RESUMO
The fluorocycline TP-271 was evaluated in mouse and nonhuman primate (NHP) models of inhalational anthrax. BALB/c mice were exposed by nose-only aerosol to Bacillus anthracis Ames spores at a level of 18 to 88 lethal doses sufficient to kill 50% of exposed individuals (LD50). When 21 days of once-daily dosing was initiated at 24 h postchallenge (the postexposure prophylaxis [PEP] study), the rates of survival for the groups treated with TP-271 at 3, 6, 12, and 18 mg/kg of body weight were 90%, 95%, 95%, and 84%, respectively. When 21 days of dosing was initiated at 48 h postchallenge (the treatment [Tx] study), the rates of survival for the groups treated with TP-271 at 6, 12, and 18 mg/kg TP-271 were 100%, 91%, and 81%, respectively. No deaths of TP-271-treated mice occurred during the 39-day posttreatment observation period. In the NHP model, cynomolgus macaques received an average dose of 197 LD50 of B. anthracis Ames spore equivalents using a head-only inhalation exposure chamber, and once-daily treatment of 1 mg/kg TP-271 lasting for 14 or 21 days was initiated within 3 h of detection of protective antigen (PA) in the blood. No (0/8) animals in the vehicle control-treated group survived, whereas all 8 infected macaques treated for 21 days and 4 of 6 macaques in the 14-day treatment group survived to the end of the study (56 days postchallenge). All survivors developed toxin-neutralizing and anti-PA IgG antibodies, indicating an immunologic response. On the basis of the results obtained with the mouse and NHP models, TP-271 shows promise as a countermeasure for the treatment of inhalational anthrax.
Assuntos
Antraz/tratamento farmacológico , Antibacterianos/uso terapêutico , Bacillus anthracis/efeitos dos fármacos , Infecções Respiratórias/tratamento farmacológico , Tetraciclinas/uso terapêutico , Animais , Antraz/microbiologia , Antraz/mortalidade , Anticorpos Antibacterianos/sangue , Anticorpos Antibacterianos/imunologia , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Antígenos de Bactérias/imunologia , Bacillus anthracis/imunologia , Toxinas Bacterianas/imunologia , Modelos Animais de Doenças , Feminino , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Macaca fascicularis , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Profilaxia Pós-Exposição/métodos , Infecções Respiratórias/microbiologia , Infecções Respiratórias/mortalidade , Esporos Bacterianos , Taxa de Sobrevida , Tetraciclinas/farmacocinéticaRESUMO
Multidrug-resistant (MDR) bacterial infections are a serious threat to public health. Among the most alarming resistance trends is the rapid rise in the number and diversity of ß-lactamases, enzymes that inactivate ß-lactams, a class of antibiotics that has been a therapeutic mainstay for decades. Although several new ß-lactamase inhibitors have been approved or are in clinical trials, their spectra of activity do not address MDR pathogens such as Acinetobacter baumannii. This report describes the rational design and characterization of expanded-spectrum serine ß-lactamase inhibitors that potently inhibit clinically relevant class A, C and D ß-lactamases and penicillin-binding proteins, resulting in intrinsic antibacterial activity against Enterobacteriaceae and restoration of ß-lactam activity in a broad range of MDR Gram-negative pathogens. One of the most promising combinations is sulbactam-ETX2514, whose potent antibacterial activity, in vivo efficacy against MDR A. baumannii infections and promising preclinical safety demonstrate its potential to address this significant unmet medical need.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Compostos Azabicíclicos/química , Compostos Azabicíclicos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Inibidores de beta-Lactamases/química , Inibidores de beta-Lactamases/farmacologia , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Animais , Compostos Azabicíclicos/uso terapêutico , Compostos Azabicíclicos/toxicidade , Carbapenêmicos/farmacologia , Cães , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Farmacorresistência Bacteriana Múltipla , Enterobacteriaceae/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Humanos , Camundongos , Modelos Moleculares , Proteínas de Ligação às Penicilinas/antagonistas & inibidores , Ratos , Sulbactam/química , Sulbactam/farmacologia , Inibidores de beta-Lactamases/uso terapêutico , Inibidores de beta-Lactamases/toxicidade , beta-Lactamases/metabolismo , beta-Lactamas/farmacologiaRESUMO
With the diminishing effectiveness of current antibacterial therapies, it is critically important to discover agents that operate by a mechanism that circumvents existing resistance. ETX0914, the first of a new class of antibacterial agent targeted for the treatment of gonorrhea, operates by a novel mode-of-inhibition against bacterial type II topoisomerases. Incorporating an oxazolidinone on the scaffold mitigated toxicological issues often seen with topoisomerase inhibitors. Organisms resistant to other topoisomerase inhibitors were not cross-resistant with ETX0914 nor were spontaneous resistant mutants to ETX0914 cross-resistant with other topoisomerase inhibitor classes, including the widely used fluoroquinolone class. Preclinical evaluation of ETX0914 pharmacokinetics and pharmacodynamics showed distribution into vascular tissues and efficacy in a murine Staphylococcus aureus infection model that served as a surrogate for predicting efficacious exposures for the treatment of Neisseria gonorrhoeae infections. A wide safety margin to the efficacious exposure in toxicological evaluations supported progression to Phase 1. Dosing ETX0914 in human volunteers showed sufficient exposure and minimal adverse effects to expect a highly efficacious anti-gonorrhea therapy.
