BEAM/ATG or cyclophosphamide/ATG as conditioning regimen in autologous haemopoietic stem cell transplantation for multiple sclerosis: a retrospective analysis of the EBMT autoimmune diseases working party.

Multiple Sclerosis (MS) is the most frequent autoimmune disease (AD) treated with autologous hematopoietic stem cell transplantation (HSCT). There are no prospective trials comparing the most used conditioning regimens, BEAM/Anti-thymocyte globulin (ATG) and cyclophosphamide (CYC)/ATG. Herein, we report a retrospective analysis of the EBMT database aimed to assess their risk/benefit ratio. We included 1114 MS patients who were conditioned with either BEAM/ATG or CYC/ATG. Neutrophil engraftment in BEAM/ATG- and CYC/ATG-treated patients occurred at a median time of 11 and 10 days after HSCT (p = 0.079). Overall, 2.0% of patients conditioned with BEAM/ATG and 1.0% with CYC/ATG died within 100 days from HSCT (p = 0.19). Overall, the incidence of NEDA (No-Evidence of Disease Activity) failure in BEAM/ATG and CYC/ATG at 5 years was 42.3% (95% CI: 36.3-48.8%) and 44.1% (95% CI: 30.8-60.1%), respectively (p = 0.081). No statistically significant differences between the two treatments [HR = 0.90 (95% CI = 0.61; 1.34), p = 0.60] were confirmed, when adjusting for disease type, disability at baseline and year of transplant. A clear difference between the regimens is lacking, both in terms of toxicity and efficacy, in this large population. Type of disease (relapsing/remitting vs progressive) is still the major determinant of neurological outcome.