RESUMO
Respiratory syncytial virus (RSV) is a leading cause of lower respiratory infections in infants and the immunocompromised, yet no efficient therapeutic exists. We have identified the AVG class of allosteric inhibitors of RSV RNA synthesis. Here, we demonstrate through biolayer interferometry and in vitro RNA-dependent RNA polymerase (RdRP) assays that AVG compounds bind to the viral polymerase, stalling the polymerase in initiation conformation. Resistance profiling revealed a unique escape pattern, suggesting a discrete docking pose. Affinity mapping using photoreactive AVG analogs identified the interface of polymerase core, capping, and connector domains as a molecular target site. A first-generation lead showed nanomolar potency against RSV in human airway epithelium organoids but lacked in vivo efficacy. Docking pose-informed synthetic optimization generated orally efficacious AVG-388, which showed potent efficacy in the RSV mouse model when administered therapeutically. This study maps a druggable target in the RSV RdRP and establishes clinical potential of the AVG chemotype against RSV disease.
Assuntos
Infecções por Vírus Respiratório Sincicial , Vírus Sincicial Respiratório Humano , Infecções Respiratórias , Animais , Humanos , Camundongos , Conformação Molecular , RNA Polimerase Dependente de RNA , Infecções por Vírus Respiratório Sincicial/tratamento farmacológico , Infecções por Vírus Respiratório Sincicial/metabolismo , Vírus Sincicial Respiratório Humano/genéticaRESUMO
Respiratory syncytial virus (RSV) represents a significant health threat to infants and to elderly or immunocompromised individuals. There are currently no vaccines available to prevent RSV infections, and disease management is largely limited to supportive care, making the identification and development of effective antiviral therapeutics against RSV a priority. To identify effective chemical scaffolds for managing RSV disease, we conducted a high-throughput anti-RSV screen of a 57,000-compound library. We identified a hit compound that specifically blocked activity of the RSV RNA-dependent RNA polymerase (RdRp) complex, initially with moderate low-micromolar potency. Mechanistic characterization in an in vitro RSV RdRp assay indicated that representatives of this compound class block elongation of RSV RNA products after initial extension by up to three nucleotides. Synthetic hit-to-lead exploration yielded an informative 3D quantitative structure-activity relationship (3D-QSAR) model and resulted in analogs with more than 20-fold improved potency and selectivity indices (SIs) of >1,000. However, first-generation leads exhibited limited water solubility and poor metabolic stability. A second optimization strategy informed by the 3D-QSAR model combined with in silico pharmacokinetics (PK) predictions yielded an advanced lead, AVG-233, that demonstrated nanomolar activity against both laboratory-adapted RSV strains and clinical RSV isolates. This anti-RSV activity extended to infection of established cell lines and primary human airway cells. PK profiling in mice revealed 34% oral bioavailability of AVG-233 and sustained high drug levels in the circulation after a single oral dose of 20 mg/kg. This promising first-in-class lead warrants further development as an anti-RSV drug.
Assuntos
Antivirais/farmacologia , RNA Polimerase Dependente de RNA/metabolismo , Infecções por Vírus Respiratório Sincicial/tratamento farmacológico , Vírus Sincicial Respiratório Humano/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos , Regulação Alostérica , Animais , Células Cultivadas , Humanos , Masculino , Camundongos , RNA Polimerase Dependente de RNA/genética , Infecções por Vírus Respiratório Sincicial/metabolismo , Infecções por Vírus Respiratório Sincicial/virologia , Proteínas Virais/metabolismoRESUMO
7-Deazapurines are known to possess broad antiviral activity, however the 2'-C-methylguanosine analogue displays poor cell permeation and limited phosphorylation, thus is not an efficient inhibitor of hepatitis C virus (HCV) replication. We previously reported the 6-O-methyl entity as a prodrug moiety to increase liphophilicity of guanine nucleosides and the ProTide approach applied to 2'-C-methyl-6-O-methylguanosine has lead to potent HCV inhibitors now in clinical trials. In this Letter, we report the synthesis and biological evaluation of 2'-C-methyl-6-O-methyl-7-deaza guanosine and ProTide derivatives. In contrast to prior studies, removal of the N-7 of the nucleobase entirely negates anti-HCV activity compared to the 2'-C-methyl-6-O-methylguanosine analogues. To understand better this significant loss of activity, enzymatic assays and molecular modeling were carried out and suggested 2'-C-methyl-6-O-methyl-7-deaza guanosine and related ProTides do not act as efficient prodrugs of the free nucleotide, in marked contrast to the case of the parent guanine analogue.
