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

Abstract 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.