Risdiplam therapy in adults with 5q-SMA: observational study on motor function and treatment satisfaction

Background: We aimed to describe the experience of a single neuromuscular center in Germany in treating adult spinal muscular atrophy (SMA) patients with risdiplam and to analyze motor function and treatment satisfaction during a follow-up period up to 20 months.

Methods: Fourteen patients with type 2 or 3 SMA (seven with SMA type 2, six with SMA type 3; age range: 18-51) were included. The Revised Upper Limb Module (RULM) and the Hammersmith Functional Motor Scale Expanded (HFMSE) were recorded at baseline and at follow-up (month 4, 8, 12, 16, 20). Treatment adverse events were collected at every follow-up visit. Patients' treatment satisfaction was assessed by the Treatment Satisfaction Questionnaire for Medication (TSQM).

Results: Half of the patients reached the 20-month follow-up. Based on the HFMSE score, no patients had clinically meaningful improvement. Twelve remained stable (92.3%), two showed transient clinically meaningful deterioration (15.4%) and one experienced lasting clinically meaningful deterioration (7.7%). Based on the RULM scores, seven patients were either stable or demonstrated clinically meaningful improvement (53.8%) and six showed clinically meaningful deterioration (46.2%). There was no treatment withdrawal during the follow-up. The most common adverse events were skin rash/increased skin sensitivity to sunlight (n = 3), diarrhea (n = 3), aphthous ulcer (n = 3) and abdominal pain (n = 2). Most patients stated to be at least "satisfied" with the medication.

Conclusions: Risdiplam was well tolerated. Half of the patients remained stable or improved after risdiplam initiation. Larger and multicentric studies are needed to better understand the long-term effects of risdiplam in adult SMA.