{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T12:40:00Z","timestamp":1791463200369,"version":"4.3.4"},"reference-count":17,"publisher":"Georg Thieme Verlag KG","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Hamostaseologie"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Efanesoctocog alfa (efa) is a recombinant coagulation factor VIII (FVIII) concentrate, engineered for improved extended half-life in hemophilia A treatment. Its design results in discrepancies in FVIII diagnostic tests, as has so far been demonstrated using spiked sample material (efa added to FVIII-deficient plasma). The aim of the present study was to evaluate FVIII assay discrepancies in post-infusion samples obtained from patients treated with efa. This retrospective analysis included 43 male patients on efa prophylaxis (26 on once weekly and 17 on twice weekly treatment scheme) summoned for determination of incremental recoveries. FVIII activity was measured at trough (3.5 or 7 days post-infusion) and peak levels (30\u2009minutes post-infusion) using three diagnostic tests: two one-stage clotting assays (OSCAs) based on Actin FSL (AFSL) or Actin FS (AFS), and a chromogenic substrate assay (FVIII CSA). Incremental recoveries as determined by the recommended AFSL-based OSCA were found to be comparable between patient groups. At peak levels (64 to 214\u2009IU\/dL), comparable overestimation (1.9-fold) of plasma efa activity relative to Actin FSL-based OSCA was observed for both, the AFS-based OSCA and the FVIII CSA. In contrast, at trough levels (5 to 64\u2009IU\/dL), rate of overestimation relative to the AFSL-based OSCA results was found to be lower for the FVIII CSA (1.3-fold) when compared with the AFS-based OSCA (1.9-fold). Further analysis demonstrated different behavior of spiked and post-infusion samples within the FVIII CSA. Future studies will reveal underlying mechanisms and assess if drug-specific calibration will sufficiently correct for this phenomenon.<\/jats:p>","DOI":"10.1055\/a-2717-3413","type":"journal-article","created":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T00:04:51Z","timestamp":1768867491000},"source":"Crossref","is-referenced-by-count":1,"title":["On Factor VIII Assay Discrepancies in Post-infusion Samples Obtained from Patients Treated with Efanesoctocog Alfa"],"prefix":"10.1055","author":[{"given":"Jens","family":"M\u00fcller","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martin","family":"B\u00fcchsel","sequence":"additional","affiliation":[{"name":"Institute for Clinical Chemistry and Laboratory Medicine, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4796-3424","authenticated-orcid":false,"given":"Behnaz","family":"Pezeshkpoor","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Heiko","family":"R\u00fchl","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bernd","family":"P\u00f6tzsch","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Claudia","family":"Klein","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Georg","family":"Goldmann","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Natascha","family":"Marquardt","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thilo","family":"Albert","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kerstin","family":"Herbst","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Johannes","family":"Oldenburg","sequence":"additional","affiliation":[{"name":"Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"194","published-online":{"date-parts":[[2026,1,19]]},"reference":[{"issue":"04","key":"ref1","doi-asserted-by":"crossref","first-page":"310","DOI":"10.1056\/NEJMoa2209226","article-title":"Efanesoctocog alfa prophylaxis for patients with severe hemophilia A","volume":"388","author":"A von Drygalski","year":"2023","journal-title":"N Engl J Med"},{"issue":"04","key":"ref2","doi-asserted-by":"crossref","first-page":"100176","DOI":"10.1016\/j.rpth.2023.100176","article-title":"Pharmacokinetics of recombinant factor VIII in adults with severe hemophilia A: fixed-sequence single-dose study of octocog alfa, rurioctocog alfa pegol, and efanesoctocog alfa","volume":"7","author":"T Lissitchkov","year":"2023","journal-title":"Res Pract Thromb Haemost"},{"issue":"01","key":"ref3","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1111\/hae.14831","article-title":"A global comparative field study to evaluate the