Methods for anti-factor VIII antibody levels in haemophilia A patients - validation of a multiplex immunoassay and comparability with assays measuring non-neutralising and neutralising antibodies (inhibitors).

Introduction: The development of neutralising (inhibitors) and non-neutralising antibodies (NNAs) is a complication to factor replacement therapy in haemophilia. The diagnostic methods available lack standardisation, have high inter-laboratory variation, and false-negative as well as false-positive results may affect treatment. Both functional inhibitors and NNAs may be detected with higher reproducibility, sensitivity and specificity using the immunological Luminex xMAP-based fluorescence-immunoassay (xFLI).

Validation of factor VIII activity for monitoring standard and extended half-life products and correlation to thrombin generation assays.

Introduction: Monitoring replacement therapy with standard and extended half-life (EHL) products is challenging, since one-stage assay (OSA) and chromogenic substrate assay (CSA) results may differ significantly. Recent recommendations include local validation of each new product with recovery within 20-30%, depending on activity level.

Aim: To validate factor VIII (FVIII) activity for monitoring products in clinical use on Atellica Coag and to correlate it with thrombin generation.