitors bearing the MK-8325 or MK-4882 core structure.
Subject(s)
Antiviral Agents/pharmacology , Drug Discovery , Hepacivirus/drug effects , Heterocyclic Compounds, 4 or More Rings/pharmacology , Macrocyclic Compounds/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Dose-Response Relationship, Drug , Hepatitis C/drug therapy , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemistry , Macrocyclic Compounds/chemical synthesis , Macrocyclic Compounds/chemistry , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , Virus Replication/drug effectsABSTRACT
As part of an ongoing effort in NS5A inhibition at Merck we now describe our efforts for introducing substitution around the tetracyclic indole core of MK-8742. Fluoro substitution on the core combined with the fluoro substitutions on the proline ring improved the potency against GT1a Y93H significantly. However, no improvement on GT2b potency was achieved. Limiting the fluoro substitution to C-1 of the tetracyclic indole core had a positive impact on the potency against the resistance associated variants, such as GT1a Y93H and GT2b, and the PK profile as well. Compounds, such as 62, with reduced potency shifts between wild type GT1a to GT2b, GT1a Y93H, and GT1a L31V were identified.
Subject(s)
Antiviral Agents/pharmacology , Benzofurans/pharmacology , Imidazoles/pharmacology , Indoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemistry , Antiviral Agents/pharmacokinetics , Benzofurans/chemistry , Benzofurans/pharmacokinetics , Imidazoles/chemistry , Imidazoles/pharmacokinetics , Indoles/chemistry , Indoles/pharmacokinetics , Structure-Activity RelationshipABSTRACT
We describe the impact of proline modifications, in our tetracyclic-indole based series of nonstructural protein 5A (NS5A) inhibitors, to their replicon profiles. This work identified NS5A inhibitors with an improved and flattened resistance profiles.
Subject(s)
Antiviral Agents/pharmacology , Benzofurans/pharmacology , Imidazoles/pharmacology , Indoles/chemistry , Proline/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemistry , Benzofurans/chemistry , Imidazoles/chemistry , Structure-Activity RelationshipABSTRACT
HCV NS5A inhibitors have demonstrated impressive in vitro potency profiles in HCV replicon assays and robust HCV RNA titer reduction in the clinic making them attractive components for inclusion in an all oral fixed dose combination regimen for the treatment of HCV infection. Herein, we describe research efforts that led to the discovery of a series of fused tricyclic core containing HCV NS5A inhibitors such as 24, 39, 40, 43, and 44 which have pan-genotype activity and are orally bioavailable in the rat.
Subject(s)
Antiviral Agents/pharmacology , Drug Discovery , Hepacivirus/drug effects , Hepatitis C/drug therapy , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Dose-Response Relationship, Drug , Genotype , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , Viral Nonstructural Proteins/genetics , Virus Replication/drug effectsABSTRACT
HCV NS5A inhibitors have shown impressive in vitro potency profiles in HCV replicon assays thus making them attractive components for inclusion in an all oral fixed dose combination treatment regimen. Herein we describe the research efforts that led to the discovery of silyl proline containing HCV NS5A inhibitors such as 7e and 8a with pan-genotype activity profile and acceptable pharmacokinetic properties.
Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Drug Discovery , Hepacivirus/drug effects , Hepacivirus/genetics , Proline/analogs & derivatives , Silanes/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemical synthesis , Dose-Response Relationship, Drug , Genotype , Microbial Sensitivity Tests , Molecular Structure , Silanes/pharmacology , Structure-Activity Relationship , Viral Nonstructural Proteins/genetics , Virus Replication/drug effectsABSTRACT
The structure-human CXCR3 binding affinity relationship of a series of pyridyl/pyrazinyl-piperazinyl-piperidine derivatives were explored with a focus to improve PK, hERG and metabolic profiles. Several small heterocycles were identified as amide surrogates, which minimized many potential metabolite issues. During the course of SAR development, we have observed the additive effect of desirable functional groups to improve hERG and PK profiles which lead to the discovery of many clinically developable CXCR3 antagonists with excellent overall profile.
Subject(s)
Amides/pharmacology , Drug Discovery , Ether-A-Go-Go Potassium Channels/metabolism , Heterocyclic Compounds/pharmacology , Receptors, CXCR3/antagonists & inhibitors , Amides/administration & dosage , Amides/chemistry , Animals , Dose-Response Relationship, Drug , Heterocyclic Compounds/administration & dosage , Heterocyclic Compounds/chemistry , Humans , Molecular Structure , Rats , Structure-Activity RelationshipABSTRACT
HCV infections are the leading causes for hepatocellular carcinoma and liver transplantation in the United States. Recent advances in drug discovery have identified direct acting antivirals which have significantly improved cure rates in patients. Current efforts are directed towards identification of novel direct acting antiviral targeting different mechanism of actions which could become part of all oral therapies. We recently disclosed the identification of a novel tricyclic indole derived inhibitors of HCV NS5B polymerase that bound to the enzyme close to the active site. In this manuscript we describe further optimization of potency and pharmacokinetics (PK) of these inhibitors to identify compounds in low nM potency against gt-1b. These analogs also demonstrate excellent PK in rats and monkeys when administered as a dimethyl ethyl amino ester prodrug.
