Neurofilament light levels are associated with long-term outcomes in multiple sclerosis

Neurofilament Light Chain Serum Levels Mirror Age and Disability in Secondary Progressive Multiple Sclerosis: A Cross-Sectional Study

OBJECTIVES

To assess neurofilament light chain serum (sNfL) levels in patients with secondary progressive multiple sclerosis (SP-MS).

METHODS

Using a single molecule array, we analyzed sNfL levels in a cross-sectional cohort study of 153 patients with SP-MS hospitalized for rehabilitation in a clinic specialized in the care for patients with multiple sclerosis (MS). In addition, we investigated the correlation of disease activity with sNfL levels in 36 patients with relapsing-remitting MS (RR-MS).

RESULTS

Mean sNfL levels in patients with SP-MS were consistently elevated when compared with age-matched controls and patients with RR-MS. In SP-MS, age dependency of sNfL levels was pronounced, whereas patients with RR-MS younger than 41 years without recent disease activity were not distinguishable from age-matched healthy controls. In a multivariate analysis, clinical disability was a risk factor for elevated sNfL levels in SP-MS, whereas no correlation with comorbidities, such as cardiovascular disease, diabetes mellitus, smoking status, or vitamin D serum levels, could be detected.

DISCUSSION

These findings highlight that measurement of sNfL levels represents a useful tool to assess the extent of neuroaxonal damage as a surrogate for clinical progression in patients with SP-MS, when age and disease activity as major confounders are taken into account.

Association of serum glial fibrillary acidic protein with progression independent of relapse activity in multiple sclerosis

OBJECTIVE

Insidious disability worsening is a common feature in relapsing-remitting multiple sclerosis (RRMS). Many patients experience progression independent of relapse activity (PIRA) despite being treated with high efficacy disease-modifying therapies. We prospectively investigated associations of body-fluid and imaging biomarkers with PIRA.

METHODS

Patients with early RRMS (n = 104) were prospectively included and followed up for 60 months. All patients were newly diagnosed and previously untreated. PIRA was defined using a composite score including the expanded disability status scale, 9-hole peg test, timed 25 foot walk test, and the symbol digit modalities test. Eleven body fluid and imaging biomarkers were determined at baseline and levels of serum neurofilament light (sNfL) and glial fibrillary acidic protein (sGFAP) were also measured annually thereafter. Association of baseline biomarkers with PIRA was investigated in multivariable logistic regression models adjusting for clinical and demographic confounding factors. Longitudinal serum biomarker dynamics were investigated in mixed effects models.

RESULTS

Only sGFAP was significantly higher in PIRA at baseline (median [IQR] 73.9 [60.9-110.1] vs. 60.3 [45.2-79.9], p = 0.01). A cut-off of sGFAP > 65 pg/mL resulted in a sensitivity of 68% and specificity of 61%, to detect patients at higher risk of PIRA. In a multivariable logistic regression, sGFAP > 65 pg/mL was associated with higher odds of developing PIRA (odds ratio 4.3, 95% CI 1.44-12.86, p = 0.009). Repeated measures of sGFAP levels showed that patients with PIRA during follow-up had higher levels of sGFAP along the whole follow-up compared to stable patients (p < 0.001).

CONCLUSION

Determination of sGFAP at baseline and follow-up may be useful in capturing disability accrual independent of relapse activity in early RRMS.

Temporal Relationship Between Serum Neurofilament Light Chain and Radiologic Disease Activity in Patients With Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Serum neurofilament light chain (sNfL) levels correlate with multiple sclerosis (MS) disease activity, but the dynamics of this correlation are unknown. We evaluated the relationship between sNfL levels and radiologic MS disease activity through monthly assessments during the 24-week natalizumab treatment interruption period in RESTORE (NCT01071083).

METHODS

In the RESTORE trial, participants with relapsing forms of MS who had received natalizumab for ≥12 months were randomized to either continue or stop natalizumab and followed with MRI and blood draws every 4 weeks to week 28 and again at week 52 The sNfL was measured, and its dynamics were correlated with the development of gadolinium-enhancing (Gd+) lesions. Log-linear trend in sNfL levels were modeled longitudinally using generalized estimating equations with robust variance estimator from baseline to week 28.

