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Hamedani NS, Donners AAMT, van Luin M, Gasper S, Rühl H, Klein C, Albert T, El Amrani M, Pötzsch B, Oldenburg J, Müller J. Functional determination of emicizumab in presence of factor VIII activity. J Thromb Haemost 2023; 21:3490-3500. [PMID: 37741510 DOI: 10.1016/j.jtha.2023.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 09/25/2023]
Abstract
BACKGROUND Accurate measurement of emicizumab in the presence of factor (F) VIII is required in patients with severe hemophilia A treated with emicizumab, as well as additional need for FVIII substitution or emicizumab prophylaxis in patients with acquired or moderate to mild hemophilia A. However, the presence of FVIII potentially biases the results. OBJECTIVES To assess the impact of plasma FVIII activity on determined emicizumab levels and evaluate different strategies for correction for or preanalytical inhibition of FVIII. METHODS Evaluated strategies comprised of the following: (1) calculation of actual emicizumab plasma levels based on measured FVIII activities and FVIII-affected emicizumab values, (2) preanalytical heat treatment (56 °C for 40 minutes), and (3) neutralization of FVIII activity using FVIII inhibitors. Emicizumab levels and FVIII activities were measured using a modified FVIII one-stage clotting assay and a chromogenic FVIII assay based on bovine factors, respectively. RESULTS Spiking experiments revealed a consistent linear association between FVIII activities and determined (FVIII-affected) emicizumab results at different emicizumab input levels (∼0.12 μg/mL per IU/dL of FVIII). This principally allowed for mathematical correction of measured emicizumab levels in the presence of FVIII. While a 40% to 50% activity loss of intrinsic plasma emicizumab through heat treatment was observed in patient samples, emicizumab spiked into FVIII-deficient plasma was not or only marginally affected. Application of inhibitor-based FVIII neutralization led to good agreement of results when compared with direct quantification of emicizumab by liquid chromatography-tandem mass spectrometry. CONCLUSION Inhibitor-based FVIII neutralization appears to be a feasible strategy for accurate measurement of plasma emicizumab levels in the presence of FVIII activity.
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Affiliation(s)
- Nasim Shahidi Hamedani
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany
| | - Anouk Anna Marie Therese Donners
- Department of Clinical Pharmacy, Division Laboratories, Pharmacy and Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Matthijs van Luin
- Department of Clinical Pharmacy, Division Laboratories, Pharmacy and Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Simone Gasper
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany
| | - Heiko Rühl
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany
| | - Claudia Klein
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany
| | - Thilo Albert
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany
| | - Mohsin El Amrani
- Department of Clinical Pharmacy, Division Laboratories, Pharmacy and Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bernd Pötzsch
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany
| | - Johannes Oldenburg
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany
| | - Jens Müller
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany.
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Meijer P, Peyvandi F, Young G, Pruthi R, de Lima Montalvão S, Kitchen S. International Council for Standardization in Haematology recommendations for laboratory measurement of factor VIII and FIX type I inhibitors. Int J Lab Hematol 2023; 45:413-424. [PMID: 37287431 DOI: 10.1111/ijlh.14109] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 05/12/2023] [Indexed: 06/09/2023]
Abstract
This guidance document has been prepared on behalf of the International Council for Standardisation in Hematology. The aim of the document is to provide guidance and recommendations on the measurement of factor VIII (FVIII) and factor IX (FIX) inhibitors. After an introduction on the clinical background and relevance of factor VIII and factor IX inhibitor testing, the following aspects of laboratory testing are included: screening for inhibitors, assay principle, sample requirements, testing requirements and interpretation, quality assurance, interferences and recent developments. This guidance document focusses on recommendations for a standardised procedure for the laboratory measurement of FVIII and FIX type I inhibitors. The recommendations are based on published data in peer-reviewed literature and expert opinion.
