MxA protein - an interferon beta biomarker in primary progressive multiple sclerosis patients

Background and purpose: Interferon beta (IFN beta) preparations have some effect on the progressive phase of multiple sclerosis ( MS). This limited effect might be partially because of a certain number of IFN beta non-responders. Myxovirus resistance protein A (MxA)-a marker of IFN beta bioactivity - was correlated with the clinical response during an uncontrolled trial, investigating the safety of IFN beta-1 beta in primary progressive (PPMS) patients. Methods: Twenty PPMS were treated with IFN beta-1 beta (s.c.) for 1 year. Blood samples were taken before and 1, 2, 3, 6, 9, 12, and 15 months after treatment initiation and MxA protein levels were measured. Patients were clinically evaluated by EDSS and the more sensitive Incapacity Status Scale (ISS) and stratified in a stable and a progressing group. Results: Using ISS criteria, 11 patients remained stable and nine patients progressed during treatment. The mean area under the curve of log MxA levels during treatment were significantly higher in stable than in progressing patients (10.87 vs. 5.99; P = 0.002). Conclusion: A good biological response to IFNb might be associated with a better clinical effect of this drug and could be helpful in future clinical studies for early identification of treatment responders.