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Hamostaseologie
DOI: 10.1055/a-2687-0107
Original Article

Laboratory Monitoring in Patients Receiving Emicizumab

Authors

  • Jens Müller

    1   Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany

  • Martin Büchsel

    2   Institute for Clinical Chemistry and Laboratory Medicine, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany

  • Olga Oleshko

    3   Department of Hematology, Hemostasis, Oncology, and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany

  • Behnaz Pezeshkpoor 

    1   Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany

  • Ulrich Sachs

    4   Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University, Giessen, Germany

  • Ute Scholz

    5   Center of Coagulation Disorders, Leipzig, Germany

  • Andreas Tiede

    3   Department of Hematology, Hemostasis, Oncology, and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany
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Abstract

Emicizumab is a bispecific monoclonal antibody that mimics the cofactor function of activated factor VIII (FVIIIa). It is approved for routine prophylaxis in patients with severe or moderate congenital hemophilia A (HA), both with and without FVIII inhibitors, and is increasingly used as a first-line treatment in acquired HA (AHA). Owing to its predictable pharmacokinetic profile, emicizumab monitoring is generally limited to cases with suspected reduced efficacy, such as due to poor adherence or the development of anti-drug antibodies (ADAs). However, emicizumab interferes with standard clotting assays, particularly by shortening activated partial thromboplastin times (APTT). To address this, modified FVIII one-stage clotting assays (mOSA), which use higher sample pre-dilution and emicizumab-specific calibration, are commonly employed to estimate plasma levels, although other assay formats like emicizumab-calibrated chromogenic substrate assays based on human factors or liquid chromatography tandem mass spectrometry are also available. Additionally, global assays such as in vitro thrombin generation testing are being explored to better reflect clinical hemostatic efficacy. This review summarizes current knowledge on assay interferences caused by emicizumab, challenges in functional measurement of plasma levels, and strategies to ensure reliable laboratory assessment. We also discuss the relevance and methods for ADA detection and provide an overview of current and emerging strategies for thrombin generation measurement as a global indicator of treatment effectiveness.

Keywords

hemophilia A - blood coagulation tests - emicizumab - factor VIII - drug monitoring

Authors' Contributions

All authors participated in writing the manuscript and approved the final version.


Standing Commission Labor (STAEKOLA) of the Society of Thrombosis and Haemostasis Research (GTH).




Publication History

Received: 01 July 2025

Accepted: 19 August 2025

Article published online:
09 October 2025

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