Assuntos
Alanina/química , Amidas/farmacologia , Antivirais/farmacologia , Ésteres/farmacologia , Guanina/análogos & derivados , Hepacivirus/efeitos dos fármacos , Ácidos Fosfóricos/farmacologia , Amidas/síntese química , Amidas/química , Antivirais/síntese química , Antivirais/química , Ésteres/síntese química , Ésteres/química , Guanina/síntese química , Guanina/química , Guanina/farmacologia , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Ácidos Fosfóricos/síntese química , Ácidos Fosfóricos/químicaRESUMO
We herein report phosphorodiamidates as a significant new phosphate prodrug motif. Sixty-seven phosphorodiamidates are reported of two 6-O-alkyl 2'-C-methyl guanosines, with significant variation in the diamidate structure. Both symmetrical and asymmetric phosphorodiamidates are reported, derived from various esterified amino acids, both d and l, and also from various simple amines. All of the compounds were evaluated versus hepatitis C virus in replicon assay, and nanomolar activity levels were observed. Many compounds were noncytotoxic at 100 µM, leading to high antiviral selectivities. The agents are stable in acidic, neutral, and moderately basic media and in selected biological media but show efficient processing by carboxypeptidases and efficiently yield the free nucleoside monophosphate in cells. On the basis of in vitro data, eight leads were selected for additional in vivo evaluation, with the intent of selecting one candidate for progression toward clinical studies. This phosphorodiamidate prodrug method may have broad application outside of HCV and antivirals as it offers many of the advantages of phosphoramidate ProTides but without the chirality issues present in most cases.
Assuntos
Antivirais/síntese química , Guanosina/análogos & derivados , Guanosina/síntese química , Hepacivirus/efeitos dos fármacos , Compostos Organofosforados/síntese química , Pró-Fármacos/síntese química , Animais , Antivirais/farmacocinética , Antivirais/farmacologia , Catepsina A/metabolismo , Linhagem Celular , Estabilidade de Medicamentos , Guanosina/farmacocinética , Guanosina/farmacologia , Hepacivirus/genética , Humanos , Fígado/metabolismo , Masculino , Modelos Moleculares , Compostos Organofosforados/farmacocinética , Compostos Organofosforados/farmacologia , Pró-Fármacos/farmacocinética , Pró-Fármacos/farmacologia , Ratos , Ratos Sprague-Dawley , Soro , Relação Estrutura-AtividadeAssuntos
Infecção Hospitalar/prevenção & controle , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Infecções Estafilocócicas/prevenção & controle , Vacinas Antiestafilocócicas , Antígenos de Bactérias/química , Antígenos de Bactérias/imunologia , Proteínas de Transporte de Cátions/química , Proteínas de Transporte de Cátions/imunologia , Ensaios Clínicos como Assunto , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/imunologia , Infecção Hospitalar/virologia , Aprovação de Drogas/legislação & jurisprudência , Aprovação de Drogas/organização & administração , Humanos , Incidência , Staphylococcus aureus Resistente à Meticilina/fisiologia , Modelos Animais , Seleção de Pacientes , Valor Preditivo dos Testes , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/virologia , Vacinas Antiestafilocócicas/administração & dosagem , Vacinas Antiestafilocócicas/efeitos adversos , Vacinas Antiestafilocócicas/uso terapêutico , Estados Unidos/epidemiologia , Vacinação/efeitos adversos , Vacinação/mortalidadeRESUMO