Assuntos
Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Barbitúricos/farmacologia , Barbitúricos/uso terapêutico , Gonorreia/tratamento farmacológico , Compostos de Espiro/farmacologia , Compostos de Espiro/uso terapêutico , Inibidores da Topoisomerase II/farmacologia , Inibidores da Topoisomerase II/uso terapêutico , Adulto , Animais , Antibacterianos/química , Barbitúricos/química , DNA Topoisomerases Tipo II/química , Modelos Animais de Doenças , Cães , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana , Feminino , Fluoroquinolonas/farmacologia , Gonorreia/microbiologia , Haplorrinos , Humanos , Isoxazóis , Masculino , Camundongos , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Modelos Moleculares , Conformação Molecular , Morfolinas , Mutação , Neisseria gonorrhoeae/efeitos dos fármacos , Neisseria gonorrhoeae/genética , Oxazolidinonas , Ratos , Compostos de Espiro/química , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Inibidores da Topoisomerase II/química , Adulto JovemRESUMO
A pyridodiazepine amine inhibitor of Helicobacter pylori glutamate racemase (MurI) was characterized. The compound was selectively active against H. pylori, and growth suppression was shown to be mediated through the inhibition of MurI by several methods. In killing kinetics experiments, the compound showed concentration-independent activity, with about a 2-log loss of viability in 24 h. A demonstration of efficacy in a mouse infection model was attempted but not achieved, and this was attributed to the failure to attain extended exposure levels above the MIC for >95% of the time. This index and magnitude were derived from pharmacokinetic-pharmacodynamic (PK-PD) studies with amoxicillin, another inhibitor of peptidoglycan biosynthesis that showed slow killing kinetics similar to those of the pyridodiazepine amines. These studies indicate that MurI and other enzymes involved in peptidoglycan biosynthesis may be less desirable targets for monotherapy directed against H. pylori if once-a-day dosing is required.
Assuntos
Isomerases de Aminoácido/antagonistas & inibidores , Antibacterianos/uso terapêutico , Azepinas/uso terapêutico , Infecções por Helicobacter/tratamento farmacológico , Helicobacter pylori/efeitos dos fármacos , Helicobacter pylori/enzimologia , Piridinas/uso terapêutico , Amoxicilina/farmacocinética , Amoxicilina/farmacologia , Animais , Antibacterianos/farmacocinética , Azepinas/farmacocinética , Feminino , Mucosa Gástrica/metabolismo , Infecções por Helicobacter/sangue , Infecções por Helicobacter/microbiologia , Cinética , Camundongos , Testes de Sensibilidade Microbiana , Peptidoglicano/metabolismo , Piridinas/farmacocinética , Ratos , Ratos Sprague-DawleyRESUMO
Optimization of clearance of adenosine inhibitors of bacterial NAD(+)-dependent DNA ligase is discussed. To reduce Cytochrome P-450-mediated metabolic clearance, many strategies were explored; however, most modifications resulted in compounds with reduced antibacterial activity and/or unchanged total clearance. The alkyl side chains of the 2-cycloalkoxyadenosines were fluorinated, and compounds with moderate antibacterial activity and favorable pharmacokinetic properties in rat and dog were identified.
Assuntos
Adenosina/química , Antibacterianos/síntese química , DNA Ligases/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , NAD/química , Adenina/química , Administração Oral , Animais , Antibacterianos/química , Disponibilidade Biológica , Cromatografia Líquida/métodos , DNA Ligases/química , Cães , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos/métodos , Flúor/química , Concentração Inibidora 50 , Espectrometria de Massas/métodos , Modelos Químicos , RatosRESUMO
DNA ligases are indispensable enzymes playing a critical role in DNA replication, recombination, and repair in all living organisms. Bacterial NAD+-dependent DNA ligase (LigA) was evaluated for its potential as a broad-spectrum antibacterial target. A novel class of substituted adenosine analogs was discovered by target-based high-throughput screening (HTS), and these compounds were optimized to render them more effective and selective inhibitors of LigA. The adenosine analogs inhibited the LigA activities of Escherichia coli, Haemophilus influenzae, Mycoplasma pneumoniae, Streptococcus pneumoniae, and Staphylococcus aureus, with inhibitory activities in the nanomolar range. They were selective for bacterial NAD+-dependent DNA ligases, showing no inhibitory activity against ATP-dependent human DNA ligase 1 or bacteriophage T4 ligase. Enzyme kinetic measurements demonstrated that the compounds bind competitively with NAD+. X-ray crystallography demonstrated that the adenosine analogs bind in the AMP-binding pocket of the LigA adenylation domain. Antibacterial activity was observed against pathogenic Gram-positive and atypical bacteria, such as S. aureus, S. pneumoniae, Streptococcus pyogenes, and M. pneumoniae, as well as against Gram-negative pathogens, such as H. influenzae and Moraxella catarrhalis. The mode of action was verified using recombinant strains with altered LigA expression, an Okazaki fragment accumulation assay, and the isolation of resistant strains with ligA mutations. In vivo efficacy was demonstrated in a murine S. aureus thigh infection model and a murine S. pneumoniae lung infection model. Treatment with the adenosine analogs reduced the bacterial burden (expressed in CFU) in the corresponding infected organ tissue as much as 1,000-fold, thus validating LigA as a target for antibacterial therapy.