Efficacy and safety of subcutaneous interferon beta-1a in relapsing-remitting multiple sclerosis: Further outcomes from the IMPROVE study

BACKGROUND: The IMPROVE study demonstrated that the fetal bovine serum (FBS)- and human serum albumin (HSA)-free formulation of subcutaneous (sc) interferon (IFN) beta-1a had beneficial effects on the numbers of combined unique active magnetic resonance imaging (MRI) lesions in relapsing-remitting multiple sclerosis (RRMS). Here we report additional MRI endpoints (including post hoc analyses), and clinical efficacy, safety, and immunogenicity outcomes. METHODS: Patients with active RRMS were randomized (2:1) to IFN beta-1a, 44 mcg sc three times weekly (tiw) (n=120), or placebo (n=60), for 16 weeks (double-blind phase). All patients then received IFN beta-1a, 44 mcg sc tiw, for 24 weeks (rater-blind phase). Patients underwent MRI brain scans every 4 weeks. RESULTS: Compared with placebo, there was a 68% reduction in the mean cumulative number of new gadolinium-enhancing lesions with IFN beta-1a as early as week 4 (p<0.001), and a 53% reduction in the mean cumulative number of new T2 lesions as early as week 8 (p=0.025; post hoc analyses). During the 16-week double-blind phase, the relapse rate was 0.14 (95% confidence interval [CI] 0.09-0.23) with IFN beta-1a and 0.33 (95% CI 0.22-0.52) with placebo (p=0.010). Safety outcomes were consistent with those expected with IFN-beta treatment. CONCLUSIONS: The FBS/HSA-free formulation of sc IFN beta-1a has a beneficial impact on MRI and efficacy outcomes as early as 4 weeks after treatment initiation in patients with RRMS and has a safety profile consistent with previous trials of sc IFN beta-1a.