Subscribe to RSS
DOI: 10.1055/a-2632-3001
Implementing an Assay Detecting Anti-drug Antibody against Emicizumab: Experience from One Center in France
Funding F.P. was partially supported by the Italian Ministry of Health – Bando Ricerca Corrente. The Hemostasis & Thrombosis Unit of the Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico is a member of the European Reference Network on Rare Haematological Diseases EuroBloodNet-Project ID No. 101157011. ERN-EuroBloodNet is partly co-funded by the European Union within the framework of the Fourth EU Health Program.

Abstract
Background
Emicizumab is an antibody that mimics the function of factor (F)VIII and has been approved for prophylaxis in hemophilia A patients. However, the development of anti-drug antibodies (ADA) against emicizumab, although rare, can impair its efficacy. In cases with low drug levels or bleeding events, differentiating between ADA- and adherence-related issues can be challenging.
Material and Methods
We aimed at evaluating the effectiveness of a modified bridging ELISA (Valsecchi et al, JTH 2021) in detecting ADA in patients suspected of developing this response. Clinical and laboratory data were retrospectively collected from six patients with suspected ADA and one with a confirmed case. The modified ELISA was performed blindly to identify potential ADA presence. After a new ADA case was confirmed, it was characterized by assessing its expression over time and neutralizing effect.
Results
Five patients had emicizumab levels ≤1 µg/mL, while two had higher levels (13 and 15 µg/mL). Among the patients, two experienced spontaneous bleeding, and four had traumatic bleeding. ADA was detected in two patients, including the one with a known ADA. In ADA-negative patients, emicizumab levels increased following adjustments for compliance or administration issues. The newly identified ADA was neutralizing, blocking emicizumab's binding to factors IX and X. Its pattern of expression was similar to that of the known ADA case, peaking 3 months after the loss of emicizumab efficacy and remaining positive for over a year after emicizumab discontinuation.
Conclusion
In bleeding patients with low emicizumab levels, the modified bridging ELISA may effectively differentiate ADA patients from those with other issues leading to decreased emicizumab concentration.
Authors' Contribution
C.A., C.V., N.K.B., and A.L.G. performed experiments; C.B. and A.H. collected the data; C.A., D.B, C.V., F.P., and D.L. designed the study; C.A. and D.L. supervised the study; C.A., C.V., and P.J.L. analyzed and interpreted the data; C.A. wrote the manuscript. All authors revised the manuscript critically and approved the version to be submitted.
Publication History
Received: 05 November 2024
Accepted: 10 June 2025
Accepted Manuscript online:
11 June 2025
Article published online:
27 June 2025
© 2025. Thieme. All rights reserved.
Georg Thieme Verlag KG
Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany
-
References
- 1 Oldenburg J, Mahlangu JN, Kim B. et al. Emicizumab prophylaxis in hemophilia A with inhibitors. N Engl J Med 2017; 377 (09) 809-818
- 2 Mahlangu J, Oldenburg J, Paz-Priel I. et al. Emicizumab prophylaxis in patients who have hemophilia A without inhibitors. N Engl J Med 2018; 379 (09) 811-822
- 3 Pipe SW, Shima M, Lehle M. et al. Efficacy, safety, and pharmacokinetics of emicizumab prophylaxis given every 4 weeks in people with haemophilia A (HAVEN 4): a multicentre, open-label, non-randomised phase 3 study. Lancet Haematol 2019; 6 (06) e295-e305
- 4 Young G, Liesner R, Chang T. et al. A multicenter, open-label phase 3 study of emicizumab prophylaxis in children with hemophilia A with inhibitors. Blood 2019; 134 (24) 2127-2138
- 5 Hassan E, Jonathan L, Jayashree M. Real-world experience on the tolerability and safety of emicizumab prophylaxis in paediatric patients with severe haemophilia A with and without FVIII inhibitors. Haemophilia 2021; 27 (06) e698-e703
- 6 Bush KA, Ding H, O'Flaherty-Keese K. et al. Real-world clinical outcomes in previously untreated and minimally treated patients with congenital factor VIII deficiency: the San Diego experience. Blood 2020; 136(Suppl 1): 31-32
- 7 Misgav M, Brutman-Barazani T, Budnik I. et al. Emicizumab prophylaxis in haemophilia patients older than 50 years with cardiovascular risk factors: real-world data. Haemophilia 2021; 27 (02) 253-260