INX-08189 is an aryl-phosphoramidate of 6-O-methyl-2'-C-methyl guanosine. INX-08189 was highly potent in replicon assays, with a 50% effective concentration of 10±6 nM against hepatitis C genotype 1b at 72 h. The inhibitory effect on viral replication was rapid, with a 50% effective concentration (EC50) of 35±8 nM at 24 h. An intracellular 2'-C-methyl guanosine triphosphate (2'-C-MeGTP) concentration of 2.43±0.42 pmol/10(6) cells was sufficient to achieve 90% inhibition of viral replication. In vitro resistance studies confirmed that the S282T mutation in the NS5b gene conferred an approximately 10-fold reduction in sensitivity to INX-08189. However, the complete inhibition of S282T mutant replicons still could be achieved with an EC90 of 344±170 nM. Drug combination studies of INX-08189 and ribavirin indicated significant synergy in antiviral potency both in wild-type and S282T-expressing replicons. Genotype 1b replicons could be cleared after 14 days of culture when exposed to as little as 20 nM INX-08189. No evidence of mitochondrial toxicity was observed after 14 days of INX-08189 exposure in both HepG2 and CEM human cell lines. In vivo studies of rats and cynomolgus monkeys demonstrated that 2'-C-MeGTP concentrations in liver equivalent to the EC90 could be attained after a single oral dose of INX-08189. Rat liver 2'-C-MeGTP concentrations were proportional to dose, sustained for greater than 24 h, and correlated with plasma concentrations of the nucleoside metabolite 2'-C-methyl guanosine. The characteristics displayed by INX-08189 support its continued development as a clinical candidate for the treatment of chronic HCV infection.
Assuntos
Amidas/química , Antivirais/farmacologia , Antivirais/farmacocinética , Guanosina/farmacologia , Guanosina/farmacocinética , Hepacivirus/efeitos dos fármacos , Ácidos Fosfóricos/química , Pró-Fármacos/farmacologia , Pró-Fármacos/farmacocinética , Animais , Linhagem Celular , Linhagem Celular Tumoral , Guanosina/análogos & derivados , Guanosina/química , Humanos , Macaca fascicularis , Masculino , Pró-Fármacos/química , Ratos , Ratos Sprague-Dawley , Replicação Viral/efeitos dos fármacosRESUMO
FV-100 is the prodrug of the highly potent anti-varicella zoster virus bicyclic nucleoside analogue CF-1743. To characterize the pharmacokinetics and safety of oral FV-100, 3 randomized, double-blind, placebo-controlled clinical trials were conducted: (i) a single-ascending-dose study in 32 healthy subjects aged 18 to 55 years (100-, 200-, 400-, and 800-mg doses) with an evaluation of the food effect in the 400-mg group; (ii) a multiple-ascending-dose study in 48 subjects aged 18 to 55 years (100 mg once daily [QD], 200 mg QD, 400 mg QD, 400 mg twice a day, and 800 mg QD for 7 days); and (iii) a 2-part study in subjects aged 65 years and older with a single 400-mg dose in 15 subjects and a 400-mg QD dosing regimen for 7 days in 12 subjects. FV-100 was rapidly and extensively converted to CF-1743, the concentration of which remained above that required to reduce viral activity by 50% for the 24-hour dosing period. Renal excretion of CF-1743 was very low. A high-fat meal reduced exposure to CF-1743; a low-fat meal did not. Pharmacokinetic parameters for the elderly subjects were comparable to those for the younger subjects. FV-100 was well tolerated by all subjects. The pharmacokinetic and safety profiles of FV-100 support its continued investigation for the treatment of herpes zoster and prevention of postherpetic neuralgia with once-daily dosing and without dose modifications for elderly or renally impaired patients.
