RESUMO
Riboswitches are non-coding RNA structures located in messenger RNAs that bind endogenous ligands, such as a specific metabolite or ion, to regulate gene expression. As such, riboswitches serve as a novel, yet largely unexploited, class of emerging drug targets. Demonstrating this potential, however, has proven difficult and is restricted to structurally similar antimetabolites and semi-synthetic analogues of their cognate ligand, thus greatly restricting the chemical space and selectivity sought for such inhibitors. Here we report the discovery and characterization of ribocil, a highly selective chemical modulator of bacterial riboflavin riboswitches, which was identified in a phenotypic screen and acts as a structurally distinct synthetic mimic of the natural ligand, flavin mononucleotide, to repress riboswitch-mediated ribB gene expression and inhibit bacterial cell growth. Our findings indicate that non-coding RNA structural elements may be more broadly targeted by synthetic small molecules than previously expected.
Assuntos
Pirimidinas/química , Pirimidinas/farmacologia , RNA Bacteriano/química , RNA Bacteriano/efeitos dos fármacos , Riboswitch/efeitos dos fármacos , Animais , Aptâmeros de Nucleotídeos/química , Bactérias/citologia , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Sequência de Bases , Cristalografia por Raios X , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Feminino , Mononucleotídeo de Flavina/metabolismo , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Proteínas de Choque Térmico/genética , Transferases Intramoleculares/genética , Ligantes , Camundongos , Camundongos Endogâmicos DBA , Modelos Moleculares , Dados de Sequência Molecular , Pirimidinas/isolamento & purificação , Pirimidinas/uso terapêutico , RNA Bacteriano/genética , Reprodutibilidade dos Testes , Riboflavina/biossíntese , Riboswitch/genética , Especificidade por SubstratoRESUMO
Resistance to antibiotics among bacterial pathogens is rapidly spreading, and therapeutic options against multidrug-resistant bacteria are limited. There is an urgent need for new drugs, especially those that can circumvent the broad array of resistance pathways that bacteria have evolved. In this study, we assessed the pharmacokinetic/pharmacodynamic relationship of the novel ß-lactamase inhibitor relebactam (REL; MK-7655) in a hollow-fiber infection model. REL is intended for use with the carbapenem ß-lactam antibiotic imipenem for the treatment of Gram-negative bacterial infections. In this study, we used an in vitro hollow-fiber infection model to confirm the efficacy of human exposures associated with the phase 2 doses (imipenem at 500 mg plus REL at 125 or 250 mg administered intravenously every 6 h as a 30-min infusion) against imipenem-resistant strains of Pseudomonas aeruginosa and Klebsiella pneumoniae Dose fractionation experiments confirmed that the pharmacokinetic parameter that best correlated with REL activity is the area under the concentration-time curve, consistent with findings in a murine pharmacokinetic/pharmacodynamic model. Determination of the pharmacokinetic/pharmacodynamic relationship between ß-lactam antibiotics and ß-lactamase inhibitors is complex, as there is an interdependence between their respective exposure-response relationships. Here, we show that this interdependence could be captured by treating the MIC of imipenem as dynamic: it changes with time, and this change is directly related to REL levels. For the strains tested, the percentage of the dosing interval time that the concentration remains above the dynamic MIC for imipenem was maintained at the carbapenem target of 30 to 40%, required for maximum efficacy, for imipenem at 500 mg plus REL at 250 mg.
Assuntos
Imipenem/farmacologia , Inibidores de beta-Lactamases/farmacologia , Animais , Compostos Azabicíclicos/farmacologia , Farmacorresistência Bacteriana Múltipla , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Camundongos , Testes de Sensibilidade MicrobianaRESUMO
Inhibition of NS5A has emerged as an attractive strategy to intervene in hepatitis C virus (HCV) replication. Ruzasvir (formerly MK-8408) was developed as a novel NS5A inhibitor to improve upon the potency and barrier to resistance of early compounds. Ruzasvir inhibited HCV RNA replication with 50% effective concentrations (EC50s) of 1 to 4 pM in Huh7 or Huh7.5 cells bearing replicons for HCV genotype 1 (GT1) to GT7. The antiviral activity was modestly (10-fold) reduced in the presence of 40% normal human serum. The picomolar potency in replicon cells extended to sequences of clinical isolates available in public databases that were synthesized and tested as replicons. In GT1a, ruzasvir inhibited common NS5A resistance-associated substitutions (RASs), with the exception of M28G. De novo resistance selection studies identified pathways with certain amino acid substitutions at residues 28, 30, 31, and 93 across genotypes. Substitutions at position 93 were more common in GT1 to -4, while changes at position 31 emerged frequently in GT5 and -6. With the exception of GT4, the reintroduction of selected RASs conferred a ≥100-fold potency reduction in the antiviral activity of ruzasvir. Common RASs from other classes of direct-acting antiviral agents (DAAs) did not confer cross-resistance to ruzasvir. The interaction of ruzasvir with an NS3/4A protease inhibitor (grazoprevir) and an NS5B polymerase prodrug (uprifosbuvir) was additive to synergistic, with no evidence of antagonism or cytotoxicity. The antiviral profile of ruzasvir supported its further evaluation in human trials in combination with grazoprevir and uprifosbuvir.
