{"title":"Additional Factor X Enhances Emicizumab-Driven Coagulation Function in Patients with Hemophilia A and Hemophilia A Mice.","authors":"Kazuki Shimizu, Yuto Nakajima, Eisuke Takami, Hirotoshi Nakano, Keiji Nogami","doi":"10.1055/a-2315-8199","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong> Bypassing agents are used for breakthrough bleedings in patients with hemophilia A with inhibitor (PwHAwI) receiving emicizumab prophylaxis. Previous study demonstrated a weak binding affinity between emicizumab and factor (F)X (<i>K</i> <sub>d</sub>; 1.85 μM), and that this value was much greater than the plasma FX concentration (∼130 nM). We speculated that increased FX levels could enhance coagulation potential in emicizumab-treated patients with hemophilia A (PwHA). To investigate the relationship between FX concentrations and emicizumab-driven coagulation.</p><p><strong>Methods: </strong> Plasma FX (up to 1,040 nM) and emicizumab (50 µg/mL) were added to FVIII-deficient plasmas, and plasma-derived FX (520 nM) or recombinant (r)FVIIa (2.2 µg/mL) was added to plasmas from three emicizumab-treated PwHAwI. The adjusted maximum coagulation velocity (Ad|min1|) by clot waveform analysis and peak thrombin (PeakTh) by thrombin generation assay in them were evaluated. Emicizumab (3.0 mg/kg), human (h)FIX (100 IU/kg), and various doses of hFX (100-500 IU/kg) were intravenously administered to HA mice. Clotting time/clot formation time (CT/CFT) were assessed using rotational thromboelastometry, and blood loss was estimated by a tail-clip assay.</p><p><strong>Results: </strong> The addition of FX to FVIII-deficient plasma with emicizumab increased Ad|min1| and PeakTh. The coagulation parameters in emicizumab-treated PwHAwI spiked with additional FX remained within the normal range as well as the additional rFVIIa. In animal models, hFX injection shortened the CT and CT + CFT. The shorter CT and CT + CFT, and the lower blood loss were evident after 200 or 500 IU/kg hFX administration, and those indices were comparable to those in wild-type mice.</p><p><strong>Conclusion: </strong> Supplementation with FX may improve emicizumab-driven hemostasis in PwHA.</p>","PeriodicalId":23036,"journal":{"name":"Thrombosis and haemostasis","volume":null,"pages":null},"PeriodicalIF":5.0000,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Thrombosis and haemostasis","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1055/a-2315-8199","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"HEMATOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background: Bypassing agents are used for breakthrough bleedings in patients with hemophilia A with inhibitor (PwHAwI) receiving emicizumab prophylaxis. Previous study demonstrated a weak binding affinity between emicizumab and factor (F)X (Kd; 1.85 μM), and that this value was much greater than the plasma FX concentration (∼130 nM). We speculated that increased FX levels could enhance coagulation potential in emicizumab-treated patients with hemophilia A (PwHA). To investigate the relationship between FX concentrations and emicizumab-driven coagulation.
Methods: Plasma FX (up to 1,040 nM) and emicizumab (50 µg/mL) were added to FVIII-deficient plasmas, and plasma-derived FX (520 nM) or recombinant (r)FVIIa (2.2 µg/mL) was added to plasmas from three emicizumab-treated PwHAwI. The adjusted maximum coagulation velocity (Ad|min1|) by clot waveform analysis and peak thrombin (PeakTh) by thrombin generation assay in them were evaluated. Emicizumab (3.0 mg/kg), human (h)FIX (100 IU/kg), and various doses of hFX (100-500 IU/kg) were intravenously administered to HA mice. Clotting time/clot formation time (CT/CFT) were assessed using rotational thromboelastometry, and blood loss was estimated by a tail-clip assay.
Results: The addition of FX to FVIII-deficient plasma with emicizumab increased Ad|min1| and PeakTh. The coagulation parameters in emicizumab-treated PwHAwI spiked with additional FX remained within the normal range as well as the additional rFVIIa. In animal models, hFX injection shortened the CT and CT + CFT. The shorter CT and CT + CFT, and the lower blood loss were evident after 200 or 500 IU/kg hFX administration, and those indices were comparable to those in wild-type mice.
Conclusion: Supplementation with FX may improve emicizumab-driven hemostasis in PwHA.
期刊介绍：
Thrombosis and Haemostasis publishes reports on basic, translational and clinical research dedicated to novel results and highest quality in any area of thrombosis and haemostasis, vascular biology and medicine, inflammation and infection, platelet and leukocyte biology, from genetic, molecular & cellular studies, diagnostic, therapeutic & preventative studies to high-level translational and clinical research. The journal provides position and guideline papers, state-of-the-art papers, expert analysis and commentaries, and dedicated theme issues covering recent developments and key topics in the field.
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