Objectives: Evaluate the effects of alemtuzumab on relapse rate over time in the CARE-MS II study.
Methods: Active RRMS patients who had relapsed on prior therapy were randomized to receive alemtuzumab 12 mg intravenously on 5 days at study start and on 3 days 1 year later or SC IFNB-1a 44 µg 3-times weekly. Relapse events were required to last ≥48 h, required objective signs as assessed by blinded raters, and were adjudicated by an independent committee.
Results: Alemtuzumab’s superior effect on relapse reduction was statistically significant (P = 0.046) within 4 months of initiating treatment and was maintained throughout the study period. Compared with IFNB-1a, alemtuzumab reduced the relapse rate by 54% in Year 1 (P < 0.0001) and 41% in Year 2 (i.e., Months 12 to 24) (P = 0.0017). Percentage of patients experiencing relapse in the alemtuzumab group versus the IFNB-1a group were 12% vs 29% through Month 6, 24% vs 43% through Month 12, and 35% vs 51% through Month 24. Analysis of cumulative monthly relapses among patients receiving alemtuzumab showed that its effect on relapse rate was consistent throughout the 24 months of the study.
Conclusions: Alemtuzumab suppressed relapses more effectively than high-dose, high-frequency SC IFNB-1a in active RRMS patients who had experienced disease activity on previous therapy. The greater effect of alemtuzumab on relapse rate became significant within 4 months of treatment initiation and was durable throughout the 2-year study period.