Assuntos
Antivirais/farmacologia , Hepacivirus/efeitos dos fármacos , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Pirrolidinas/farmacologia , Tiazóis/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Amidas , Carbamatos , Linhagem Celular Tumoral , Ciclopropanos , Farmacorresistência Viral/efeitos dos fármacos , Quimioterapia Combinada/métodos , Genótipo , Hepatite C Crônica/tratamento farmacológico , Hepatite C Crônica/virologia , Humanos , Inibidores de Proteases/farmacologia , Quinoxalinas/farmacologia , Replicon/efeitos dos fármacos , Sulfonamidas , Uridina/análogos & derivados , Uridina/farmacologiaRESUMO
Compound 5 (SCH772984) was identified as a potent inhibitor of ERK1/2 with excellent selectivity against a panel of kinases (0/231 kinases tested @ 100â¯nM) and good cell proliferation activity, but suffered from poor PK (rat AUC PK @10â¯mpkâ¯=â¯0⯵Mâ¯h; F%â¯=â¯0) which precluded further development. In an effort to identify novel ERK inhibitors with improved PK properties with respect to 5, a systematic exploration of sterics and composition at the 3-position of the pyrrolidine led to the discovery of a novel 3(S)-thiomethyl pyrrolidine analog 28 with vastly improved PK (rat AUC PK @10â¯mpkâ¯=â¯26⯵Mâ¯h; F%â¯=â¯70).
Assuntos
Antineoplásicos/farmacologia , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Inibidores de Proteínas Quinases/farmacologia , Pirrolidinas/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Modelos Moleculares , Estrutura Molecular , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Pirrolidinas/síntese química , Pirrolidinas/química , Ratos , Relação Estrutura-Atividade , Células Tumorais CultivadasRESUMO
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.
Assuntos
Antivirais/farmacologia , Benzofuranos/farmacologia , Hepacivirus/efeitos dos fármacos , Imidazóis/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Animais , Antivirais/síntese química , Antivirais/química , Benzofuranos/síntese química , Benzofuranos/química , Relação Dose-Resposta a Droga , Hepatite C/tratamento farmacológico , Imidazóis/síntese química , Imidazóis/química , Masculino , Testes de Sensibilidade Microbiana , Estrutura Molecular , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Replicação Viral/efeitos dos fármacosRESUMO
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.
Assuntos
Antivirais/farmacologia , Descoberta de Drogas , Hepacivirus/efeitos dos fármacos , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Compostos Macrocíclicos/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Antivirais/síntese química , Antivirais/química , Relação Dose-Resposta a Droga , Hepatite C/tratamento farmacológico , Compostos Heterocíclicos de 4 ou mais Anéis/síntese química , Compostos Heterocíclicos de 4 ou mais Anéis/química , Compostos Macrocíclicos/síntese química , Compostos Macrocíclicos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-Atividade , Replicação Viral/efeitos dos fármacosRESUMO
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.
Assuntos
Antivirais/farmacologia , Benzofuranos/farmacologia , Imidazóis/farmacologia , Indóis/química , Prolina/química , Proteínas não Estruturais Virais/antagonistas & inibidores , Antivirais/química , Benzofuranos/química , Imidazóis/química , Relação Estrutura-AtividadeRESUMO
Starting from weak µM hits identified through affinity based Automated Ligand Identification System (ALIS) screenings, double digit nM hydroxyaniline amide Erk inhibitors were discovered. This class of compounds had the unique dual mechanism of inhibiting activated and non-activated forms of Erk. They generally had high degree of selectivity in kinase panel tested.
