Astermark Jan, Miesbach Wolfgang, Coppens Michiel, Gielen Sander, Twisk Jaap, Dolmetsch Ricardo, Verweij Stephanie, Monahan Paul E, Ewenstein Bruce M, Nuthalapati Silpa, Galante Nick, Young Guy
Institution of Translational Medicine, Lund University and Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Malmö, Sweden.
Medical Clinic 2, Frankfurt University Hospital, Frankfurt, Germany.
Haemophilia. 2025 Jul;31(4):799-806. doi: 10.1111/hae.70053. Epub 2025 Jun 18.
Accurate and reproducible measures of factor activity are required to guide clinical decision-making following gene therapy for haemophilia B (HB). Highly significant discrepancies have been observed in measurements of various factor IX (FIX) concentrates that carry molecular modifications to extend their half-life, arguing for the need for careful analysis of new HB treatment modalities with respect to FIX assay performance.
To further characterise variability in FIX activity measured using different one-stage assays (OSAs) and chromogenic assays (CAs) in patients with HB receiving gene therapy utilising the FIX Padua variant and to assess whether assay differences were due to the FIX-Padua variant.
FIX activity was assessed centrally (OSA and CA) and locally (OSA only) using plasma samples collected from a phase 2b and phase 3 study of etranacogene dezaparvovec and in an in vitro study of wild-type (wt) recombinant human FIX (rhFIX) and rhFIX-Padua.
Lower CA than OSA FIX activity for plasma samples from the phase 3 trial was observed (CA:OSA ratio: 0.408 [±0.049]-0.547 [±0.062]). Local OSA:central OSA FIX activity ratios were 0.789 (±0.314)-1.021 (±0.159). Local OSA:central OSA FIX activity ratios across methods and/or reagents were 0.81 (±0.02)-1.28 (±0.04) for rhFIX-wt-spiked samples and 0.67 (±0.02)-1.13 (±0.09) for rhFIX-Padua-spiked samples.
FIX activity differences between central and local OSAs were modest; similar differences were observed in vitro with rhFIX-wt versus rhFIX-Padua. Commonly available OSAs can be used to monitor patients post-etranacogene dezaparvovec administration; we recommend using the same assay platform throughout the post-treatment period.
在B型血友病（HB）基因治疗后，需要准确且可重复的因子活性测量方法来指导临床决策。在对各种携带分子修饰以延长半衰期的凝血因子IX（FIX）浓缩物的测量中，观察到了高度显著的差异，这表明需要针对FIX检测性能仔细分析新的HB治疗方式。
进一步表征在接受利用FIX帕多瓦变体进行基因治疗的HB患者中，使用不同的一步法检测（OSA）和显色检测（CA）所测得的FIX活性的变异性，并评估检测差异是否归因于FIX - 帕多瓦变体。
使用从etranacogene dezaparvovec的2b期和3期研究中收集的血浆样本，以及在野生型（wt）重组人FIX（rhFIX）和rhFIX - 帕多瓦的体外研究中收集的血浆样本，集中（OSA和CA）和本地（仅OSA）评估FIX活性。
观察到3期试验血浆样本的CA FIX活性低于OSA FIX活性（CA：OSA比率：0.408 [±0.049] - 0.547 [±0.062]）。本地OSA：集中OSA FIX活性比率为0.789（±0.314） - 1.021（±0.159）。对于rhFIX - wt加标样本，跨方法和/或试剂的本地OSA：集中OSA FIX活性比率为0.81（±0.02） - 1.28（±0.04），对于rhFIX - 帕多瓦加标样本为0.67（±0.02） - 1.13（±0.09）。
中央和本地OSA之间的FIX活性差异不大；在体外，rhFIX - wt与rhFIX - 帕多瓦也观察到了类似的差异。常用的OSA可用于监测etranacogene dezaparvovec给药后的患者；我们建议在整个治疗后期间使用相同的检测平台。