Assuntos
Antivirais/farmacocinética , Herpes Zoster/tratamento farmacológico , Pró-Fármacos/farmacocinética , Nucleosídeos de Pirimidina/farmacocinética , Administração Oral , Adolescente , Adulto , Fatores Etários , Idoso , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nucleosídeos de Pirimidina/administração & dosagem , Nucleosídeos de Pirimidina/efeitos adversos , Nucleosídeos de Pirimidina/sangueRESUMO
The extracellular adherence protein (Eap) from Staphylococcus aureus has been suggested as a vaccine candidate and for therapeutic use due to its immunomodulating and antiangiogenic properties; however, little is known about anti-Eap antibodies in humans. We determined anti-Eap antibody titers by enzyme-linked immunosorbent assay and Western blot and measured serum samples from 92 patients with proven S. aureus infections and 93 healthy controls. The functionality of antibodies was assessed by a phagocytosis assay using Eap-coated fluorescent microspheres. Antibodies were detected in all human samples, but not in mice. Patients showed significantly higher titers than controls [immunoglobulin M (IgM), P=0.007; IgG, P<0.0001]. Patients with deep or severe infections showed higher titers than those with superficial or mild disease. Eap alone was sufficient to promote phagocytosis by peripheral blood mononuclear cell and granulocytes that was moderately enhanced in the presence of human serum, but no correlation was found with the levels of anti-Eap antibodies. Anti-Eap antibodies are prevalent in all tested humans and correlate with the severity of S. aureus infection; however, they do not seem to provide protection against invasive infections. Before considering Eap for therapy or as a vaccine candidate, further studies are warranted to assess the impact of the interference between Eap and its specific antibodies.
Assuntos
Anticorpos Antibacterianos/sangue , Proteínas de Bactérias/imunologia , Proteínas de Ligação a RNA/imunologia , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/fisiopatologia , Staphylococcus aureus/imunologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Western Blotting , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Fagocitose , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/metabolismo , Adulto JovemRESUMO
We herein report a novel double pro-drug approach applied to the anti-HCV agent 2'-beta-C-methyl guanosine. A phosphoramidate ProTide motif and a 6-O-methoxy base pro-drug moiety are combined to generate lipophilic prodrugs of the monophosphate of the guanine nucleoside. Modification of the ester and amino acid moieties lead to a compound INX-08189 that exhibits 10nM potency in the HCV genotype 1b subgenomic replicon, thus being 500 times more potent than the parent nucleoside. The potency of the lead compound INX-08189 was shown to be consistent with intracellular 2'-C-methyl guanosine triphosphate levels in primary human hepatocytes. The separated diastereomers of INX-08189 were shown to have similar activity in the replicon assay and were also shown to be similar substrates for enzyme processing. INX-08189 has completed investigational new drug enabling studies and has been progressed into human clinical trials for the treatment of chronic HCV infection.
Assuntos
Antivirais/síntese química , Guanosina Monofosfato/análogos & derivados , Hepacivirus/efeitos dos fármacos , Pró-Fármacos/síntese química , Amidas/química , Antivirais/química , Antivirais/toxicidade , Células Cultivadas , Desenho de Fármacos , Guanosina/análogos & derivados , Guanosina/síntese química , Guanosina/toxicidade , Guanosina Monofosfato/síntese química , Guanosina Monofosfato/química , Guanosina Monofosfato/farmacologia , Humanos , Ácidos Fosfóricos/química , Pró-Fármacos/química , Pró-Fármacos/toxicidadeRESUMO
Two monoclonal antibodies (MAbs) were raised against the Candida albicans cell-surface glycoprotein Als3 using the N-terminal domain of the protein as the immunogen. ELISA was used to demonstrate the specificity of the MAbs for the Als3 fragment, but not for the corresponding N-terminal domain fragments from other proteins in the Als family. The anti-Als3 MAbs immunolabeled the surface of germ tubes from a diverse collection of wild-type C. albicans isolates, but did not label yeast cells, an als3Delta/als3Delta deletion mutant strain, nor isolates of other Candida species associated with human disease. Als3 was visualized readily in fresh and formalin-fixed, paraffin-embedded kidney tissue from a murine model of candidiasis. The anti-Als3 MAbs were also useful for immunogold electron microscopy and Western blotting. Both MAbs blocked C. albicans adhesion to vascular endothelial cells and buccal epithelial cells. These versatile MAbs are a valuable addition to the reagents available to study C. albicans cell surface dynamics and interaction of the fungus with host cells.