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Affiliation(s)
- Piet Meijer
- ECAT Foundation, Voorschoten, The Netherlands
| | - Flora Peyvandi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
| | - Guy Young
- Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, California, USA
| | - Rajiv Pruthi
- Division of Hematology and Hematopathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Silmara de Lima Montalvão
- Laboratory Hemostasis, Hematology and Hemotherapy Center, University of Campinas UNICAMP, Campinas, São Paulo, Brazil
| | - Steve Kitchen
- Sheffield Haemophilia and Thrombosis Centre, Sheffield, UK
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Yoshimura T, Furukawa S, Oda A, Matsumoto T, Sasai K, Shima M, Nogami K. Longitudinal profiling of anti-factor VIII antibodies in Japanese patients with congenital hemophilia A during factor VIII replacement and immune-tolerance induction therapy. Int J Hematol 2022; 116:423-433. [PMID: 35503593 DOI: 10.1007/s12185-022-03359-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/14/2022] [Accepted: 04/14/2022] [Indexed: 10/18/2022]
Abstract
When patients with hemophilia A develop factor VIII (FVIII) inhibitors, FVIII replacement therapy becomes ineffective. Although immune-tolerance induction (ITI) therapy has been used to eradicate inhibitors, treatment is unsuccessful in approximately 30% of cases. However, the mechanism behind treatment failure remains unclarified. We retrospectively examined the longitudinal profiles of immunoglobulin G (IgG) subclasses and/or the inhibitory activities of FVIII in plasma samples from 14 Japanese patients with congenital hemophilia A during hemostatic, FVIII replacement, and/or ITI therapies. In five patients, an increase in IgG4 was observed simultaneously with a decrease in IgG1 when the patient had a history of relatively high FVIII inhibitor titers, reflecting an apparent change in humoral immunity. In addition, we examined the reactivity and specificity of the patients' anti-FVIII IgG1 and IgG4 to FVIII domains by immunoblotting. Under our experimental conditions, plasma from three patients with historically higher inhibitor titers appeared to have high titers of antibodies against the A2-a2 domain, which did not necessarily correlate with ITI failure. These observations may improve scientific understanding of the immune response to infused FVIII in patients with hemophilia A.
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Affiliation(s)
- Takuji Yoshimura
- Department of Pediatrics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-0813, Japan.
| | - Shoko Furukawa
- Department of Pediatrics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-0813, Japan. .,Department of Thrombosis and Hemostasis Molecular Pathology, Nara Medical University, Kashihara, Nara, Japan.
| | - Akihisa Oda
- Department of Pediatrics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-0813, Japan
| | - Tomoko Matsumoto
- Department of Pediatrics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-0813, Japan.,Tenri School of Medical Technology, Tenri, Nara, Japan
| | - Kana Sasai
- Department of Pediatrics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-0813, Japan
| | - Midori Shima
- Department of Pediatrics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-0813, Japan.,The Center of Thrombosis and Hemostasis, Nara Medical University, Kashihara, Nara, Japan
| | - Keiji Nogami
- Department of Pediatrics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-0813, Japan
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Batty P, Riddell A, Kitchen S, Sardo Infirri S, Walker I, Woods T, Jennings I, Hart DP. Factor VIII/IX inhibitor testing practices in the United Kingdom: Results of a UKHCDO and UKNEQAS national survey. Haemophilia 2021; 27:490-499. [PMID: 33650732 DOI: 10.1111/hae.14158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/07/2020] [Accepted: 09/03/2020] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Inhibitor formation is the greatest challenge facing persons with haemophilia treated with factor concentrates. The gold standard testing methodologies are the Nijmegen-Bethesda assay (NBA) for FVIII and Bethesda assay (BA) for FIX inhibitors, which are affected by pre-analytical and inter-laboratory variability. AIMS To evaluate inhibitor testing methodology and assess correlation between self-reported and actual methodology. METHODS Methodology was evaluated using a survey distributed alongside a UK National External Quality Assessment Service Blood Coagulation external quality assurance (EQA) exercise for FVIII and FIX inhibitor testing. RESULTS Seventy four survey and EQA exercise responses were received (response rate 63.2%), with 50 paired survey/EQA results. 47.1% (33/70) reported using the NBA and 42.9% (30/70) the BA for FVIII inhibitor testing. Review of FVIII inhibitor assay methodology demonstrated discrepancy (self-reported to actual) in 64.3% (BA reporting) and 27.6% (NBA reporting). Pre-analytical heat treatment was used by 32.4%, most commonly 56°C for 30 minutes. Assay cut-offs of 0.1-1.0 BU/mL were reported. EQA samples (acquired FVIII and congenital FIX) demonstrated titres and coefficients of variation (CV) of 3.1 BU/mL (0.7-15.4 BU/mL; CV = 43%) and 18.0 BU/mL (0-117 BU/mL; CV = 33%), respectively. No significant assay or laboratory factors were found to explain this variance, which could have resulted in change in management for 6 patients (5 misclassified high-titre FVIII inhibitors and 1 false negative for a FIX inhibitor). CONCLUSIONS Heterogeneity was seen at each stage of assay methodology. No assay-related factors were found to explain variation in inhibitor titres. Further standardization is required to improve inhibitor quantification to guide patient care.
