RESUMO
Lead inhibitors that target the function of the hepatitis C virus (HCV) nonstructural 5A (NS5A) protein have been identified by phenotypic screening campaigns using HCV subgenomic replicons. The demonstration of antiviral activity in HCV-infected subjects by the HCV NS5A replication complex inhibitor (RCI) daclatasvir (1) spawned considerable interest in this mechanistic approach. In this Perspective, we summarize the medicinal chemistry studies that led to the discovery of 1 and other chemotypes for which resistance maps to the NS5A protein and provide synopses of the profiles of many of the compounds currently in clinical trials. We also summarize what is currently known about the NS5A protein and the studies using NS5A RCIs and labeled analogues that are helping to illuminate aspects of both protein function and inhibitor interaction. We conclude with a synopsis of the results of notable clinical trials with HCV NS5A RCIs.
Assuntos
Descoberta de Drogas , Hepacivirus/metabolismo , Proteínas não Estruturais Virais/antagonistas & inibidores , Replicação Viral/efeitos dos fármacos , Hepacivirus/fisiologia , Proteínas não Estruturais Virais/metabolismoRESUMO
The biphenyl derivatives 2 and 3 are prototypes of a novel class of NS5A replication complex inhibitors that demonstrate high inhibitory potency toward a panel of clinically relevant HCV strains encompassing genotypes 1-6. However, these compounds exhibit poor systemic exposure in rat pharmacokinetic studies after oral dosing. The structure-activity relationship investigations that improved the exposure properties of the parent bis-phenylimidazole chemotype, culminating in the identification of the highly potent NS5A replication complex inhibitor daclatasvir (33) are described. An element critical to success was the realization that the arylglycine cap of 2 could be replaced with an alkylglycine derivative and still maintain the high inhibitory potency of the series if accompanied with a stereoinversion, a finding that enabled a rapid optimization of exposure properties. Compound 33 had EC50 values of 50 and 9 pM toward genotype-1a and -1b replicons, respectively, and oral bioavailabilities of 38-108% in preclinical species. Compound 33 provided clinical proof-of-concept for the NS5A replication complex inhibitor class, and regulatory approval to market it with the NS3/4A protease inhibitor asunaprevir for the treatment of HCV genotype-1b infection has recently been sought in Japan.
Assuntos
Antivirais/farmacologia , Inibidores Enzimáticos/farmacologia , Hepacivirus/efeitos dos fármacos , Imidazóis/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Replicação Viral/efeitos dos fármacos , Animais , Antivirais/química , Antivirais/farmacocinética , Área Sob a Curva , Carbamatos , Cães , Descoberta de Drogas , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacocinética , Hepacivirus/enzimologia , Hepacivirus/fisiologia , Imidazóis/química , Imidazóis/farmacocinética , Espectroscopia de Ressonância Magnética , Pirrolidinas , Ratos , Espectrometria de Massas por Ionização por Electrospray , Relação Estrutura-Atividade , Valina/análogos & derivadosRESUMO
A medicinal chemistry campaign that was conducted to address a potential genotoxic liability associated with an aniline-derived scaffold in a series of HCV NS5A inhibitors with dual GT-1a/-1b inhibitory activity is described. Anilides 3b and 3c were used as vehicles to explore structural modifications that retained antiviral potency while removing the potential for metabolism-based unmasking of the embedded aniline. This effort resulted in the discovery of a highly potent biarylimidazole chemotype that established a potency benchmark in replicon assays, particularly toward HCV GT-1a, a strain with significant clinical importance. Securing potent GT-1a activity in a chemotype class lacking overt structural liabilities was a critical milestone in the effort to realize the full clinical potential of targeting the HCV NS5A protein.
