RESUMO
Factor VIII (FVIII) circulates in a noncovalent complex with von Willebrand Factor (VWF), the latter determining FVIII half-life. The VWF-binding aptamer rondaptivon pegol (BT200) increases plasma levels of VWF/FVIII in healthy volunteers. This trial assessed its safety, pharmacokinetics, and pharmacodynamics in hemophilia A. Nineteen adult patients (ages 20-62 years, 4 women) with hemophilia A (8 mild, 2 moderate, and 9 severe) received subcutaneous injections of rondaptivon pegol. After an initial fixed dose of 3 mg on days 0 and 4, patients received weekly doses of 2 to 9 mg until day 28. Severe hemophilia A patients underwent sparse-sampling population pharmacokinetics individual profiling after the final dose of rondaptivon pegol. Adverse events, pharmacokinetics, and pharmacodynamics were assessed. FVIII activity and VWF levels were measured. All patients tolerated rondaptivon pegol well. The geometric mean half-life of rondaptivon pegol was 5.4 days and rondaptivon pegol significantly increased VWF levels. In severe hemophilia A, 6 doses of rondaptivon pegol increased the half-lives of 5 different FVIII products from a median of 10.4 hours to 31.1 hours (range, 20.8-56.0 hours). Median FVIII increased from 22% to 48% in mild hemophilia A and from 3% to 7.5% in moderate hemophilia A. Rondaptivon pegol is a first-in-class prohemostatic molecule that extended the half-life of substituted FVIII approximately 3-fold and increased endogenous FVIII levels approximately 2-fold in hemophilia patients. This trial was registered at www.clinicaltrials.gov as #NCT04677803.
Assuntos
Hemofilia A , Hemostáticos , Adulto , Humanos , Feminino , Adulto Jovem , Pessoa de Meia-Idade , Fator de von Willebrand/uso terapêutico , Hemofilia A/tratamento farmacológico , Fator VIII , Hemostáticos/uso terapêutico , Meia-VidaRESUMO
Von Willebrand factor (VWF) and factor VIII (FVIII) circulate in a noncovalent complex in blood and promote primary hemostasis and clotting, respectively. A new VWF A1-domain binding aptamer, BT200, demonstrated good subcutaneous bioavailability and a long half-life in non-human primates. This first-in-human, randomized, placebo-controlled, doubleblind trial tested the hypothesis that BT200 is well tolerated and has favorable pharmacokinetic and pharmacodynamic effects in 112 volunteers. Participants received one of the following: a single ascending dose of BT200 (0.18-48 mg) subcutaneously, an intravenous dose, BT200 with concomitant desmopressin or multiple doses. Pharmacokinetics were characterized, and the pharmacodynamic effects were measured by VWF levels, FVIII clotting activity, ristocetin-induced aggregation, platelet function under high shear rates, and thrombin generation. The mean half-lives ranged from 7-12 days and subcutaneous bioavailability increased dose-dependently exceeding 55% for doses of 6-48 mg. By blocking free A1 domains, BT200 dose-dependently decreased ristocetin-induced aggregation, and prolonged collagen-adenosine diphosphate and shear-induced platelet plug formation times. However, BT200 also increased VWF antigen and FVIII levels 4-fold (P<0.001), without increasing VWF propeptide levels, indicating decreased VWF/FVIII clearance. This, in turn, increased thrombin generation and accelerated clotting. Desmopressin-induced VWF/FVIII release had additive effects on a background of BT200. Tolerability and safety were generally good, but exaggerated pharmacology was seen at saturating doses. This trial identified a novel mechanism of action for BT200: BT200 dose-dependently increases VWF/FVIII by prolonging half-life at doses well below those which inhibit VWF-mediated platelet function. This novel property can be exploited therapeutically to enhance hemostasis in congenital bleeding disorders.