RESULTS

Of 175 patients enrolled in RESTORE, 166 had serum samples for analysis. Participants with Gd+ lesions were younger (37.7 vs 43.1, p = 0.001) and had lower Expanded Disability Status Scale scores at baseline (2.7 vs 3.4, p = 0.017) than participants without Gd+ lesions. sNfL levels increased in participants with Gd+ lesions (n = 65) compared with those without (n = 101, mean change from baseline to maximum sNfL value, 12.1 vs 3.2 pg/mL, respectively; p = 0.003). As the number of Gd+ lesions increased, peak median sNfL change also increased by 1.4, 3.0, 4.3, and 19.6 pg/mL in the Gd+ lesion groups of 1 (n = 12), 2-3 (n = 18), 4-9 (n = 21), and ≥10 (n = 14) lesions, respectively. However, 46 of 65 (71%) participants with Gd+ lesions did not increase above the 95th percentile threshold of the group without Gd+ lesions. The initial increase of sNfL typically trailed the first observation of Gd+ lesions, and the peak increase in sNfL was a median [interquartile range] of 8 [0, 12] weeks after the first appearance of the Gd+ lesion.

DISCUSSION

Although sNfL correlated with the presence of Gd+ lesions, most participants with Gd+ lesions did not have elevations in sNfL levels. These observations have implications for the use and interpretation of sNfL as a biomarker for monitoring MS disease activity in controlled trials and clinical practice.

Current use of fluid biomarkers as outcome measures in Multiple Sclerosis (MS): a review of ongoing pharmacological clinical trials

The present study aims to describe the state of the art of fluid biomarkers use in ongoing multiple sclerosis (MS) clinical trials.A review of 608 ongoing protocols in the clinicaltrials.gov and EudraCT databases was performed. The trials enrolled patients with a diagnosis of relapsing remitting MS, secondary progressive MS, and/or primary progressive MS according to Revised McDonald criteria or relapsing MS according to Lublin et al. (2014). The presence of fluid biomarkers among the primary and/or secondary study outcomes was assessed.Overall, 5% of ongoing interventional studies on MS adopted fluid biomarkers. They were mostly used as secondary outcomes in phase 3-4 clinical trials to support the potential disease-modifying properties of the intervention. Most studies evaluated neurofilament light chains (NfLs). A small number considered other novel fluid biomarkers of neuroinflammation and neurodegeneration such as glial fibrillary acid protein (GFAP).Considering the numerous ongoing clinical trials in MS, still a small number adopted fluid biomarkers as outcome measures, thus testifying the distance from clinical practice. In most protocols, fluid biomarkers were used to evaluate the effectiveness of approved second-line therapies, but also, new drugs (particularly Bruton kinase inhibitors). NfLs were also adopted to monitor disease progression after natalizumab suspension in stable patients, cladribine efficacy after anti-CD20 discontinuation, and the efficacy of autologous hematopoietic stem cell transplant (AHSCT) compared to medical treatment. Nevertheless, further validation studies are needed for all considered fluid biomarkers to access clinical practice, and cost-effectiveness in the "real word" remains to be clarified.

Guidance for use of neurofilament light chain as a cerebrospinal fluid and blood biomarker in multiple sclerosis management

Neurofilament light chain (NfL) is a long-awaited blood biomarker that can provide clinically useful information about prognosis and therapeutic efficacy in multiple sclerosis (MS). There is now substantial evidence for this biomarker to be used alongside magnetic resonance imaging (MRI) and clinical measures of disease progression as a decision-making tool for the management of patients with MS. Serum NfL (sNfL) has certain advantages over traditional measures of MS disease progression such as MRI because it is relatively noninvasive, inexpensive, and can be repeated frequently to monitor activity and treatment efficacy. sNfL levels can be monitored regularly in patients with MS to determine change from baseline and predict subclinical disease activity, relapse risk, and the development of gadolinium-enhancing (Gd+) lesions. sNfL does not replace MRI, which provides information related to spatial localisation and lesion stage. Laboratory platforms are starting to be made available for clinical application of sNfL in several countries. Further work is needed to resolve issues around comparisons across testing platforms (absolute values) and normalisation (reference ranges) in order to guide interpretation of the results.

