Abstract
OBJECTIVE: To compare interferon β-1b (IFNβ-1b) and glatiramer acetate (GA) on new lesion (NL) (gadolinium-enhancing, new T2) evolution into permanent black holes (PBH)--a marker of irreversible tissue damage--in patients with relapsing-remitting multiple sclerosis (RRMS). METHODS: BEYOND was a large, phase III, clinical trial comparing IFNβ-1b 250 μg, IFNβ-1b 500 μg, and GA (2:2:1). Patient scans were reexamined post hoc for PBH in a rater-blinded manner. Two predefined coprimary endpoints compared IFNβ-1b 250 μg with GA: first, number of PBH per patient at year 2 evolving from year 1 NL, then proportion of year 1 NL evolving into PBH at year 2. IFNβ-1b 500 μg and GA were compared in an exploratory fashion. RESULTS: Approximately 90% (1,957/2,244) of patients had NL at year 1 with follow-up at year 2. Mean numbers of PBH per patient at year 2 evolving from year 1 NL were lower for IFNβ-1b 250 μg than GA (0.30 vs 0.43; p = 0.0451). The proportion of NL evolving into PBH was similar (IFNβ-1b 250 μg vs GA: 21.6% vs 23.5%; p > 0.20). For IFNβ-1b 500 μg, both the mean PBH number per patient at year 2 evolving from year 1 NL (0.26 vs 0.43; p = 0.0037) and proportion of NL evolving into PBH (16.3% vs 23.5%; p = 0.0409) were lower relative to GA. CONCLUSION: IFNβ-1b affected PBH development to a similar or better extent than GA. IFNβ-1b favorably influences an MRI outcome indicative of permanent tissue destruction in the brains of patients with multiple sclerosis. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that IFNβ-1b is associated with a reduction in MRI PBH formation and evolution compared with GA between years 1 and 2 of treatment.