Assuntos
Amidas/farmacologia , Aminofenóis/farmacologia , Descoberta de Drogas , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Inibidores de Proteínas Quinases/farmacologia , Amidas/síntese química , Amidas/química , Aminofenóis/síntese química , Aminofenóis/química , Relação Dose-Resposta a Droga , Humanos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Estrutura Molecular , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Relação Estrutura-AtividadeRESUMO
Dynamic in vitro antibacterial studies provide valuable insight on effective dosing strategies prior to translating to in vivo models. Frequent sampling is required to monitor the pharmacodynamics (PD) of these studies, leading to significant work when quantifying the bacterial load of the samples. Spreading a bacterial suspension on agar to allow colony counting is a proven process for measuring very low levels of growth, but commercial automation equipment to handle agar plating and colony counting at scale is not readily available. We describe a process to greatly decrease the hands-on time required for PD assays by utilizing general-purpose liquid handling robots to plate bacteria and a custom-made plate imager to automate colony counting. The platform developed handles the biological assay from beginning to end as well as sample tracking at each step of the process. The process relies heavily on custom automation scheduling software to enable dynamic process decisions and coordinate data flow throughout. Using the described platform, we can efficiently quantify >100 PD samples per day while maintaining the necessary dynamic range of the assay. Alleviating the main bottleneck in the dynamic antibacterial studies has allowed us to accelerate the rate of experiments to provide antibacterial dosing data within shorter timelines.
Assuntos
Bactérias , Software , Ágar , Antibacterianos/farmacologia , AutomaçãoRESUMO
Our hollow-fiber infection model simulated the projected steady-state pharmacokinetics of ceftolozane and tazobactam in lung epithelial lining fluid of patients with pneumonia receiving 3 g of ceftolozane/tazobactam every 8 hours. Results confirmed the previously established in vitro activity of ceftolozane/tazobactam at and above approved breakpoints against multidrug-resistant Pseudomonas aeruginosa, regardless of Pseudomonas-derived cephalosporinase allele.
RESUMO
MEK1 is a member of the MAPK signal transduction pathway that responds to growth factors and cytokines. We have determined that the kinase domain spans residues 35-382 by proteolytic cleavage. The complete kinase domain has been crystallized and its X-ray crystal structure as a complex with magnesium and ATP-gammaS determined at 2.1 A. Unlike crystals of a truncated kinase domain previously published, the crystals of the intact domain can be grown either as a binary complex with a nucleotide or as a ternary complex with a nucleotide and one of a multitude of allosteric inhibitors. Further, the crystals allow for the determination of costructures with ATP competitive inhibitors. We describe the structures of nonphosphorylated MEK1 (npMEK1) binary complexes with ADP and K252a, an ATP-competitive inhibitor (see Table 1), at 1.9 and 2.7 A resolution, respectively. Ternary complexes have also been solved between npMEK1, a nucleotide, and an allosteric non-ATP competitive inhibitor: ATP-gammaS with compound 1 and ADP with either U0126 or the MEK1 clinical candidate PD325089 at 1.8, 2.0, and 2.5 A, respectively. Compound 1 is structurally similar to PD325901. These structures illustrate fundamental differences among various mechanisms of inhibition at the molecular level. Residues 44-51 have previously been shown to play a negative regulatory role in MEK1 activity. The crystal structure of the integral kinase domain provides a structural rationale for the role of these residues. They form helix A and repress enzymatic activity by stabilizing an inactive conformation in which helix C is displaced from its active state position. Finally, the structure provides for the first time a molecular rationale that explains how mutations in MEK may lead to the cardio-facio-cutaneous syndrome.
