Long-term evolution of anti-INFbeta antibodies in IFNbeta-treated MS patients: the London, Canada, MS Clinic experience.

Abstract

Interferon β-1b (IFNβ-1b) has been the first approved therapy to demonstrate efficacy in reducing frequency and severity of relapses and activity of MRI lesions in patients with relapsing multiple sclerosis (MS).1 Because binding antibodies and neutralizing antibodies (NAbs) have been identified in IFNβ-treated patients with MS,2 it has been observed that this development may reverse some clinical and MRI measures of IFN efficacy.2,3⇓ There is only limited and controversial information about the long-term persistence of NAb. We review our experience with NAb in a group of patients with MS receiving long-term IFNβ-1b treatment.4 IFNβ-1b was given regulatory approval in the spring of 1993 after the pivotal study in relapsing MS, in which 372 patients were randomized to receive the drug in either of two doses or placebo and were followed for 4 years.1,2⇓ Subsequently, all study patients were offered 8 MIU INFβ-1b subcutaneously on alternate days, and the majority of patients in our center have continued to take the drug. Serum was drawn from these patients every 3 months during the study and again during a subsequent review in the autumn of 1997. Binding antibody assays were performed in Vancouver using a noncompetitive ELISA.5 In addition, samples were coded and assayed by …