Background: Evidence suggests that Epstein-Barr virus (EBV) plays a role in triggering or perpet-

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BackgroundWalking impairment is a hallmark of multiple sclerosis (MS). It affects > 90% of individuals over time, reducing independence and negatively impacting health-related quality of life, productivity, and daily activities. Walking impairment is consistently reported as one of the most distressing impairments by individuals with MS. Prolonged-release (PR)-fampridine previously has been shown to improve objectively measured walking speed in walking-impaired adults with MS. The impact of PR-fampridine from the perspective of the individual with MS warrants full and detailed examination.ObjectiveThe objective of this study was to evaluate whether PR-fampridine has a clinically meaningful effect on self-reported walking ability in walking-impaired participants with MS.MethodsENHANCE was a phase III, randomized, double-blind, placebo-controlled study of PR-fampridine 10 mg twice daily in walking-impaired individuals age 18–70 years with either relapsing or progressive forms of MS and an Expanded Disability Status Scale (EDSS) score of 4.0–7.0 at screening. Participants were stratified by EDSS score (≤ 6.0 or 6.5–7.0) at randomization to ensure a balanced level of disability in the treatment groups. The primary endpoint was the proportion of participants with a mean improvement in the 12-item Multiple Sclerosis Walking Scale (MSWS-12) score exceeding the predefined threshold for clinically meaningful improvement (≥ 8 points) over 24 weeks. Secondary endpoints included the proportion with ≥ 15% improvement in Timed Up and Go (TUG) speed, and mean changes in Multiple Sclerosis Impact Scale physical impact subscale (MSIS-29 PHYS), Berg Balance Scale (BBS), and ABILHAND scores over 24 weeks.ResultsIn total, 636 participants with MS were randomized (PR-fampridine, n = 317; placebo, n = 319; modified intention-to-treat sample: PR-fampridine, n = 315; placebo, n = 318). At baseline in the PR-fampridine and placebo groups, 46% and 51% had a progressive form of MS, median [range] EDSS scores were 6.0 [4.0–7.0] and 5.5 [4.0–7.0], mean [range] MSWS-12 scores were 63.6 [0–100] and 65.4 [0–100], and mean [range] TUG speed was 0.38 [0.0–1.0] and 0.38 [0.0–1.2] feet/s, respectively. A significantly higher percentage of PR-fampridine-treated participants (136/315 [43.2%]) had clinically meaningful improvement in MSWS-12 score over 24 weeks versus placebo (107/318 [33.6%]; odds ratio 1.61 [95% confidence interval 1.15–2.26]; p = 0.006). For PR-fampridine versus placebo, significantly more participants had a ≥ 15% improvement in TUG speed, and there was significantly greater mean improvement in MSIS-29 PHYS score (p < 0.05); numerical improvements that were not statistically significant were observed in BBS/ABILHAND. Adverse events that were more common in the PR-fampridine group than placebo group (difference ≥ 3%) by Medical Dictionary for Regulatory Activities (MedDRA®) Preferred Term were urinary tract infection and insomnia. There were no seizures reported.ConclusionsPR-fampridine treatment resulted in sustained, clinically mea...