Motor Function Improved After 1 Year of Spinraza in Children With SMA Types 1–2

Marta Figueiredo, PhD avatar

by Marta Figueiredo, PhD |

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One year of Spinraza (nusinersen) treatment safely and significantly improves motor function in children with spinal muscular atrophy (SMA) types 1 and 2, according to a real-life study in French patients.

Greater motor benefits were seen among children with more severe disease and those treated earlier in life. However, several patients still required nutritional and respiratory support.

The study, “Effects of nusinersen after one year of treatment in 123 children with SMA type 1 or 2: a French real-life observational study,” was published in the Orphanet Journal of Rare Diseases.

Spinraza, a disease-modifying therapy developed by Biogen, was the first approved treatment for all types of SMA in children and adults.

In clinical trials, Spinraza was shown to extend the lives of children with SMA and improve their ability to move, breathe, and swallow. Nevertheless, a large proportion of Spinraza-treated children with type 1 SMA, one of the most severe types, may still need ventilation support and feeding tubes.

Real-life data are key to understanding the true benefits of Spinraza in the SMA population and optimizing treatment decisions in everyday clinical practice.

Researchers have now reported the real-life safety and effectiveness of one year of Spinraza treatment in children with SMA types 1 and 2 in France. The therapy, given directly into the spinal canal every four months, became available in that country in May 2017.

The team retrospectively analyzed the data of SMA patients followed at 23 French centers for rare pediatric diseases between May 2017 and February 2019. Of the 204 patients treated with Spinraza, 123 (68 girls and 55 boys) with type 1 or 2 disease had at least one year of treatment and were included in the study.

Most children had type 2 SMA, while 34 were classified as type 1 (10 as type 1a/b and 24 as type 1c). Subtypes a, b, and c depend on the severity of disease or the achievement of motor milestones before or after a certain age, with subtype 1a being considered the most severe.

The children’s ages ranged from 3 months to 16 years when they started treatment, with 30 children (24.4%) being treated when they were younger than 2 years (including all 10 with type 1a/b). A total of 47 children were 2–5 years of age when they started Spinraza, and 46 were 6–17 years old.

Motor development in children younger than 2 years was assessed with the Hammersmith Infant Neurological Examination Part 2 and the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders.

Motor function in children older than 2 years was mainly evaluated with the Motor Function Measure. It assesses motor function in three domains: standing and transfers between positions; motor function of axial muscles (those of the trunk and head) and proximal muscles (those closer to the center of the body); and distal motor function (that of the hands and lower arms).

Caregivers’ impressions about the children’s improvements were assessed through the Clinical Global Impressions-Improvement (CGI-I) scale.

Results showed that after one year of treatment, children across all ages achieved significant motor function improvements.

Notably, such improvements were observed in 90% of those treated before the age of 2. However, none of these children were able to walk and the maximum motor function level achieved seemed to match that of type 2 patients, the researchers noted.

In addition, compared to before treatment, there was a “non-significant increase” after one year in the number of type 1 patients younger than 2 who needed nutritional support (increase of two children) or ventilatory support (increase of three children), which was consistent with previous reports.

Children older than 2 who received treatment showed clinically meaningful improvements in the motor function of muscles in the trunk and head, those closer to the body, and those of the arms and hands. However, the children’s ability to stand or change positions, as well as the number of children needing nutritional or ventilatory support, remained unchanged. Also, none of these children gained the ability to walk.

Greater motor function benefits were observed in the subgroup of children treated before the age of 6, and most of them (85%) were able to perform normal daily activities, such as eating alone, combing their hair, and rolling over during sleep.

These findings support the notion that SMA patients should be treated as early as possible, so that they can benefit most from treatment.

Of the 105 caregivers (one parent per child) who completed the CGI-I scale, most (81%) reported at least some improvement in their child’s condition, with no reports of disease worsening. Nearly half (46%) considered that their child’s condition was much improved, and 6% considered it to be very much improved.

“The positive responses of the caregivers despite generally mild motor benefits may reflect the considerable hopes invested in this new therapy, or on the [other] hand, reflect limitations in the scales used to evaluate the benefits of the treatment,” the researchers wrote.

Moreover, Spinraza was well-tolerated, with no reports of severe adverse events, which is in agreement with previous studies, the team noted.

The researchers also emphasized that while Spinraza defies the natural history of SMA, particularly for severe forms and in younger children, type 1 and 2 patients still need intensive support care and remain severely disabled.

“Families need to know more about what it means to live with SMA and what the benefits and burdens of the available treatments are,” the researchers wrote, adding that both parents and the patients themselves as they age “face high stakes decisions about chronic treatment and potentially aggressive life prolonging therapies.”