NfL may be biomarker of response to Spinraza in early stages of SMA
Levels of neurofilament light chain (NfL) in bodily fluids may be a marker of response to treatment with Spinraza (nusinersen) in children with spinal muscular atrophy (SMA) in the early stages of disease, a new study reports.
“NfL can be a valuable biomarker for reflecting disease activities, particularly in SMA type 1,” researchers wrote in a study, “Evaluation of the neurofilament light chain as a biomarker in children with spinal muscular atrophy treated with nusinersen,” published in Brain & Development.
Spinraza was the first treatment for SMA to win widespread approvals. The therapy is administered via injection through the spine every few months. It works to boost levels of the SMN protein whose defect causes SMA. The therapy is sold by Biogen, which was not involved in the study.
Analysis included 8 children with SMA
A team of scientists in South Korea conducted an analysis to see how treatment with Spinraza affects levels of NfL, a structural protein in nerve fibers. When nerves become damaged, NfL protein leaks out into the body’s fluids, so levels of this protein are commonly used as a marker of nerve damage.
NfL levels were measured in the patients’ blood, and also in cerebrospinal fluid, the liquid that surrounds the brain and spinal cord. In each child, levels of NfL were similar in both types of bodily fluid, the researchers noted.
Prior to Spinraza treatment, NfL levels were generally higher in children with the more severe type 1 disease compared to those with the milder type 2, and levels of this marker were typically higher among the SMA children compared to children without the disease.
Following Spinraza treatment, NfL levels decreased sharply among younger patients who were in the early stages of SMA (regardless of whether they had type 1 or 2). Among patients who had more advanced SMA when they started on Spinraza, NfL levels were generally stable following treatment.
NfL can be useful for monitoring disease activities and treatment response in patients with SMA types 1 and 2 within their initial stages although not in patients with later stages.
Scores on motor function tests tended to improve among patients who started on Spinraza early in their disease, and for these patients, there was a statistical association between motor improvements and the decrease in NfL levels. For patients with more advanced disease when they started on treatment, there were slight improvements in motor function scores, but NfL levels and motor function tests were not significantly correlated.
Collectively, these findings indicate that “early treatment initiation in the course of a disease is a decisive factor for future changes in motor function achievement and NfL level,” the researchers wrote.
While this study was limited by the small number of patients, the data suggest “NfL can be useful for monitoring disease activities and treatment response in patients with SMA types 1 and 2 within their initial stages although not in patients with later stages,” the researchers noted.
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