Autologous haematopoietic stem cell transplantation for multiple sclerosis in the <scp>UK</scp>: A 20‐year retrospective analysis of activity and haematological outcomes from the British Society of Blood and Marrow Transplantation and Cellular Therap

Autologous haematopoietic stem cell transplantation (AHSCT) has been developed as a treatment for multiple sclerosis (MS) since 1995. The United Kingdom is one of the most active countries performing AHSCT for MS in Europe. We report the UK experience of AHSCT for MS in 364 patients with MS treated with AHSCT between 2002 and 2023. We report transplant-related mortality (TRM), AHSCT complications and efficacy as defined by expanded disability status scale (EDSS) progression-free survival (PFS) at 2 years and 5 years. 209 (58%) had relapsing-remitting MS (RRMS) and 130 (36%) had progressive MS. Median EDSS at the time of HSCT was 6.0 (range: 0-9) and duration of disease was 10 years (range: 4-34). TRM was 1.4%, exclusively occurred in patients with advanced baseline disability (median EDSS: 6.5). Epstein-Barr virus (EBV) reactivation occurred in 75.9% of patients where EBV results were reported (235/311). Overall PFS was 83.5% at 2 years post-HSCT and 62.4% at 5 years. This large study demonstrates the evolution of this one-off treatment across the United Kingdom, its safety and sustained efficacy in patients with severe/refractory MS. The uneven geographical access is a future consideration in equitable delivery across the UK NHS as the evidence base for AHSCT in MS treatment pathways becomes stronger.