Sørensen M H, Andersen S, Ezban M
Novo Nordisk A/S, Måløv, Denmark.
Haemophilia. 2015 Nov;21(6):832-6. doi: 10.1111/hae.12680. Epub 2015 Apr 30.
Evaluation of assay performance with new modified coagulation factors, such as N9-GP, may require testing of different assays and assay conditions. Validation of assays used for clinical monitoring of haemophilia B patients is challenging due to limited availability of blood samples from patients exposed to these new agents.
The aim of the study is to investigate correlations between assays measuring N9-GP concentration and factor IX (FIX) activity, and to evaluate whether in vitro FIX-deficient plasma samples spiked with N9-GP and in vivo post-administration samples from patients exposed to N9-GP perform similarly in these assays.
In vitro samples, prepared by adding N9-GP to FIX-deficient plasma, were compared to samples from haemophilia B patients participating in the phase 3 paradigm 2(™) clinical trial (in vivo samples), in assays measuring N9-GP concentration (ELISA) and FIX activity (one-stage clotting assay and chromogenic assay). The results of the FIX activity assays and ELISAs were compared and analysed to determine the similarity between the in vitro and in vivo sample analyses.
Regression analysis demonstrated a linear relationship between N9-GP concentration and FIX activity. Furthermore, there was no significant difference between the regression lines for the in vitro and in vivo sample analyses.
The one-stage clot assay using SynthAFax and the chromogenic assay show promise for use in measuring FIX activity in haemophilia B patients treated with N9-GP. Since in vitro and in vivo samples performed similarly in these assays, N9-GP-spiked FIX-deficient plasma could be used as controls in routine measurements of N9-GP activity in haemophilia B patients.
使用新的改良凝血因子（如N9-GP）评估检测性能可能需要对不同的检测方法和检测条件进行测试。由于接触这些新药物的血友病B患者的血样有限，用于血友病B患者临床监测的检测方法的验证具有挑战性。
本研究的目的是调查测量N9-GP浓度的检测方法与凝血因子IX（FIX）活性之间的相关性，并评估添加了N9-GP的体外FIX缺乏血浆样本和接触N9-GP的患者体内给药后的样本在这些检测方法中的表现是否相似。
将通过向FIX缺乏血浆中添加N9-GP制备的体外样本与参与3期范例2（™）临床试验的血友病B患者的样本（体内样本）进行比较，这些样本用于测量N9-GP浓度（ELISA）和FIX活性（一步凝血检测法和发色底物法）。比较并分析FIX活性检测和ELISA的结果，以确定体外和体内样本分析之间的相似性。
回归分析表明N9-GP浓度与FIX活性之间存在线性关系。此外，体外和体内样本分析的回归线之间没有显著差异。
使用SynthAFax的一步凝血检测法和发色底物法有望用于测量接受N9-GP治疗的血友病B患者的FIX活性。由于体外和体内样本在这些检测方法中的表现相似，添加N9-GP的FIX缺乏血浆可作为血友病B患者N9-GP活性常规测量的对照。