Assuntos
Antivirais/farmacologia , Genótipo , Hepacivirus/efeitos dos fármacos , Imidazóis/farmacologia , RNA Polimerase Dependente de RNA/antagonistas & inibidores , Replicon/efeitos dos fármacos , Proteínas não Estruturais Virais/antagonistas & inibidores , Antivirais/química , Antivirais/farmacocinética , Cristalografia por Raios X , Descoberta de Drogas , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacocinética , Inibidores Enzimáticos/farmacologia , Hepacivirus/enzimologia , Hepacivirus/genética , Hepacivirus/fisiologia , Imidazóis/química , Imidazóis/farmacocinética , Espectroscopia de Ressonância Magnética , Espectrometria de Massas por Ionização por Electrospray , Relação Estrutura-AtividadeRESUMO
A series of symmetrical E-stilbene prolinamides that originated from the library-synthesized lead 3 was studied with respect to HCV genotype 1a (G-1a) and genotype 1b (G-1b) replicon inhibition and selectivity against BVDV and cytotoxicity. SAR emerging from an examination of the prolinamide cap region revealed 11 to be a selective HCV NS5A inhibitor exhibiting submicromolar potency against both G-1a and G-1b replicons. Additional structural refinements resulted in the identification of 30 as a potent, dual G-1a/1b HCV NS5A inhibitor.
Assuntos
Antivirais/farmacologia , Genótipo , Hepacivirus/efeitos dos fármacos , Inibidores de Proteases/farmacologia , RNA Polimerase Dependente de RNA/antagonistas & inibidores , Replicon/efeitos dos fármacos , Proteínas não Estruturais Virais/antagonistas & inibidores , Replicação Viral/efeitos dos fármacos , Antivirais/química , Hepacivirus/genética , Hepacivirus/fisiologia , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Inibidores de Proteases/química , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
The isoquinolinamide series of HCV NS5A inhibitors exemplified by compounds 2b and 2c provided the first dual genotype-1a/1b (GT-1a/1b) inhibitor class that demonstrated a significant improvement in potency toward GT-1a replicons compared to that of the initial program lead, stilbene 2a. Structure-activity relationship (SAR) studies that uncovered an alternate phenylglycine-based cap series that exhibit further improvements in virology profile, along with some insights into the pharmacophoric elements associated with the GT-1a potency, are described.
Assuntos
Antivirais/química , Glicina/análogos & derivados , Hepacivirus/enzimologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Animais , Antivirais/síntese química , Antivirais/farmacocinética , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Genótipo , Glicina/síntese química , Glicina/química , Glicina/farmacocinética , Meia-Vida , Hepacivirus/genética , Hepacivirus/fisiologia , Microssomos Hepáticos/metabolismo , Conformação Molecular , Ratos , Relação Estrutura-Atividade , Proteínas não Estruturais Virais/metabolismo , Replicação Viral/efeitos dos fármacosRESUMO
In a recent disclosure, we described the discovery of dimeric, prolinamide-based NS5A replication complex inhibitors exhibiting excellent potency towards an HCV genotype 1b replicon. That disclosure dealt with the SAR exploration of the peripheral region of our lead chemotype, and herein is described the SAR uncovered from a complementary effort that focused on the central core region. From this effort, the contribution of the core region to the overall topology of the pharmacophore, primarily vector orientation and planarity, was determined, with a set of analogs exhibiting <10 nM EC(50) in a genotype 1b replicon assay.
Assuntos
Antivirais/química , Proteínas não Estruturais Virais/antagonistas & inibidores , Antivirais/farmacologia , Carbamatos , Hepacivirus/efeitos dos fármacos , Imidazóis/química , Imidazóis/farmacologia , Concentração Inibidora 50 , Estrutura Molecular , Prolina/análogos & derivados , Prolina/química , Prolina/farmacologia , Pirrolidinas , Relação Estrutura-Atividade , Valina/análogos & derivados , Proteínas não Estruturais Virais/química , Replicação Viral/efeitos dos fármacosRESUMO
In a previous disclosure,(1) we reported the dimerization of an iminothiazolidinone to form 1, a contributor to the observed inhibition of HCV genotype 1b replicon activity. The dimer was isolated via bioassay-guided fractionation experiments and shown to be a potent inhibitor of genotype 1b HCV replication for which resistance mapped to the NS5A protein. The elements responsible for governing HCV inhibitory activity were successfully captured in the structurally simplified stilbene prolinamide 2. We describe herein the early SAR and profiling associated with stilbene prolinamides that culminated in the identification of analogs with PK properties sufficient to warrant continued commitment to this chemotype. These studies represent the key initial steps toward the discovery of daclatasvir (BMS-790052), a compound that has demonstrated clinical proof-of-concept for inhibiting the NS5A replication complex in the treatment of HCV infection.
