Motor Gains Best With Early Use of Spinraza for Likely Type 1 Infants
Spinraza (nusinersen) continues to show sustained efficacy in improving motor function in infants and toddlers with spinal muscular atrophy (SMA), according to newly released interim data from the SHINE study.
The greatest benefits were among children who began being treated with Spinraza before they were 10 months old.
Biogen, which markets the therapy, presented the findings in the poster “Long-Term Safety and Efficacy of Nusinersen in Infantile-Onset Spinal Muscular Atrophy: 5-Year Interim From SHINE” at the 3rd International Scientific Congress on SMA that took place in Barcelona on Oct. 21–23.
Gains seen with Spinraza and likely SMA type 1 across motor tests
Spinraza was the first disease-modifying therapy (DMT) approved and for all SMA types. Administered directly into the spinal canal, it works by raising the levels of full-length survival motor neuron (SMN) protein, whose deficiency due to mutations in the SMN1 gene is the underlying cause of SMA. SMN is essential for the health of motor neurons, nerve cells that control muscle movement.
The ongoing Phase 3 SHINE trial (NCT02594124) is an international, open-label extension study of Spinraza in a range of SMA patients who participated in five previous investigational trials of the therapy, including infants in the Phase 3 ENDEAR study (NCT02193074).
ENDEAR participants were randomly assigned to Spinraza or a so-called sham procedure as a control group. Previous results showed Spinraza significantly prolonged survival and aided motor function in children with the severe SMA type 1,
Researchers involved in the SHINE trial now presented interim data — with a collection cut-off date Aug. 9, 2021 — covering 105 infantile-onset SMA patients, all likely to have SMA type 1, who had been followed for up to seven years (median of 5.3 years). SHINE is expected to conclude in late August 2023.
Participants were divided into three groups according to their age and the timing of their first Spinraza dose: one group included babies under 6 months of age and another group babies between 6 and 10 months old, who in both cases received either Spinraza or a sham procedure in ENDEAR; the last group included toddlers ages 10 to 23 months who started on Spinraza in the SHINE study.
As of the cut-off date, 80 of these 105 patients started on Spinraza in ENDEAR, while the remaining 25 began with the treatment in SHINE.
Results showed that across all age groups motor function improved after treatment with Spinraza, as assessed by the increase (improvement) in CHOP INTEND mean scores. This test is designed to measure motor abilities in children with severe motor impairments.
After 4.2 years of treatment, total CHOP INTEND scores rose by a mean of 20.6 points in infants younger than 6 months old at first dose, by 16.9 points in those between 6 and 10 months old at first dose, and by 8.8 points in toddlers 10 to 23 months old at a first treatment dose.
Scores on the Hammersmith Functional Motor Scale Expanded (HFMSE; also a general motor function test), and in the Revised Upper Limb Module (RULM; assessing arm function) also followed the same improvement trend after a follow-up of 2.9 years. However, gains here were only seen in the two youngest patient groups, while those who began treatment as toddlers showed no improvements.
Specifically, RULM scores increased by a mean of 8.3 points in infants first treated before age 6 months, and they rose by 10.3 points in those first treated at 6–10 months. HFMSE scores increased by a mean of 6.5 points in the youngest group and 4.7 in those 6–10 months at first dose.
Findings of the greatest gains with Spinraza’s use in infants first treated before 10 months of age further support “the importance of early treatment of infantile-onset SMA,” they wrote.
Spinraza’s safety profile over up to seven years of follow-up was consistent with that previously reported, with no treatment-related serious side effects.
Overall, these interim findings support Spinraza’s “continued and clinically meaningful benefit in motor function” in patients with infantile-onset SMA, the researchers wrote.
According to the Biogen, more than 13,000 people have been treated with Spinraza worldwide in clinical trials and real-world settings, and they have followed for up to eight years.
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