Assuntos
Doenças de von Willebrand , Fator de von Willebrand , Desamino Arginina Vasopressina , Fator VIII , Humanos , Ristocetina/farmacologia , Trombina , Fator de von Willebrand/metabolismoRESUMO
Type 2B von Willebrand disease (VWD) is characterized by an increased binding affinity of von Willebrand factor (VWF) to platelet glycoprotein Ib. This can lead to clearance of high-molecular-weight (HMW) multimers and thrombocytopenia with a resulting moderate-severe bleeding phenotype. Rondoraptivon pegol (BT200) is a pegylated aptamer binding to the A1 domain of VWF with a novel mechanism of action: it enhances VWF/factor VIII (FVIII) levels by decreasing their clearance. To study the potential benefit of rondoraptivon pegol in patients with type 2B VWD, we conducted a prospective phase 2 trial. Patients with type 2B VWD received 3 mg rondoraptivon pegol subcutaneously on study days 1, 4, and 7, followed by 6 to 9 mg every week until day 28. Five patients (male:female ratio = 3:2) were included. Rondoraptivon pegol rapidly tripled platelet counts from a median of 60 to 179 × 10E9/L (P < .001). Circulating VWF antigen increased from a median of 64% to 143%, which doubled FVIII activity levels from 67% to 134%. In all thrombocytopenic patients, plasma levels of VWF:GPIbM normalized, VWF ristocetin cofactor and VWF collagen-binding activity increased, and HMW multimers appeared. These pronounced improvements reversed during washout of the drug, thus demonstrating causality. The A1 domain binding aptamer directly corrects the underlying defect of type 2B VWD, thus providing a novel potential option for prophylaxis and treatment of patients with this VWD type. These data provide the basis for a phase 2b/3 trial in such patients. This trial was registered at www.clinicaltrials.gov as #NCT04677803.
Assuntos
Hemostáticos , Doença de von Willebrand Tipo 2 , Doenças de von Willebrand , Colágeno , Fator VIII/uso terapêutico , Feminino , Hemostáticos/uso terapêutico , Humanos , Masculino , Contagem de Plaquetas , Complexo Glicoproteico GPIb-IX de Plaquetas/metabolismo , Polietilenoglicóis/uso terapêutico , Estudos Prospectivos , Doenças de von Willebrand/tratamento farmacológico , Fator de von Willebrand/metabolismoRESUMO
The effect of conventional anti-platelet agents is limited in secondary stroke prevention, and their effects are blunted under high shear stress in the presence of increased levels of circulating von Willebrand factor (VWF). VWF is critically involved in thrombus formation at sites of stenotic extracranial/intracranial arteries. A third generation anti-VWF aptamer (BT200) has been generated which could be useful for secondary stroke prevention. To characterize the effects of BT200 in blood of patients with large artery atherosclerosis stroke (LAA). Blood samples were obtained from 33 patients with acute stroke or transient ischemic attack to measure inhibition of VWF activity and VWF-dependent platelet function. Patients who received clopidogrel or dual antiplatelet therapy did not differ in VWF dependent platelet function tests from aspirin treated patients. Of 18 patients receiving clopidogrel with or without aspirin, only 3 had a prolonged collagen adenosine diphosphate closure time, and none of the patients had ristocetin induced aggregation in the target range. BT200 concentration-dependently reduced median VWF activity from 178 to < 3%, ristocetin induced platelet aggregation from 40U to < 10U and prolonged collagen adenosine diphosphate closure times from 93 s to > 300 s. Baseline VWF activity correlated (r = 0.86, p < 0.001) with concentrations needed to reduce VWF activity to < 20% of normal, indicating that BT200 acts in a target concentration-dependent manner. Together with a long half-life supporting once weekly administration, the safety and tolerability observed in an ongoing phase I trial, and the existence of a reversal agent, BT200 is an interesting drug candidate.