Assuntos
Antivirais/farmacologia , Imidazóis/farmacologia , Prolina/análogos & derivados , Estilbenos/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Replicação Viral/efeitos dos fármacos , Antivirais/síntese química , Antivirais/química , Carbamatos , Relação Dose-Resposta a Droga , Imidazóis/síntese química , Imidazóis/química , Estrutura Molecular , Prolina/síntese química , Prolina/química , Prolina/farmacologia , Pirrolidinas , Estilbenos/síntese química , Estilbenos/química , Relação Estrutura-Atividade , Valina/análogos & derivadosRESUMO
The iminothiazolidinone BMS-858 (2) was identified as a specific inhibitor of HCV replication in a genotype 1b replicon assay via a high-throughput screening campaign. A more potent analogue, BMS-824 (18), was used in resistance mapping studies, which revealed that inhibitory activity was related to disrupting the function of the HCV nonstructural protein 5A. Despite the development of coherent and interpretable SAR, it was subsequently discovered that in DMSO 18 underwent an oxidation and structural rearrangement to afford the thiohydantoin 47, a compound with reduced HCV inhibitory activity. However, HPLC bioassay fractionation studies performed after incubation of 18 in assay media led to the identification of fractions containing a dimeric species 48 that exhibited potent antiviral activity. Excision of the key elements hypothesized to be responsible for antiviral activity based on SAR observations reduced 48 to a simplified, symmetrical, pharmacophore realized most effectively with the stilbene 55, a compound that demonstrated potent inhibition of HCV in a genotype 1b replicon with an EC50 = 86 pM.
RESUMO
Using a cell-based replicon screen, we identified a class of compounds with a thiazolidinone core structure as inhibitors of hepatitis C virus (HCV) replication. The concentration of one such compound, BMS-824, that resulted in a 50% inhibition of HCV replicon replication was approximately 5 nM, with a therapeutic index of >10,000. The compound showed good specificity for HCV, as it was not active against several other RNA and DNA viruses. Replicon cells resistant to BMS-824 were isolated, and mutations were identified. A combination of amino acid substitutions of leucine to valine at residue 31 (L31V) and glutamine to leucine at residue 54 (Q54L) in NS5A conferred resistance to this chemotype, as did a single substitution of tyrosine to histidine at amino acid 93 (Y93H) in NS5A. To further explore the region(s) of NS5A involved in inhibitor sensitivity, genotype-specific NS5A inhibitors were used to evaluate a series of genotype 1a/1b hybrid replicons. Our results showed that, consistent with resistance mapping, the inhibitor sensitivity domain also mapped to the N terminus of NS5A, but it could be distinguished from the key resistance sites. In addition, we demonstrated that NS5A inhibitors, as well as an active-site inhibitor that specifically binds NS3 protease, could block the hyperphosphorylation of NS5A, which is believed to play an essential role in the viral life cycle. Clinical proof of concept has recently been achieved with derivatives of these NS5A inhibitors, indicating that small molecules targeting a nontraditional viral protein like NS5A, without any known enzymatic activity, can also have profound antiviral effects on HCV-infected subjects.
Assuntos
Hepacivirus/efeitos dos fármacos , Tiazolidinas/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Substituição de Aminoácidos , Antivirais/química , Antivirais/farmacologia , Domínio Catalítico , Linhagem Celular , Avaliação Pré-Clínica de Medicamentos/métodos , Genótipo , Humanos , Fosforilação/efeitos dos fármacos , Replicon/efeitos dos fármacos , Tiazolidinas/uso terapêutico , Proteínas não Estruturais Virais/genética , Proteínas não Estruturais Virais/metabolismo , Replicação Viral/efeitos dos fármacosRESUMO
A series of fluoroglycosylated fluoroindolocarbazoles was examined with respect to their topoisomerase I activity, cytotoxicity, and selectivity. The lead clinical candidate from this series, BMS-250749, displays broad spectrum antitumor activity superior to CPT-11 against some preclinical xenograft models, including curative antitumor activity against Lewis lung carcinoma.
