Introduction: This post hoc subset analysis of RESPOND evaluated the effectiveness of dimethyl fumarate (DMF) 240 mg twice daily in patients with relapsing multiple sclerosis (RMS) after suboptimal response to glatiramer acetate (GA; "first switch" patients), including patients with early MS ("early MS switch" patients).
Methods: Patients had discontinued GA due to suboptimal response and initiated DMF treatment within 60 days after enrollment. Relapse data were collected from medical records. First switch patients had had one prior approved MS therapy (GA) before initiating DMF treatment. Early MS switch patients were first switch patients with baseline Patient-Reported Expanded Disability Status Scale (PR-EDSS) score ≤ 3.5, ≤ 1 relapses in the past 1 year, or both.
Results: Among first switch patients (n = 231), the annualized relapse rate (ARR) was 0.48 (95% confidence interval [CI] 0.40-0.58) for 12 months before DMF initiation and 0.11 (95% CI 0.06-0.18) for 12 months after DMF initiation, a 78% decrease in ARR. Among early MS switch patients with baseline PR-EDSS score ≤ 3.5 (n = 120), ≤ 1 relapses in the prior year (n = 219), or both (n = 114), the ARRs (95% CIs) for 12 months before DMF initiation were 0.47 (0.37-0.59), 0.37 (0.32-0.44), and 0.39 (0.31-0.49), respectively; values for 12 months after DMF initiation were 0.06 (0.02-0.19), 0.09 (0.05-0.17), and 0.06 (0.02-0.20), respectively, an 87, 75, and 83% decrease in ARR. The proportion of patients relapse-free 12 months after DMF initiation versus 12 months before were 94 versus 59% in first switch patients, and 97 versus 58%, 94 versus 63%, and 97 versus 61% in early MS switch patients in the PR-EDSS score ≤ 3.5, ≤ 1 relapses in the prior year, or PR-EDSS score ≤ 3.5 and ≤ 1 relapses subgroups, respectively. After 12 months of DMF treatment, most patient-reported outcomes scores showed significant improvement.
Conclusions: DMF may be an effective treatment option in first switch and early MS switch patients with RMS who experience a suboptimal response to GA.
Trial registration: ClinicalTrials.gov identifier: NCT01903291.
Keywords: Annualized relapse rate; Dimethyl fumarate; Glatiramer acetate; Patient-reported outcomes; Relapsing multiple sclerosis.