Assuntos
Aptâmeros de Peptídeos/farmacologia , Ataque Isquêmico Transitório/sangue , Acidente Vascular Cerebral/tratamento farmacológico , Fator de von Willebrand/efeitos dos fármacos , Idoso , Aspirina/uso terapêutico , Plaquetas/efeitos dos fármacos , Colágeno/metabolismo , Feminino , Humanos , Arteriosclerose Intracraniana/sangue , Arteriosclerose Intracraniana/complicações , Arteriosclerose Intracraniana/patologia , Ataque Isquêmico Transitório/patologia , Ataque Isquêmico Transitório/prevenção & controle , Masculino , Agregação Plaquetária/efeitos dos fármacos , Acidente Vascular Cerebral/sangue , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/patologia , Trombose/sangue , Trombose/tratamento farmacológico , Trombose/etiologia , Trombose/patologiaRESUMO
Von Willebrand factor (VWF) plays a major role in arterial thrombosis. Antiplatelet drugs induce only a moderate relative risk reduction after atherothrombosis, and their inhibitory effects are compromised under high shear rates when VWF levels are increased. Therefore, we investigated the ex vivo effects of a third-generation anti-VWF aptamer (BT200) before/after stimulated VWF release. We studied the concentration-effect curves BT200 had on VWF activity, platelet plug formation under high shear rates (PFA), and ristocetin-induced platelet aggregation (Multiplate) before and after desmopressin or endotoxin infusions in healthy volunteers. VWF levels increased > 2.5-fold after desmopressin or endotoxin infusion (p < 0.001) and both agents elevated circulating VWF activity. At baseline, 0.51 µg/ml BT200 reduced VWF activity to 20% of normal, but 2.5-fold higher BT200 levels were required after desmopressin administration (p < 0.001). Similarly, twofold higher BT200 concentrations were needed after endotoxin infusion compared to baseline (p < 0.011). BT200 levels of 0.49 µg/ml prolonged collagen-ADP closure times to > 300 s at baseline, whereas 1.35 µg/ml BT200 were needed 2 h after desmopressin infusion. Similarly, twofold higher BT200 concentrations were necessary to inhibit ristocetin induced aggregation after desmopressin infusion compared to baseline (p < 0.001). Both stimuli elevated plasma VWF levels in a manner representative of thrombotic or pro-inflammatory conditions such as arterial thrombosis. Even under these conditions, BT200 potently inhibited VWF activity and VWF-dependent platelet function, but higher BT200 concentrations were required for comparable effects relative to the unstimulated state.
Assuntos
Aptâmeros de Nucleotídeos/farmacologia , Plaquetas/efeitos dos fármacos , Agregação Plaquetária , Fator de von Willebrand/antagonistas & inibidores , Difosfato de Adenosina/metabolismo , Adulto , Plaquetas/metabolismo , Plaquetas/fisiologia , Células Cultivadas , Colágeno/metabolismo , Desamino Arginina Vasopressina/farmacologia , Feminino , Humanos , Lipopolissacarídeos/farmacologia , Masculino , Pessoa de Meia-Idade , Fator de von Willebrand/metabolismoRESUMO
Osteoprotegerin (OPG) regulates bone metabolism by reducing the activation of osteoclasts, but may also be involved in blood vessel calcification and atherosclerosis. Within endothelial cells OPG is stored in Weibel-Palade bodies (WPBs). Blood kinetics of OPG are essentially unknown. We aimed to assess these using two distinct in vivo models; one after stimulation with desmopressin (DDAVP) and another after stimulation with lipopolysaccharide (LPS). Both clinical trials were conducted at the Department of Clinical Pharmacology at the Medical University of Vienna, Austria. Participants received desmopressin (0.3 µg/kg), LPS (2 ng/kg), or placebo (sodium chloride 0.9%) with subsequent blood sampling at time points up to 24 hours after administration. The primary objective of this study was to investigate the plasma kinetics of OPG after stimulation with desmopressin and LPS. Secondary analyses included the release of other WPB contents including von Willebrand factor (vWF). This analysis included 31 healthy volunteers (n = 16 for desmopressin and placebo, n = 15 for LPS). Infusion of desmopressin did not increase OPG concentrations compared with placebo, while LPS infusion significantly increased OPG levels, both compared with desmopressin (p < 0.0001) and to placebo (p = 0.004), with a maximum of â¼twofold increase in OPG levels â¼6 hours after infusion. von Willebrand factor levels increased after both desmopressin and LPS infusion (p < 0.0001), with a maximum of â¼threefold increase 2 hours after desmopressin and a maximum of â¼twofold increase 6 hours after LPS administration. In conclusion, we report that, in contrast to vWF, OPG is not released upon stimulation with desmopressin, but increases significantly during experimental endotoxemia.
