title: Prevalence of anti-drug antibodies against interferon beta has decreased since routine analysis of neutralizing antibodies became clinical practice.
abstract: BACKGROUND
  Neutralizing antibodies (NAbs) against interferon beta (IFNβ) lead to loss of treatment efficacy in multiple sclerosis patients. The seroprevalence of NAbs in multiple sclerosis patients treated with IFNβ during 2003-2004 was 32% in a cross-sectional analysis of routine data.
  
  
  OBJECTIVE
  The aim of this study was to investigate whether the seroprevalence of NAbs, the levels of NAb titres and the IFNβ preparations used for treatment of multiple sclerosis patients had changed in 2009-2010.
  
  
  METHODS
  This study included 1296 patients, analysed for NAbs with the myxovirus resistance protein A gene expression assay in 2009-2010.
  
  
  RESULTS
  The seroprevalence of NAbs had decreased to 19% in 2009-2010, which is significantly lower compared with the previous study in 2003-2004 (p<0.0001). This decrease was attributed to the IFNβ-1a preparations only, not to IFNβ-1b. The frequency of patients with high positive titres decreased the most, from 16% to 7% (p<0.0001).
  
  
  CONCLUSIONS
  NAb seroprevalence has decreased since NAb monitoring became clinical practice in 2003, especially for patients with high NAb titres. This might be due to the stricter monitoring of NAb titres that prompt NAb positive patients to stop treatment, to preferential use of less immunogenic drugs and to alteration of drug formulations.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Sweden.
authors.forename: Roger
authors.initials: R
authors.lastname: Jungedal
authors.forename: Malin
authors.initials: M
authors.lastname: Lundkvist
authors.forename: Elin
authors.initials: E
authors.lastname: Engdahl
authors.forename: Ryan
authors.initials: R
authors.lastname: Ramanujam
authors.forename: Helga
authors.initials: H
authors.lastname: Westerlind
authors.forename: Ajith
authors.initials: A
authors.lastname: Sominanda
authors.forename: Jan
authors.initials: J
authors.lastname: Hillert
authors.forename: Anna
authors.initials: A
authors.lastname: Fogdell-Hahn
mesh_terms: D057134:Antibodies, Neutralizing / Q000097:blood*; D006801:Humans; D007155:Immunologic Factors / Q000276:immunology* / Q000627:therapeutic use; D016899:Interferon-beta / Q000276:immunology* / Q000627:therapeutic use; D009103:Multiple Sclerosis / Q000097:blood* / Q000188:drug therapy / Q000276:immunology; D016036:Seroepidemiologic Studies
chemical_list: D057134:Antibodies, Neutralizing; D007155:Immunologic Factors; D016899:Interferon-beta