CSL Behring, Marburg, Germany.
Hôpital Louis Pradel, University Claude Bernard Lyon 1, Lyon, France.
J Thromb Haemost. 2019 Jan;17(1):138-148. doi: 10.1111/jth.14332. Epub 2018 Dec 16.
Essentials Performance of the one-stage clotting (OSC) assay varies with the clotting activator used. Recombinant FIX-albumin fusion protein (rIX-FP) was reliably monitored with most OSC reagents. rIX-FP shows comparable reagent-dependent variability to other rFIX products in the OSC assay. Actin FS and kaolin-based reagents underestimated rIX-FP activity by around 50% in the OSC assay. SUMMARY: Background Measuring factor IX activity (FIX:C) with one-stage clotting (OSC) assays, based on the activated partial thromboplastin time (APTT), is the current mainstay of diagnostic techniques for hemophilia B. Assessing the performance of new recombinant FIX (rFIX) products in OSC assays is essential, as APTT reagents from different manufacturers yield different potency estimates for rFIX. Objectives To evaluate the extent to which choice of reagent composition influences rFIX potency measurements of recombinant FIX-albumin fusion protein (rIX-FP, IDELVION) activity in OSC assays. Methods rIX-FP was added to FIX-deficient plasma, and FIX:C was assessed centrally and locally in a multicenter international field study with a variety of commercial OSC APTT reagents. Paired sample analysis of clinical samples was performed to compare values of FIX:C from local and central laboratories. In-house bioanalytical investigations with spiked samples were conducted to compare the APTT-reagent dependent variability of rIX-FP with unmodified rFIX and rFIX Fc fusion protein (rFIXFc). Results Central and local assessments of FIX:C from 10 countries and 21 participating centers showed comparable results to those from the central laboratory across the majority of 18 different APTT reagents from both clinical and spiked samples. There was a consistent underestimation of rIX-FP activity of ≈ 50% with OSC assays using Actin FS or kaolin-based APTT reagents. In the bioanalytical study, rIX-FP showed comparable variability in OSC assays to unmodified rFIX and rFIXFc. Conclusions rIX-FP activity can be accurately measured by the use of OSC assays with the majority of commercial reagents. Actin FS or kaolin-based reagents will probably lead to a 50% underestimation of activity.
一阶段凝血（OSC）检测的基本性能因所使用的凝血激活剂而异。重组 FIX-白蛋白融合蛋白（rIX-FP）可以使用大多数 OSC 试剂可靠地监测。rIX-FP 在 OSC 检测中与其他 rFIX 产品表现出类似的试剂依赖性变异性。Actin FS 和基于高岭土的试剂在 OSC 检测中使 rIX-FP 的活性低估了约 50%。
背景 基于活化部分凝血活酶时间（APTT）的一阶段凝血（OSC）检测是血友病 B 诊断技术的当前主流，用于测量因子 IX 活性（FIX：C）。评估新型重组 FIX（rFIX）产品在 OSC 检测中的性能至关重要，因为来自不同制造商的 APTT 试剂对 rFIX 的效价估计不同。
目的 评估试剂成分的选择在多大程度上影响重组 FIX-白蛋白融合蛋白（rIX-FP，IDELVION）在 OSC 检测中的活性的 rFIX 效价测量。
方法 将 rIX-FP 添加到 FIX 缺乏的血浆中，并在一项具有各种商业 OSC APTT 试剂的多中心国际现场研究中进行中央和局部评估。对临床样本进行配对样本分析，以比较来自当地和中央实验室的 FIX：C 值。进行了内部生物分析研究，用加标样本比较了 rIX-FP 与未修饰的 rFIX 和 rFIX Fc 融合蛋白（rFIXFc）的 APTT 试剂依赖性变异性。
结果 来自 10 个国家和 21 个参与中心的 18 种不同 APTT 试剂的中央和局部评估结果，与来自大多数试剂的中央实验室结果相当。使用 Actin FS 或基于高岭土的 APTT 试剂的 OSC 检测会一致地低估 rIX-FP 活性约 50%。在生物分析研究中，rIX-FP 在 OSC 检测中与未修饰的 rFIX 和 rFIXFc 具有相似的变异性。
结论 大多数商业试剂的 OSC 检测可以准确测量 rIX-FP 的活性。Actin FS 或基于高岭土的试剂可能会导致活性低估 50%。
