Background: Neutralizing antibodies (NAb) affect efficacy of interferon-beta (IFN-b) treatment in multiple sclerosis (MS) patients. NAbs evolve in up to 44% of treated patients, usually between 6-18 months on therapy.
Objectives: To investigate whether early binding antibody (BAb) titers or different IFN-b biomarkers predict NAb evolution.
Methods: We included patients with MS or clinically isolated syndrome (CIS) receiving de novo IFN-b treatment in this prospective European multicenter study. Blood samples were collected at baseline, before and after the first IFN-b administration, and again after 3, 12 and 24 months on that therapy; for determination of NAbs, BAbs, gene expression of MxA and protein concentrations of MMP-9, TIMP-1, sTRAIL, CXCL-10 and CCL-2.
Results: We found that 22 of 164 (13.4%) patients developed NAbs during a median time of 23.8 months on IFN-b treatment. Of these patients, 78.9% were BAb-positive after 3 months. BAb titers ≥ 1:2400 predicted NAb evolution with a sensitivity of 74.7% and a specificity of 98.5%. Cross-sectionally, MxA levels were significantly diminished in the BAb/NAb-positive samples; similarly, CXCL-10 and sTRAIL concentrations in BAb/NAb-positive and BAb-positive/NAb-negative samples, respectively, were also diminished compared to BAb/NAb-negative samples.
Conclusions: BAb titers reliably predict NAbs. CXCL-10 is a promising sensitive biomarker for IFN-b response and its abrogation by anti-IFN-b antibodies.
Keywords: Binding antibody; CXCL-10; biomarker; clinically-isolated syndrome; drug resistance; interferon-beta; multicenter study; multiple sclerosis; myxovirus protein A; neutralizing antibody; sTRAIL.