Assuntos
Anticorpos Antifúngicos/imunologia , Anticorpos Monoclonais/imunologia , Candida albicans/fisiologia , Candidíase/microbiologia , Proteínas Fúngicas/imunologia , Interações Hospedeiro-Patógeno , Animais , Candida albicans/genética , Candida albicans/imunologia , Candidíase/imunologia , Células Epiteliais/imunologia , Células Epiteliais/microbiologia , Humanos , Camundongos , Camundongos Endogâmicos BALB CRESUMO
Enterococci are opportunistic pathogens known to cause numerous clinical infections and complications in humans. Adhesin-mediated binding to extracellular matrix (ECM) proteins of the host is thought to be a crucial step in the pathogenesis of these bacterial infections. Adhesin of collagen from Enterococcus faecalis (Ace) is a cell-wall anchored protein of E. faecalis that has been shown to be important for bacterial binding to the ECM. In this report, we characterize the conditions for Ace expression and demonstrate Ace binding to mammalian epithelial and endothelial cells as well as to collagens found in the ECM. To further characterize Ace expression and function, we report the generation of a panel of monoclonal antibodies (mAbs) directed against this important E. faecalis virulence factor. Through the use of multiple in vitro assays, surface plasmon resonance and flow cytometry, we have characterized this panel of mAbs which may prove to be not only beneficial in studies that address the precise biological role of adhesion of E. faecalis, but may also serve as beneficial therapeutic agents against E. faecalis infections.
Assuntos
Adesinas Bacterianas/metabolismo , Anticorpos Antibacterianos/imunologia , Anticorpos Monoclonais/imunologia , Proteínas de Bactérias/metabolismo , Proteínas de Transporte/metabolismo , Colágeno/metabolismo , Enterococcus faecalis/imunologia , Adesinas Bacterianas/imunologia , Animais , Anticorpos Antibacterianos/isolamento & purificação , Anticorpos Monoclonais/isolamento & purificação , Proteínas de Bactérias/imunologia , Proteínas de Transporte/imunologia , Linhagem Celular , Enterococcus faecalis/metabolismo , Feminino , Citometria de Fluxo , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Modelos Animais , Ligação Proteica , Ressonância de Plasmônio de SuperfícieRESUMO
Staphylococcus epidermidis is an important opportunistic human pathogen that has recently emerged as a major cause of foreign-body infections. The most important stage contributing to the pathogenesis of this bacteria is the initial adherence to host tissue. SdrG is a cell-wall-anchored fibrinogen-binding adhesin of S. epidermidis that has been shown to be necessary for bacterial binding to fibrinogen-coated foreign bodies, such as catheters. Here we report the generation and characterization of a panel of monoclonal antibodies (MAbs) directed against this S. epidermidis virulence factor. Through the use of multiple in vitro assays, surface plasmon resonance, and flow cytometry, we have characterized a diverse array of MAbs that may prove to be beneficial in studies that address the precise biologic role of SdrG.
Assuntos
Adesinas Bacterianas/imunologia , Anticorpos Monoclonais/metabolismo , Proteínas de Bactérias/imunologia , Proteínas de Transporte/imunologia , Fibrinogênio/metabolismo , Staphylococcus epidermidis/imunologia , Adesinas Bacterianas/genética , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Feminino , Lactococcus lactis/genética , Lactococcus lactis/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Ligação Proteica/imunologia , Staphylococcus epidermidis/genéticaRESUMO
Two cohorts of four subjects requiring hemodialysis received tefibazumab (10 or 20 mg/kg). The mean elimination half-life was between 17 and 18 days, the average volume of distribution was 7.3 liters, and the average clearance was 12 ml/h for both dose groups. At a dose of 20 mg/kg of body weight, plasma levels were 88 microg/ml at 21 days.
