In vitro evidence of a tissue factor-independent mode of action of recombinant factor VIIa in hemophilia

Augustsson, Cecilia; Persson, Egon

doi:10.1182/blood-2014-05-576892

Cited by 25 publications

(22 citation statements)

References 13 publications

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“…Finally, FVIIa mode of action studies using TGA should be performed with caution; in sharp contrast to our TGA finding, the relatively poor factor X–activating ability of FVIIa in solution leaves little doubt in our minds that phospholipid association is utterly important for the pharmacologic effect of FVIIa, and neither does the documented effect of FVIIa on platelet adhesion and activation under flow conditions . Recent data strongly supporting a TF‐independent mode of action of FVIIa, neither competing with zymogen for TF nor requiring TF for its own effect, support the necessity of a direct interaction with procoagulant membrane surfaces …”

Section: Resultscontrasting

confidence: 59%

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Limited factor VIIa surface localization requirement of the factor VIIa–induced overall thrombin generation in platelet‐rich hemophilia A plasma

Persson

Winther

2019

Research and Practice in Thrombosis and Haemostasis

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BackgroundThrombin generation assay (TGA) and thrombelastography (TEG) are increasingly employed, global, in vitro methods for assessment of the procoagulant potential of plasma/blood and possibly ideally suited tools to monitor, for example, therapy with recombinant factor VIIa (FVIIa). It remains controversial to what extent results obtained with spiked and postinfusion samples reflect the outcome in patients.ObjectiveTo characterize the TGA response to FVIIa in hemophilic plasma and compare with TEG data.MethodsHemophilia A (HA) was induced in platelet‐rich plasma (PRP) from healthy volunteers, followed by spiking with FVIIa, γ‐carboxyglutamic acid (Gla)‐domainless FVIIa or V158D/E296V/M298Q‐FVIIa (FVIIaDVQ). Samples were triggered with tissue factor and analyzed by TGA and TEG in parallel.ResultsAddition of 25 nmol L−1 FVIIa to HA PRP normalized TEG parameters angle and R time, as well as TGA lag time, but had poor effects on the thrombin peak height and velocity index. All parameters (at least) returned to normal levels either upon adding a much higher concentration of FVIIa (~1500 nmol L−1) or by using the superactive variant FVIIaDVQ. Surprisingly, Gla‐domainless derivatives of FVIIa and FVIIaDVQ also yielded considerable effects in HA PRP.ConclusionsThe good general responses to clinically effective concentrations of FVIIa (25 and 75 nmol L−1) seen in TEG analyses, as well as for TGA lag time, were accompanied by far‐from‐normal thrombin peaks. A near‐normal thrombin peak response required the presence of considerably higher FVIIa activity but, intriguingly, relied only marginally on a functional Gla domain (ie, on platelet surface localization).

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Section: Resultscontrasting

confidence: 59%

“…18 Recent data strongly supporting a TFindependent mode of action of FVIIa, neither competing with zymogen for TF nor requiring TF for its own effect, support the necessity of a direct interaction with procoagulant membrane surfaces. [19][20][21]…”

Section: Resultsmentioning

confidence: 99%

Limited factor VIIa surface localization requirement of the factor VIIa–induced overall thrombin generation in platelet‐rich hemophilia A plasma

Persson

Winther

2019

Research and Practice in Thrombosis and Haemostasis

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“…The effects of binding of rhFVIIa to platelets is more prominent than those of tissue factor binding. Thus, a platelet‐spiked TGA assay (TGAp) is more representative of its clinical mode of action than the platelet‐free assay . Plasma samples were obtained at prespecified times after rhFVIIa administration.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, a platelet-spiked TGA assay (TGAp) is more representative of its clinical mode of action than the platelet-free assay. 18,27,28 Plasma samples were obtained at prespecified times after rhFVIIa administration. Thrombin generation was measured and mean thrombin generation peaks were calculated.…”