Blood-brain barrier dysfunction in multiple sclerosis: causes, consequences, and potential effects of therapies

Established by brain endothelial cells, the blood-brain barrier (BBB) regulates the trafficking of molecules, restricts immune cell entry into the CNS, and has an active role in neurovascular coupling (the regulation of cerebral blood flow to support neuronal activity). In the early stages of multiple sclerosis, around the time of symptom onset, inflammatory BBB damage is accompanied by pathogenic immune cell infiltration into the CNS. In the later stages of multiple sclerosis, dysregulation of neurovascular coupling is associated with grey matter atrophy. Genetic and environmental factors associated with multiple sclerosis, including dietary habits, the gut microbiome, and vitamin D concentrations, might contribute directly and indirectly to brain endothelial cell dysfunction. Damage to brain endothelial cells leads to an influx of deleterious molecules into the CNS, accelerating leakage across the BBB. Potential future therapeutic approaches might help to prevent BBB damage (eg, monoclonal antibodies targeting cell adhesion molecules and fibrinogen) and help to repair BBB dysfunction (eg, mesenchymal stromal cells) in people with multiple sclerosis.

How Early Is Early Multiple Sclerosis?

The development and further optimization of the diagnostic criteria for multiple sclerosis (MS) emphasize the establishment of an early and accurate diagnosis. So far, numerous studies have revealed the significance of early treatment administration for MS and its association with slower disease progression and better late outcomes of the disease with regards to disability accumulation. However, according to current research results, both neuroinflammatory and neurodegenerative processes may exist prior to symptom initiation. Despite the fact that a significant proportion of individuals with radiologically isolated syndrome (RIS) progress to MS, currently, there is no available treatment approved for RIS. Therefore, our idea of "early treatment administration" might be already late in some cases. In order to detect the individuals who will progress to MS, we need accurate biomarkers. In this review, we present notable research results regarding the underlying pathology of MS, as well as several potentially useful laboratory and neuroimaging biomarkers for the identification of high-risk individuals with RIS for developing MS. This review aims to raise clinicians' awareness regarding "subclinical" MS, enrich their understanding of MS pathology, and familiarize them with several potential biomarkers that are currently under investigation and might be used in clinical practice in the future for the identification of individuals with RIS at high risk for conversion to definite MS.

Neurofilament light chain in spinal fluid and plasma in multiple system atrophy: a prospective, longitudinal biomarker study

PURPOSE

There is a critical need for reliable diagnostic biomarkers as well as surrogate markers of disease progression in multiple system atrophy (MSA). Neurofilament light chain (NfL) has been reported to potentially meet those needs. We therefore sought to explore the value of NfL in plasma (NfL-p) in contrast to cerebrospinal fluid (NfL-c) as a diagnostic marker of MSA, and to assess NfL-p and NfL-c as markers of clinical disease progression.

METHODS

Well-characterized patients with early MSA (n = 32), Parkinson's disease (PD; n = 21), and matched controls (CON; n = 15) were enrolled in a prospective, longitudinal study of synucleinopathies with serial annual evaluations. NfL was measured using a high-sensitivity immunoassay, and findings were assessed by disease category and relationship with clinical measures of disease progression.

RESULTS

Measurements of NfL-c were highly reproducible across immunoassay platforms (Pearson, r = 0.99), while correlation between NfL-c and -p was only moderate (r = 0.66). NfL was significantly higher in MSA compared with CON and PD; the separation was essentially perfect for NfL-c, but there was overlap, particularly with PD, for NfL-p. While clinical measures of disease severity progressively increased over time, NfL-c and -p remained at stable elevated levels within subjects across serial measurements. Neither change in NfL nor baseline NfL were significantly associated with changes in clinical markers of disease severity.

CONCLUSIONS

These findings confirm NfL-c as a faithful diagnostic marker of MSA, while NfL-p showed less robust diagnostic value. The significant NfL elevation in MSA was found to be remarkably stable over time and was not predictive of clinical disease progression.

Visual function resists early neurodegeneration in the visual system in primary progressive multiple sclerosis

BACKGROUND

Neurodegeneration in multiple sclerosis (MS) affects the visual system but dynamics and pathomechanisms over several years especially in primary progressive MS (PPMS) are not fully understood.

