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Abstract Introduction Lonoctocog alfa is a single‐chain factor VIII (FVIII) molecule with high binding affinity to von‐Willebrand‐factor. While it is well known that its plasma activity is underestimated by one‐stage clotting assays (OSCA), there is a lack of knowledge on the post‐infusion performance of lonoctocog alfa in global coagulation assays or its potential impact on the haemostatic balance in vivo. Aim To characterize lonoctocog alfa versus octocog alfa in pre‐ and post‐infusion samples obtained from patients undergoing repeated investigation of incremental recovery (IR). Methods Eighteen patients with severe haemophilia A (lonoctocog alfa: 10, octocog alfa: 8) were included. A panel of factor‐specific and global coagulation assays was applied, comprising a FVIII OSCA, two FVIII chromogenic substrate assays (CSA), rotational thrombelastography and thrombin generation (TG). Potential activation of coagulation was assessed by measuring plasma thrombin markers and levels of activated protein C. Results Comparable IRs were found for lonoctocog alfa and octocog alfa (2.36 IU/dL/IU/kg vs. 2.55 IU/dL/IU/kg, respectively). Lonoctocog alfa activities were found to be underestimated by the FVIII OSCA while also the two FVIII CSAs showed statistically significant assay discrepancies on lonoctocog alfa. Effects of both FVIII products on rotational thrombelastography were less distinct than those on TG parameters. No elevated pre‐ or significantly shifting post‐infusion plasma levels of coagulation biomarkers were detected. Conclusion Lonoctocog alfa and octocog alfa showed comparable recovery and safety in vivo as well as similar impacts on TG in vitro. Observed assay discrepancies on lonoctocog alfa demonstrated variability of results also between different FVIII CSAs.
Müller et al. (Tue,) studied this question.