Herzog Eva, Harris Stephen, Henson Claire, McEwen Andrew, Schenk Sabrina, Nolte Marc W, Pragst Ingo, Dickneite Gerhard, Schulte Stefan, Zollner Sabine
CSL Behring GmbH, Preclinical Research and Development, 35041 Marburg, Germany.
Quotient Bioresearch Metabolic Chemistry, Rushden, UK.
Thromb Res. 2014 May;133(5):900-7. doi: 10.1016/j.thromres.2014.02.010. Epub 2014 Feb 22.
The recombinant fusion protein linking coagulation factor IX with albumin (rIX-FP) is undergoing clinical trials for prophylaxis and on-demand treatment of haemophilia B patients. The aim of this study was to investigate the pharmacokinetics, whole-body and knee joint distribution of rIX-FP following intravenous administration to rats, compared with a marketed, non-fused rFIX and recombinant human albumin.
[(3)H]-rIX-FP, [(3)H]-rFIX or [(3)H]-albumin were administered to rats followed by quantitative whole-body autoradiography over 24 or 240 hours, and the tissue distribution as well as elimination of radioactivity were measured.
Elimination of all radioactivity derived from the three proteins was shown to occur primarily via the urine. The tissue distribution of [(3)H]-rIX-FP and [(3)H]-rFIX (but not of [(3)H]-albumin) was comparable, both penetrating predominantly into bone, and well-perfused tissues, suggesting that the rIX moiety determines the distribution pattern of rIX-FP, while the albumin moity is responsible for the prolonged plasma and tissue retention. Detailed knee-joint analysis indicated rapid presence of [(3)H]-rIX-FP and [(3)H]-rFIX in synovial and mineralised bone tissue, mostly localised to the zone of calcified cartilage. Longest retention times were observed in the bone marrow and the endosteum of long bones. Intriguingly, [(3)H]-rIX-FP- and [(3)H]-albumin-derived radioactive signals were detectable up to 240 hours, while [(3)H]-rFIX-derived radioactivity rapidly declined after 1hour post-dosing correlating to the extended plasma half-life of [(3)H]-rIX-FP.
The prolonged plasma and tissue retention of rIX-FP achieved by albumin fusion may allow a reduction in dosing frequency leading to increased therapeutic compliance and convenience.
连接凝血因子IX与白蛋白的重组融合蛋白（rIX-FP）正在进行临床试验，用于B型血友病患者的预防和按需治疗。本研究的目的是研究rIX-FP静脉注射给大鼠后的药代动力学、全身和膝关节分布，并与市售的未融合rFIX和重组人白蛋白进行比较。
将[³H]-rIX-FP、[³H]-rFIX或[³H]-白蛋白注射给大鼠，然后在24或240小时内进行定量全身放射自显影，并测量放射性的组织分布和消除情况。
结果表明，源自这三种蛋白质的所有放射性主要通过尿液消除。[³H]-rIX-FP和[³H]-rFIX（但不包括[³H]-白蛋白）的组织分布具有可比性，二者主要渗透到骨骼和灌注良好的组织中，这表明rIX部分决定了rIX-FP的分布模式，而白蛋白部分则负责延长血浆和组织中的保留时间。详细的膝关节分析表明，[³H]-rIX-FP和[³H]-rFIX在滑膜和矿化骨组织中迅速出现，主要定位于钙化软骨区域。在骨髓和长骨的骨内膜中观察到最长的保留时间。有趣的是，[³H]-rIX-FP和[³H]-白蛋白衍生的放射性信号在240小时内均可检测到，而[³H]-rFIX衍生的放射性在给药后1小时迅速下降，这与[³H]-rIX-FP延长的血浆半衰期相关。
白蛋白融合实现的rIX-FP在血浆和组织中的保留时间延长，可能允许减少给药频率，从而提高治疗依从性和便利性。