METHODS

We assessed longitudinal changes in visual function, retinal neurodegeneration using optical coherence tomography, MRI and serum NfL (sNfL) levels in a prospective PPMS cohort and matched healthy controls. We investigated the changes over time, correlations between outcomes and with loss of visual function.

RESULTS

We followed 81 patients with PPMS (mean disease duration 5.9 years) over 2.7 years on average. Retinal nerve fibre layer thickness (RNFL) was reduced in comparison with controls (90.1 vs 97.8 µm; p<0.001). Visual function quantified by the area under the log contrast sensitivity function (AULCSF) remained stable over a continuous loss of RNFL (0.46 µm/year, 95% CI 0.10 to 0.82; p=0.015) up until a mean turning point of 91 µm from which the AULCSF deteriorated. Intereye RNFL asymmetry above 6 µm, suggestive of subclinical optic neuritis, occurred in 15 patients and was related to lower AULCSF but occurred also in 5 out of 44 controls. Patients with an AULCSF progression had a faster increase in Expanded Disability Status Scale (beta=0.17/year, p=0.043). sNfL levels were elevated in patients (12.2 pg/mL vs 8.0 pg/mL, p<0.001), but remained stable during follow-up (beta=-0.14 pg/mL/year, p=0.291) and were not associated with other outcomes.

CONCLUSION

Whereas neurodegeneration in the anterior visual system is already present at onset, visual function is not impaired until a certain turning point. sNfL is not correlated with structural or functional impairment in the visual system.

Intrathecal kappa free light chain synthesis is associated with worse prognosis in relapsing-remitting multiple sclerosis

BACKGROUND

While kappa free light chain (KFLC) index has become a useful diagnostic biomarker in multiple sclerosis (MS), its prognostic properties are less explored. B cells play a crucial role in MS pathogenesis, but the impact from increased intrathecal production of immunoglobulins and KFLC remains to be determined. Recently, it has become evident that insidious worsening is not confined to progressive MS but is also common in relapsing-remitting MS (RRMS), a feature known as progression independent of relapse activity (PIRA).

METHODS

We retrospectively identified 131 patients with clinically isolated syndrome or early RRMS who had determined KFLC index as part of their diagnostic workup. Demographic and clinical data were extracted from the Swedish MS registry. Associations of baseline KFLC index with evidence of disease activity (EDA) and PIRA were investigated in multivariable cox proportional hazards regression models.

RESULTS

KFLC index was significantly higher in PIRA (median 148.5, interquartile range [IQR] 106.9-253.5) compared with non-PIRA (78.26, IQR 28.93-186.5, p = 0.009). In a multivariable cox regression model adjusted for confounders, KFLC index emerged as an independent risk factor for PIRA (adjusted hazard ratio [aHR] 1.005, 95% confidence interval [CI] 1.002-1.008, p = 0.002). Dichotomized by the cut-off value KFLC index > 100, patients with KFLC index > 100 had an almost fourfold increase in the risk for developing PIRA. KFLC index was also predictive of evidence of disease activity during follow-up.

CONCLUSIONS

Our data indicate that high KFLC index at baseline is predictive of PIRA, EDA-3, and overall worse prognosis in MS.

Insights on therapeutic potential of clemastine in neurological disorders

Clemastine, a Food and Drug Administration (FDA)-approved compound, is recognized as a first-generation, widely available antihistamine that reduces histamine-induced symptoms. Evidence has confirmed that clemastine can transport across the blood-brain barrier and act on specific neurons and neuroglia to exert its protective effect. In this review, we summarize the beneficial effects of clemastine in various central nervous system (CNS) disorders, including neurodegenerative disease, neurodevelopmental deficits, brain injury, and psychiatric disorders. Additionally, we highlight key cellular links between clemastine and different CNS cells, in particular in oligodendrocyte progenitor cells (OPCs), oligodendrocytes (OLs), microglia, and neurons.

Immune cell subpopulations and serum neurofilament light chain are associated with increased risk of disease worsening in multiple sclerosis

Changes is lymphocyte subpopulations in peripheral blood have been proposed as biomarkers for evaluation of disease activity in multiple sclerosis (MS). Serum neurofilament light chain (sNfL) is a biomarker reflecting neuro-axonal injury in MS that could be used to monitor disease activity, response to drugs and to prognosticate disease course. Here we show a moderate correlation between sNfL and lymphocyte cell subpopulations, and our data furthermore suggest that sNfL and specific immune cell subpopulations together could predict future disease worsening in MS.

