Autologous hematopoietic stem cell transplantation is superior to alemtuzumab in patients with highly active relapsing multiple sclerosis and severe disability.

Objective: To assess the differences of treatment outcomes regarding disease activity in patients with highly active relapsing multiple sclerosis (RMS), treated with autologous hematopoietic stem cell transplantation (HSCT) or alemtuzumab (ATZ).

Methods: Open-label prospective single-center observational cohort study, enrolling patients with highly active RMS for treatment with ATZ or HSCT between 2014 and 2021.

Results: A total of 50 patients (31/50 (62 %) in HSCT vs 19/50 (38 %) in ATZ group) were included. There were no significant differences in relapse rate, MRI activity or disability worsening between the two study groups during the first two years after treatment onset. However, at 3 to 5 years follow-up, HSCT was superior to ATZ in all the aforementioned aspects. Kaplan-Meier analysis at 5 years post treatment revealed superiority of HSCT in relapse rate (69.6 % vs 95.7 %, p = 0.027), MRI activity (54.5 % vs 75.1 %, p = 0.038) and disability worsening (57.1 % vs 90.9 %, p =  0.031).

Conclusions: ATZ may halt disability progression early in the course of highly active RMS, but the disability starts accumulating later, while in HSCT patients disability improvement is consistent both 3 and 5 years after treatment onset.