Assuntos
Inibidores Enzimáticos/química , MAP Quinase Quinase 1/química , Nucleotídeos/química , Difosfato de Adenosina/química , Difosfato de Adenosina/metabolismo , Regulação Alostérica , Sítios de Ligação , Carbazóis/química , Carbazóis/metabolismo , Cristalografia por Raios X , Inibidores Enzimáticos/metabolismo , Alcaloides Indólicos/química , Alcaloides Indólicos/metabolismo , MAP Quinase Quinase 1/metabolismo , Modelos Moleculares , Nucleotídeos/metabolismo , Conformação Proteica , Relação Estrutura-Atividade , Especificidade por SubstratoRESUMO
OBJECTIVES: Relebactam is a small molecule ß-lactamase inhibitor under clinical investigation for use as a fixed-dose combination with imipenem/cilastatin. Here we present a translational pharmacokinetic/pharmacodynamic mathematical model to support optimal dose selection of relebactam. METHODS: Data derived from in vitro checkerboard and hollow fiber infection studies of imipenem-resistant strains of Pseudomonas aeruginosa were incorporated into the model. The model integrates the effect of relebactam concentration on imipenem susceptibility in a semi-mechanistic manner using the checkerboard data and characterizes the bacterial time-kill profiles from the hollow fiber infection model data. RESULTS: Simulations demonstrated that the ratio of the area under the concentration-time curve for free drug to the minimum inhibitory concentration (fAUC/MIC) was the pharmacokinetic driver for relebactam, with a target fAUC/MIC=7.5 associated with 2-log kill. At a clinical dose of 250mg relebactam, greater than 2-log reductions in bacterial load are projected for imipenem-resistant strains with an imipenem/relebactam MIC≤4µg/mL. CONCLUSIONS: The study confirms that the pharmacokinetic/pharmacodynamic driver for relebactam is fAUC/MIC, that an fAUC/MIC ratio of 7.5 is associated with 2-log kill in vitro, and that a 250mg clinical dose of relebactam achieves this target value when delivered in combination with imipenem/cilastatin.
Assuntos
Antibacterianos/farmacocinética , Compostos Azabicíclicos/farmacocinética , Imipenem/farmacocinética , Modelos Teóricos , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/efeitos dos fármacos , Inibidores de beta-Lactamases/farmacocinética , Antibacterianos/administração & dosagem , Compostos Azabicíclicos/administração & dosagem , Cilastatina/administração & dosagem , Cilastatina/farmacocinética , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana , Humanos , Imipenem/administração & dosagem , Testes de Sensibilidade Microbiana , Infecções por Pseudomonas/microbiologia , Inibidores de beta-Lactamases/administração & dosagemRESUMO
We describe the discovery of MK-6169, a potent and pan-genotype hepatitis C virus NS5A inhibitor with optimized activity against common resistance-associated substitutions. SAR studies around the combination of changes to both the valine and aminal carbon region of elbasvir led to the discovery of a series of compounds with substantially improved potency against common resistance-associated substitutions in the major genotypes, as well as good pharmacokinetics in both rat and dog. Through further optimization of key leads from this effort, MK-6169 (21) was discovered as a preclinical candidate for further development.
Assuntos
Antivirais/farmacologia , Descoberta de Drogas , Farmacorresistência Viral/efeitos dos fármacos , Hepacivirus/efeitos dos fármacos , Proteínas não Estruturais Virais/antagonistas & inibidores , Animais , Antivirais/farmacocinética , Cães , Genótipo , Hepacivirus/genética , Hepacivirus/metabolismo , Masculino , Ratos , Distribuição TecidualRESUMO
BACKGROUND: Constitutive activation of ERK1/2 occurs in various cancers, and its reactivation is a well-described resistance mechanism to MAPK inhibitors. ERK inhibitors may overcome the limitations of MAPK inhibitor blockade. The dual mechanism inhibitor SCH772984 has shown promising preclinical activity across various BRAFV600/RAS-mutant cancer cell lines and human cancer xenografts. METHODS: We have developed an orally bioavailable ERK inhibitor, MK-8353; conducted preclinical studies to demonstrate activity, pharmacodynamic endpoints, dosing, and schedule; completed a study in healthy volunteers (P07652); and subsequently performed a phase I clinical trial in patients with advanced solid tumors (MK-8353-001). In the P07652 study, MK-8353 was administered as a single dose in 10- to 400-mg dose cohorts, whereas in the MK-8353-001 study, MK-8353 was administered in 100- to 800-mg dose cohorts orally twice daily. Safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity were analyzed. RESULTS: MK-8353 exhibited comparable potency with SCH772984 across various preclinical cancer models. Forty-eight patients were enrolled in the P07652 study, and twenty-six patients were enrolled in the MK-8353-001 study. Adverse events included diarrhea (44%), fatigue (40%), nausea (32%), and rash (28%). Dose-limiting toxicity was observed in the 400-mg and 800-mg dose cohorts. Sufficient exposure to MK-8353 was noted that correlated with biological activity in preclinical data. Three of fifteen patients evaluable for treatment response in the MK-8353-001 study had partial response, all with BRAFV600-mutant melanomas. CONCLUSION: MK-8353 was well tolerated up to 400 mg twice daily and exhibited antitumor activity in patients with BRAFV600-mutant melanoma. However, antitumor activity was not particularly correlated with pharmacodynamic parameters. TRIAL REGISTRATION: ClinicalTrials.gov NCT01358331. FUNDING: Merck Sharp & Dohme Corp., a subsidiary of Merck & Co. Inc., and NIH (P01 CA168585 and R35 CA197633).
