A comprehensive multicenter study assessing the impact of abelacimab, asundexian and milvexian on coagulation assays
Phase 3 trials evaluating inhibitors of coagulation factor (F) XI and/or its activated form (FXIa) as novel anticoagulant drugs are ongoing. These agents include parenteral monoclonal antibody (abelacimab) and oral small molecules (milvexian, asundexian). We investigated the extent to which standard and specialized coagulation assays are affected by FXI(a) inhibitors in a multicenter study involving 23 laboratories. FXI(a) inhibitors were spiked into pooled normal plasma at concentrations covering those observed in phase 2/3 clinical trials: 50-2,000 ng/mL for milvexian and asundexian and 1-30 µg/mL for abelacimab. Actual plasma concentrations were measured by HPLC-MS/MS. Assays were performed blindly using 5 to 11 different combinations of reagent/analyzer depending on the assay. Prothrombin time, Clauss fibrinogen, and clotting activity of FII, FV, FVII and FX were not affected in a clinically relevant manner. Activated partial thromboplastin time (aPTT) was prolonged in a concentration-dependent manner, with milvexian having the greatest impact followed by abelacimab and asundexian. Clotting activity of FVIII, FIX, FXI, and FXII was underestimated. Such interference was prevented by high plasma dilution (up to 1/160) before the test, except for abelacimab: FXI clotting activity remained decreased, even at low concentration (2.5 µg/mL). FXI(a) inhibitors did not affect lupus anticoagulant (LA) testing using dilute Russell viper venom time, but might lead to false-negative result with LA sensitive aPTT reagents. Protein C anticoagulant activity was overestimated, while no impact on Protein S anticoagulant activity was observed. This study provides a comprehensive laboratory framework for interpreting clotting assays in future patients receiving FXI(a) inhibitors.
Authors
- Emmanuel Curis (ORCID: https://orcid.org/0000-0001-8382-1493)
- Christophe Nougier (ORCID: https://orcid.org/0000-0003-0578-242X)
- Sophie Voisin (ORCID: https://orcid.org/0000-0002-2871-166X)
- Elodie Boissier (ORCID: https://orcid.org/0000-0002-7790-6375)
- Nicolas Sillamy
- Georges Jourdi (ORCID: https://orcid.org/0000-0001-8738-5975)
- Dorothée Faille (ORCID: https://orcid.org/0000-0003-4414-739X)
- Claire Flaujac (ORCID: https://orcid.org/0000-0002-3662-3416)
- Isabelle Gouin‐Thibault (ORCID: https://orcid.org/0000-0003-3740-9005)
- Virginie Siguret (ORCID: https://orcid.org/0000-0002-6509-8964)
- Paul Billoir (ORCID: https://orcid.org/0000-0001-5632-7713)
- Julien Demagny (ORCID: https://orcid.org/0000-0002-8536-9733)
- Dominique Lasne (ORCID: https://orcid.org/0000-0001-6600-0263)
- Agathe Herb (ORCID: https://orcid.org/0000-0003-1040-0086)
- Xavier Delavenne (ORCID: https://orcid.org/0000-0001-7134-0713)
- Sophie Hodin
- Adrien Genin
- Laurie Goubeau (ORCID: https://orcid.org/0009-0005-6310-8996)
- Nathalie Hézard
- François Grand (ORCID: https://orcid.org/0000-0002-5955-5460)
- C. Mouton
- F. Ménard
- C Frere
- Emmanuel De Maistre (ORCID: https://orcid.org/0000-0003-3459-7397)
- Francois Mullier (ORCID: https://orcid.org/0000-0001-6947-6099)
- Laetitia Mauge (ORCID: https://orcid.org/0000-0002-3946-2312)
- Pierre Fontana (ORCID: https://orcid.org/0000-0003-1546-0774)
- Annabelle Dupont
Institutions
- Université de Tours (FR)
- University of Geneva (CH)
- Hôpital Necker-Enfants Malades (FR)
- Inserm (FR)
- Université Paris Cité (FR)
- Institut Pasteur de Lille (FR)
- Centre Hospitalier Universitaire de Nantes (FR)
- Centre Hospitalier Universitaire de Toulouse (FR)
- Mines Saint-Étienne (FR)
- Université Rennes 2 (FR)
- Université de Poitiers (FR)
- Sorbonne Université (FR)
- HES-SO Genève (CH)
- Centre Hospitalier Universitaire de Tours (FR)
- Centre Hospitalier Universitaire Amiens-Picardie (FR)
- Assistance Publique – Hôpitaux de Paris (FR)
- Hospices Civils de Lyon (FR)
- Normandie Université (FR)
- Centre Hospitalier Intercommunal Aix-Pertuis (FR)
- Institut de Recherche en Santé, Environnement et Travail (FR)
- Hôpital Européen (FR)
- Hôpital Lariboisière (FR)
- Pitié-Salpêtrière Hospital (FR)
- Centre Hospitalier de la Côte Basque (FR)
- Maison des Sciences sociales et des Humanités de Dijon (FR)
- Hôpital Bichat-Claude-Bernard (FR)
- Hôpitaux Universitaires de Strasbourg (FR)
- Centre Hospitalier de Versailles (FR)
- Institut Polytechnique de Bordeaux (FR)
- Hôpital de la Timone (FR)
- Université de Rennes (FR)
- Université de Rouen Normandie (FR)
- UCLouvain (BE)
Publication Details
- Journal
- Blood Advances
- Published
- 2026-05-27
- DOI
- https://doi.org/10.1182/bloodadvances.2026020472
- Primary Topic
- Blood Coagulation and Thrombosis Mechanisms
- Type
- article
- Field-Weighted Citation Impact
- 0.00