Assuntos
Adesinas Bacterianas/imunologia , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais/farmacocinética , Falência Renal Crônica/terapia , Diálise Renal , Adulto , Anticorpos Monoclonais/administração & dosagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infecções Estafilocócicas/terapia , Resultado do TratamentoRESUMO
Tefibazumab (Aurexis), a humanized monoclonal antibody that binds to the surface-expressed adhesion protein clumping factor A, is under development as adjunctive therapy for serious Staphylococcus aureus infections. Sixty patients with documented S. aureus bacteremia (SAB) were randomized and received either tefibazumab at 20 mg/kg of body weight as a single infusion or a placebo in addition to an antibiotic(s). The primary objective of the study was determining safety and pharmacokinetics. An additional objective was to assess activity by a composite clinical end point (CCE). Baseline characteristics were evenly matched between groups. Seventy percent of infections were healthcare associated, and 57% had an SAB-related complication at baseline. There were no differences between the treatment groups in overall adverse clinical events or alterations in laboratory values. Two patients developed serious adverse events that were at least possibly related to tefibazumab; one hypersensitivity reaction was considered definitely related. The tefibazumab plasma half-life was 18 days. Mean plasma levels were <100 microg/ml by day 14. A CCE occurred in six patients (four placebo and two tefibazumab patients) and included five deaths (four placebo and one tefibazumab patient). Progression in the severity of sepsis occurred in four placebo and no tefibazumab patients. Tefibazumab was well tolerated, with a safety profile similar to those of other monoclonal antibodies. Additional trials are warranted to address the dosing range and efficacy of tefibazumab.
Assuntos
Anticorpos Monoclonais/farmacocinética , Bacteriemia/tratamento farmacológico , Infecções Estafilocócicas/terapia , Staphylococcus aureus/efeitos dos fármacos , Adulto , Idoso , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais/uso terapêutico , Área Sob a Curva , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
A human donor-selected immunoglobulin G for intravenous injection (IGIV) product with elevated titers against the staphylococcal fibrinogen-binding MSCRAMM proteins ClfA and SdrG (INH-A21) was tested in vitro and in vivo. INH-A21 contained a significantly increased ability to inhibit the fibrinogen-binding activity of recombinant forms of both ClfA and SdrG. Evaluation of the opsonizing potential of INH-A21 was evaluated using fluorescently labeled bacteria; this assay indicated an increase in phagocytic activity compared to normal IGIV. The prophylactic efficacy of INH-A21 against an intraperitoneal challenge of methicillin-resistant Staphylococcus epidermidis (MRSE) was evaluated in a neonatal rat model. INH-A21 was also evaluated for prophylactic and therapeutic efficacy in a rabbit model of catheter-induced aortic valve infective endocarditis caused by either MRSE or methicillin-resistant Staphylococcus aureus (MRSA). Results from the in vivo models demonstrated potent prophylactic and therapeutic efficacy against both MRSE and MRSA. These data suggest that INH-A21 may be an important tool for the prevention and treatment of staphylococcal infections, especially in high-risk populations.