Assuntos
Desamino Arginina Vasopressina/farmacologia , Células Endoteliais/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Osteoprotegerina/sangue , Corpos de Weibel-Palade/efeitos dos fármacos , Áustria , Biomarcadores/sangue , Estudos Cross-Over , Método Duplo-Cego , Células Endoteliais/metabolismo , Voluntários Saudáveis , Humanos , Cinética , Projetos Piloto , Corpos de Weibel-Palade/metabolismo , Fator de von Willebrand/metabolismoRESUMO
BACKGROUND: von Willebrand factor (VWF) is crucial for arterial thrombosis and its plasma levels are increased in acute coronary syndromes (ACSs). The effects of conventional platelet inhibitors are compromised by elevated VWF under high shear rates. BT200 is a third-generation aptamer that binds and inhibits the A1 domain of human VWF. This article aims to study whether VWF is a predictor of mortality in ACS patients under potent P2Y12 blocker therapy and to examine the effects of a VWF inhibiting aptamer BT200 and its concentrations required to inhibit VWF in plasma samples of patients with ACS. METHODS: VWF activity was measured in 320 patients with ACS, and concentration effect curves of BT200 were established in plasma pools containing different VWF concentrations. RESULTS: Median VWF activity in patients was 170% (interquartile range % confidence interval [CI]: 85-255) and 44% of patients had elevated (> 180%) VWF activity. Plasma levels of VWF activity predicted 1-year (hazard ratio [HR]: 2.68; 95% CI: 1.14-6.31; p < 0.024) and long-term (HR: 2.59; 95% CI: 1.10-6.09) mortality despite treatment with potent platelet inhibitors (dual-antiplatelet therapy with aspirin and prasugrel or ticagrelor). Although half-maximal concentrations were 0.1 to 0.2 µg/mL irrespective of baseline VWF levels, increasing concentrations (0.42-2.13 µg/mL) of BT200 were needed to lower VWF activity to < 20% of normal in plasma pools containing increasing VWF activity (p < 0.001). CONCLUSION: VWF is a predictor of all-cause mortality in ACS patients under contemporary potent P2Y12 inhibitor therapy. BT200 effectively inhibited VWF activity in a target concentration-dependent manner.
Assuntos
Síndrome Coronariana Aguda/tratamento farmacológico , Antagonistas do Receptor Purinérgico P2Y/uso terapêutico , Fator de von Willebrand/antagonistas & inibidores , Fator de von Willebrand/metabolismo , Síndrome Coronariana Aguda/sangue , Síndrome Coronariana Aguda/metabolismo , Síndrome Coronariana Aguda/mortalidade , Idoso , Aptâmeros de Nucleotídeos/farmacologia , Biomarcadores/sangue , Biomarcadores/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inibidores da Agregação Plaquetária/farmacologia , Receptores Purinérgicos P2Y12/metabolismo , Fator de von Willebrand/análiseRESUMO
BACKGROUND AND AIMS: Von Willebrand factor (VWF) plays an important role in thrombogenesis and mediates platelet adhesion particularly under high shear stress. Such conditions are generally found in stenotic arteries and can eventually cause myocardial infarction or stroke. We aimed to study whether levels of VWF antigen (VWF:Ag) predict future major adverse cardiovascular events (MACE) in patients suffering from carotid artery stenosis. METHODS: Patients with atherosclerotic carotid artery disease defined by the presence of nonstenotic plaques or any degree of carotid stenosis were prospectively enrolled. Concentrations of VWF were measured by enzyme immunoassay. RESULTS: VWF:Ag levels were more stable after 4 freeze-thaw cycles, when compared to VWF activity, and we showed similar concentrations of VWF in citrated plasma and serum (±4%). Levels of VWF:Ag predicted future cardiovascular events in 811 patients with carotid stenosis independent of known cardiovascular risk factors. Patients with VWF:Ag concentrations in the 4th quartile had a 44% event rate after an average 3-year follow up and a hazard ratio of 2.15 (95% confidence interval 1.46-3.16; pâ¯<â¯0.001). CONCLUSIONS: High concentrations of VWF:Ag predict major cardiovascular events in patients with carotid stenosis, and given their high event rate may be useful for risk stratification of such patients.