Subject(s)
Esters/pharmacokinetics , Hepacivirus/drug effects , Indoles/pharmacokinetics , Viral Nonstructural Proteins/antagonists & inhibitors , Administration, Oral , Animals , Drug Discovery , Esters/chemistry , Haplorhini , Hepacivirus/enzymology , Humans , Indoles/chemistry , Prodrugs/pharmacology , Rats , Structure-Activity RelationshipABSTRACT
A novel series of benzimidazolone-containing histamine H3-receptor antagonists were prepared and their structure-activity relationship was explored. These benzimidazolone analogs demonstrate potent H3-receptor binding affinities, no P450 enzyme inhibition, and strong H3 functional activity. Compound 1o exhibits the best overall profile with H3Ki=0.95nM and rat AUC=12.9µMh.
Subject(s)
Benzimidazoles/chemistry , Benzimidazoles/pharmacology , Histamine H3 Antagonists/chemistry , Histamine H3 Antagonists/pharmacology , Animals , Benzimidazoles/chemical synthesis , Benzimidazoles/pharmacokinetics , Cytochrome P-450 Enzyme System/metabolism , Guinea Pigs , Histamine H3 Antagonists/chemical synthesis , Histamine H3 Antagonists/pharmacokinetics , Humans , Rats , Receptors, Histamine H3/metabolism , Structure-Activity RelationshipABSTRACT
The discovery of lead compound 2e was described. Its covalent binding to HCV NS5B polymerase enzyme was investigated by X-ray analysis. The results of distribution, metabolism and pharmacokinetics were reported. Compound 2e was demonstrated to be potent (replicon GT-1b EC50 = 0.003 µM), highly selective, and safe in in vitro and in vivo assays.
Subject(s)
Enzyme Inhibitors/chemistry , Hepacivirus/enzymology , Indoles/chemistry , Quinolines/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Crystallography, X-Ray , Dogs , Drug Evaluation, Preclinical , Enzyme Activation/drug effects , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacokinetics , Enzyme Inhibitors/pharmacology , Haplorhini , Humans , Indoles/chemical synthesis , Indoles/pharmacokinetics , Indoles/pharmacology , Male , Molecular Dynamics Simulation , Protein Binding , Protein Structure, Tertiary , Quinolines/chemical synthesis , Quinolines/pharmacokinetics , Quinolines/pharmacology , Rats , Rats, Sprague-Dawley , Viral Nonstructural Proteins/metabolismABSTRACT
The characterization of HCV genome has identified various vital functional proteins involved in the life cycle of hepatitis C virus. This has resulted in many novel enzymatic targets that are potential for development of therapeutic agents. The HCV RNA dependent RNA polymerase (HCV NS5B) is one such essential enzyme for HCV replication that has been well characterized and studied by various groups to develop novel therapies for hepatitis C. In this paper, we describe our efforts towards the identification and structure-activity relationship (SAR) of novel tricyclic indole derivatives that bind close to the palm site of the NS5B polymerase. X-ray crystal structure of an inhibitor bound to the polymerase is also described.
Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Hepacivirus/enzymology , Indoles/chemistry , Indoles/pharmacology , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Binding Sites , Crystallography, X-Ray , Hepacivirus/chemistry , Hepatitis C/drug therapy , Hepatitis C/virology , Humans , Molecular Docking Simulation , RNA-Dependent RNA Polymerase/chemistry , RNA-Dependent RNA Polymerase/metabolism , Structure-Activity RelationshipABSTRACT
OBJECTIVES: Respiratory Syncytial Virus (RSV) is a leading cause of death and hospitalization among infants and young children. People with an immunocompromised status are also at risk for severe RSV infection. There is no specific treatment for RSV infection available. Ribavirin, an antiviral drug approved for severe lung infection by RSV, has shown limited clinical efficacies with severe side effects. Additionally, given the genetic variability of RSV genomes and seasonal change of different strains, a broad-spectrum antiviral drug is highly desirable. The RNA-dependent RNA polymerase (RdRp) domain is relatively conserved and indispensable for the replication of the virus genome and therefore serves as a potential therapeutic target. Previous attempts to identify an RdRp inhibitor have not been successful due to lack of potency or high enough blood exposure. DZ7487 is a novel orally available small molecule inhibitor specifically designed to target the RSV RdRp. Here we present our data showing that DZ7487 can potently inhibited all clinical viral isolates tested, with large safety margin predicted for human. METHODS: HEp-2 cells were infected by RSV A and B. Antiviral activities were assessed by in vitro cytopathic effect assay (CPE) and Reverse transcription-quantitative polymerase chain reaction (RT-qPCR). DZ7487 antiviral effects in lower airway cells were evaluated in A549 and human small airway epithelial cells (SAEC) cells. DZ7487 induced RSV A2 escape mutations were selected through continuous culture with increasing DZ7487 concentrations in the culture medium. Resistant mutations were identified by next generation sequencing and confirmed by recombinant RSV CPE assays. RSV infection models in both BALB/c mice and cotton rats were used to evaluate DZ7487 in vivo antiviral effects. RESULTS: DZ7487 potently inhibited viral replication of all clinical isolates of both RSVA and B subtypes. In lower airway cells, DZ7487 showed superior efficacy than the nucleoside analog ALS-8112. Acquired resistant mutation was predominantly restricted at the RdRp domain resulting asparagine to threonine mutation (N363T) of the L protein. This finding is consistent with DZ7487's presumed binding mode. DZ7487 was well tolerated in animal models. Unlike fusion inhibitors, which can only prevent viral infection, DZ7487 potently inhibited RSV replication before and after RSV infection in vitro and in vivo. CONCLUSIONS: DZ7487 demonstrated potent anti-RSV replication effect both in vitro and in vivo assays. It has the desired drug-like physical properties to be an effective orally available anti-RSV replication drug with broad spectrum.
