Abstract Number: PB0101
Meeting: ISTH 2021 Congress
Background: The standard treatment for hemophilia A patients is FVIII replacement therapy with recombinant FVIII (rFVIII) or plasma-derived FVIII concentrates. Discrepancies in the measurements of extended half-life FVIII products have been observed depending on the assay and reagents used.
Aims: The study aim was to evaluate the recovery of a pegylated rFVIII product by a chromogenic FVIII (CS) and one-stage clotting (OSC) assay.
Methods: Recovery was investigated in a BAY94-9027 ECAT evaluation set containing five levels of FVIII activity (0.05, 0.10, 0.25, 0.50, 1.50 IU/mL) in a lyophilized format. After reconstitution, each level was measured in triplicate at three dilutions (neat, 1:2, and 1:4). BAY94-9027 was also diluted in congenital FVIII deficient and FVIII immunodepleted plasma to create five levels analogous to the ECAT sample set. Two pre-dilutions (1:2 and 1:4) of the neat plasma were prepared and measured in triplicate as fresh and frozen samples on an IL ACL TOP instrument using Chromogenic Factor VIII (Precision BioLogic) and HemosIL SynthAsil assays.
Results: The mean percent recoveries across all levels in the ECAT sample set were 73.7% and 96.7% for the CS and OSC assay, respectively. The recovery was improved by directly spiking drug product into congenital FVIII deficient plasma with mean recoveries of 85.3% and 101.4% for fresh and 87.6% and 101.1% for frozen samples by the CS and OSC assays, respectively. For the CS assay the recovery was dose-dependent with increased recovery (≥ 96%) in the normal range (0.5-1.5 IU/mL) than at lower doses. Switching the matrix to FVIII immunodepleted plasma showed a significant dose-dependent impact on the recovery across all levels for the OSC assay but not the CS assay.
Conclusions: The CS and OSC assays demonstrated acceptable recovery at clinically relevant concentrations when BAY94-9027 was directly spiked into congenital FVIII deficient plasma. The CS assay was less susceptible to matrix effects.
To cite this abstract in AMA style:Quinton T, Fraser J, M Black K, Sadeghi-Khomami A. Comparison of a Chromogenic vs. APTT-based Factor VIII Activity Assay in the Recovery of a Pegylated Factor VIII Replacement Therapy in Plasma Samples [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/comparison-of-a-chromogenic-vs-aptt-based-factor-viii-activity-assay-in-the-recovery-of-a-pegylated-factor-viii-replacement-therapy-in-plasma-samples/. Accessed November 28, 2023.
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