PB0095 - Effect of extended half-life products and emicizumab on routine coagulation and thrombin generation tests

Background: People with hemophilia are routinely treated with novel medication types such as factor (F) suppletion with extended half-life (EHL) products and FVIII mimetic emicizumab. Monitoring of these types of medication in routinely used laboratory tests is known to produce results that deviate between assays, causing an over- or underestimation of the actual FVIII activity.

Aims: We tested the effects of Adynovi, Elocta and emicizumab (Hemlibra) on one-stage and chromogenic based FVIII tests as well as thrombin generation on various platforms to establish reagent- and method related measurement bias and compared these results to previously published data.

Methods: Dilution series of Elocta, Adynovi and emicizumab were made in factor VIII deficient plasma, ranging from 0 - 1,5 IU/mL and 0 – 75 µg/mL respectively. FVIII activity was determined using Werfen, Stago and Roche equipment and reagents, as well as Siemens and Hyphen Biomed reagents. Thrombin generation was measured using the Ceveron S100 TGA RB reagent and the Nijmegen Hemostasis Assay and results were normalized for comparability to the normalized mean of normal individuals.

Results: Except for SynthaSIL reagent, all Adynovi measurements from mid to high range (10-150%) overestimated FVIII activity. In the low range all reagents overestimated FVIII activity with more than 20% except for the BioPhen FVIII and CK Prest reagent. For Elocta, only the SynthaSIL reagent measured FVIII activity accurately in the mid to high range. In the low range all reagents overestimated FVIII activity. Thrombin generation increased with incremental Elocta, Adynovi and emicizumab concentrations, as represented by the results for Peak Height in Figure 1.

Conclusion(s): In accordance with published literature, measurement of FVIII activity is overstimated by the majority of tested reagents and equipment in case of Elocta or Adynovi treatment. Increasing concentrations of Elocta, Adynovi and emicizumab yields higher thrombin generation which differ between the platforms.