Herrmann Sabrina, Doerr Baerbel, May Frauke, Kuehnemuth Benjamin, Cherpokova Deya, Herzog Eva, Dickneite Gerhard, Nolte Marc W
Research Marburg, CSL Behring GmbH, Marburg, Germany.
J Thromb Haemost. 2020 Dec;18(12):3194-3202. doi: 10.1111/jth.15069. Epub 2020 Oct 25.
Hemophilia B is caused by coagulation factor IX (FIX) deficiency. Recombinant fusion protein linking coagulation FIX with recombinant albumin (rIX-FP; Idelvion ) is used for replacement therapy with an extended half-life. A previous quantitative whole-body autoradiography (QWBA) study investigating the biodistribution of rIX-FP indicated equal biodistribution, but more prolonged tissue retention compared with a marketed recombinant FIX product.
To complete and confirm the QWBA study data by directly measuring rIX-FP protein and activity levels in tissues following intravenous (i.v.) administration to normal rats and FIX-deficient (hemophilia B) mice.
After i.v. administration of rIX-FP at a dose of 2000 IU/kg, animals were euthanized at specific time points up to 72 hours postdosing. Subsequently, plasma and various tissues, which were selected based on the previous QWBA results, were harvested and analyzed for FIX antigen levels using an ELISA (both species) or an immunohistochemistry method (mice only), as well as for FIX activity levels (mice only) using a chromogenic assay.
In rats, rIX-FP distributed extravascularly into all tissues analyzed (ie, liver, kidney, skin and knee) with peak antigen levels reached between 1 and 7 hours postdosing. In hemophilia B mice, rIX-FP tissue distribution was comparable to rats. FIX antigen levels correlated well with FIX activity readouts.
Our results confirm QWBA data showing that rIX-FP distributes into relevant target tissues. Importantly, it was demonstrated that rIX-FP available in tissues retains its functional activity and can thus facilitate its therapeutic activity at sites of potential injury.
乙型血友病由凝血因子IX（FIX）缺乏引起。将凝血FIX与重组白蛋白连接的重组融合蛋白（rIX-FP；Idelvion）用于半衰期延长的替代疗法。先前一项研究rIX-FP生物分布的定量全身放射自显影（QWBA）研究表明，其生物分布与市售重组FIX产品相当，但组织滞留时间更长。
通过直接测量正常大鼠和FIX缺乏（乙型血友病）小鼠静脉注射（i.v.）rIX-FP后组织中的rIX-FP蛋白和活性水平，完善并确认QWBA研究数据。
以2000 IU/kg的剂量静脉注射rIX-FP后，在给药后长达72小时的特定时间点对动物实施安乐死。随后，根据先前QWBA结果选择采集血浆和各种组织，使用ELISA（两种动物）或免疫组织化学方法（仅用于小鼠）分析FIX抗原水平，以及使用显色测定法分析FIX活性水平（仅用于小鼠）。
在大鼠中，rIX-FP血管外分布到所有分析的组织（即肝脏、肾脏、皮肤和膝盖），给药后1至7小时达到抗原水平峰值。在乙型血友病小鼠中，rIX-FP的组织分布与大鼠相当。FIX抗原水平与FIX活性读数相关性良好。
我们的结果证实了QWBA数据，表明rIX-FP分布到相关靶组织中。重要的是，已证明组织中的rIX-FP保留其功能活性，因此可在潜在损伤部位促进其治疗活性。
