Optimizing IFN Beta - 1B Dose

BetaferonR is effective in reducing relapse rate and MRI T2-weighted lesion frequency in MS patients at the dose of 8 MIU on alternate days (THE IFNB MS Study Group, 1993). Relapse rate is reduced by 30-35% (The IFNB MS Study Group, 1993), MRI activity is decreased up to 100% in most cases (Stone et al 1995). In some patients, however, MRI activity still occurs or reappears during treatment (Stone et al 1995). MRI activity has been demonstrated to correlate with relapse occurrence (McFarland et al, 1992; Miller et al, 1996), and in some patients relapses still occur during IFN beta treatment. In other patients relapses may occur in association with the appearance, after 9-18 months of treatment, of anti-IFN beta NAB (The IFNB M S Study Group, 1995). This protocol hypothesizes that the dose of 12 MIU BetaferonR on alternate days has more pronounced MRI and clinical effects in MS patients than that of 8 MIU. MS patients who do not respond to 8 MIU may take advantage of a higher dose. We, therefore decided to assess MRI effects after increasing the Betaferon dose (12 MIU) in RRMS patients showing a residual MRI activity (at least one new Gd enhancing lesion) during six months of standard Betaferon dose treatment (8 MIU).