Sample S18:24 was constructed by in-vitro addition of emicizumab from a patient with severe haemophilia A without an inhibitor.Ĭentres using Siemens SHP calibrator material collectively gave a range of IU/dL surrogate FVIII activity results between 18.4-34.3 IU/dL for sample S18:23 and 19.1-37 IU/dL for S18:24. Sample S18:23 was obtained from a patient with severe haemophilia A who had a FVIII inhibitor treated with emicizumab for 7 weeks at the time of sample donation. UK NEQAS BC investigations were performed with the Hyphen assay to assess the use of different test sample dilutions using 2 lyophilised samples containing emicizumab, (S18:23 and S18:24). Methodology details were requested from these 9 participating laboratories including how testing was performed, calibrant source, analyser platform and assay dilutions used. In this supplementary exercise 9 of 29 participating centres performed FVIII Hyphen Biomed™ chromogenic assays with results showing higher than expected CVs (CVs >38%). UK NEQAS BC data from a supplementary survey identified an inter-laboratory variability of results reported using the Hyphen Biomed™ chromogenic FVIII kit when measuring patient samples containing emicizumab. P002 | Human chromogenic FVIII assay results are dependent on sample dilution when emicizumab is present: Additional analysis from the first UK NEQAS BC FVIII inhibitor/emicizumab supplementary exercise There were no found differences between in-vitro spiked samples and patient samples, indicating spiked samples to be commutable. At higher levels of Elocta, 55-70 IU/dL, Chromogenic assays were at most 20% higher compared to 1-stage FVIII assay results. Result levels of ≤11 IU/dL for 1-stage FVIII assays were at most ~15% higher compared to chromogenic assays. S19:05 Median results IU/dL = 71.0 Range = 55-107 IU/dL CV = 14.8%Ĭareful interpretation of patient results is required.
9 participating centres performed both a 1-stage and a Chromogenic FVIII assay. Result data was collected from 78 centres for a FVIII assay on all samples, with 56 centres performing a 1-stage FVIII assay and 22 centres performing a Chromogenic FVIII assay. Participants were invited to perform a FVIII assay on each of the four samples using testing methods in regular routine use in their laboratory. Samples S19:04 and S19.05 were constructed by ‘spiking’ FVIII deficient plasma, from a severe haemophilia A donor, with Elocta-Sample S19.04 at a level similar to a patient trough level and Sample S19:05 at a level similar to a patient post treatment level. S19:03 was from a patient with severe Haemophilia A patient, treated with 2000 iu/kg Elocta 15 minutes prior to sample collection. Sample S19:02 was from a patient with severe Haemophilia A treated with Elocta, but prior to sample collection was at a treatment trough level. In a supplementary UK NEQAS BC exercise 4 lyophilised samples containing Elocta were distributed to 81 participating centres. Several different laboratory assay methods can be used to monitor Elocta in patient plasma samples.
WalkerĮlocta ® is an Fc Fusion Protein classified as an extended half-life (EHL) drug for the management of patients with Haemophilia A. POSTER ABSTRACTS P001 | One stage and chromogenic FVIII assay results at trough levels: A UK national external quality assessment scheme for blood coagulation (UK NEQAS BC) exerciseĪ.
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