RESUMO
There is an increasingly urgent and unmet medical need for novel antibiotic drugs that tackle infections caused by multidrug-resistant (MDR) pathogens. Novel bacterial type II topoisomerase inhibitors (NBTIs) are of high interest due to limited cross-resistance with fluoroquinolones, however analogues with Gram-negative activity often suffer from hERG channel inhibition. A novel series of bicyclic-oxazolidinone inhibitors of bacterial type II topoisomerase were identified which display potent broad-spectrum anti-bacterial activity, including against MDR strains, along with an encouraging in vitro safety profile. In vivo proof of concept was achieved in a A. baumannii mouse thigh infection model.
Assuntos
Oxazolidinonas , Inibidores da Topoisomerase , Animais , Antibacterianos/farmacologia , DNA Girase/metabolismo , Fluoroquinolonas/farmacologia , Camundongos , Testes de Sensibilidade Microbiana , Oxazolidinonas/farmacologia , Relação Estrutura-Atividade , Inibidores da Topoisomerase II/farmacologia , Inibidores da Topoisomerase/farmacologiaRESUMO
Clinical studies of new antitubercular drugs are costly and time-consuming. Owing to the extensive tuberculosis (TB) treatment periods, the ability to identify drug candidates based on their predicted clinical efficacy is vital to accelerate the pipeline of new therapies. Recent failures of preclinical models in predicting the activity of fluoroquinolones underline the importance of developing new and more robust predictive tools that will optimize the design of future trials. Here, we used high-content imaging screening and pharmacodynamic intracellular (PDi) modeling to identify and prioritize fluoroquinolones for TB treatment. In a set of studies designed to validate this approach, we show moxifloxacin to be the most effective fluoroquinolone, and PDi modeling-based Monte Carlo simulations accurately predict negative culture conversion (sputum sterilization) rates compared to eight independent clinical trials. In addition, PDi-based simulations were used to predict the risk of relapse. Our analyses show that the duration of treatment following culture conversion can be used to predict the relapse rate. These data further support that PDi-based modeling offers a much-needed decision-making tool for the TB drug development pipeline.
Assuntos
Antituberculosos/farmacologia , Antituberculosos/farmacocinética , Fluoroquinolonas/farmacologia , Fluoroquinolonas/farmacocinética , Modelos Biológicos , Tuberculose Pulmonar/tratamento farmacológico , Tuberculose Pulmonar/metabolismo , Linhagem Celular , Simulação por Computador , Técnicas de Apoio para a Decisão , Desenvolvimento de Medicamentos , Humanos , Macrófagos/efeitos dos fármacos , Macrófagos/microbiologia , Método de Monte Carlo , Moxifloxacina/farmacocinética , Moxifloxacina/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Células THP-1 , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Resistente a Múltiplos Medicamentos/metabolismoRESUMO
According to the World Health Organization (WHO), approximately 1.7 million deaths per year are caused by tuberculosis infections. Furthermore, it has been predicted that, by 2050, antibacterial resistance will be the cause of approximately 10 million deaths annually if the issue is not tackled. As a result, novel approaches to treating broad-spectrum bacterial infections are of vital importance. During the course of our wider efforts to discover unique methods of targeting multidrug-resistant (MDR) pathogens, we identified a novel series of amide-linked pyrimido[4,5-b]indol-8-amine inhibitors of bacterial type II topoisomerases. Compounds from the series were highly potent against gram-positive bacteria and mycobacteria, with excellent potency being retained against a panel of relevant Mycobacterium tuberculosis drug-resistant clinical isolates.
