Alemtuzumab for multiple sclerosis.

Background: Multiple sclerosis (MS) is an autoimmune, T-cell-dependent, inflammatory, demyelinating disease of the central nervous system, with an unpredictable course. Current MS therapies focus on treating and preventing exacerbations, and avoiding the progression of disability. At present, there is no treatment that is capable of safely and effectively reaching these objectives. Clinical trials suggest that alemtuzumab, a humanized monoclonal antibody, could be a promising option for MS.

Objectives: To evaluate the benefits and harms of alemtuzumab alone or associated with other treatments in people with any form of MS.

Search Methods: We used standard, extensive Cochrane search methods. The latest search date was 21 June 2022.

Selection Criteria: We included randomized controlled trials (RCTs) in adults with any subtype of MS comparing alemtuzumab alone or associated with other medications versus placebo; another active drug; or alemtuzumab in another dose, regimen, or duration.

Data Collection And Analysis: We used standard Cochrane methods. Our co-primary outcomes were 1. relapse-free survival, 2. sustained disease progression, and 3. number of participants experiencing at least one adverse event. Our secondary outcomes were 4. participants free of clinical disability, 5. quality of life, 6. change in disability, 7. fatigue, 8. new or enlarging lesions on resonance imaging, and 9. dropouts. We used GRADE to assess certainty of evidence for each outcome.

Main Results: We included three RCTs (1713 participants) comparing intravenous alemtuzumab versus subcutaneous interferon beta-1a for relapsing-remitting MS. Participants were treatment-naive (two studies) or had experienced at least one relapse after interferon or glatiramer (one study). Alemtuzumab was given at doses of 12 mg/day or 24 mg/day for five days at months 0 and 12, or 24 mg/day for three days at months 12 and 24. Participants in the interferon beta-1a group received 44 μg three times weekly. Alemtuzumab 12 mg: 1. may improve relapse-free survival at 36 months (hazard ratio [HR] 0.31, 95% confidence interval [CI] 0.18 to 0.53; 1 study, 221 participants; low-certainty evidence); 2. may improve sustained disease progression-free survival at 36 months (HR 0.25, 95% CI 0.11 to 0.56; 1 study, 223 participants; low-certainty evidence); 3. may make little to no difference on the proportion of participants with at least one adverse event at 36 months (risk ratio [RR] 1.00, 95% CI 0.98 to 1.02; 1 study, 224 participants; low-certainty evidence), although the proportion of participants with at least one adverse event was high with both drugs; 4. may slightly reduce disability at 36 months (mean difference [MD] -0.70, 95% CI -1.04 to -0.36; 1 study, 223 participants; low-certainty evidence). The evidence is very uncertain regarding the risk of dropouts at 36 months (RR 0.81, 95% CI 0.57 to 1.14; 1 study, 224 participants; very low-certainty evidence). Alemtuzumab 24 mg: 1. may improve relapse-free survival at 36 months (HR 0.21, 95% CI 0.11 to 0.40; 1 study, 221 participants; low-certainty evidence); 2. may improve sustained disease progression-free survival at 36 months (HR 0.33, 95% CI 0.16 to 0.69; 1 study, 221 participants; low-certainty evidence); 3. may make little to no difference on the proportion of participants with at least one adverse event at 36 months (RR 0.99, 95% CI 0.97 to 1.02; 1 study, 215 participants; low-certainty evidence), although the proportion of participants with at least one adverse event was high with both drugs; 4. may slightly reduce disability at 36 months (MD -0.83, 95% CI -1.16 to -0.50; 1 study, 221 participants; low-certainty evidence); 5. may reduce the risk of dropouts at 36 months (RR 0.08, 95% CI 0.01 to 0.57; 1 study, 215 participants; low-certainty evidence). For quality of life, fatigue, and participants free of clinical disease activity, the studies either did not consider these outcomes or they used different measuring tools to those planned in this review.

Authors' Conclusions: Compared with interferon beta-1a, alemtuzumab may improve relapse-free survival and sustained disease progression-free survival, and make little to no difference on the proportion of participants with at least one adverse event for people with relapsing-remitting MS at 36 months. The certainty of the evidence for these results was very low to low.