Therapy up to 4.5 years led to gains in motor function: analysis published in Brain & Development

Up to 4.5 years of Spinraza (nusinersen) treatment led to meaningful improvements in motor function in adolescents and adults with spinal muscular atrophy (SMA), according to a medical records analysis.

“[Spinraza] was effective in long-term follow-up,” researchers wrote.

Noting a dearth of data on Spinraza’s long-term effectiveness among teens and adults with SMA, a team of researchers in Japan had sought to determine the treatment’s impact on patients ages 12 and older over time.

“The efficacy of [Spinraza] … has been established in clinical trials only for pediatric patients, not for adolescent and adult patients who developed SMA in infancy or early childhood,” the team wrote. “This study showed the efficacy of [Spinraza] in adolescent and adult patients with SMA types 1 and 2.”

The findings were published in the journal Brain & Development.

Spinraza treatment for adults and teens

Spinraza is an RNA-based treatment designed to increase the body’s levels of the survival motor neuron (SMN) protein, which is deficient in SMA patients due to genetic defects. SMN is essential for the specialized nerve cells, called motor neurons, that control voluntary movement.

Although Spinraza’s efficacy has been established in children up to 12 years of age, data for adolescents and adults who developed SMA in infancy or early childhood are limited — to up to two years of evaluation. Therefore, the long-term effects of Spinraza in this patient population needed to be investigated.

To do so, researchers at the Aichi Medical University, in Japan, reviewed the medical records of seven SMA patients, ages 12–40. One patient was diagnosed with SMA type 1 and six with SMA type 2. All used a power wheelchair, and three required a feeding tube and non-invasive breathing support.

After initial Spinraza treatment, maintenance doses were administered three times a year for the SMA type 1 patient and twice a year for the type 2 patients.

Upon further examination, and given that three patients initially diagnosed with SMA type 2 showed poor motor function, clinicians changed their diagnosis to type 1, and treatments were adjusted.

Overall, the median duration of treatment was 3.55 years, ranging from 1.8–4.5 years. The COVID-19 pandemic delayed therapy for 27–160 days in five patients.

Improvements were seen in motor function, as assessed with the standard tool CHOP-INTEND. While the gains were not statistically significant, they were “meaningful according to the definition of CHOP-INTEND response,” the researchers wrote.

No changes were observed in physical disability, as indicated by the Hammersmith Functional Motor Scale Expanded (HFMSE). The Revised Upper Limb Module (RULM) saw similar findings for upper limb strength.

Among the three patients whose diagnosis was changed to SMA type 1, two showed a CHOP-INTEND increase, and one demonstrated better RULM scores.

RULM scores, but not CHOP-INTEND scores, dropped in two patients due to Spinraza treatment delays caused by the pandemic.

“The interval between doses of nusinersen should not be prolonged,” the team noted.

“[Spinraza] was effective in long-term follow-up in adolescent and adult patients with SMA types 1 and 2,” the researchers concluded. “CHOP-INTEND was able to detect the improvement with [Spinraza] in those patients.”

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