Profiling serum neurofilament light chain and glial fibrillary acidic protein in primary progressive multiple sclerosis

The role of serum neurofilament light (sNfL) as a biomarker in multiple sclerosis: insights from a systematic review

OBJECTIVE

This systematic literature review (SLR) was conducted to explore the role of serum neurofilament light chain (sNfL) as a biomarker in multiple sclerosis (MS) disease management.

METHODS

The review was conducted in accordance with the recommendation laid by the Cochrane Handbook for Systematic Reviews. A comprehensive literature search was performed in key biomedical databases (EMBASE®, MEDLINE®, MEDLINE®-In-Process, and all Evidence-Based Medicine [EBM] Reviews databases) to retrieve studies reporting the association between sNfL and disease activity in patients with MS. Additional evidence was also identified through hand searching of key conference proceedings and gray literature.

RESULTS

Following review of 1831 records, 75 studies from 180 publications were included in the review. The studies included in the SLR consistently demonstrated an association between higher sNfL levels and an increased risk of future relapses within 2 years and MS disease progression. Higher levels of sNfL were also linked to an increased likelihood of experiencing gadolinium-enhancing T1 and T2 lesions. Patients with lower sNfL levels had a higher likelihood of achieving no evidence of disease activity status. Furthermore, an inverse correlation was observed between sNfL levels and cognitive impairment as assessed via the Symbol Digit Modalities Test performance and Timed 25-Foot Walk scores.

CONCLUSION

This SLR demonstrates the significance of sNfL as a sensitive biomarker for monitoring MS progression. Convenient and reliable sNfL measurement could benefit routine clinical practice, providing clinicians with a simple and effective tool to monitor disease and treatment response.

The Role of Glial Fibrillary Acidic Protein as a Biomarker in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder: A Systematic Review and Meta-Analysis

There is debate on the role of glial fibrillary acidic protein (GFAP) as a reliable biomarker in multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD), and its potential to reflect disease progression. This review aimed to investigate the role of GFAP in MS and NMOSD. A systematic search of electronic databases, including PubMed, Embase, Scopus, and Web of Sciences, was conducted up to 20 December 2023 to identify studies that measured GFAP levels in people with MS (PwMS) and people with NMOSD (PwNMOSD). R software version 4.3.3. with the random-effect model was used to pool the effect size with its 95% confidence interval (CI). Of 4109 studies, 49 studies met our inclusion criteria encompassing 3491 PwMS, 849 PwNMOSD, and 1046 healthy controls (HCs). The analyses indicated that the cerebrospinal fluid level of GFAP (cGFAP) and serum level of GFAP (sGFAP) were significantly higher in PwMS than HCs (SMD = 0.7, 95% CI: 0.54 to 0.86, p < 0.001, I2 = 29%, and SMD = 0.54, 95% CI: 0.1 to 0.99, p = 0.02, I2 = 90%, respectively). The sGFAP was significantly higher in PwNMOSD than in HCs (SMD = 0.9, 95% CI: 0.73 to 1.07, p < 0.001, I2 = 10%). Among PwMS, the Expanded Disability Status Scale (EDSS) exhibited significant correlations with cGFAP (r = 0.43, 95% CI: 0.26 to 0.59, p < 0.001, I2 = 91%) and sGFAP (r = 0.36, 95% CI: 0.23 to 0.49, p < 0.001, I2 = 78%). Regarding that GFAP is increased in MS and NMOSD and has correlations with disease features, it can be a potential biomarker in MS and NMOSD and indicate the disease progression and disability in these disorders.

Serum GFAP and NfL Levels Differentiate Subsequent Progression and Disease Activity in Patients With Progressive Multiple Sclerosis

Background and Objectives

Neurodegeneration and astrocytic activation are pathologic hallmarks of progressive multiple sclerosis (MS) and can be quantified by serum neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP). We investigated sNfL and sGFAP as tools for stratifying patients with progressive MS based on progression and disease activity status.

Methods

We leveraged our Comprehensive Longitudinal Investigation of MS at the Brigham and Women's Hospital (CLIMB) natural history study, which includes clinical, MRI data and serum samples collected over more than 20 years. We included patients with MS with a confirmed Expanded Disability Status Scale (EDSS) score ≥3 that corresponds with our classifier for patients at high risk of underlying progressive pathology. We analyzed sNfL and sGFAP within 6 months from the confirmed EDSS score ≥3 corresponding with our baseline visit. Patients who further developed 6-month confirmed disability progression (6mCDP) were classified as progressors. We further stratified our patients into active/nonactive based on new brain/spinal cord lesions or relapses in the 2 years before baseline or during follow-up. Statistical analysis on log-transformed sGFAP/sNfL assessed the baseline association with demographic, clinical, and MRI features and associations with future disability.

Results

We included 257 patients with MS who had an average EDSS score of 4.0 and a median follow-up after baseline of 7.6 years. sNfL was higher in patients with disease activity in the 2 years before baseline (adjusted β = 1.21; 95% CI 1.04–1.42;p= 0.016), during the first 2 years of follow-up (adjusted β = 1.17; 95% CI = 1.01–1.36;p= 0.042). sGFAP was not increased in the presence of disease activity. Higher sGFAP levels, but not sNfL levels, were associated with higher risk of 6mCDP (adjusted hazard ratio [HR] = 1.71; 95% CI = 1.19–2.45;p= 0.004). The association was stronger in patients with low sNfL (adjusted HR = 2.44; 95% CI 1.32–4.52;p= 0.005) and patients who were nonactive in the 2 years prior or after the sample.

Discussion

Higher levels of sGFAP correlated with subsequent progression, particularly in nonactive patients, whereas sNfL reflected acute disease activity in patients with MS at high risk of underlying progressive pathology. Thus, sGFAP and sNfL levels may be used to stratify patients with progressive MS for clinical research studies and clinical trials and may inform clinical care.