- 8 Young G, Pipe SW, Kenet G. et al. Emicizumab is well tolerated and effective in people with congenital hemophilia A regardless of age, severity of disease, or inhibitor status: a scoping review. Res Pract Thromb Haemost 2024; 8 (04) 102415
- 9 Schmitt C, Emrich T, Chebon S. et al. Low immunogenicity of emicizumab in persons with haemophilia A. Haemophilia 2021; 27 (06) 984-992
- 10 Harkins Druzgal C, Kizilocak H, Brown J, Sennett M, Young G. Neutralizing antidrug antibody to emicizumab in a patient with severe hemophilia A with inhibitors: new case with detailed laboratory evaluation. J Thromb Haemost 2020; 18 (09) 2205-2208
- 11 Valsecchi C, Gobbi M, Beeg M. et al. Characterization of the neutralizing anti-emicizumab antibody in a patient with hemophilia A and inhibitor. J Thromb Haemost 2021; 19 (03) 711-718
- 12 Harroche A, Sefiane T, Desvages M. et al. Non-inhibitory antibodies inducing increased emicizumab clearance in a severe haemophilia A inhibitor patient. Haematologica 2021; 106 (08) 2287-2290
- 13 Kaneda M, Kawasaki R, Matsumoto N. et al. Detailed analysis of anti-emicizumab antibody decreasing drug efficacy, using plasma samples from a patient with hemophilia A. J Thromb Haemost 2021; 19 (12) 2938-2946
- 14 Kizilocak H, Guerrera MF, Young G. Neutralizing antidrug antibody to emicizumab in patients with severe hemophilia A: case report of a first noninhibitor patient and review of the literature. Res Pract Thromb Haemost 2023; 7 (06) 102194
- 15 Valsecchi C, Schiavone L, Arcudi S. et al. Development and clinical utility of anti-emicizumab antibody detection assays. (abstract) Res Pract Thromb Haemost 2023; 7 (Suppl 2): 101164
- 16 Pezeshkpoor B, Sereda N, Becker-Gotot J. et al. Comprehensive evaluation of anti-emicizumab antibodies in acquired hemophilia A: a detailed case study and methodological evaluation. J Thromb Haemost 2025; 23 (01) 85-96
- 17 Nogami K, Soeda T, Matsumoto T, Kawabe Y, Kitazawa T, Shima M. Routine measurements of factor VIII activity and inhibitor titer in the presence of emicizumab utilizing anti-idiotype monoclonal antibodies. J Thromb Haemost 2018; 16 (07) 1383-1390
- 18 Partridge MA, Purushothama S, Elango C, Lu Y. Emerging technologies and generic assays for the detection of anti-drug antibodies. J Immunol Res 2016; 2016: 6262383
- 19 Patton A, Mullenix MC, Swanson SJ, Koren E. An acid dissociation bridging ELISA for detection of antibodies directed against therapeutic proteins in the presence of antigen. J Immunol Methods 2005; 304 (1-2): 189-195
- 20 Kavita U, Duo J, Crawford SM. et al. A systematic study of the effect of low pH acid treatment on anti-drug antibodies specific for a domain antibody therapeutic: impact on drug tolerance, assay sensitivity and post-validation method assessment of ADA in clinical serum samples. J Immunol Methods 2017; 448: 91-104
- 21 Zoghbi J, Xu Y, Grabert R, Theobald V, Richards S. A breakthrough novel method to resolve the drug and target interference problem in immunogenicity assays. J Immunol Methods 2015; 426: 62-69
- 22 Smith HW, Butterfield A, Sun D. Detection of antibodies against therapeutic proteins in the presence of residual therapeutic protein using a solid-phase extraction with acid dissociation (SPEAD) sample treatment prior to ELISA. Regul Toxicol Pharmacol 2007; 49 (03) 230-237
- 23 Du J, Yang Y, Zhu L. et al. Method validation of a bridging immunoassay in combination with acid-dissociation and bead treatment for detection of anti-drug antibody. Heliyon 2023; 9 (03) e13999
- 24 Emicizumab US Medical Information Site. Accessed August 16, 2024 at: https://www.emicizumabinfo.global/us/en/homepage/faq.html
- 25 Nieuwlaat R, Wilczynski N, Navarro T. et al. Interventions for enhancing medication adherence. Cochrane Database Syst Rev 2014; 2014 (11) CD000011
- 26 Okolo A, Shapiro A, Janson I. et al. Psychometrics and applications of a novel self-report measure of emicizumab adherence: VERITASNexGen. Haemophilia 2023; 29 (05) 1299-1305
- 27 Uchida N, Sambe T, Yoneyama K. et al. A first-in-human phase 1 study of ACE910, a novel factor VIII-mimetic bispecific antibody, in healthy subjects. Blood 2016; 127 (13) 1633-1641
- 28 Colman RJ, Portocarrero-Castillo A, Chona D, Hellmann J, Minar P, Rosen MJ. Favorable outcomes and anti-TNF durability after addition of an immunomodulator for anti-drug antibodies in pediatric IBD patients. Inflamm Bowel Dis 2021; 27 (04) 507-515
- 29 Falsey A, Jo D, Sirak H. et al. Corticosteroids can be used to decrease antidrug antibodies in pediatric patients with inflammatory bowel disease. Inflamm Bowel Dis 2021; 27 (12) e159-e160