Neurofilaments: A Biomarker of Long-Term Outcome in MS?

In patients with multiple sclerosis (MS), levels of light-chain neurofilament (NfL) in CSF at diagnosis seem to predict long-term clinical outcome and conversion from the relapsing-remitting phase of the disease to the secondary progressive phase, according to a study published in the September issue of Multiple Sclerosis Journal. “NfL is thought to reflect ongoing axonal degeneration, which dominates early in the disease phase, and our results support that increased early disease activity, as identified by increased levels of CSF-NfL, has a prognostic effect several years later,” said lead author Alok Bhan, MD, and colleagues. Dr. Bhan works in the Department of Neurology at Stavanger University Hospital in Norway.

Searching for Prognostic Markers

To test whether CSF-NfL levels in patients with MS could predict clinical outcome, Dr. Bhan and colleagues conducted standardized clinical assessments of patients with newly diagnosed MS at baseline and at five- and 10-year follow-up. Expanded Disability Status Scale (EDSS) progression between assessments was defined as an increase of 1 point or more for scores less than 6 and of 0.5 points or more for scores of 6 or greater. CSF obtained at baseline was analyzed for levels of NfL using enzyme-linked immunosorbent assay technology.

The study cohort included 44 patients, of whom 35 (80%) had relapsing-remitting MS, seven (16%) had secondary progressive MS, and two (4%) had primary progressive MS at baseline. Patients who progressed on EDSS tended to have higher median baseline CSF-NfL levels than patients who did not progress after five years (947 ng/L vs 246 ng/L, respectively) and those who did not progress after 10 years (708 ng/L vs 265 ng/L, respectively), although the latter difference was not statistically significant. Patients who converted from relapsing-remitting MS to secondary progressive MS at five years had a significantly higher median CSF level of NfL (2,122 ng/L), compared with those who did not convert (246 ng/L).

“We found a statistically significant correlation between NfL levels at baseline and EDSS progression and conversion from relapsing-remitting MS to secondary progressive MS at the five-year follow-up, but a weaker correlation at the 10-year follow-up,” the researchers said. “This [finding] may be due to the increasing number of patients on disease-modifying therapy throughout the study period, as only 16% received therapy at baseline, but 54% [did] at 10-year follow-up.”

The Predictive Value of NfL

“This is now another important report underscoring the predictive value of NfL levels for the evolution of future disability in MS, but the … study clearly suffers from the relatively low number of patients investigated,” said Michael Khalil, MD, PhD, in an accompanying editorial. Dr. Khalil is an Associate Professor of General Neurology at the Medical University of Graz in Austria. “Nevertheless, neurofilaments are currently the most promising markers to indicate neuro-axonal damage in MS and other neurologic diseases. The availability of a highly sensitive blood assay now facilitates its use for further research and in clinical practice.”

—Glenn S. Williams

Suggested Reading

Bhan A, Jacobsen C, Myhr KM, et al. Neurofilaments and 10-year follow-up in multiple sclerosis. Mult Scler. 2018; 24(10):1301-1307.

Khalil M. Are neurofilaments valuable biomarkers for long-term disease prognostication in MS? Mult Scler. 2018; 24(10):1270-1271.