title: BAY 81-8973, a full-length recombinant factor VIII: results from an International comparative laboratory field study.
abstract: BACKGROUND
  BAY 81-8973 is a full-length, unmodified, recombinant human factor VIII (FVIII) with the same primary amino acid sequence as sucrose-formulated recombinant FVIII but produced with certain more advanced manufacturing technologies.
  
  
  OBJECTIVE
  This global laboratory study evaluated variability in measurement of BAY 81-8973 using one-stage and chromogenic assays compared with antihaemophilic factor (recombinant) plasma/albumin-free method (rAHF-PFM; Advate(®) ) under assay conditions routinely used in clinical laboratories.
  
  
  METHODS
  BAY 81-8973 or rAHF-PFM was spiked into FVIII-deficient plasma at 0.043 (low), 0.375 (medium) and 0.865 (normal) IU mL(-1) . Participating laboratories analysed blinded samples and normal plasma in triplicate using their routine assay, reagents and standards. Results were analysed for intra- and interlaboratory variability.
  
  
  RESULTS
  Forty-one laboratories in 11 countries participated in the study. One-stage assay and chromogenic assays were used by 40 and 10 laboratories, respectively; 9 laboratories used both assays. Intralaboratory variability was <11% for both assays and both products at all concentrations. Interlaboratory variability was highest at the low concentration in the chromogenic and one-stage assay for BAY 81-8973 (60.0% and 33.7%, respectively) and rAHF-PFM (51.0% and 30.8%) and was lowest at the normal concentration (BAY 81-8973, 5.4% and 14.0%; rAHF-PFM, 5.8% and 12.4%), which was similar to the plasma control (6.6% and 10.3%). The chromogenic:one-stage assay ratio ranged from 0.95 (low concentration) to 1.10 (normal concentration) for BAY 81-8973 and 0.96-1.18 for rAHF-PFM.
  
  
  CONCLUSIONS
  BAY 81-8973 can be accurately measured in plasma using the one-stage and chromogenic assays routinely used in clinical laboratories without a product-specific standard.
authors.affiliation: Royal Hallamshire Hospital, Sheffield, UK.
authors.forename: S
authors.initials: S
authors.lastname: Kitchen
authors.affiliation: Bayer Pharma AG, Wuppertal, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Beckmann
authors.affiliation: Bayer Pharma AG, Berlin, Germany.
authors.forename: Y
authors.initials: Y
authors.lastname: Katterle
authors.affiliation: Winicker Norimed GmbH, Nuremberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Bruns
authors.affiliation: Bayer Pharma AG, Berlin, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Tseneklidou-Stoeter
authors.affiliation: Bayer Pharma AG, Wuppertal, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Maas Enriquez
mesh_terms: D005169:Factor VIII / Q000032:analysis* / Q000627:therapeutic use; D006467:Hemophilia A / Q000188:drug therapy; D006801:Humans; D007391:International Cooperation; D007753:Laboratories; D015588:Observer Variation; D004364:Pharmaceutical Preparations / Q000032:analysis*; D010949:Plasma / Q000737:chemistry*; D011994:Recombinant Proteins / Q000032:analysis* / Q000627:therapeutic use
chemical_list: D004364:Pharmaceutical Preparations; D011994:Recombinant Proteins; C078147:F8 protein, human; D005169:Factor VIII
keywords: chromogenic assay; factor VIII; field study; one-stage assay; postinfusion monitoring; recombinant factor VIII