BEAM or cyclophosphamide in autologous haematopoietic stem cell transplantation for relapsing-remitting multiple sclerosis.

The most widely used conditioning regimens in autologous haematopoietic stem cell transplantation (ASCT) for multiple sclerosis (MS) are BEAM with anti-thymocyte globulin (ATG) and high-dose cyclophosphamide with ATG (Cy/ATG). In this retrospective study, we compare efficacy and safety of these regimens when used for relapsing-remitting MS. We assessed 231 patients treated in Sweden before January 1, 2020. The final cohort comprised 33 patients treated with BEAM/ATG and 141 with Cy/ATG. Prospectively collected data from the Swedish MS registry were used for efficacy, and electronic health records for procedure-related safety. The Kaplan-Meier estimate of 'no evidence of disease activity' (NEDA) at 5 years was 81% (CI 68-96%) with BEAM/ATG and 71% (CI 63-80%) with Cy/ATG, p = 0.29. Severe adverse events were more common with BEAM/ATG, mean 3.1 vs 1.4 per patient, p = <0.001. Febrile neutropaenia occurred in 88% of BEAM/ATG patients and 68% of Cy/ATG patients, p = 0.023. Average hospitalisation was 3.0 days longer in BEAM/ATG patients from day of stem-cell infusion, p < 0.001. While both regimens showed similar efficacy, BEAM/ATG was associated with more severe adverse events and prolonged hospitalisation. In the absence of randomised controlled trials, Cy/ATG may be preferable for ASCT in patients with relapsing-remitting MS due to its favourable safety profile.