Neurofilament Light Chain in Spinal Fluid and Plasma in Multiple System Atrophy - A Prospective, Longitudinal Biomarker Study

Purpose There is a critical need for reliable diagnostic biomarkers as well as surrogate markers of disease progression in multiple system atrophy (MSA). Neurofilament light chain (NfL) has been reported to potentially meet those needs. We therefore sought to explore the value of NfL in plasma (NfL-p) in contrast to CSF (NfL-c) as diagnostic marker of MSA, and to assess NfL-p and NfL-c as markers of clinical disease progression. Methods Well-characterized patients with early MSA (n=32), Parkinson's disease (PD, n=21), and matched controls (CON, n=15) were enrolled in a prospective, longitudinal study of synucleinopathies with serial annual evaluations. NfL was measured using a high sensitivity immunoassay, and findings were assessed by disease category and relationship with clinical measures of disease progression. Results Measurements of NfL-c were highly reproducible across immunoassay platforms (Pearson,r=0.99), while correlation between NfL-c and -p was only moderate (r=0.66). NfL was significantly higher in MSA compared to CON and PD; the separation was essentially perfect for NfL-c, but there was overlap, particularly with PD, for NfL-p. While clinical measures of disease severity progressively increased over time, NfL-c and -p remained at stable elevated levels within subjects across serial measurements. Neither change in NfL nor baseline NfL were significantly associated with changes in clinical markers of disease severity. Conclusions These findings confirm NfL-c as faithful diagnostic marker of MSA, while NfL-p showed less robust diagnostic value. The significant NfL elevation in MSA was found to be remarkably stable over time and was not predictive of clinical disease progression.

Predictive value of brain atrophy, serum biomarkers and information processing speed for early disease progression in multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a chronic autoimmune-mediated demyelinating disease of the central nervous system (CNS). A clinical presentation of the disease is highly differentiated even from the earliest stages of the disease. The application of stratifying tests in clinical practice would allow for improving clinical decision-making including a proper assessment of treatment benefit/risk balance.

METHODS

This prospective study included patients with MS diagnosed up to 1 year before recruitment. We analyzed serum biomarkers such as CXCL13, CHI3L1, OPN, IL-6, and GFAP and neurofilament light chains (NfLs); brain MRI parameters of linear atrophy such as bicaudate ratio (BCR), third ventricle width (TVW); and information processing speed were measured using the Symbol Digit Modalities Test (SDMT) during the 2 years follow-up.

RESULTS

The study included a total of 50 patients recruited shortly after the diagnosis of MS diagnosis (median 0 months; range 0-11 months), and the mean time of observation was 28 months (SD = 4.75). We observed a statistically significant increase in the EDSS score (Wilcoxon test: Z = 3.06, p = 0.002), BCR (Wilcoxon test: Z = 4.66, p < 0.001), and TVW (Wilcoxon test: Z = 2.84, p = 0.005) after 2 years of disease. Patients who had a significantly higher baseline level of NfL suffered from a more severe disease course as per the EDSS score (Mann-Whitney U-test: U = 107, Z = -2,74, p = 0.006) and presence of relapse (Mann-Whitney U-test: U = 188, Z = -2.01, p = 0.044). In the logistic regression model, none of the parameters was a significant predictor for the achieving of no evidence of disease activity status (NEDA). In the model considering all assessed parameters, only the level of NfL had a significant impact on disease progression, measured as the increase in EDSS (logistic regression: β = 0.002, p = 0.017).

CONCLUSION

We confirmed that NfL levels in serum are associated with more active disease. Moreover, we found that TVW at the time of diagnosis was associated with an impairment in cognitive function measured by information processing speed at the end of the 2-year observation. The inclusion of serum NfL and TVW assessment early in the disease may be a good predictor of disease progression independent of NEDA.