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Affiliation(s)
- Paul Batty
- The Royal London Hospital Haemophilia Centre, Barts and The London School of Medicine and Dentistry, QMUL, London, UK
| | - Anne Riddell
- Katharine Dormandy Haemophilia Centre and Thrombosis Unit, Royal Free Hospital, London, UK
| | | | - Sofia Sardo Infirri
- The Royal London Hospital Haemophilia Centre, Barts and The London School of Medicine and Dentistry, QMUL, London, UK
| | | | - Tim Woods
- UK NEQAS (Blood Coagulation), Sheffield, UK
| | | | - Daniel P Hart
- The Royal London Hospital Haemophilia Centre, Barts and The London School of Medicine and Dentistry, QMUL, London, UK
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Chan AK, Alamelu J, Barnes C, Chuansumrit A, Garly M, Meldgaard RM, Young G. Nonacog beta pegol (N9-GP) in hemophilia B: First report on safety and efficacy in previously untreated and minimally treated patients. Res Pract Thromb Haemost 2020; 4:1101-1113. [PMID: 33134776 PMCID: PMC7590314 DOI: 10.1002/rth2.12412] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 06/11/2020] [Accepted: 06/13/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND/OBJECTIVE We report the first analysis of an extended half-life recombinant factor IX, nonacog beta pegol (N9-GP), in previously untreated patients (PUPs) and minimally treated patients with hemophilia B. METHODS Paradigm 6 (Safety and Efficacy of Nonacog Beta Pegol [N9-GP] in Previously Untreated Patients With Haemophilia B) is a multicenter, open-label, single-arm, phase 3 trial. Main inclusion criteria were males aged < 6 years, with hemophilia B with factor IX (FIX) activity ≤ 2%, who were previously untreated or with ≤ 3 exposure days (EDs) to FIX-containing products. Patients received N9-GP 40 IU/kg once weekly (prophylaxis) or individualized dosing (preprophylaxis). Bleeds were treated with N9-GP 40 IU/kg (80 IU/kg if severe). The primary end point was incidence of anti-FIX inhibitory antibodies (inhibitors). Secondary end points included safety outcomes and annualized bleeding rate (ABR). RESULTS At data cutoff (August 31, 2018), 38 patients had been screened, and 37 had received N9-GP (median age, 1.0 years [range, 0-4]). Total in-trial EDs amounted to 2833, representing ~ 65 patient-years. Two (6.1%) of 33 "at-risk" patients (patients with ≥ 10 EDs plus patients who developed inhibitors) developed high-titer inhibitors and were withdrawn. No other safety concerns, including thromboembolic events, were identified. In the prophylaxis group (n = 28), 67.9% were bleed free; all bleeds (n = 15) were treated with one N9-GP injection; and overall, spontaneous, and traumatic ABRs were low (median ABRs of 0.0, 0.0, and 0.0, respectively; modeled mean ABRs of 0.31, 0.08, and 0.23, respectively). Estimated mean FIX trough activity was 15.0%. CONCLUSION We report an inhibitor incidence of 6.1%, which is within the expected range for PUPs with hemophilia B. No other safety concerns were identified; moreover, N9-GP provided effective hemostatic coverage.