Serum neurofilament-light and glial fibrillary acidic protein levels in hydroxychloroquine-treated primary progressive multiple sclerosis

BACKGROUND

In a recent trial, hydroxychloroquine (HCQ) treatment reduced the expected rate of disability worsening at 18 months in primary progressive multiple sclerosis (PPMS). Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) are emerging biomarkers in multiple sclerosis.

METHODS

We measured NfL and GFAP levels in serum samples from 39 patients with inactive PPMS included in a phase II clinical trial of HCQ treatment in PPMS at multiple time points over 18 months, and investigated the association of these biomarkers with clinical disability at screening and during follow-up. Screening and 12-month retinal nerve fiber layer (RNFL) thickness was also recorded and analyzed.

RESULTS

NfL and GFAP levels increased over time, but only significantly from screening to month 6. NfL and GFAP levels did not significantly increase from month 6 up to month 18. At screening, NfL and GFAP levels did not correlate with the Expanded Disability Status Scale (EDSS), and GFAP but not NfL modestly correlated with Timed 25-Foot Walk test (T25FW). Screening NfL and GFAP levels did not predict disability worsening (≥20% worsening on the T25FW) at month 18. RNFL thickness decreased significantly from screening to month 12 and independently predicted disability worsening.

CONCLUSIONS

In this cohort of people with inactive PPMS, HCQ treatment attenuated the increase of NfL and GFAP after 6 months of treatment and up to 18 months of follow-up, suggesting a treatment effect of HCQ over these biomarkers. RNFL thickness, a marker of neuroaxonal atrophy, was associated with disability worsening, and should be explored further as a prognostic marker in this population.

A Narrative Review on Axonal Neuroprotection in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) resulting in demyelination and neurodegeneration. The therapeutic strategy is now largely based on reducing inflammation with immunosuppressive drugs. Unfortunately, when disease progression is observed, no drug offers neuroprotection apart from its anti-inflammatory effect. In this review, we explore current knowledge on the assessment of neurodegeneration in MS and look at putative targets that might prove useful in protecting the axon from degeneration. Among them, Bruton's tyrosine kinase inhibitors, anti-apoptotic and antioxidant agents, sex hormones, statins, channel blockers, growth factors, and molecules preventing glutamate excitotoxicity have already been studied. Some of them have reached phase III clinical trials and carry a great message of hope for our patients with MS.

Plasma glial fibrillary acidic protein and neurofilament light chain in relation to disability worsening in multiple sclerosis

Background:

Predicting disability worsening in multiple sclerosis (MS) remains an important challenge. Glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) seem promising biomarkers. Studies investigating blood GFAP in relation to longitudinal outcome measures in MS are scarce.

Objective:

To compare plasma-GFAP (p-GFAP) and plasma-NfL (p-NfL) levels in relation to sustained disability worsening.

Methods:

We measured baseline p-GFAP and p-NfL in a prospective cohort of 115 individuals with MS and 30 matched controls, using Single Molecule Array (Simoa). Disability worsening was defined as an increase in at least one of three measures (Expanded Disability Status Scale, Timed 25-foot walk, 9-Hole Peg test), confirmed after 6 months and persistent upon data closure.

Results:

In a multivariable Cox proportional-hazards model, p-GFAP was not significantly associated with sustained disability worsening after 4.40 ± 0.82 years, while p-NfL (HR = 1.046, p = 0.001), EDSS (HR = 1.24, p = 0.039), and disease duration (HR = 1.048, p = 0.017) were. Area under the curve of ROC curves in relation to worsening was 0.61 for p-GFAP ( p = 0.031) and 0.63 for p-NfL ( p = 0.015). Kaplan–Meier curves showed similar patterns for both proteins.

Conclusion:

p-NfL emerged as a significant explanatory variable for worsening in Cox regression analysis, and p-GFAP did not. Both p-GFAP and p-NfL were related to worsening based on ROC curves.

Serum neurofilament light chain levels predict long-term disability progression in patients with progressive multiple sclerosis

ObjectiveThere is a lack of sensitive and specific biomarkers for use in progressive multiple sclerosis (MS). The study aimed to assess the potential of serum neurofilament light chain (sNfL) levels as biomarker of disability progression in patients with progressive MS.

METHODS

We performed a prospective observational cohort study in 51 patients with progressive MS who participated in a 2-year phase II single-centre, randomised, double-blind, placebo-controlled trial of interferon-beta. Mean (SD) follow-up duration was 13.9 (6.2) years. Levels of sNfL were measured using a single molecule array immunoassay at baseline, 1, 2 and 6 years. Univariable and multivariable analyses were carried out to evaluate associations between sNfL levels and disability progression at short term (2 years), medium term (6 years) and long term (at the time of the last follow-up).

RESULTS

A sNfL cut-off value of 10.2 pg/mL at baseline discriminated between long-term progressors and non-progressors with a 75% sensitivity and 67% specificity (adjusted OR 7.8; 95% CI 1.8 to 46.4; p=0.01). Similar performance to discriminate between long-term progressors and non-progressors was observed using age/body mass index-adjusted sNfL Z-scores derived from a normative database of healthy controls. A cut-off increase of 5.1 pg/mL in sNfL levels between baseline and 6 years also discriminated between long-term progressors and non-progressors with a 71% sensitivity and 86% specificity (adjusted OR 49.4; 95% CI 4.4 to 2×103; p=0.008).

CONCLUSIONS

sNfL can be considered a prognostic biomarker of future long-term disability progression in patients with progressive MS. These data expand the little knowledge existing on the role of sNfL as long-term prognostic biomarker in patients with progressive MS.