Assuntos
Estenose das Carótidas/sangue , Estenose das Carótidas/epidemiologia , Infarto do Miocárdio/epidemiologia , Acidente Vascular Cerebral/epidemiologia , Fator de von Willebrand/análise , Idoso , Áustria/epidemiologia , Biomarcadores/sangue , Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/mortalidade , Ponte de Artéria Coronária , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/diagnóstico , Infarto do Miocárdio/mortalidade , Infarto do Miocárdio/terapia , Intervenção Coronária Percutânea , Valor Preditivo dos Testes , Prevalência , Intervalo Livre de Progressão , Estudos Prospectivos , Medição de Risco , Fatores de Risco , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/mortalidade , Acidente Vascular Cerebral/terapia , Fatores de Tempo , Regulação para CimaRESUMO
Defibrotide is approved for the treatment of sinusoidal obstruction syndrome after allogeneic stem cell transplantation. The exact mode of action of defibrotide is unclear and human in vivo data are scarce. In this randomized, double blind, crossover trial we included 20 healthy volunteers. Four were randomized to receive placebo, while 16 received a 2 ng/kg bodyweight bolus of lipopolysaccharide (LPS). Infusion of 6.25 mg/kg defibrotide or placebo was started one hour before the injection of the LPS bolus. Plasma levels of prothrombin fragments F1 + 2, thrombin-antithrombin complexes, von Willebrand factor, E-selectin, tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), plasmin-antiplasmin complexes (PAP), tumor necrosis factor-α, interleukin 6, and C-reactive protein were measured. Thromboelastometry was performed. Infusion of defibrotide did not reduce the LPS-induced activation of coagulation, the endothelium or the release of pro-inflammatory cytokines. However, defibrotide increased t-PA antigen levels by 31% (Quartiles: 2-49%, p = 0.026) and PAP concentrations by 13% (-4-41%, p = 0.039), while PAI-1 levels remained unaffected. Moreover, defibrotide reduced C-reactive protein levels by 13% (0-17%, p = 0.002). A transient increase in the clotting time in thromboelastometry and a decrease in F1 + 2 prothrombin fragments suggests modest anticoagulant properties. In conclusion, defibrotide infusion enhanced fibrinolysis and reduced C-reactive protein levels during experimental endotoxemia.
Assuntos
Endotoxemia/tratamento farmacológico , Fibrinólise/efeitos dos fármacos , Fibrinolíticos/uso terapêutico , Polidesoxirribonucleotídeos/uso terapêutico , Adulto , Coagulação Sanguínea/efeitos dos fármacos , Proteína C-Reativa/metabolismo , Estudos Cross-Over , Citocinas/metabolismo , Método Duplo-Cego , Endotoxemia/metabolismo , Feminino , Fibrinolisina/metabolismo , Voluntários Saudáveis , Humanos , Lipopolissacarídeos/administração & dosagem , Masculino , Adulto Jovem , alfa 2-Antiplasmina/metabolismoRESUMO
Aptamers are synthetic molecules structured as single-stranded DNA or RNA oligonucleotides that can be designed to mimic the functional properties of monoclonal antibodies. They bind to the target molecules (typically soluble or cell-bound proteins) with high affinity (with picomolar to low nanomolar range) and specificity, and therefore can be an alternative to therapeutic antibodies or peptide ligands. This paper reviews published data regarding pharmacokinetics, pharmacodynamics and safety of aptamers from preclinical and clinical studies. Aptamers have been developed for the treatment of a variety of diseases, including cancer, macular degeneration,g cardiovascular disease, diabetes and anaemia of chronic diseases. There are several preclinical studies with unmodified aptamers, but the vast majority of aptamer trials in humans have been conducted with modified aptamers, because unmodified aptamers demonstrate metabolic instability, as well as rapid renal filtration and elimination. Various strategies have been developed to improve the pharmacokinetic profile of aptamers. Aside from chemical modification of nucleotides in order to stabilize them against nuclease degradation, the main modification to extend the half-life is pegylation. Therefore, the process of pegylation as well as its benefits and possible shortcomings will briefly be discussed.