Clinical validation of a multi-protein, serum-based assay for disease activity assessments in multiple sclerosis

An 18-protein multiple sclerosis (MS) disease activity (DA) test was validated based on associations between algorithm scores and clinical/radiographic assessments (N = 614 serum samples; Train [n = 426; algorithm development] and Test [n = 188; evaluation] subsets). The multi-protein model was trained based on presence/absence of gadolinium-positive (Gd+) lesions and was also strongly associated with new/enlarging T2 lesions, and active versus stable disease (composite of radiographic and clinical evidence of DA) with improved performance (p < 0.05) compared to the neurofilament light single protein model. The odds of having ≥1 Gd + lesions with a moderate/high DA score were 4.49 times that of a low DA score, and the odds of having ≥2 Gd + lesions with a high DA score were 20.99 times that of a low/moderate DA score. The MSDA Test was clinically validated with improved performance compared to the top-performing single-protein model and can serve as a quantitative tool to enhance the care of MS patients.

High serum neurofilament levels are observed close to disease activity events in pediatric-onset MS and MOG antibody-associated diseases

BACKGROUND

Serum neurofilament light chain (sNfL) is an emerging multiple sclerosis (MS) biomarker which measures neuro-axonal damage. However, understanding its temporal association with disease activity in pediatric-onset MS (POMS) and Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) remains limited.

OBJECTIVE

To investigate the association of sNfL levels and time from disease activity in children with MS and MOGAD.

METHODS

POMS and MOGAD cases with onset before 18 years of age were enrolled at the University of California San Francisco (UCSF) Regional Pediatric MS Center. Frequency-matched healthy subjects were recruited from general pediatric clinics. Serum samples were tested for MOG-IgG at Mayo Clinic using a live cell-based fluorescent activated cell sorting assay. sNfL levels were measured using single-molecule array (Simoa) technology measured in pg/mL. Data on demographics, clinical features, MRI, CSF, and treatment data were collected by chart review.

RESULTS

We included 201 healthy controls healthy controls, 142 POMS, and 20 confirmed MOGAD cases with available sNfL levels. The median (IQR) age at the time of sampling was 15.6 (3.9), 15.5 (3.1), and 8.8 (4.1) years for controls, POMS, and MOGAD, respectively. Median sNfL levels (pg/ml) were higher in POMS (19.6) and MOGAD (32.7) cases compared to healthy controls (3.9) (p<0.001). sNfL levels ≥100 pg/ml were only detected within four months of a clinical event or MRI activity in both POMS and MOGAD cases. In addition, sNfL levels were higher in POMS patients with new/enlarged T2 and gadolinium-enhanced lesions than those without MRI activity within four months of sampling in POMS cases.

CONCLUSION

High sNfL levels were observed close to clinical or MRI events in POMS and MOGAD. Our findings support sNfL as a biomarker of disease activity in pediatric demyelinating disorders.

Validity of serum neurofilament light chain as a prognostic biomarker of disease activity in multiple sclerosis

Multiple sclerosis (MS) is a chronic demyelinating and neuroinflammatory disease of the human central nervous system with complex pathoetiology, heterogeneous presentations and an unpredictable course of disease progression. There remains an urgent need to identify and validate a biomarker that can reliably predict the initiation and progression of MS as well as identify patient responses to disease-modifying treatments/therapies (DMTs). Studies exploring biomarkers in MS and other neurodegenerative diseases currently focus mainly on cerebrospinal fluid (CSF) analyses, which are invasive and impractical to perform on a repeated basis. Recent studies, replacing CSF with peripheral blood samples, have revealed that the elevation of serum neurofilament light chain (sNfL) in the clinical stages of MS is, potentially, an ideal prognostic biomarker for predicting disease progression and for possibly guiding treatment decisions. However, there are unresolved factors (the definition of abnormal values of sNfL concentration, the standardisation of measurement and the amount of change in sNfL concentration that is significant) that are preventing its use as a biomarker in routine clinical practice for MS. This updated review critiques these recent findings and highlights areas for focussed work to facilitate the use of sNfL as a prognostic biomarker in MS management.

Serum neurofilament light-chain levels and long-term treatment outcomes in relapsing-remitting multiple sclerosis patients: A post hoc analysis of the randomized CombiRx trial

Background

CombiRx was a randomized, double-blind, placebo-controlled phase 3 trial in treatment-naive relapsing-remitting multiple sclerosis (RRMS) patients randomized to intramuscular interferon beta-1a (IM IFN beta-1a), glatiramer acetate (GA), or both therapies.

