Qualification of a select one‐stage activated partial thromboplastin time‐based clotting assay and two chromogenic assays for the post‐administration monitoring of nonacog beta pegol

• Published in: Journal of thrombosis and haemostasis Vol. 15; no. 10; pp. 1901 - 1912
• Main Authors: Tiefenbacher, S., Bohra, R., Amiral, J., Bowyer, A., Kitchen, S., Lochu, A., Rosén, S., Ezban, M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Limited 01-10-2017
• Subjects: Blood Coagulation - drug effects; blood coagulation tests; Chromogenic Compounds - chemistry; Chromogenic Compounds - standards; Clotting; Coagulants - administration & dosage; Coagulants - blood; Coagulants - pharmacokinetics; Coagulation factors; Colorado; Drug Monitoring - methods; Drug Monitoring - standards; Europe; Factor IX - administration & dosage; Factor IX - pharmacokinetics; Factor IX deficiency; Freeze-thawing; Half-Life; Hemophilia; hemophilia B; Humans; N9‐GP; nonacog beta pegol; Observer Variation; Partial Thromboplastin Time - standards; Polyethylene Glycols - administration & dosage; Polyethylene Glycols - pharmacokinetics; Predictive Value of Tests; Prophylaxis; recombinant factor IX; Recombinant Proteins - administration & dosage; Recombinant Proteins - blood; Recombinant Proteins - pharmacokinetics; Reproducibility of Results; Thromboplastin; recombinant factor IX; nonacog beta pegol; blood coagulation tests; hemophilia B; N9-GP
• ISSN: 1538-7933; 1538-7836; 1538-7836
• DOI: 10.1111/jth.13787

Essentials
Nonacog beta pegol (N9‐GP) is an extended half‐life, recombinant human factor IX (FIX).
One‐stage clotting (OSC) and chromogenic FIX activity assays were assessed for N9‐GP recovery.
OSC STA®‐Cephascreen®, ROX FIX and BIOPHEN FIX chromogenic assays were qualified for N9‐GP.
Other extended half‐life factor products should be assessed in a similar way prior to approval.
Summary
Background
Nonacog beta pegol (N9‐GP) is an extended half‐life, glycoPEGylated recombinant human factor IX that is under development for the prophylaxis and treatment of bleeding episodes in hemophilia B patients. Considerable reagent‐dependent variability has been observed when one‐stage clotting assays are used to measure the recovery of recombinant FIX products, including N9‐GP.
Objective
To qualify select one‐stage clotting and chromogenic FIX activity assays for measuring N9‐GP recovery.
Methods
The accuracy and precision of the one‐stage clotting assay (with the STA‐Cephascreen activated partial thromboplastin [APTT] reagent) and the ROX Factor IX and BIOPHEN Factor IX chromogenic assays for measuring N9‐GP recovery were assessed in N9‐GP‐spiked hemophilia B plasma samples in a systematic manner at three independent sites, with manufacturer‐recommended protocols and/or site‐specific assay setups, including different instruments.
Results
For each of the three FIX activity assays qualified on five different reagent–instrument systems, acceptable intra‐assay and interassay accuracy and precision, dilution integrity, reagent robustness and freeze–thaw and short‐term sample stabilities were demonstrated. The STA‐Cephascreen assay showed a limited reportable range at one of the three qualification sites, and the BIOPHEN Factor IX assay showed suspect low‐end sensitivity at one of the three qualification sites. An individual laboratory would account for these limitations by adjusting the assay's reportable range; thus, these findings are not considered to impact the respective assay qualifications.
Conclusion
The one‐stage clotting assay with the STA‐Cephascreen APTT reagent, the ROX Factor IX chromogenic assay and the BIOPHEN Factor IX chromogenic assay are considered to be qualified for the measurement of N9‐GP in 3.2% (0.109 m) citrated human plasma.