Assuntos
Indazóis/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Inibidores de Proteínas Quinases/farmacologia , Piridinas/farmacologia , Pirrolidinas/farmacologia , Triazóis/farmacologia , Administração Oral , Adulto , Animais , Disponibilidade Biológica , Linhagem Celular Tumoral , Diarreia/induzido quimicamente , Diarreia/epidemiologia , Cães , Relação Dose-Resposta a Droga , Toxidermias/epidemiologia , Toxidermias/etiologia , Avaliação Pré-Clínica de Medicamentos , Fadiga/induzido quimicamente , Fadiga/epidemiologia , Feminino , Humanos , Indazóis/uso terapêutico , Masculino , Dose Máxima Tolerável , Camundongos , Pessoa de Meia-Idade , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Náusea/induzido quimicamente , Náusea/epidemiologia , Estadiamento de Neoplasias , Neoplasias/genética , Neoplasias/patologia , Inibidores de Proteínas Quinases/uso terapêutico , Piridinas/uso terapêutico , Pirrolidinas/uso terapêutico , Ratos , Triazóis/uso terapêutico , Ensaios Antitumorais Modelo de Xenoenxerto , Adulto JovemRESUMO
The emergence and evolution of new immunological cancer therapies has sparked a rapidly growing interest in discovering novel pathways to treat cancer. Toward this aim, a novel series of pyrrolidine derivatives (compound 5) were identified as potent inhibitors of ERK1/2 with excellent kinase selectivity and dual mechanism of action but suffered from poor pharmacokinetics (PK). The challenge of PK was overcome by the discovery of a novel 3(S)-thiomethyl pyrrolidine analog 7. Lead optimization through focused structure-activity relationship led to the discovery of a clinical candidate MK-8353 suitable for twice daily oral dosing as a potential new cancer therapeutic.
RESUMO
The growing prevalence of drug resistant bacteria is a significant global threat to human health. The antibacterial drug rifampin, which functions by inhibiting bacterial RNA polymerase (RNAP), is an important part of the antibacterial armamentarium. Here, in order to identify novel inhibitors of bacterial RNAP, we used affinity-selection mass spectrometry to screen a chemical library for compounds that bind to Escherichia coli RNAP. We identified a novel small molecule, MRL-436, that binds to RNAP, inhibits RNAP, and exhibits antibacterial activity. MRL-436 binds to RNAP through a binding site that differs from the rifampin binding site, inhibits rifampin-resistant RNAP derivatives, and exhibits antibacterial activity against rifampin-resistant strains. Isolation of mutants resistant to the antibacterial activity of MRL-436 yields a missense mutation in codon 622 of the rpoC gene encoding the RNAP ß' subunit or a null mutation in the rpoZ gene encoding the RNAP ω subunit, confirming that RNAP is the functional cellular target for the antibacterial activity of MRL-436, and indicating that RNAP ß' subunit residue 622 and the RNAP ω subunit are required for the antibacterial activity of MRL-436. Similarity between the resistance determinant for MRL-436 and the resistance determinant for the cellular alarmone ppGpp suggests a possible similarity in binding site and/or induced conformational state for MRL-436 and ppGpp.
Assuntos
Antibacterianos/farmacologia , RNA Polimerases Dirigidas por DNA/antagonistas & inibidores , Farmacorresistência Bacteriana/efeitos dos fármacos , Sítios de Ligação , Farmacorresistência Bacteriana/genética , Inibidores Enzimáticos/farmacologia , Escherichia coli/enzimologia , Espectrometria de Massas , Ligação Proteica , Rifampina/farmacologia , Bibliotecas de Moléculas PequenasRESUMO
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.
