Cumulative effect of a weekly low dose of interferon beta Ist on standard and triple dose contrast-enhanced MRI from multiple sclerosis patients

In patients with multiple sclerosis (MS), we assessed the short- and long-t erm effects of a weekly low dose of recombinant human interferon beta 1a (r h-IFN beta 1a) on the development of new magnetic resonance imaging (MRI) l esions enhancing at different gadolinium-DTPA (Gd) doses. Every 4 weeks, st andard dose (SD) (0.1 mmol/kg of Gd) and triple dose (TD) (0.3 mmol/kg of G d) Gd-enhanced brain MRI scans were obtained from 18 patients with relapsin g-remitting MS for 3 months before treatment, 4 months after treatment init iation (treatment period [TP] I) and 4 months after 1 year of treatment (TP II) with 44 mu g of rh-IFN beta la subcutaneously, once a week The mean nu mbers of new enhancing lesions/patient/month were 1.4 (baseline), 1.1 (TP I ) and 0.7 (TP II) on SD scans and 2.4 (baseline), 1.3 (TP I) and 0.8 (TP II ) on TD scans. On average, treatment decreased the rate of new enhancing le sion appearance by 24% (SD scans) and 45% (TD scans) during TP I and by 52% (SD scans) and 66% (TD scans) during TP Il. This study indicates that the effect of 44 mu g of rh-IFN beta 1a given once a week on MRI-monitored MS a ctivity increases over time. It also suggests that TD MRI is useful in dete cting early treatment effect, that would otherwise be missed. (C) 1999 Else vier Science BN. All rights reserved.