Assuntos
Anticorpos Antibacterianos/uso terapêutico , Proteínas de Bactérias/imunologia , Proteínas de Transporte/imunologia , Coagulase/imunologia , Imunoglobulina G/uso terapêutico , Imunoglobulinas Intravenosas/uso terapêutico , Infecções Estafilocócicas/prevenção & controle , Staphylococcus aureus/imunologia , Staphylococcus epidermidis/imunologia , Animais , Feminino , Humanos , Coelhos , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND: Prophylactic administration of intravenous immunoglobulin has been inconsistent in reducing the risk of sepsis in very low birth weight (VLBW) infants presumably because of varying titers of organism specific IgG antibodies. INH-A21 is an intravenous immunoglobulin from donors with high titers of antistaphylococcal antibodies. This dose-ranging study explored safety and preliminary activity of INH-A21 for prevention of staphylococcal sepsis in VLBW infants. METHODS: This was a multicenter, double blind, group-sequential study. Infants with birth weights 500-1250 g were randomized to receive up to 4 doses of placebo, 250 mg/kg, 500 mg/kg or 750 mg/kg INH-A21. Safety and frequencies of sepsis were compared across treatment groups. RESULTS: All treatment groups had similar mean gestational age, birth weight, Apgar score and maternal use of antibiotics. Randomizations to 250 mg/kg (N = 94) and 500 mg/kg (N = 96) doses were terminated after interim analyses demonstrated a low probability of finding a difference when compared with placebo. Infants randomized to the INH-A21 750 mg/kg group (N = 157) had fewer episodes of Staphylococcus aureus sepsis [relative risk (RR), 0.37; 95% confidence interval (CI), 0.12-1.12; P = 0.14], candidemia (RR 0.34; 95% CI 0.09-1.22; P = 0.09) and mortality (RR 0.64; 95% CI 0.25-1.61; P = 0.27) when compared with the placebo-treated cohort (N = 158). No dose-related trends were observed for adverse events or morbidities associated with prematurity. CONCLUSIONS: INH-A21 750 mg/kg demonstrated potential to reduce sepsis caused by S. aureus, candidemia and mortality in VLBW infants. Although statistical significance was not reached, based on the magnitude of the estimated differences, the efficacy and safety of INH-A21 750 mg/kg should be evaluated in an adequately powered, well-controlled study.
Assuntos
Infecção Hospitalar/prevenção & controle , Imunoglobulinas Intravenosas/efeitos adversos , Imunoglobulinas Intravenosas/uso terapêutico , Doenças do Prematuro/prevenção & controle , Recém-Nascido de muito Baixo Peso , Sepse/prevenção & controle , Infecção Hospitalar/mortalidade , Método Duplo-Cego , Feminino , Humanos , Imunoglobulinas Intravenosas/administração & dosagem , Recém-Nascido , Recém-Nascido Prematuro , Doenças do Prematuro/etiologia , Doenças do Prematuro/mortalidade , Masculino , Sepse/etiologia , Sepse/mortalidade , Staphylococcus/imunologia , Resultado do TratamentoRESUMO
Nosocomial or late-onset sepsis is a common complication among premature infants, with a frequency inversely correlated with birth weight. Increased susceptibility to infection is due in part to an immature humoral (antibody-mediated) immune response. This study investigated the pharmacokinetics (PKs) and safety of a donor-selected specific intravenous immune globulin (IVIG) preparation, INH-A21 (Veronate), for prevention of sepsis in premature infants. Thirty-six infants weighing between 500 and 1,250 g during the first postnatal week were eligible to begin a series of up to four intravenous infusions of 500 or 750 mg/kg of body weight INH-A21. Blood samples were analyzed for antibodies against the Ser-Asp dipeptide repeat G (SdrG) and clumping factor A (ClfA) surface proteins of staphylococci. Sparse sampling and population PK analyses were performed to derive PK parameters. Following administration of the 500- and 750-mg/kg doses, the estimated average steady-state levels of anti-ClfA were 6.1 U/ml and 9.2 U/ml, respectively, and those of anti-SdrG were 5.2 U/ml and 7.7 U/ml, respectively. The elimination half-lives for anti-ClfA and anti-SdrG were 719 h and 701 h, respectively, and the clearances were 0.18 ml/h and 0.21 ml/h, respectively. In the final model, the values of the PK parameters were independent of gestational age. Both doses of INH-A21 were well tolerated, and the safety profile was similar to those of other IVIG preparations. These results suggest that a shorter dosing interval should be utilized between the first and second doses to achieve and maintain higher titers of anti-ClfA and anti-SdrG antibodies. Further studies examining INH-A21 for the prevention of late-onset sepsis in infants within the weight range studied are warranted.
