Clinical significance of neutralizing antibodies to interferon beta in patients with Multiple Sclerosis

Abstract Development of neutralizing antibodies (NAbs) is a major problem in relapsing-remitting Multiple Sclerosis (RRMS) patients treated with interferon-beta (IFN-b). NAbs against IFN-b are associated with a loss of bioactivity and decreased clinical efficacy of the drug. The objective of this study was to evaluate the clinical significance of NAbs to IFN-b in RRMS patients receiving three different types of this drug including: CinnoVex, Rebif, and Betaferon. The NAbs against IFN-b were measured in 31 RRMS patients receiving at least 12 months of IFN-b using a MxA gene expression assay (real-time RT-PCR). Expanded Disability Status Scale (EDSS) scores and relapse were analyzed using the results of NAbs assays. Of the 31 RRMS patients receiving IFN-b, 25 (80.6 %) showed NAbs after 12 months of treatment. There was no significant difference in the number of relapse (P = 0.1) and EDSS (P = 0.9) among three groups, but there was statistically significant difference in duration of treatment (P = 0.017) among three groups. In conclusion, samples showing NAb positivity failed to be associated with worsening of symptoms based on the EDSS of patients. It also can be concluded that development of Nabs should not be predicted by response of patients to treatment.