Long-term follow up of alemtuzumab-treated patients: a retrospective study in a Belgian tertiary care center.

BACKGROUND: Pivotal studies have reported a significant proportion of patients achieving no evidence of disease activity (NEDA) after 2 cycles of treatment with alemtuzumab (ATZ), that can be maintained for several years. Long-term real-world evidence regarding ATZ as well as subsequent treatment trajectories is still scarce.

OBJECTIVE: To analyze the effectiveness and safety of ATZ-treated patients in a tertiary care Belgian center.

METHODS: A retrospective cohort study including 32 patients treated with ATZ between 2015 and 2021 was performed.

RESULTS: 32 patients received 2 ATZ courses with a mean follow-up (FU) duration of 5.6 years (range: 2.25-8.2). 21.75% patients were treatment naïve. 40.5% were previously treated with natalizumab or fingolimod. NEDA-3 was achieved in 61.3-85% of patients, with failure mostly attributed to recurrence of radiological disease activity. During FU, annualized relapse rates remained very low (0.06-0.14), disability improvement occurred in up to 40.5%, whereas disability worsening occurred in up to 13.5%. Retreatment risk was associated with younger age (< 45 years old, Odds Ratio 8.0, p = 0.02) and a higher number of previous DMTs (Hazard ratio 2.7, 95%CI 1.3-7.4, p = 0.02). Safety in our cohort was consistent with the known profile of ATZ. At the end of FU, 65.6% patients remained untreated after 2 or 3 courses of ATZ, while the remaining switched to anti-CD20 therapy or cladribine.

CONCLUSION: ATZ is a high efficacy therapy for active MS, providing long-term remission in a significant proportion of patients. Retreatment was more frequent in younger patients or patients having failed a higher number of previous DMTs.