Efficacy and safety of alemtuzumab treatment in a real-world cohort of patients with multiple sclerosis.

: Alemtuzumab is a monoclonal anti-CD52 antibody prescribed to treat relapsing-remitting multiple sclerosis (RRMS). Alemtuzumab affects the balance of the immune system by depleting circulating lymphocytes, leading to the formation of a new immune repertoire less likely to induce autoimmune attack against CNS myelin. We collected real-world data of RRMS patients treated with alemtuzumab. We assessed relapse rate, disability progression, and MRI-related disease activity over a 24 month period. Our study included 35 RRMS patients (19 female and 16 male) with a mean age of 37.3 years (SD = 10.5). The patient cohort had a mean disease duration of 10.4 years, median previous disease modifying treatments (DMTs) of 3.0, and a median expanded disability status scale (EDSS) score of 4.0 (IQR 2.5-6.0). Neurological disability remained stable during treatment and there was no statistically significant change in EDSS score. Prior to treatment, the median relapse rate was 2.0 (IQR 1.0-3.0); after treatment the median relapse rate was 0.0. This 2.0 decrease in relapse rate is statistically significant (p < 0.0001). Moreover, the treated patients exhibited a statistically significant decrease in gadolinium (GD) enhancing lesions on MRI [both in number (p < 0.005) and volume (p < 0.005)]. Thirty-three percent of patients reached NEDA-3 (no evidence of disease activity) status by the end of treatment. In a real-world setting, alemtuzumab treatment significantly decreased relapse rate and GD-enhancing lesions while preventing disability progression. Tolerability of treatment was high, with patients experiencing only minor adverse events.