Assuntos
Antibacterianos/farmacologia , DNA Girase/metabolismo , Desenho de Fármacos , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Inibidores da Topoisomerase II/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Bactérias Gram-Positivas/metabolismo , Células Hep G2 , Humanos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Relação Estrutura-Atividade , Inibidores da Topoisomerase II/síntese química , Inibidores da Topoisomerase II/químicaRESUMO
The novel bacterial topoisomerase inhibitor class is an investigational type of antibacterial inhibitor of DNA gyrase and topoisomerase IV that does not have cross-resistance with the quinolones. Here, we report the evaluation of the in vitro properties of a new series of this type of small molecule. Exemplar compounds selectively and potently inhibited the catalytic activities of Escherichia coli DNA gyrase and topoisomerase IV but did not block the DNA breakage-reunion step. Compounds showed broad-spectrum inhibitory activity against a wide range of Gram-positive and Gram-negative pathogens, including biodefence microorganisms and Mycobacterium tuberculosis No cross-resistance with fluoroquinolone-resistant Staphylococcus aureus and E. coli isolates was observed. Measured MIC90 values were 4 and 8 µg/ml against a panel of contemporary multidrug-resistant isolates of Acinetobacter baumannii and E. coli, respectively. In addition, representative compounds exhibited greater antibacterial potency than the quinolones against obligate anaerobic species. Spontaneous mutation rates were low, with frequencies of resistance typically <10-8 against E. coli and A. baumannii at concentrations equivalent to 4-fold the MIC. Compound-resistant E. coli mutants that were isolated following serial passage were characterized by whole-genome sequencing and carried a single Arg38Leu amino acid substitution in the GyrA subunit of DNA gyrase. Preliminary in vitro safety data indicate that the series shows a promising therapeutic index and potential for low human ether-a-go-go-related gene (hERG) inhibition (50% inhibitory concentration [IC50], >100 µM). In summary, the compounds' distinct mechanism of action relative to the fluoroquinolones, whole-cell potency, low potential for resistance development, and favorable in vitro safety profile warrant their continued investigation as potential broad-spectrum antibacterial agents.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , DNA Topoisomerase IV/antagonistas & inibidores , Escherichia coli/efeitos dos fármacos , Mycobacterium tuberculosis/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Inibidores da Topoisomerase II/farmacologia , Ciprofloxacina/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Humanos , Testes de Sensibilidade MicrobianaRESUMO
OBJECTIVES: The objective of this study was to characterize the in vitro and in vivo biological properties of a novel series of small-molecule bacterial type IIA topoisomerase inhibitors. METHODS: Bacterial susceptibility testing was performed by broth microdilution. Resistance frequencies were determined by plating bacteria onto agar containing test compound and enumerating mutants. Bacteria were passaged using subinhibitory concentrations of antibacterials to generate resistance. Target enzyme inhibition was determined by exposure to antibacterials and DNA; topoisomers were visualized by gel electrophoresis. Oral and intravenous pharmacokinetic profiles were determined in mice. In vivo efficacy was determined using a mouse model of septicaemia and thigh infection with MSSA and MRSA, respectively. RESULTS: Representative compounds REDX04139, REDX05604 and REDX05931 demonstrated in vitro potency against a range of Gram-positive and fastidious Gram-negative pathogens. Clinical isolate testing revealed REDX04139 and REDX05931 had MIC90 values of 0.25 and 0.5 mg/L, respectively, for MRSA and MIC90 values of 2 mg/L for streptococci. REDX04139 was bactericidal in vitro against Staphylococcus aureus at 8× MIC over 6 h. Pharmacokinetic profiling of REDX04139 and REDX05604 in mice revealed low clearance and excellent bioavailability (≥71%). REDX04139 provided 100% survival against S. aureus in a mouse septicaemia model, while REDX05604 reduced bacterial load by up to 3.7 log units in the MRSA mouse thigh infection model. CONCLUSIONS: Redx Pharma has discovered a novel series of topoisomerase inhibitors that are being further developed for drug-resistant bacteria.
