Factor IX‐deficient plasma spiked with N9‐GP behaves similarly to N9‐GP post‐administration clinical samples in N9‐GP ELISA and FIX activity assays. (30th April 2015)

• Record Type: Journal Article
• Authors: Sørensen, M. H.; Andersen, S.; Ezban, M.
• Is Part Of: Haemophilia. Volume 21:Number 6(2015:Nov.)
• Page Start: 832
• Page End: 836
• Publication Date: 2015-04-30
• Subjects: Hemophilia -- Periodicals; 616.1572005
• DOI: 10.1111/hae.12680
• Languages: English
• ISSNs: 1351-8216

Abstract

<abstract abstract-type="main" id="hae12680-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="hae12680-sec-0001" sec-type="section"> <title> <bold>Introduction:</bold> </title> <p>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.</p> </sec> <sec id="hae12680-sec-0002" sec-type="section"> <title> <bold>Aim:</bold> </title> <p>The aim of the study is to investigate correlations between assays measuring N9‐GP concentration and factor IX (FIX) activity, and to evaluate whether <italic>in vitro</italic> FIX‐deficient plasma samples spiked with N9‐GP and <italic>in vivo</italic> post‐administration samples from patients exposed to N9‐GP perform similarly in these assays.</p> </sec> <sec id="hae12680-sec-0003" sec-type="section"> <title> <bold>Methods:</bold> </title> <p> <italic>In vitro</italic> 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<sup>™</sup> clinical trial (<italic>in vivo</italic> 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 <italic>in vitro</italic> and <italic>in vivo</italic> sample analyses.</p> </sec> <sec id="hae12680-sec-0004" sec-type="section"> <title> <bold>Results:</bold> </title> <p>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 <italic>in vitro</italic> and <italic>in vivo</italic> sample analyses.</p> </sec> <sec id="hae12680-sec-0005" sec-type="section"> <title> <bold>Conclusion:</bold> </title> <p>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 <italic>in vitro</italic> and <italic>in vivo</italic> 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.</p> </sec> </abstract>