Assuntos
Antivirais/química , Antivirais/farmacologia , Hepacivirus/efeitos dos fármacos , Compostos Heterocíclicos de 4 ou mais Anéis/química , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Polimorfismo Genético , Pirrolidinas/química , Pirrolidinas/farmacologia , Tiazóis/química , Tiazóis/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Animais , Antivirais/farmacocinética , Linhagem Celular , Cães , Haplorrinos , Hepacivirus/genética , Compostos Heterocíclicos de 4 ou mais Anéis/farmacocinética , Humanos , Pirrolidinas/farmacocinética , Ratos , Relação Estrutura-Atividade , Tiazóis/farmacocinéticaRESUMO
Ongoing curricular renewal is a necessary phenomenon in nursing education to align learning with ever-changing professional practice demands. The McMaster Mohawk Conestoga BScN Program in Hamilton, Ontario, Canada recently engaged in a comprehensive curriculum renewal. The purpose of this study was to evaluate the impact of curricular changes on students' deep learning. Faculty perceptions about student learning outcomes during final year clinical placements were gathered through a combination of individual interviews and focus groups using Interpretive Descriptive qualitative research methodology. Twenty five faculty members who supervised BScN students in clinical placements before and after curriculum renewal shared perceptions of changes in students' overall performance. The chosen clinical learning outcomes were: changes in students' performance related to person-centred care, clinical reasoning and judgment, pathophysiology, and evidence-informed decision-making. Faculty described three major themes in students' performance 1) pulling it all together, 2) seeing the whole person, and 3) finding their nursing voices. This reflected a shift to person-centred care, increasing professional confidence, and improved clinical reasoning and judgment and no changes to integrating pathophysiology or evidence-informed decision-making. In this study curriculum renewal provided an excellent starting point for the scholarship of teaching and learning within nursing education.
Assuntos
Currículo/tendências , Curva de Aprendizado , Avaliação de Processos e Resultados em Cuidados de Saúde/métodos , Estudantes de Enfermagem/psicologia , Canadá , Bacharelado em Enfermagem/métodos , Bacharelado em Enfermagem/normas , Grupos Focais , Humanos , Pesquisa QualitativaRESUMO
An affinity-based mass spectrometry screening technology was used to identify novel binders to both nonphosphorylated and phosphorylated ERK2. Screening of inactive ERK2 identified a pyrrolidine analogue 1 that bound to both nonphosphorylated and phosphorylated ERK2 and inhibited ERK2 kinase activity. Chemical optimization identified compound 4 as a novel, potent, and highly selective ERK1,2 inhibitor which not only demonstrated inhibition of phosphorylation of ERK substrate p90RSK but also demonstrated inhibition of ERK1,2 phosphorylation on the activation loop. X-ray cocrystallography revealed that upon binding of compound 4 to ERK2, Tyr34 undergoes a rotation (flip) along with a shift in the poly-Gly rich loop to create a new binding pocket into which 4 can bind. This new binding mode represents a novel mechanism by which high affinity ATP-competitive compounds may achieve excellent kinase selectivity.
Assuntos
Anilidas/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Inibidores de Proteínas Quinases/síntese química , Pirrolidinas/metabolismo , Marcadores de Afinidade , Anilidas/farmacologia , Cristalografia por Raios X , Concentração Inibidora 50 , Espectrometria de Massas/métodos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Pirrolidinas/farmacologia , Relação Estrutura-AtividadeRESUMO
The high frequency of activating RAS or BRAF mutations in cancer provides strong rationale for targeting the mitogen-activated protein kinase (MAPK) pathway. Selective BRAF and MAP-ERK kinase (MEK) inhibitors have shown clinical efficacy in patients with melanoma. However, the majority of responses are transient, and resistance is often associated with pathway reactivation of the extracellular signal-regulated kinase (ERK) signaling pathway. Here, we describe the identification and characterization of SCH772984, a novel and selective inhibitor of ERK1/2 that displays behaviors of both type I and type II kinase inhibitors. SCH772984 has nanomolar cellular potency in tumor cells with mutations in BRAF, NRAS, or KRAS and induces tumor regressions in xenograft models at tolerated doses. Importantly, SCH772984 effectively inhibited MAPK signaling and cell proliferation in BRAF or MEK inhibitor-resistant models as well as in tumor cells resistant to concurrent treatment with BRAF and MEK inhibitors. These data support the clinical development of ERK inhibitors for tumors refractory to MAPK inhibitors.