Background: In CARE-MS II (NCT00548405), alemtuzumab (two courses; 12 mg/day; baseline: 5 days; 12 months later: 3 days) significantly improved outcomes versus subcutaneous interferon beta-1a (SC IFNB-1a) in relapsing-remitting multiple sclerosis (RRMS) patients with inadequate response to prior therapy. In a 4-year extension (NCT00930553), patients could receive additional alemtuzumab courses (12 mg/day on 3 days; at least 12 months apart) as needed for disease activity or receive another disease-modifying therapy (DMT; investigator discretion); efficacy was maintained with 50% receiving no additional alemtuzumab or DMT through Year 6. Following this extension, patients could continue in TOPAZ (NCT02255656), an additional 5-year extension.

Objectives: Evaluate alemtuzumab efficacy/safety through Year 8 in CARE-MS II patients.

Methods: In TOPAZ, patients can receive as-needed alemtuzumab (at least 12 months apart) or receive another DMT.

Results: 300/435 (69%) patients completed TOPAZ Year 2 (Year 8 post-alemtuzumab); 44% received neither additional alemtuzumab nor another DMT. In Year 8, annualized relapse rate was 0.18; 85% were relapse-free. From baseline through Year 8, 70% had stable/improved EDSS, mean change in EDSS was +0.17, 64% were free from 6-month confirmed disability worsening, and 47% achieved 6-month confirmed disability improvement. In Year 8, 70% were free of magnetic resonance imaging (MRI) disease activity; 58% achieved no evidence of disease activity. Median percent cumulative brain volume loss from baseline through Year 8 was −1.06%. Safety remained consistent through Year 8.

Conclusion: Alemtuzumab efficacy and safety were maintained through Year 8 in the absence of continuous treatment, with 69% of patients completing Year 8 post-alemtuzumab and 44% receiving no additional treatment after the initial two courses.