Measuring factor IX activity of nonacog beta pegol with commercially available one‐stage clotting and chromogenic assay kits: a two‐center study. (13th June 2016)

• Record Type: Journal Article
• Authors: Bowyer, A. E.; Hillarp, A.; Ezban, M.; Persson, P.; Kitchen, S.
• Is Part Of: Journal of thrombosis and haemostasis. Volume 14:Number 7(2016:Jul.)
• Page Start: 1428
• Page End: 1435
• Publication Date: 2016-06-13
• Subjects: blood coagulation test -- factor IX -- hemophilia B -- nonacog beta pegol -- poly(ethylene glycol); Thrombosis -- Periodicals; Hemostasis -- Periodicals; Blood coagulation disorders -- Periodicals; 616.1
• DOI: 10.1111/jth.13348
• Languages: English
• ISSNs: 1538-7933

Abstract

Abstract : Essentials Validated assays are required to precisely measure factor IX (FIX) activity in FIX products. N9‐GP and two other FIX products were assessed in various coagulation assay systems at two sites. Large variations in FIX activity measurements were observed for N9‐GP using some assays. One‐stage and chromogenic assays accurately measuring FIX activity for N9‐GP were identified. Summary: Background: Measurement of factor IX activity (FIX:C) with activated partial thromboplastin time‐based one‐stage clotting assays is associated with a large degree of interlaboratory variation in samples containing glycoPEGylated recombinant FIX (rFIX), i.e. nonacog beta pegol (N9‐GP). Validation and qualification of specific assays and conditions are necessary for the accurate assessment of FIX:C in samples containing N9‐GP. Objectives: To assess the accuracy of various one‐stage clotting and chromogenic assays for measuring FIX:C in samples containing N9‐GP as compared with samples containing rFIX or plasma‐derived FIX (pdFIX) across two laboratory sites. Methods: FIX:C, in severe hemophilia B plasma spiked with a range of concentrations (from very low, i.e. 0.03 IU mL −1, to high, i.e. 0.90 IU mL −1 ) of N9‐GP, rFIX (BeneFIX), and pdFIX (Mononine), was determined at two laboratory sites with 10 commercially available one‐stage clotting assays and two chromogenic FIX:C assays. Assays were performed with a plasma calibrator and different analyzers. Results: A high degree of variation in FIX:C measurement was observed for one‐stage clotting assays for N9‐GP as compared with rFIX or pdFIX. Acceptable N9‐GP recovery was observed in the low‐concentration to high‐concentration samples tested with one‐stage clotting assays using SynthAFax or DG Synth, or with chromogenic FIX:C assays. Similar patterns of FIX:C measurement were observed at both laboratory sites, with minor differences probably being attributable to the use of different analyzers. Conclusions: These results suggest that, of the reagents tested, FIX:C in N9‐GP‐containing plasma samples can be most accurately measured with one‐stage clotting assays using SynthAFax or DG Synth, or with chromogenic FIX:C assays.