Assuntos
Antibacterianos/farmacologia , DNA Girase/metabolismo , DNA Topoisomerase IV/antagonistas & inibidores , Hidrocarbonetos Cíclicos/farmacologia , Staphylococcus/efeitos dos fármacos , Animais , Antibacterianos/isolamento & purificação , Antibacterianos/farmacocinética , Disponibilidade Biológica , Sobrevivência Celular/efeitos dos fármacos , Modelos Animais de Doenças , Células Hep G2 , Humanos , Hidrocarbonetos Cíclicos/isolamento & purificação , Hidrocarbonetos Cíclicos/farmacocinética , Masculino , Camundongos , Testes de Sensibilidade Microbiana , Sepse/tratamento farmacológico , Sepse/microbiologia , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/microbiologia , Streptococcus/efeitos dos fármacos , Análise de SobrevidaRESUMO
OBJECTIVES: To evaluate the in vitro biological properties of a novel class of isothiazolone inhibitors of the bacterial type II topoisomerases. METHODS: Inhibition of DNA gyrase and topoisomerase IV activity was assessed using DNA supercoiling and decatenation assays. MIC and MBC were determined according to CLSI guidelines. Antibacterial combinations were assessed using a two-dimensional chequerboard MIC method. Spontaneous frequency of resistance was measured at various multiples of the MIC. Resistant mutants were generated by serial passage at subinhibitory concentrations of antibacterials and genetic mutations were determined through whole genome sequencing. Mammalian cytotoxicity was evaluated using the HepG2 cell line. RESULTS: Representative isothiazolone compound REDX04957 and its enantiomers (REDX05967 and REDX05990) showed broad-spectrum bactericidal activity against the ESKAPE organisms, with the exception of Enterococcus spp., as well as against a variety of other human bacterial pathogens. Compounds retained activity against quinolone-resistant strains harbouring GyrA S83L and D87G mutations (MIC ≤4 mg/L). Compounds inhibited the supercoiling activity of wild-type DNA gyrase and the decatenation function of topoisomerase IV. Frequency of resistance of REDX04957 at 4× MIC was <9.1â×â10(-9). Against a panel of recent MDR isolates, REDX05967 demonstrated activity against Acinetobacter baumannii with MIC50 and MIC90 of 16 and 64 mg/L, respectively. Compounds showed a lack of cytotoxicity against HepG2 cells at 128 mg/L. CONCLUSIONS: Isothiazolone compounds show potent activity against Gram-positive and -negative pathogens with a dual targeting mechanism-of-action and a low potential for resistance development, meriting their continued investigation as broad-spectrum antibacterial agents.
Assuntos
Antibacterianos/farmacologia , DNA Topoisomerases Tipo II/metabolismo , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Tiazóis/farmacologia , Inibidores da Topoisomerase II/farmacologia , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/enzimologia , Acinetobacter baumannii/genética , Técnicas de Tipagem Bacteriana , DNA Girase/metabolismo , DNA Topoisomerase IV/antagonistas & inibidores , DNA Bacteriano/metabolismo , Enterococcus/efeitos dos fármacos , Enterococcus/enzimologia , Bactérias Gram-Negativas/enzimologia , Bactérias Gram-Positivas/enzimologia , Células Hep G2 , Humanos , Testes de Sensibilidade Microbiana , Mutação , Tiazóis/química , Tiazóis/isolamento & purificação , Tiazóis/metabolismo , Inibidores da Topoisomerase II/química , Inibidores da Topoisomerase II/isolamento & purificaçãoRESUMO
There is an urgent and unmet medical need for new antibacterial drugs that tackle infections caused by multidrug-resistant (MDR) pathogens. During the course of our wider efforts to discover and exploit novel mechanism of action antibacterials, we have identified a novel series of isothiazolone based inhibitors of bacterial type II topoisomerase. Compounds from the class displayed excellent activity against both Gram-positive and Gram-negative bacteria with encouraging activity against a panel of MDR clinical Escherichia coli isolates when compared to ciprofloxacin. Representative compounds also displayed a promising in vitro safety profile.