Objective

This analysis investigated changes in serum neurofilament light-chain (sNfL) levels in response to treatment and assessed baseline sNfL as a predictor of relapse.

Methods

RRMS patients treated with IM IFN beta-1a 30 µg weekly + placebo (n = 159), GA 20 mg/mL daily + placebo (n = 172), or IM IFN beta-1a + GA (n = 344) were included. A linear mixed model compared sNfL values over time. Cox regression models analyzed baseline sNfL and gadolinium-enhancing (Gd+) lesions as predictors of relapse.

Results

In all treatment arms, the proportion of patients with sNfL ≥16 pg/mL decreased significantly from baseline to 6 months and was maintained at 36 months. A significantly higher percentage of patients with both baseline sNfL ≥16 pg/mL and ≥1 Gd+ lesion experienced relapses within 90 days compared to patients with sNfL <16 pg/mL and/or no Gd+ lesions.

Conclusion

sNfL levels were reduced within 6 months and remained low at 36 months. Results suggest that the combination of lesion activity and sNfL was a stronger predictor of relapse than either factor alone.

Serum neurofilament light chain as a reliable biomarker of hereditary transthyretin-related amyloidosis-A Swiss reference center experience

Hereditary transthyretin-related (hATTR) amyloidosis is a rare disease, causing a disabling and life-threatening axonal length-dependent polyneuropathy. Monitoring of disease progression and treatment response is difficult. We aimed to determine if serum neurofilament light chain (sNfL) is a reliable and early biomarker of peripheral neuropathy in hATTR amyloidosis. We prospectively included 20 hATTR patients, 14 symptomatic and 6 asymptomatic. Patients were assessed at baseline and 1 year, including a full clinical examination with disease severity and functional scores, electrochemical skin conductance measurement with Sudoscan and nerve conduction studies, and sNfL level. hATTR patient sNfL were also compared with sNfL of 4532 healthy controls of a reference database by calculating age and BMI-adjusted Z scores. At baseline, median sNfL concentration was 3.6-fold higher in symptomatic than asymptomatic hATTR patients (P = .003), and this difference was also found in our under 60-years-old patients (P = .003). There was no significant difference of sNfL concentration between asymptomatic patients and healthy controls (Z-score of -0.29), but a significant difference between symptomatic patients and healthy controls (Z-score of 2.52). We found a significant correlation between sNfL levels and most clinical and electrophysiological disease severity scores, the strongest correlation being with the NIS score. sNfL seems to be a reliable biomarker of peripheral neuropathy severity in hATTR amyloidosis and can distinguish between asymptomatic and symptomatic patients. sNfL could also become a reliable biomarker to establish disease onset and treatment response.

High serum neurofilament light chain levels correlate with brain atrophy and physical disability in multiple sclerosis

BACKGROUND AND PURPOSE

Serum neurofilament light chain (sNfL) is a promising biomarker of neuroaxonal damage in persons with multiple sclerosis (pwMS). In cross-sectional studies, sNfL has been associated with disease activity and brain magnetic resonance imaging (MRI) changes; however, it is still unclear to what extent in particular high sNfL levels impact on subsequent disease evolution.

METHODS

sNfL was quantified by an ultrasensitive single molecule array (Simoa) in 199 pwMS (median age = 34.2 years, 64.3% female) and 49 controls. All pwMS underwent 3-T MRI to assess global and compartmental normalized brain volumes, T2-lesion load, and cortical mean thickness. Follow-up data and serum samples were available in 144 pwMS (median follow-up time = 3.8 years). Linear and binary logistic models were used to estimate the independent contribution of sNfL for changes in MRI and Expanded Disability Status Scale (EDSS). Age-corrected sNfL z-scores from a normative database of healthy controls were used for sensitivity analyses.

RESULTS

High sNfL levels at baseline were associated with atrophy measures of the whole brain (standardized beta coefficient βj = -0.352, p < 0.001), white matter (βj = -0.229, p = 0.007), thalamus (βj = -0.372, p = 0.004), and putamen (βj = -1.687, p = 0.012). pwMS with high levels of sNfL at baseline and follow-up had a greater risk of EDSS worsening (p = 0.007).

