title: Use of a standardized MxA protein measurement-based assay for validation of assays for the assessment of neutralizing antibodies against interferon-β.
abstract: Effective monitoring of the development of neutralizing antibodies (NAbs) against IFN-β in multiple sclerosis (MS) patients on IFN-β therapy is important for clinical decision making and disease management. To date, antiviral assays have been the favored approach for NAb determination, but variations in assay conditions between laboratories and the increasing use of novel assays have contributed to the reporting of inconsistent antibody data between laboratories and between products. This study, undertaken at the request of the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA), is a joint effort by manufacturers of IFN-β products (approved in Europe) towards harmonization of a NAb assay that facilitates generation of comparable NAb data, which, in conjunction with clinical outcomes, should prove useful for clinicians treating MS patients with IFN-β products. This article describes the standardized cellular myxovirus resistance protein A (MxA) protein measurement-based assay for detection of IFN-β NAbs and its use for the validation of assays used for the quantitative determination of such antibodies. Although titers varied between laboratories and the products used, utilization of IFN-β1a rather than IFN-β1b as the challenge antigen produced more consistent results in the NAb assay. Adoption of the standardized assay improves comparability between laboratories circumventing problems that arise when different, nonstandardized assays are employed for immunogenicity assessment. Based on the data, the EMA recommended for standardization purposes, the use of IFN-β1a in NAb assays, independent of the therapeutic product used for therapy and validation of new NAb procedures against the standardized assay described.
authors.affiliation: 1 Biotherapeutics Group, National Institute for Biological Standards and Control , Hertfordshire, United Kingdom .
authors.forename: Meenu
authors.initials: M
authors.lastname: Wadhwa
authors.forename: Meena
authors.initials: M
authors.lastname: Subramanyam
authors.forename: Susan
authors.initials: S
authors.lastname: Goelz
authors.forename: Jaya
authors.initials: J
authors.lastname: Goyal
authors.forename: Vijay
authors.initials: V
authors.lastname: Jethwa
authors.forename: Wendy
authors.initials: W
authors.lastname: Jones
authors.forename: James G
authors.initials: JG
authors.lastname: Files
authors.forename: Daniel
authors.initials: D
authors.lastname: Kramer
authors.forename: Chris
authors.initials: C
authors.lastname: Bird
authors.forename: Paula
authors.initials: P
authors.lastname: Dilger
authors.forename: Michael
authors.initials: M
authors.lastname: Tovey
authors.forename: Christophe
authors.initials: C
authors.lastname: Lallemand
authors.forename: Robin
authors.initials: R
authors.lastname: Thorpe
mesh_terms: D057134:Antibodies, Neutralizing / Q000097:blood* / Q000276:immunology*; D006801:Humans; D016899:Interferon-beta / Q000097:blood* / Q000276:immunology* / Q000627:therapeutic use; D009103:Multiple Sclerosis / Q000097:blood* / Q000188:drug therapy / Q000276:immunology*; D064547:Myxovirus Resistance Proteins / Q000097:blood* / Q000276:immunology; D012015:Reference Standards
chemical_list: D057134:Antibodies, Neutralizing; C579071:MX1 protein, human; D064547:Myxovirus Resistance Proteins; D016899:Interferon-beta