Cantó E, Barro C, Zhao C, et al. - In longitudinal multiple sclerosis (MS) data set, researchers assessed the potential of serum neurofilament light chain (sNFL) measurements as a biomarker of disease activity and progression. Participants in this single-center, ongoing, prospective observational cohort study were 607 patients [mean age was 42.5 (9.8) years] with MS. According to findings, sNFL levels in those with disability worsening significantly faster than those who remained clinically stable. It was noted that sNFL level was linked to brain fraction loss, whereas for clinical outcomes such as relapses or worsening of Expanded Disability Status Scale, this was less the case. The association of sNFL level with changes in relevant clinical and neuroimaging results in MS has been confirmed, reinforcing this biomarker's potential as a measure of disease activity in MS. However, for the individual patient, the clinically helpful prognostic value of the sNFL level was restricted.