Section: Pharmacodynamicsmentioning

confidence: 99%

Safety and dose‐dependency of eptacog beta (activated) in a dose escalation study of non‐bleeding congenital haemophilia A or B patients, with or without inhibitors

et al. 2017

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Introduction Varying initial doses of activated eptacog beta (recombinant human FVIIa, rhFVIIa) may provide therapeutic options when treating bleeding in patients with congenital haemophilia who have developed inhibitory antibodies to factor VIII (FVIII) or factor IX (FIX). This study evaluated escalated doses of a new rhFVIIa product as a prelude to selecting the doses for clinical efficacy evaluation in haemophilia patients. Aim To assess the safety, pharmacokinetics, and laboratory pharmacodynamics of 3 doses of rhFVIIa in non‐bleeding patients with congenital haemophilia A or B with or without inhibitors. Methods Adult male patients (18‐75 years old) with congenital haemophilia A or B (with or without inhibitors) received infusions of rhFVIIa at doses of 25, 75 or 225 μg/kg body weight. Ten patients were treated at each dose level, and each patient received 2 different dose levels. Descriptive methods were used to analyse the data. Results Administration of rhFVIIa at all doses was well tolerated. Pharmacokinetic analyses showed that peak FVIIa plasma levels (Cmax) were approximately proportional to dose and correlated well with peak thrombin generation. Total AUC0‐inf also was approximately dose proportional. Clot formation and duration correlated with FVIIa activity. Repeat doses did not produce an immunological response. Conclusion In the first dose‐escalation study of rhFVIIa to support product registration, eptacog beta at doses of 25, 75, and 225 μg/kg was pharmacodynamically active and well tolerated in non‐bleeding patients with congenital haemophilia A or B.

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“…It was thought therefore that high FVIIa concentrations are needed to compete with endogenous FVII for binding to TF. 11,32 The need…”

Section: Discussionmentioning

confidence: 99%

A single‐domain antibody that blocks factor VIIa activity in the absence but not presence of tissue factor

Ferrière

Kawecki

Ottavi³

et al. 2019

Journal of Thrombosis and Haemostasis

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Background Activated factor VII (FVIIa) is pertinent to the initiation of blood coagulation. Proteolytic and amidolytic activity of FVIIa are greatly enhanced by its cofactor, tissue factor (TF). Objective We aimed to generate a single‐domain antibody (sdAb) that recognizes free FVIIa rather than TF‐bound FVIIa. Methods A llama‐derived phage library was used to screen for anti‐FVIIa sdAbs. Results One sdAb, KB‐FVIIa‐004, bound to FVIIa, but not to its precursor FVII or to homologous proteins (prothrombin, factor X, or their activated derivatives). FVIIa amidolytic activity was inhibited by KB‐FVIIa‐004 (Ki = 28‐45 nM) in a competitive manner. KB‐FVIIa‐004 also inhibited FVIIa‐mediated FX activation (Ki = 26 nM). In contrast, KB‐FVIIa‐004 was inefficient in prolonging the clotting time of the prothrombin time‐test, which was prolonged by a maximum of 10 s at high sdAb concentrations (10 μM). Furthermore, FVIIa/TF amidolytic activity or FVIIa/TF‐mediated FX activation remained unaffected up to a 50‐fold to 1000‐fold molar excess of KB‐FVIIa‐004. These data suggest that KB‐FVIIa‐004 loses its inhibitory activity in the presence of TF. A KB‐FVIIa‐004/albumin fusion‐protein (004‐HSA) was generated for in vivo testing. By using 004‐HSA, we observed that this sdAb blocked the therapeutic capacity of FVIIa to correct bleeding in FVIII‐deficient mice. Discussion This observation is compatible with the view that FVIIa functions independently of TF under these conditions. In conclusion, we have generated a sdAb that specifically blocks TF‐independent activity of FVIIa. This antibody can be used to gain insight into the roles of TF‐bound and TF‐free FVIIa.

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In vitro evidence of a tissue factor-independent mode of action of recombinant factor VIIa in hemophilia

Cited by 25 publications

References 13 publications

Limited factor VIIa surface localization requirement of the factor VIIa–induced overall thrombin generation in platelet‐rich hemophilia A plasma

Limited factor VIIa surface localization requirement of the factor VIIa–induced overall thrombin generation in platelet‐rich hemophilia A plasma

Safety and dose‐dependency of eptacog beta (activated) in a dose escalation study of non‐bleeding congenital haemophilia A or B patients, with or without inhibitors

A single‐domain antibody that blocks factor VIIa activity in the absence but not presence of tissue factor

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