Spinraza treatment improves motor function in older SMA patients
Treatment with Spinraza (nusinersen) generally stabilized or improved motor function for older patients with spinal muscular atrophy (SMA), according to a review and meta-analysis of previously published observational studies.
The new analysis, which spanned a treatment period of up to two years, involved adults and adolescents with various SMA types and walking abilities.
“Our comprehensive … meta-analysis indicates that [Spinraza] is effective in improving or stabilizing motor function in many adolescents and adults with a broad spectrum of SMA,” the researchers wrote.
The study, “Effectiveness of Nusinersen in Adolescents and Adults with Spinal Muscular Atrophy: Systematic Review and Meta-analysis,” was published in the journal Neurology and Therapy. It was funded by Biogen, the company that markets Spinraza.
Most clinical trials focused on children with SMA, not older patients
Spinraza was the first therapy to be approved for SMA that addresses the disease’s underlying cause: the lack of the SMN protein due to mutations in SMN1, the main SMN-producing gene.
The treatment, infused directly into the spinal canal, works to increase SMN production from the so-called backup SMN-producing gene, SMN2. In the U.S., Europe, and other regions, Spinraza is approved for treating SMA patients of all ages and across disease types.
Spinraza clinical trials have demonstrated the numerous benefits of the therapy, including gains in motor function and survival. However, these clinical studies were most heavily focused on infants and children with more severe forms of SMA. Meanwhile, Spinraza is also used widely in adult and adolescent patients in real-world settings.
According to the researchers, there’s a need to consolidate this real-world data to get a better picture of the true effects of Spinraza in older patients.
To that end, the team, from Germany, Italy, and the U.S., conducted a systematic review and meta-analysis of previously published clinical and observational studies. These studies had evaluated Spinraza’s effectiveness in adolescents and adults with SMA. A meta-analysis is a type of statistical analysis that combines results from separate studies and analyzes them together.
The systematic literature review ultimately included 14 observational studies, cumulatively involving 539 patients, ages 13-72. Most patients had SMA type 2 or type 3 and 40% were ambulatory, or able to walk.
Across the studies, a few assessments of motor function were used. These included the Hammersmith Functional Motor Scale-Expanded (HFMSE), a validated tool of global motor function in SMA, and the Revised Upper Limb Module (RULM), which specifically evaluates upper limb function.
The Six-Minute Walk Test (6MWT), which measures how far a person can walk in six minutes, also was used in some studies for ambulatory patients.
Meta-analysis shows stabilization or improvement with Spinraza treatment
In general, the results from the studies indicated improvements or stabilizations across these measures with up to two years of Spinraza treatment. For reference, the scientists pointed out that with the natural course of SMA progression, declines in motor function would be expected over time without treatment.
Findings from the meta-analysis, which used data from 11 studies involving 433 SMA adults and adolescents, showed that the overall mean increase (improvement) in HFMSE scores was 1.4 points after six months of treatment, which rose steadily to 2.3 points after 1.5 years on Spinraza.
By one and a half years, 32.1% of patients were considered to have experienced a clinically meaningful improvement in HFMSE scores, defined as an increase of at least three points. The greatest gains were observed in patients with SMA type 3 and in those who were ambulatory.
[This study] provides consolidated evidence from real-world cohorts that [Spinraza] is effective in improving or stabilizing motor function in many adolescents and adults with SMA up to 24 months after treatment initiation.
In terms of upper limb function, RULM scores also steadily increased over time, with 38.3% of patients achieving a clinically meaningful response — an increase of at least two points — by 14 months, or slightly longer than one year. In this measure, SMA type 2 patients and nonambulatory individuals saw greater gains.
Again, for the 6MWT, the percentage of patients with clinically meaningful improvements steadily increased over time, reaching more than 50% after 14 months. Here, such improvements were an increase of at least 30 meters or about 98 feet in the distance walked,
Overall, the study “provides consolidated evidence from real-world cohorts that [Spinraza] is effective in improving or stabilizing motor function in many adolescents and adults with SMA up to 24 months after treatment initiation,” the researchers wrote.
The team noted that the findings are largely consistent with earlier meta-analyses on the topic. However, they say this study expands on those findings by including more publications with longer follow-up data, and by looking more closely at subgroups of patients, specifically regarding disease type and ambulation status.
“These analyses can enhance the clinical interpretation and applicability of our meta-analysis for clinicians and decision-makers, helping them understand the observed outcomes in [relation] to disease severity,” the researchers wrote.
Further, according to the team, these findings highlight the importance of selecting the appropriate scale to evaluate motor function in SMA patients. They noted that RULM is more likely to demonstrate benefit in more severely affected patients, while HFMSE may be more appropriate for those with less severe disease.
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