ABSTRACT
Development of SAR at the C2 position of indole lead 1, a palm site inhibitor of HCV NS5B polymerase (NS5B IC(50)=0.053µM, replicon EC(50)=4.8µM), is described. Initial screening identified an acyl sulfonamide moiety as an isostere for the C2 carboxylic acid group. Further SAR investigation resulted in identification of acyl sufonamide analog 7q (NS5B IC(50)=0.039µM, replicon EC(50)=0.011µM) with >100-fold improved replicon activity.
Subject(s)
Antiviral Agents/pharmacology , Indoles/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Chemistry, Pharmaceutical/methods , Crystallography, X-Ray/methods , Drug Design , Humans , Hydrogen Bonding , Inhibitory Concentration 50 , Models, Chemical , Models, Molecular , Molecular Conformation , Structure-Activity Relationship , Sulfonamides/chemistryABSTRACT
The structure-human CXCR3 binding affinity relationship of a series of pyridyl-piperazinyl-piperidine derivatives was explored. The optimization campaign highlighted the pronounced effect of 2'-piperazine substitution on CXCR3 receptor affinity. Analog 18j, harboring a 2'(S)-ethylpiperazine moiety, exhibited a human CXCR3 IC(50) of 0.2 nM.
Subject(s)
Piperazines/chemical synthesis , Piperidines/chemical synthesis , Pyridines/chemical synthesis , Receptors, CXCR3/agonists , Humans , Inhibitory Concentration 50 , Molecular Structure , Piperazine , Piperazines/chemistry , Piperazines/pharmacology , Piperidines/chemistry , Piperidines/pharmacology , Pyridines/chemistry , Pyridines/pharmacology , Structure-Activity RelationshipABSTRACT
The SAR of a novel pyrazinyl-piperazinyl-piperidine scaffold with CXCR3 receptor antagonist activity was explored. Optimization of the DMPK profile and reduction of hERG inhibition is described. Compound 16e with single-digit CXCR3 affinity, good rat PK and hERG profiles has been identified as a lead for further study.
Subject(s)
Piperazines/chemistry , Pyrazines/chemistry , Receptors, CXCR3/antagonists & inhibitors , Animals , Inhibitory Concentration 50 , Molecular Structure , Piperazines/pharmacology , Protein Binding/drug effects , Pyrazines/pharmacology , Rats , Structure-Activity RelationshipABSTRACT
SAR development of indole-based palm site inhibitors of HCV NS5B polymerase exemplified by initial indole lead 1 (NS5B IC(50)=0.9 µM, replicon EC(50)>100 µM) is described. Structure-based drug design led to the incorporation of novel heterocyclic moieties at the indole C3-position which formed a bidentate interaction with the protein backbone. SAR development resulted in leads 7q (NS5B IC(50)=0.032 µM, replicon EC(50)=1.4 µM) and 7r (NS5B IC(50)=0.017 µM, replicon EC(50)=0.3 µM) with improved enzyme and replicon activity.
Subject(s)
Drug Discovery , Enzyme Inhibitors/pharmacology , Heterocyclic Compounds/pharmacology , Indoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Carboxylic Acids , Catalytic Domain/drug effects , Crystallography, X-Ray , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Heterocyclic Compounds/chemical synthesis , Heterocyclic Compounds/chemistry , Indoles/chemical synthesis , Indoles/chemistry , Models, Molecular , Molecular Structure , Stereoisomerism , Structure-Activity Relationship , Viral Nonstructural Proteins/metabolismABSTRACT
Recent reports suggest that an increasing number of patients with lung cancer, especially those with activating mutations of the epidermal growth factor receptor (EGFR), also present with brain metastases and leptomeningeal metastases. These patients have poor prognosis as there are no approved drugs for these indications. Available agents have poor efficacy for these patients even at well above their standard dose. Herein, we report the discovery of (4-[(3-chloro-2-fluorophenyl)amino]-7-methoxyquinazolin-6-yl (2R)-2,4-dimethylpiperazine-1-carboxylate 1m (AZD3759), an investigational drug currently in Phase 1 clinical trial, which has excellent central nervous system penetration and which induces profound regression of brain metastases in a mouse model.