基于基因的 FVIIa 预防治疗可调节血友病 A 大鼠的自发性出血表型。

Gene-based FVIIa prophylaxis modulates the spontaneous bleeding phenotype of hemophilia A rats.

机构信息

The Children's Hospital of Philadelphia, Philadelphia, PA.

Department of Biostatistics, Epidemiology and Informatics, The University of Pennsylvania, Philadelphia, PA.

出版信息

Blood Adv. 2019 Feb 12;3(3):301-311. doi: 10.1182/bloodadvances.2018027219.

Abstract

A sizable proportion of hemophilia inhibitor patients fails immune tolerance induction and requires bypass agents for long-term bleed management. Recombinant human-activated coagulation Factor VII (rhFVIIa) is an on-demand bypass hemostatic agent for bleeds in hemophilia inhibitor patients. Prophylactic use of rhFVIIa may enable sustained hemostatic management of inhibitor patients, but the critical relationship of rhFVIIa circulating levels and clinical outcome in that setting remains unclear. To address this in vivo, we used the rat hemophilia A (HA) model that exhibits spontaneous bleeds and allows longitudinal studies with sufficient statistical power. We simulated activated Factor VII (FVIIa) prophylaxis by adeno-associated virus (AAV) gene transfer of a rat FVIIa transgene. Compared with naive HA animals, rat FVIIa continuous expression affected the overall observed bleeds, which were resolved with on-demand administration of recombinant rat FVIIa. Specifically, although 91% of naive animals exhibited bleeds, this was reduced to 83% and 33% in animals expressing less than 708 ng/mL (<14 nM) and at least 708 ng/mL (≥14 nM) rat FVIIa, respectively. No bleeds occurred in animals expressing higher than 1250 ng/mL (>25 nM). Rat FVIIa expression of at least 708 ng/mL was also sufficient to normalize the blood loss after a tail vein injury. Continuous, AAV-mediated rat FVIIa transgene expression had no apparent adverse effects in the hemostatic system of HA rats. This work establishes for the first time a dose dependency and threshold of circulating FVIIa antigen levels for reduction or complete elimination of bleeds in a setting of FVIIa-based HA prophylaxis.

摘要

相当一部分血友病抑制剂患者无法进行免疫耐受诱导,需要使用旁路制剂进行长期出血管理。重组人激活凝血因子 VII(rhFVIIa)是血友病抑制剂患者出血时按需使用的旁路止血剂。rhFVIIa 的预防性使用可能使抑制剂患者能够进行持续的止血管理,但在这种情况下,rhFVIIa 循环水平与临床结果的关键关系仍不清楚。为了解决这个问题,我们使用了自发性出血的大鼠血友病 A(HA)模型,该模型允许进行具有足够统计效力的纵向研究。我们通过腺相关病毒(AAV)基因转移大鼠 FVIIa 转基因来模拟激活的因子 VII(FVIIa)预防。与未处理的 HA 动物相比,大鼠 FVIIa 的持续表达影响了整体观察到的出血,这些出血通过按需给予重组大鼠 FVIIa 得到解决。具体来说,尽管 91%的未处理动物出现了出血,但在表达低于 708ng/mL(<14nM)和至少 708ng/mL(≥14nM)大鼠 FVIIa 的动物中,这一比例分别降低到 83%和 33%。在表达高于 1250ng/mL(>25nM)的动物中则没有出血发生。表达至少 708ng/mL 的大鼠 FVIIa 也足以使尾静脉损伤后的失血量正常化。AAV 介导的大鼠 FVIIa 转基因的持续表达在 HA 大鼠的止血系统中没有明显的不良反应。这项工作首次建立了一个剂量依赖性和循环 FVIIa 抗原水平的阈值,用于减少或完全消除基于 FVIIa 的 HA 预防中的出血。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7b34/6373746/3ad2d4ad070f/advances027219absf1.jpg

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