Absence of MxA induction is related to a poor clinical response to interferon beta treatment in multiple sclerosis patients.

The aim of this study is to investigate whether induction of myxovirus resistance protein A (MxA) mRNA after 3 months of interferon-β administration is related to the treatment response in multiple sclerosis (MS) patients. In this prospective study, MS patients were enrolled before starting treatment. Demographic, clinical and radiological variables were recorded. Blood samples were obtained before, and at 3 and 12 months after interferon-β treatment. Real-time PCR was used to analyze MxA mRNA expression. Patients were classified as MxA-low or -high depending on MxA levels at baseline, and as MxA-induced or -non-induced according to whether an increase in MxA expression was detected at month 3. Time to the next relapse was investigated using Cox proportional hazards regression analysis. One hundred and four patients were selected and followed for a median of 2.2 years (IQR 1.6-3.5). On Cox regression analysis, a higher EDSS score before treatment (HR 1.57; 95 % CI 1.02-2.40; p = 0.039), MxA-high status at baseline (HR 2.71; 95 % CI 1.26-5.81; p = 0.010), and MxA-non-induced at month 3 (HR 2.49; 95 % CI 1.08-5.68; p = 0.031), were predictors of poor response to interferon-β in naïve MS patients. Patients showing a lower capacity for MxA induction following 3 months of interferon-β treatment are more likely to be non-responders to this therapy.