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Affiliation(s)
- Anthony K. Chan
- McMaster Children’s Hospital/McMaster UniversityHamiltonONCanada
| | | | - Chris Barnes
- The Royal Children’s HospitalMelbourneVICAustralia
| | | | | | | | - Guy Young
- Children’s Hospital Los AngelesUniversity of Southern California Keck School of MedicineLos AngelesCAUSA
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Sahud M, Zhukov O, Naides SJ, Serrano C, Wong E, Dlott J, Racke F. The rapid Bethesda assay is equivalent to the standard Bethesda assay for detection of factor IX inhibitors in patients with severe haemophilia B. Haemophilia 2020; 26:735-740. [PMID: 32420682 DOI: 10.1111/hae.14028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/28/2020] [Accepted: 04/20/2020] [Indexed: 06/11/2023]
Abstract
INTRODUCTION The time-dependent nature of factor VIII (FVIII) inhibitors is well described, and the standard FVIII Bethesda assay used to measure inhibitors incorporates a 2-hour incubation. Despite case reports and reviews describing the immediate-acting nature of factor IX (FIX) inhibitors, many coagulation laboratories continue to use a traditional prolonged incubation for FIX Bethesda assays. To our knowledge, a comprehensive evaluation of the FIX Bethesda assay without incubation has not been reported. AIM The goal of this study was to evaluate the performance of a rapid FIX Bethesda (ie no incubation) compared with the standard Bethesda assay (2-hour incubation). METHODS The analysis used a Bethesda assay configured for either immediate testing or a 2-hour incubation. Samples from 14 haemophilia B patients with inhibitors and 9 non-human controls were tested. RESULTS The two assays yielded similar performance overall. The average per cent difference in inhibitor titre between the rapid and standard FIX Bethesda assay was -3% (range -15% to +13%; P = .175) for patient samples and -2% (range -17% to +14%; P = .376) for controls. CONCLUSION The rapid Bethesda assay showed good agreement with the standard Bethesda assay for determination of inhibitor levels in patients with severe haemophilia B. The rapid assay allows for faster assessment of inhibitors in patients with severe haemophilia B and has the potential to improve the ability of the coagulation laboratory to perform testing from a logistical viewpoint. Further studies involving larger numbers of patients would be important to confirm our findings.
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Miller CH. Laboratory testing for factor VIII and IX inhibitors in haemophilia: A review. Haemophilia 2018; 24:186-197. [PMID: 29446525 PMCID: PMC6033270 DOI: 10.1111/hae.13424] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2017] [Indexed: 12/13/2022]
Abstract
Inhibitors are antibodies directed against haemophilia treatment products which interfere with their function. Factor VIII (FVIII) inhibitors in haemophilia A and factor IX (FIX) inhibitors in haemophilia B are significant clinically when they require a change in a patient's treatment regimen. Their persistence may increase morbidity and mortality. Multiple laboratory tests are now available for detecting and understanding inhibitors in haemophilia. Inhibitors are traditionally measured by their interference in clotting or chromogenic factor assays. They may also be detected using immunologic assays, such as enzyme-linked immunosorbent assay or fluorescence immunoassay. Anti-FVIII or anti-FIX antibodies of IgG4 subclass best correlate with the presence of functional inhibitors. Improvements in inhibitor measurement have been recently introduced. Preanalytical heat treatment of patient specimens allows testing of patients without delaying treatment. Use of chromogenic and immunologic assays may aid in identification of false-positive results, which are frequent among low-titre inhibitors. Validated reagent substitutions can be used to reduce assay cost. New methods for defining assay positivity and reporting low-titre inhibitors have been suggested. Challenges remain in the areas of quality control, assay standardization, monitoring of patients undergoing immune tolerance induction therapy and testing in the presence of modified and novel treatment products.
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Affiliation(s)
- C H Miller
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA, USA
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