Risdiplam in non-sitter patients aged 16 years and older with 5q spinal muscular atrophy

Introduction/AimsRisdiplam has been approved for the treatment of patients with 5q spinal muscular atrophy (SMA), but data from type 2 non-sitter patients are lacking. In this study we describe our experience regarding the use of risdiplam in a series of type 2 non-sitter patients. MethodsType 2 SMA patients over 16 years of age were administered risdiplam through the expanded access program (NCT04256265). Patients were followed-up with a battery of scales and clinical measures. ResultsSix non-sitter patients (17 to 46 years old) were treated with risdiplam. One patient reported mild adverse events (dyspepsia and headache). After 1 year of treatment, all patients showed clinically meaningful improvements in at least one scale and none of them showed any clinically meaningful deterioration. Two patients showed a clinically meaningful increase in body mass index (>5%) and two others scored higher on the Revised Upper Limb Module (>2 points). Moreover, five patients had clinically meaningful improvements on the Egen Klassifikation 2 scale (>2 points), including the motor (axial and upper limbs), bulbar (speech and swallowing), and respiratory (coughing) domains. Four subjects achieved at least one of the goals set with the Goal Attainment Scale (GAS). DiscussionThis series suggests that risdiplam is safe and may be effective in non-sitter SMA patients older than 16 years of age. In these patients, functional scales and the GAS would be more sensitive than motor scales to detect changes, because they include axial, bulbar, and respiratory domains. Larger studies are needed to confirm these results.