Interferon beta-1b is effective in Japanese RRMS patients - A randomized, multicenter study

Objective: To assess the efficacy of interferon beta-1b (IFNB-1b) in Japanese patients with relapsing-remitting multiple sclerosis (RRMS). Background: The effects of IFNB in RRMS have been assessed in study populations comprised predominantly of white patients. MS in Japanese patients is different from that in white patients in that there are two different presentations-classic MS (C-MS) and optic-spinal MS (OS-MS)-and chronic progressive forms are infrequent. Methods: A total of 205 Japanese patients with RRMS were randomized to receive 50 mug or 250 mug (1.6 or 8.0 MIU) IFNB- 1b administered SC every other day for up to 2 years. The primary endpoint was annual relapse rate. Secondary endpoints included further relapse-related and MRI outcome measures, as well as changes in Expanded Disability Status Scale and Neurologic Rating Scale. Efficacy was assessed in 188 patients, and safety was assessed in 192 patients. Supplemental ad hoc subgroup analyses were also performed for patients with OS-MS and those with C-MS. Results: Annual relapse rates were 0.763 in the 250 mug group and 1.069 in the 50 mug group, a relative reduction of 28.6% (p = 0.047). Results for all secondary endpoints favored 250 mug IFNB-1b. Subgroup analyses suggested that the magnitude and direction of treatment effect in patients with OS-MS and C-MS was similar, albeit not significant due to small sample size. Conclusions: Interferon beta-1b (IFNB-1b) 250 mug significantly reduced relapse rates and change in MRI lesion area in Japanese patients with relapsing-remitting multiple sclerosis, and seemed to be comparably effective in optic-spinal multiple sclerosis (MS) and classic MS. The response to treatment with IFNB- 1b in Japanese patients with MS suggests that a common pathogenesis and underlying genetic characteristics are shared with white patients.