Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany; and.
Molecular Biochemistry, Octapharma Biopharmaceuticals GmbH, Berlin, Germany.
Blood. 2021 Feb 25;137(8):1072-1081. doi: 10.1182/blood.2020006468.
Conventional treatment of hemophilia A (HA) requires repetitive IV injection of coagulation factor VIII (FVIII). Subcutaneous administration of FVIII is inefficient because of binding to the extravascular matrix, in particular to phospholipids (PLs), and subsequent proteolysis. To overcome this, recombinant dimeric fragments of von Willebrand factor (VWF) containing the FVIII-stabilizing D3 domain were engineered. Two fragments, called VWF-12 and VWF-13, demonstrated high binding affinity to recombinant human FVIII (rhFVIII) and suppressed PL binding in a dose-dependent manner. High concentrations of VWF fragments did not interfere with the functional properties of full-length VWF in vitro. The HA mouse model was used to study the effects of VWF-12 or VWF-13 on the in vivo pharmacokinetics of rhFVIII, demonstrating (1) no significant impact on rhFVIII recovery or half-life after a single IV administration; (2) enhanced bioavailability (up to 18.5%) of rhFVIII after subcutaneous administration; and (3) slow absorption (peak concentration, 6 hours) and prolonged half-life (up to 2.5-fold) of rhFVIII after subcutaneous administration. Formation of anti-FVIII antibodies was not increased after administration of rhFVIII/VWF-12 subcutaneously compared with rhFVIII IV. A single subcutaneous dose of rhFVIII/VWF-12 provided protection in the HA tail-bleeding model for up to 24 hours. In summary, recombinant VWF fragments support FVIII delivery through the subcutaneous space into vascular circulation without interfering with VWF or FVIII function. Slow resorption and excretion of FVIII after subcutaneous administration highlight the potential application of VWF fragments for subcutaneous FVIII prophylaxis in HA.
A 型血友病（HA）的常规治疗需要重复进行静脉注射凝血因子 VIII（FVIII）。由于与血管外基质（尤其是磷脂（PL））结合，以及随后的蛋白水解，FVIII 的皮下给药效率低下。为了克服这一问题，工程设计了包含 FVIII 稳定化 D3 结构域的 von Willebrand 因子（VWF）重组二聚体片段。两种片段，称为 VWF-12 和 VWF-13，对重组人 FVIII（rhFVIII）具有高结合亲和力，并以剂量依赖性方式抑制 PL 结合。VWF 片段的高浓度不会干扰全长 VWF 在体外的功能特性。使用 HA 小鼠模型研究 VWF-12 或 VWF-13 对 rhFVIII 体内药代动力学的影响，表明：（1）单次静脉给药后，对 rhFVIII 恢复或半衰期没有显著影响；（2）皮下给药后 rhFVIII 的生物利用度提高（高达 18.5%）；（3）皮下给药后 rhFVIII 吸收缓慢（峰值浓度 6 小时）和半衰期延长（高达 2.5 倍）。与 rhFVIII 静脉给药相比，皮下给予 rhFVIII/VWF-12 后不会增加抗 FVIII 抗体的形成。rhFVIII/VWF-12 单次皮下给药可在 HA 尾巴出血模型中提供长达 24 小时的保护。总之，重组 VWF 片段通过皮下空间将 FVIII 递送至血管循环，而不会干扰 VWF 或 FVIII 的功能。皮下给予 FVIII 后缓慢吸收和排泄，突出了 VWF 片段在 HA 皮下 FVIII 预防中的潜在应用。
