A Blood Test for MS? How One Protein Could Transform Diagnosis and Treatment
A study by Kuhle et al. (2019), published in Neurology, has brought us a step closer to using a protein in our blood—called neurofilament light chain (NfL)—to monitor MS activity, predict disease progression, and even evaluate how well treatments are working.
Let’s unpack what that means—and why it could matter to the millions living with MS.
What Is MS, and Why Are Biomarkers Important?
MS is a chronic autoimmune disease that attacks the central nervous system, leading to inflammation and damage to the protective covering (myelin) of nerves. Over time, this causes irreversible damage to nerve fibers, resulting in physical and cognitive disability.
Right now, clinicians rely heavily on MRI scans to track the disease. While MRI is useful, it's expensive, hard to standardize across clinics, and it doesn’t always reflect ongoing damage that’s invisible to the scan.
That's where biomarkers come in—measurable substances in blood or other fluids that can signal disease activity. One promising candidate? Neurofilament light chain.
What Is Neurofilament Light Chain (NfL)?
NfL is a structural protein found inside neurons. When nerve cells are damaged—as in MS—NfL leaks into the cerebrospinal fluid (CSF) and then into the blood. Thanks to ultra-sensitive testing methods like SIMOA (Single Molecule Array), we can now accurately detect NfL levels in just a drop of blood.
Higher levels = more nerve damage.
The Study: Two Major MS Trials, One Simple Question
Kuhle and colleagues analyzed blood samples from 589 patients with relapsing-remitting MS who were part of two large clinical trials of the drug fingolimod:
FREEDOMS (vs. placebo)
TRANSFORMS (vs. interferon beta-1a)
They compared blood NfL levels with MRI scans, relapses, brain volume loss, and disability progression. They also included 35 healthy controls for comparison.
Key Findings (And Why They Matter)
MS patients had significantly higher NfL levels than healthy people.
In both trials, average NfL levels were nearly double those seen in healthy participants. Even MS patients without visible MRI lesions had elevated NfL—suggesting nerve damage may happen even when MRIs look normal.
Higher NfL levels = more active disease.
High NfL at baseline was linked to:
More new or enlarging lesions on MRI
Increased relapse rate
Faster brain volume loss
Nearly double the risk of disability progression
In short, NfL is a powerful predictor of what’s likely to come.
Fingolimod significantly lowered NfL levels.
Within 6 months of treatment, fingolimod cut NfL by over 35%, and the effect was sustained for two years. Patients on placebo or interferon didn’t see the same drop. This suggests NfL could serve as a real-time indicator of treatment success.
So, Could This Become a Routine Blood Test?
Not just yet—but it’s getting close.
While the study proves NfL is a strong group-level marker, we still need reference ranges for healthy individuals across different ages, and we need to understand how other health conditions might affect NfL.
Still, the potential is huge:
Quick blood draws instead of frequent MRIs
Earlier warnings about disease progression
Better treatment tracking for patients and doctors
Bottom Line
Kuhle et al.'s work gives us compelling evidence that blood NfL is a reliable, non-invasive biomarker of MS disease activity and treatment response.
It's not just another lab value. It's a potential game-changer in how we understand and manage MS—one blood test at a time.
Disclaimer: This blog post is based on the provided research article and is intended for informational purposes only. It is not intended to provide medical advice. Please consult with a healthcare professional for any health concerns.
References:
Kuhle, J., Kropshofer, H., Haering, D. A., Kundu, U., Meinert, R., Barro, C., ... & Kappos, L. (2019). Blood neurofilament light chain as a biomarker of MS disease activity and treatment response. Neurology, 92(10), e1007-e1015.