Assuntos
Antineoplásicos/síntese química , Camptotecina/análogos & derivados , Camptotecina/farmacologia , Carbazóis/síntese química , Glucosídeos/síntese química , Indóis/síntese química , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Carbazóis/química , Carbazóis/farmacologia , Linhagem Celular Tumoral , Avaliação Pré-Clínica de Medicamentos , Resistencia a Medicamentos Antineoplásicos , Ensaios de Seleção de Medicamentos Antitumorais , Glucosídeos/química , Glucosídeos/farmacologia , Humanos , Técnicas In Vitro , Indóis/química , Indóis/farmacologia , Irinotecano , Camundongos , Microssomos Hepáticos/metabolismo , Inibidores da Topoisomerase I , Transplante HeterólogoRESUMO
[reaction: see text] Both 6'- and 4'-fluoro-glycosylated indolo[2,3-a]carbazoles are substrates for base-induced loss of fluorine as a leaving group from sp3 carbon. In the case of alpha-N-glycosylated substrate 3, loss of fluorine from the 6'-position leads to 3,6-anhydroglucose analogue 1. A novel N12,N13-bridged sugar analogue 2 results from loss of 4'-fluorine from beta-N-glycosylated analogue 4. Both analogues 1 and 2 display topo I inhibitory potencies similar to camptothecin.
Assuntos
Carbazóis/síntese química , Carbono/química , Inibidores Enzimáticos/síntese química , Flúor/química , Glicosídeos/síntese química , Compostos Heterocíclicos de Anel em Ponte/síntese química , Hidrocarbonetos Fluorados/síntese química , Indóis/síntese química , Inibidores da Topoisomerase I , Animais , Carbazóis/farmacologia , Inibidores Enzimáticos/farmacologia , Glicosídeos/farmacologia , Compostos Heterocíclicos de Anel em Ponte/farmacologia , Hidrocarbonetos Fluorados/química , Indóis/química , Leucemia P388 , Conformação Molecular , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
A series of fluoroindolocarbazoles were studied with respect to their topoisomerase I activity, cytotoxicity, selectivity, and in vivo antitumor activity. Emerging from this series was BMS-251873, a potential clinical candidate possessing a robust pharmacological profile including curative antitumor activity against prostate carcinoma.
Assuntos
Antineoplásicos/síntese química , Carbazóis/síntese química , Glucosídeos/síntese química , Neoplasias da Próstata/tratamento farmacológico , Inibidores da Topoisomerase I , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Carbazóis/química , Carbazóis/farmacologia , Glucosídeos/química , Glucosídeos/farmacologia , Masculino , Camundongos , Transplante de Neoplasias , Solubilidade , Relação Estrutura-Atividade , Água , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The synthesis and biological activity of sordarin oxazepine derivatives are described. The key step features a regioselective oxidation of an unprotected triol followed by double reductive amination to afford the ring-closed products. The spectrum of antifungal activity for these novel derivatives includes coverage of Candida albicans, Candida glabrata, and Cryptococcus neoformans.
Assuntos
Antifúngicos/síntese química , Antifúngicos/farmacologia , Fungos/efeitos dos fármacos , Oxazepinas/síntese química , Oxazepinas/farmacologia , Candida albicans/efeitos dos fármacos , Candida glabrata/efeitos dos fármacos , Cryptococcus neoformans/efeitos dos fármacos , Ligação de Hidrogênio , Indenos , Testes de Sensibilidade Microbiana , Relação Estrutura-AtividadeRESUMO
Oxime derivatives of the sordarin aglycone have been identified as potent antifungal agents. The in vitro spectrum of activity includes coverage against Candida albicans and Candida glabrata with MICs as low as 0.06 microg/mL. The antifungal activity was established to be exquisitely sensitive to the spatial orientation of the lipophilic side chains.