factor VIII activity of efanesoctocog alfa by one-stage clotting and chromogenic substrate assays at clinical haemostasis laboratories","volume":"30","author":"S Pipe","year":"2024","journal-title":"Haemophilia"},{"issue":"05","key":"ref6","doi-asserted-by":"crossref","first-page":"1480","DOI":"10.1016\/j.jtha.2025.01.024","article-title":"Monitoring ultralong half-life recombinant factor VIII: a product-specific 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synovium: a randomized study","volume":"23","author":"M ND Di Minno","year":"2025","journal-title":"J Thromb Haemost"},{"issue":"04","key":"ref10","doi-asserted-by":"crossref","first-page":"1089","DOI":"10.1182\/bloodadvances.2021006119","article-title":"Efanesoctocog alfa for hemophilia A: results from a phase 1 repeat-dose study","volume":"6","author":"T Lissitchkov","year":"2022","journal-title":"Blood Adv"},{"issue":"07","key":"ref11","doi-asserted-by":"crossref","first-page":"633","DOI":"10.1007\/s40265-023-01866-9","article-title":"Efanesoctocog alfa: first approval","volume":"83","author":"S J Keam","year":"2023","journal-title":"Drugs"},{"issue":"01","key":"ref12","doi-asserted-by":"crossref","first-page":"e19","DOI":"10.1111\/hae.13656","article-title":"Accurate measurement of extended half-life and unmodified factor VIII low levels with one-stage FVIII assays is dependent on the matrix of calibration curves","volume":"25","author":"D Van den Bossche","year":"2019","journal-title":"Haemophilia"},{"issue":"02","key":"ref13","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1007\/s11095-019-2689-1","article-title":"In vivo stability of therapeutic proteins","volume":"37","author":"J Schuster","year":"2020","journal-title":"Pharm Res"},{"issue":"01","key":"ref14","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1111\/hae.13643","article-title":"Analytical variation in factor VIII one-stage and chromogenic assays: experiences from the ECAT external quality assessment programme","volume":"25","author":"I van Moort","year":"2019","journal-title":"Haemophilia"},{"issue":"04","key":"ref15","doi-asserted-by":"crossref","first-page":"248","DOI":"10.1055\/a-1665-6232","article-title":"An update on laboratory diagnostics in haemophilia A and B","volume":"42","author":"J M\u00fcller","year":"2022","journal-title":"Hamostaseologie"},{"issue":"07","key":"ref16","doi-asserted-by":"crossref","first-page":"1084","DOI":"10.1055\/s-0039-1688687","article-title":"Effects and interferences of emicizumab, a humanised bispecific antibody mimicking activated factor VIII cofactor function, on coagulation assays","volume":"119","author":"J I Adamkewicz","year":"2019","journal-title":"Thromb Haemost"},{"issue":"09","key":"ref17","doi-asserted-by":"crossref","first-page":"1384","DOI":"10.1055\/s-0039-1692427","article-title":"Laboratory monitoring in emicizumab-treated persons with hemophilia A","volume":"119","author":"J M\u00fcller","year":"2019","journal-title":"Thromb Haemost"},{"issue":"05","key":"ref18","doi-asserted-by":"crossref","first-page":"1516","DOI":"10.1016\/j.jtha.2024.12.034","article-title":"Accurate evaluation of factor VIII activity of efanesoctocog alfa in the presence of emicizumab","volume":"23","author":"C Nougier","year":"2025","journal-title":"J Thromb Haemost"},{"key":"ref19","doi-asserted-by":"publisher","DOI":"10.1111\/hae.70096","article-title":"Letter in response to the article \u201cA global comparative field study to evaluate the factor VIII activity of efanesoctocog alfa by one-stage clotting and chromogenic substrate assays at clinical haemostasis laboratories\u201d","author":"B Buffart","year":"2025","journal-title":"Haemophilia"}],"container-title":["H\u00e4mostaseologie"],"original-title":[],"language":"de","link":[{"URL":"http:\/\/www.thieme-connect.de\/products\/ejournals\/pdf\/10.1055\/a-2717-3413.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T00:04:53Z","timestamp":1768867493000},"score":1,"resource":{"primary":{"URL":"http:\/\/www.thieme-connect.de\/DOI\/DOI?10.1055\/a-2717-3413"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,19]]},"references-count":17,"URL":"https:\/\/doi.org\/10.1055\/a-2717-3413","archive":["Portico","CLOCKSS"],"relation":{},"ISSN":["0720-9355","2567-5761"],"issn-type":[{"value":"0720-9355","type":"print"},{"value":"2567-5761","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,19]]}}}