Subcutaneous interferon β-1a three times weekly and the natural evolution of gadolinium-enhancing lesions into chronic black holes in relapsing and progressive multiple sclerosis: Analysis of PRISMS and SPECTRIMS trials

Background Evolution of gadolinium-enhancing lesions into chronic black holes (CBH) may be reduced by interferon (IFN) therapy. Objective The objective of this paper is to assess the effect of IFN β-1a and placebo on CBH evolution and disability in patients with relapsing–remitting multiple sclerosis (RRMS), as well as CBH evolution in patients with secondary progressive multiple sclerosis (SPMS). Methods A post hoc, exploratory analysis of patients with RRMS and SPMS with monthly MRI scans (months –1 to 9) from two separate placebo-controlled clinical trials of IFN β-1a was conducted. Results In RRMS patients, the risk of ≥1 evolved CBH was lower for IFN β-1a versus placebo (odds ratio 0.42; p = 0.024); volume of newly evolved CBH was numerically reduced. A numerically higher proportion of patients with ≥1 evolving CBH vs no evolving CBH had confirmed three-month disability progression (four-year rate 55.8% vs 43.1%, respectively). Proportion of lesions evolving into CBH (patient level: 34.7% vs 12.6%, p