Characteristics of Patients With Spinal Muscular Atrophy Who Have Switched Treatments: A Multi‐Center Experience in the United Kingdom

INTRODUCTION/AIMS: The evolving landscape of spinal muscular atrophy (SMA) treatment in the United Kingdom allows patients to switch, with health authority approval, from one treatment to another. This retrospective analysis explores the characteristics of pediatric patients across the United Kingdom who switched between available therapies that included nusinersen, risdiplam, and onasemnogene abeparvovec (OA). METHODS: Demographic data were collected, along with indicators of disease severity and motor function scores for all pediatric patients registered with the SMA REACH UK database who received nusinersen or risdiplam as initial treatments. RESULTS: Data were available for 375 patients across 19 sites. In total, 289 patients received nusinersen (of whom 21% switched to risdiplam and 16% to OA), and 86 patients received risdiplam (of whom 5% switched to OA). The top reported reasons for treatment changes were as follows: nusinersen to risdiplam: related to spine complexity (28/52), other difficulties related to administration (23/52); nusinersen to OA: parent preference (19/36), bridging to OA (14/36); risdiplam to OA: parent preference (2/2). After switching, no patients requested to go back to the initial treatment. No patients demonstrated deterioration beyond the expected disease trajectory prior to switching. DISCUSSION: The availability of treatments in the United Kingdom has fundamentally influenced treatment choices, but deterioration in a treatment was not identified as a factor in switching treatments. Further work will be needed to investigate the long-term trajectory of these patients.