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Performance of a recombinant fusion protein linking coagulation factor IX with recombinant albumin in one‐stage clotting assays
Author(s) -
Horn C.,
Négrier C.,
Kalina U.,
Seifert W.,
Friedman K. D.
Publication year - 2019
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.14332
Subject(s) - recombinant dna , coagulation , factor ix , clotting factor , albumin , fusion protein , chemistry , medicine , biochemistry , gene
SummaryEssentials 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 (r FIX ) products in OSC assays is essential, as APTT reagents from different manufacturers yield different potency estimates for r FIX . Objectives To evaluate the extent to which choice of reagent composition influences r FIX potency measurements of recombinant FIX –albumin fusion protein (r IX ‐ FP , IDELVION ) activity in OSC assays. Methods r IX ‐ 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 r IX ‐ FP with unmodified r FIX and r FIX Fc fusion protein (r FIXF c). 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 r IX ‐ FP activity of ≈ 50% with OSC assays using Actin FS or kaolin‐based APTT reagents. In the bioanalytical study, r IX ‐ FP showed comparable variability in OSC assays to unmodified r FIX and r FIXF c. Conclusions r IX ‐ 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.