Later efficacy of nusinersen treatment in adult patients with spinal muscular atrophy: A retrospective case study with a median 4-year follow-up

BACKGROUND

Spinal muscular atrophy (SMA) is a hereditary neuromuscular disorder characterized by skeletal muscle atrophy and weakness. New treatments for SMA have been developed namely, the drugs nusinersen, onasemnogene abeparvovec, and risdiplam. However, there are limited reports on their effects on adult patients with SMA, particularly over long periods. Therefore, this study aimed to determine the efficacy of nusinersen treatment in adult patients with SMA.

METHODS

We retrospectively reviewed patients with SMA type 2 or 3 who received nusinersen treatment between January 2018 and January 2023. All patients were evaluated using the Hammersmith Functional Motor Scale-Expanded (HFMSE) before the commencement of nusinersen treatment, and the change with respect to the baseline HFMSE score was compared.

RESULTS

A total of six patients, three patients each with SMA type 2 or 3, were treated with nusinersen. The median age of the patients before the commencement of nusinersen treatment was 51.5 years (range, 33-59 years), and the median treatment period was 50.5 months (range, 33-57 months). Three patients showed an increased tendency of improvement on the HFMSE at 15-26 months after nusinersen treatment, and the HFMSE score was maintained in two patients. Significant adverse events were observed in three patients: one subdural hematoma, one incidental bone fracture, and one cheek dermatofibrosarcoma.

CONCLUSIONS

Nusinersen treatment showed later efficacy in adult patients with SMA type 2 or 3. The distinct efficacy of nusinersen requires further investigation using a large number of cases and a long follow-up period.

Muscle impairment in MRI affect variability in treatment response to nusinersen in patients with spinal muscular atrophy type 2 and 3: A retrospective cohort study

BACKGROUND

Real-world data have shown variability in treatment responses to nusinersen in spinal muscular atrophy (SMA). We investigated whether the magnitude of muscle impairment assessed by magnetic resonance imaging (MRI) at baseline can predict the treatment response.

METHODS

We retrospectively assessed the clinical data in relevance to the thigh and pelvic MRI taken before the nusinersen treatment. A total of 16 patients with SMA types 2 and 3 (age = mean [SD]; 9.2 [4.6] year) receiving nusinersen treatment were enrolled. The T1-weighted MRI images of the pelvis and thigh were scored for muscle fatty infiltration and atrophy. The minimally clinically important difference (MCID) was considered as gaining at least 3 points of Hammersmith Functional Motor Scale-Expanded (HFMSE) from baseline.

RESULTS

Of these 16 individuals, 14 had been treated for at least 15 months with baseline data. At 15 months, seven individuals obtained MCID in HFMSE. Baseline muscle MRI score could not differentiate the two groups; however, individuals who obtained MCID had significantly less severe scoliosis. In addition, there was a significant and negative relationship between baseline MRI score and the change of score in HFMSE after 15 months of treatment. Further, baseline Cobb angle along with MRI score also indicated the correlation to the degree of change in motor function.

CONCLUSION

The degree of muscle damage may confer the variability in response to nusinersen in SMA types 2 and 3. Muscle MRI score along with the severity of scoliosis assessed at baseline may help to predict the motor function change.