Objective: To investigate the relationship between neutralizing antibodies (NAB) and disease progression, relapses, and MR measures of MS.
Methods: Sequential serum samples from all 718 patients of the European Study Group in Interferon beta-1b in Secondary Progressive MS were analyzed to investigate relations between NAB and disease progression, relapses, and MR measures.
Results: This study showed no attenuating effect of NAB development on progression in disability. The effects of NAB on relapse rate showed substantial variation, depending on the statistical approach and definition of positivity, though analyses comparing low- and high-NAB+ periods with NAB- periods suggested a titer-related effect. MR T2 lesion volume changes from baseline were significantly higher for NAB+ patients but remained lower than for placebo patients. A substantial proportion of NAB+ patients became NAB-. No untoward effect of NAB development on safety was observed.
Conclusion: These results support the conclusion that even though high NAB titers appear to have impact on treatment efficacy with respect to relapses, treatment decisions should be based primarily on clinical grounds.