Magnetization transfer ratio in new MS lesions before and during therapy with IFNβ-1a

Objective: The authors examined the effect of 6.0 MIU interferon beta-1a (IFN beta-1a) administered IM each week on the evolution of monthly magnetization transfer ratio (MTR) within new gadolinium-enhancing (Gd+) lesions in patients with very early relapsing-remitting (RR) MS. Background: IFN beta is an effective disease-modifying treatment for patients with RRMS. Among other effects, it has been shown to decrease the number of new Gd+ and T2-weighted lesions. MTR is a putative marker for irreversible tissue damage and evolution of MTR within a lesion may reflect recovery of tissue damage. It is not known whether IFN beta-1a affects the recovery phase of lesions. Methods: Eight untreated patients with RRMS who completed up to 14 monthly brain MRI sessions elected to initiate treatment with IFN beta-1a. Four out of eight patients developed new Gd+ lesions during treatment. MTR of lesions at the time of appearance and subsequent rate of change of monthly MTR were compared before and after treatment (stratified Mann-Whitney test). Results: The difference between MTR at appearance of 47 new Gd+ lesions before treatment versus 23 new Gd+ lesions during treatment was not significant. Twenty-two of 47 new Gd+ lesions before treatment and 11 of 23 new Gd+ lesions after treatment were monitored for up to 6 months. After appearance of new Gd+ lesions, the rate of increase in MTR was faster during therapy (p = 0.037). Conclusion: MTR abnormalities within new Gd+ lesions evolve at a faster rate during treatment with IFN beta-1a than before initiating therapy. This is consistent with the hypothesis that IFN beta-1a promotes resolution of new Gd+ lesions.