Analytical Performance of Different Laboratory Methods for Measuring Susoctocog-Alfa

Abstract

Recombinant porcine factor VIII (rpFVIII) is indicated for treating bleeding episodes in acquired haemophilia A, but there are few data regarding laboratory methods to adequately monitor treatment. This study involving three Italian laboratories aimed to evaluate the analytical performance of different assays for measuring rpFVIII. Five spiked rpFVIII samples (0.5–1.5 IU/mL) were analysed on three days, in triplicate, with eleven combinations of reagents (Werfen, Boston, MA, USA: SynthasIL and SynthaFax for one-stage assay, Chromogenix Coamatic FVIII for chromogenic assay), FVIII depleted plasmas (with or without von Willebrand factor—VWF) and calibrators (HemosIL human calibrator plasma, porcine calibrator diluted in FVIII deficient plasma with or without VWF). The assays were performed on ACL TOP analysers (Werfen, Boston, MA, USA). Intra- and inter-assay and inter-laboratory Coefficient of Variation (CV%) were calculated together with percentage of recovery (% recovery) on the expected value. The results showed that the reagent combinations reaching satisfactory analytical performance are: SynthasIL/human calibrator/deficient plasma+VWF (total recovery 99.4%, inter-laboratory CV 4.04%), SynthasIL/porcine calibrator/deficient plasma+VWF (total recovery 111%, inter-laboratory CV 2.75%) and Chromogenic/ porcine calibrator/deficient plasma+VWF (total recovery 96.6%, inter-laboratory CV 8.32%). This study highlights that the use of porcine standard (when available) and FVIII deficient plasma with VWF should be recommended.

Measurement of recombinant porcine factor VIII in patients with congenital haemophilia A and inhibitors in the presence of emicizumab

“…Calibration of bCSA with human FVIII resulted in a 50% lower recovery of rpFVIII. A recent study has shown that the use of a chromogenic assay with a porcine calibrator and VWF‐containing FVIII‐deficient plasma provides satisfactory results 13 . We found a recovery of 70%−120% for the combination of bCSA with rpFVIII calibration.…”

“…A recent study has shown that the use of a chromogenic assay with a porcine calibrator and VWFcontaining FVIII-deficient plasma provides satisfactory results. 13 We found a recovery of 70%−120% for the combination of bCSA with rpFVIII calibration. The recovery was only 50%−80% in our patients with a rpFVIII inhibitors below the detection limit and the recovery of rpFVIII was further influenced by the presence of detectable inhibitory antibodies against human and porcine FVIII.…”

Agreement between one stage and chromogenic assays in samples from patients receiving recombinant porcine FVIII (Obizur, Susoctocog‐alfa)

“…One recent study has used porcine FVIII to prepare the calibration curve and compared it to HemosIL human plasma calibrator. Recovery was improved by use of the porcine calibrator 6 highlighting how different reagent and standard combinations lead to variation within the results obtained. It is, therefore, important for laboratories to perform their own assessments of their assay's performances in patients receiving rpFVIII treatment.…”

“…OSA are known to vary in FVIII:C and FIX:C levels measured in many modified FVIII and FIX concentrates. A recent small study of five spiked plasma samples with rpFVIII highlighted the differences obtained when using plasma calibrators, porcine standards and FVIII deficient plasma with and without VWF 6 when measuring rpFVIII by two OSA (Synthasil and SynthAFax) and CSA (Coamatic FVIII). In a worldwide laboratory field study using spiked samples, CSA have been shown to underestimate rpFVIII 7 .…”

Surgery and Prophylaxis with Susoctocog-Alfa in Acquired Hemophilia: Case Series and Literature Review

“…The latter has recently been licensed for management of acute bleeding in AHA [9] based on a prospective study in adult patients with major bleedings [10]. rpFVIII advantages include the possibility of monitoring response with standard coagulation laboratory assays and minimizing thrombotic risk [11][12][13][14][15]. Thromboembolic risk is, indeed, increased in patients treated with bypassing agents, particularly the elderly and those with underlying pro thrombotic conditions (i.e., previous thrombosis, immobilization, malignancy, indwelling catheters, surgery, and pregnancy/post-partum) [7,16,17].…”