Early MRI activity predicts treatment nonresponse with intramuscular interferon beta-1a in clinically isolated syndrome.

Objective: Determine whether MRI activity 6 months after treatment initiation in the Controlled High-Risk Subjects Avonex® Multiple Sclerosis Prevention Study (CHAMPS) predicted progression to clinically definite multiple sclerosis (CDMS) over the subsequent 30 months in intramuscular interferon beta-1a (IM IFNβ-1a)-treated patients vs placebo-treated patients.

Methods: CHAMPS patients were randomized to once-weekly IM IFNβ-1a 30 μg or placebo for up to 36 months. MRI was performed every 6 months until CDMS confirmation. Patient groups were defined based on new T2 and/or Gd+ lesions at 6 months.

Results: Thirteen IM IFNβ-1a patients (6.7%) and 24 placebo patients (12.6%) developed CDMS prior to month 6 and did not undergo the 6-month MRI. At 6 months, 29.7% of IM IFNβ-1a-treated patients vs 40.9% of placebo-treated patients were defined as having high MRI activity levels (≥2 new T2 and/or ≥2 Gd+ lesions). In this subgroup, estimated cumulative probabilities of CDMS were similar between groups (HR=0.88 [0.44-1.77], p=0.7227). A significant treatment response was seen for patients with <2 new T2 and <2 Gd+ lesions at 6 months (HR=0.39 [0.19-0.82], p=0.0120).

Conclusion: MRI scans 6 months after IM IFNβ-1a initiation in CIS patients predict early treatment non-response. Standardized scanning and monitoring may facilitate early disease management.