Natalizumab remains detectable in patients with multiple sclerosis long after treatment is stopped

Mult Scler. 2012 Jun;18(6):899-901. doi: 10.1177/1352458511431073. Epub 2011 Dec 19.


Natalizumab is frequently used as a treatment for multiple sclerosis (MS). The occurrence of progressive multifocal leukoencephalopathy (PML) in natalizumab-treated patients indicates that its prominent beneficial effects need to be balanced against the risks. Also, cessation of the drug seems to be associated with recurrence of disease activity. Both the moment of rebound disease activity and the outcome of PML are related to clearance of the drug. Specific features of this IgG4 antibody (i.e. half-antibody exchange) may result in underestimated drug levels. Here, we demonstrate natalizumab levels in 10 patients with relapsing MS, using a recently developed sensitive assay. Remarkably, natalizumab was detectable up to 200 days after cessation of therapy.

MeSH terms

  • Antibodies, Monoclonal, Humanized / administration & dosage
  • Antibodies, Monoclonal, Humanized / adverse effects
  • Antibodies, Monoclonal, Humanized / blood
  • Antibodies, Monoclonal, Humanized / pharmacokinetics*
  • Drug Administration Schedule
  • Humans
  • Immunoassay
  • Immunologic Factors / administration & dosage
  • Immunologic Factors / adverse effects
  • Immunologic Factors / blood
  • Immunologic Factors / pharmacokinetics*
  • Leukoencephalopathy, Progressive Multifocal / chemically induced
  • Multiple Sclerosis, Relapsing-Remitting / blood
  • Multiple Sclerosis, Relapsing-Remitting / drug therapy*
  • Natalizumab
  • Netherlands
  • Recurrence
  • Risk Assessment
  • Risk Factors
  • Sensitivity and Specificity
  • Time Factors
  • Treatment Outcome


  • Antibodies, Monoclonal, Humanized
  • Immunologic Factors
  • Natalizumab