ABSTRACT
BACKGROUND: Inhibition of PCSK9 (proprotein convertase subtilisin/kexin type 9)-low density lipoprotein receptor interaction with injectable monoclonal antibodies or small interfering RNA lowers plasma low density lipoprotein-cholesterol, but despite nearly 2 decades of effort, an oral inhibitor of PCSK9 is not available. Macrocyclic peptides represent a novel approach to target proteins traditionally considered intractable to small-molecule drug design. METHODS: Novel mRNA display screening technology was used to identify lead chemical matter, which was then optimized by applying structure-based drug design enabled by novel synthetic chemistry to identify macrocyclic peptide (MK-0616) with exquisite potency and selectivity for PCSK9. Following completion of nonclinical safety studies, MK-0616 was administered to healthy adult participants in a single rising-dose Phase 1 clinical trial designed to evaluate its safety, pharmacokinetics, and pharmacodynamics. In a multiple-dose trial in participants taking statins, MK-0616 was administered once daily for 14 days to characterize the safety, pharmacokinetics, and pharmacodynamics (change in low density lipoprotein cholesterol). RESULTS: MK-0616 displayed high affinity (Ki = 5pM) for PCSK9 in vitro and sufficient safety and oral bioavailability preclinically to enable advancement into the clinic. In Phase 1 clinical studies in healthy adults, single oral doses of MK-0616 were associated with >93% geometric mean reduction (95% CI, 84-103) of free, unbound plasma PCSK9; in participants on statin therapy, multiple-oral-dose regimens provided a maximum 61% geometric mean reduction (95% CI, 43-85) in low density lipoprotein cholesterol from baseline after 14 days of once-daily dosing of 20 mg MK-0616. CONCLUSIONS: This work validates the use of mRNA display technology for identification of novel oral therapeutic agents, exemplified by the identification of an oral PCSK9 inhibitor, which has the potential to be a highly effective cholesterol lowering therapy for patients in need.
Subject(s)
Anticholesteremic Agents , Hydroxymethylglutaryl-CoA Reductase Inhibitors , Hypercholesterolemia , Adult , Humans , Anticholesteremic Agents/adverse effects , Cholesterol , Cholesterol, LDL , Hydroxymethylglutaryl-CoA Reductase Inhibitors/therapeutic use , Peptides/therapeutic use , Proprotein Convertase 9/genetics , Proprotein Convertase 9/metabolism , Receptors, LDL/genetics , Receptors, LDL/metabolismABSTRACT
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
We describe the research that led to the discovery of compound 40 (ruzasvir, MK-8408), a pan-genotypic HCV nonstructural protein 5A (NS5A) inhibitor with a "flat" GT1 mutant profile. This NS5A inhibitor contains a unique tetracyclic indole core while maintaining the imidazole-proline-valine Moc motifs of our previous NS5A inhibitors. Compound 40 is currently in early clinical trials and is under evaluation as part of an all-oral DAA regimen for the treatment of chronic HCV infection.
Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Hepacivirus/drug effects , Heterocyclic Compounds, 4 or More Rings/chemistry , Heterocyclic Compounds, 4 or More Rings/pharmacology , Polymorphism, Genetic , Pyrrolidines/chemistry , Pyrrolidines/pharmacology , Thiazoles/chemistry , Thiazoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/pharmacokinetics , Cell Line , Dogs , Haplorhini , Hepacivirus/genetics , Heterocyclic Compounds, 4 or More Rings/pharmacokinetics , Humans , Pyrrolidines/pharmacokinetics , Rats , Structure-Activity Relationship , Thiazoles/pharmacokineticsABSTRACT
Herein, we describe our research efforts to develop unique cores in molecules which function as HCV nonstructural protein 5A (NS5A) inhibitors. In particular, various fused tetracyclic cores were identified which showed genotype and mutant activities comparable to the indole-based tetracyclic core.
Subject(s)
Indoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/pharmacology , Hepacivirus/drug effectsABSTRACT
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
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
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
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
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
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
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.