Risdiplam in Adult Patients With 5q Spinal Muscular Atrophy: A Single-Center Longitudinal Study

Risdiplam was the first orally administered drug approved to treat spinal muscular atrophy (SMA). Efficacy in adults is based on short-term observational studies. This longitudinal study aimed to examine risdiplam's efficacy and safety in adults over a long period of follow-up.

All eligible SMA patients ≥ 16 years old, followed at the Muscular Dystrophy Association Hellas Neuromuscular Diseases Unit between April 2021 and December 2023, were included. We prospectively evaluated motor function, muscle strength, and pulmonary function before and after 6, 12, 18, 24, and 30 months of treatment. Laboratory assessments and patient-reported adverse events were recorded.

Overall, 14 patients (18-57 years, 93% treatment-naive) received risdiplam for a median period of 28.5 months (range 6-30). There were statistically significant improvements in the Hammersmith Functional Motor Scale-Expanded (mean difference [MD] 1.5 [95%CI 0.49-2.42]), Revised Upper Limb Module (MD 1.6 [95%CI 0.54-2.73]), Motor Function Measurement-32 (MD 2.7[95%CI 1.52-3.93]), Medical Research Council scores of the upper (MD 3 [95%CI 0.8-5.2]), and lower (MD 1.7 [95%CI 0.1-3.3]) limbs (all p ≤ 0.05). Eighty-two percent of patients achieved a clinically meaningful improvement (CMI) in at least one scale. Overall, CMI occurred earlier in type 3 patients. SMA functional rating scale and respiratory function tests remained stable over time. Fifty-seven percent of patients did not report any adverse events. None discontinued treatment.

Risdiplam treatment over 30 months resulted in overall CMI in most treated adult SMA type 2 or 3 patients. Outpatient drug administration and overall patient management proved feasible and safe. Larger studies are warranted.