Assuntos
Anticorpos Antibacterianos/sangue , Imunoglobulinas Intravenosas/efeitos adversos , Imunoglobulinas Intravenosas/farmacocinética , Recém-Nascido de Baixo Peso , Estudos Multicêntricos como Assunto , Teorema de Bayes , Meia-Vida , Humanos , Imunoglobulinas Intravenosas/administração & dosagem , Recém-Nascido , Recém-Nascido Prematuro , Cinética , Ensaios Clínicos Controlados Aleatórios como Assunto , Sepse/prevenção & controle , Infecções Estafilocócicas/prevenção & controle , Estados UnidosRESUMO
We report the humanization and characterization of monoclonal antibody (MAb) T1-2 or tefibazumab, a monoclonal antibody that recognizes clumping factor A expressed on the surface of Staphylococcus aureus. We demonstrate that the binding kinetics of MAb T1-2 is indistinguishable compared to that of its murine parent. Furthermore, MAb T1-2 is shown to enhance the opsonophagocytic uptake of ClfA-coated latex beads, protect against an intravenous challenge in a prophylactic model of rabbit infective endocarditis, and enhance the efficacy of vancomycin therapy in a therapeutic model of established infective endocarditis.
Assuntos
Anticorpos Monoclonais/imunologia , Coagulase/imunologia , Staphylococcus aureus/imunologia , Animais , Anticorpos Monoclonais/sangue , Linhagem Celular , Humanos , CoelhosRESUMO
The ability of Staphylococcus aureus to adapt to different environments is due to a regulatory network comprising several loci. Here we present a detailed study of the interaction between the two global regulators sae and sigmaB of S. aureus and their influence on virulence gene expression in vitro, as well as during device-related infection. The expression of sae, asp23, hla, clfA, coa, and fnbA was determined in strain Newman and its isogenic saeS/R and sigB mutants by Northern analysis and LightCycler reverse transcription-PCR. There was no indication of direct cross talk between the two regulators. sae had a dominant effect on target gene expression during device-related infection. SigmaB seemed to be less active throughout the infection than under induced conditions in vitro.
Assuntos
Proteínas de Bactérias/fisiologia , Regulação Bacteriana da Expressão Gênica , Próteses e Implantes/efeitos adversos , Fator sigma/fisiologia , Staphylococcus aureus/genética , Animais , Proteínas de Bactérias/genética , Sequência de Bases , Cobaias , Dados de Sequência Molecular , RNA Mensageiro/análise , Fator sigma/genética , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/patogenicidade , Fatores de Transcrição , VirulênciaRESUMO
Tefibazumab (Aurexis) is a humanized monoclonal antibody being evaluated as adjunctive therapy for the treatment of Staphylococcus aureus infections. This open-label, dose escalation study evaluated the safety and pharmacokinetics of tefibazumab in 19 healthy volunteers aged 18 to 69 years. Each subject received a single administration of tefibazumab at a dose of 2, 5, 10, or 20 mg/kg of body weight infused over 15 min. Plasma samples for pharmacokinetic assessments were obtained before infusion as well as 1, 6, 12, and 24 h and 3, 4, 7, 21, 28, 42, and 56 days after dosing. Plasma concentrations of tefibazumab were detected 1 h after the end of the infusion, with a mean maximum concentration of drug in serum (C(max)) of 59, 127, 252, and 492 microg/ml following doses of 2, 5, 10, and 20 mg/kg, respectively. The median time to maximum concentration of drug in serum (T(max)) was 1.0 h for each dose. The mean elimination half-life (t(1/2)) was approximately 22 days. The volume of distribution (V) was 4.7, 6.7, 7.2, and 7.2 liters after doses of 2, 5, 10, and 20 mg/kg, respectively. Clearance (CL) was 6.0, 9.2, 10.2, and 9.9 ml/hr, respectively. At the highest dose, plasma levels of tefibazumab were >100 microg/ml for 21 days. On day 56, the mean plasma concentrations were 6.3, 10.0, 16.4, and 30.5 microg/ml for the 2, 5, 10, and 20 mg/kg doses, respectively. Tefibazumab exhibited linear kinetics across doses of 5, 10, and 20 mg/kg. No anti-tefibazumab antibodies were detected after dosing in any subject. There were no serious adverse events, and tefibazumab was well tolerated over the entire dose range.