CONCLUSIONS

Already single time point elevation of sNfL has a distinct effect on brain volume changes over a short-term period, and repeated high levels of sNfL indicate accumulating physical disability. Serial assessment of sNfL may provide added value in the clinical management of pwMS.

Serum and cerebrospinal fluid BDNF concentrations are associated with neurological and cognitive improvement in multiple sclerosis: A pilot study

BACKGROUND

Biomarkers of disease activity have been intensively studied in multiple sclerosis (MS) but knowledge on predictors of disability improvement is limited. The aim of this pilot study was to explore whether increased brain-derived neurotrophic factor concentrations in serum and CSF (sBDNF/cBDNF) precede neurological and cognitive improvement in MS.

METHODS

In this pilot, monocentric prospective cohort study we collected serum/CSF samples at baseline together with EDSS (n = 36) and cognitive testing (n = 34) in patients with relapsing-remitting/primary progressive MS or clinically isolated syndrome. BDNF was assessed in serum and CSF with a single molecule array (SIMOA) HD-1 analyser (Quanterix). Twelve months later EDSS and cognitive testing were repeated. BDNF concentrations of patients with vs. without disability or cognitive improvement (disability improvement: decrease in EDSS ≥ 0.5; cognitive improvement: average z-score increase in neuropsychological performance ≥ 0.5) were compared using univariate ANOVAs adjusting for covariates.

RESULTS

Compared to subjects without, patients with disability improvement had higher sBDNF at baseline (q = 0.04). Subjects with cognitive improvement had higher cBDNF at baseline than those without cognitive improvement (q = 0.004). Secondary analysis demonstrated significant correlations between sBDNF and EDSS change (q = 0.036), cBDNF and average z-score change (q = 0.04) and cBDNF and number of cognitive tests with improvement (q = 0.04), while controlling for covariates.

CONCLUSIONS

Our findings suggest a possible role for BDNF in neurological and cognitive improvement in MS. These findings have to be confirmed in a larger sample but they already highlight the potential of BDNF as a biomarker for disability improvement and neuroplasticity in MS.

Serum neurofilament light levels in natalizumab-treated patients with multiple sclerosis who switch to extended interval dosing from every-4-week dosing in real-world clinical practice

BACKGROUND

Serum levels of neurofilament light chain (sNfL) are a potentially useful biomarker for assessing the efficacy of multiple sclerosis (MS) treatments.

OBJECTIVE

To compare levels of sNfL in patients with MS who switched from natalizumab every 4 weeks (Q4W) to extended interval dosing (EID) and patients who remained on Q4W dosing in real-world clinical practice.

METHODS

This was a retrospective analysis of samples from patients treated with natalizumab from 2010 to 2015 at a single center in the United States. Levels of sNfL were compared in patients who stayed on Q4W dosing or who switched to EID (parallel-arm analyses) and during Q4W and EID periods in patients who switched to EID (pre- and post-switch analyses).

RESULTS

The analysis included 139 patients (Q4W: n = 79; EID: n = 60). After adjustment, levels of sNfL did not significantly differ between patients who remained on Q4W dosing and those who switched to EID in parallel-arm analyses (adjusted Q4W-EID difference = 0.51 pg/mL; p = 0.60) or pre- and post-switch analyses (adjusted difference = 0.96 pg/mL; p = 0.10).

CONCLUSION

These sNfL biomarker results suggest that the effectiveness of natalizumab is maintained in patients who switch from Q4W dosing to EID.

Metabolic syndrome parameters and multiple sclerosis disease outcomes: A Portuguese cross-sectional study

BACKGROUND

Metabolic syndrome and multiple sclerosis [MS] share the presence of chronic inflammation in their pathogenic mechanisms. This study aimed to estimate the prevalence of metabolic syndrome parameters in MS and their association with disease disability, cognitive function, and Neurofilament Light chain [NfL] levels.

METHODS

Clinical, analytical, and magnetic resonance imaging data were obtained through medical records. Disease disability was measured by the Expanded Disability Status Scale [EDSS], the MS Severity Scale [MSSS] along with cognitive impairment by the Brief International Cognitive Assessment for MS [BICAMS] and Word List Generation test [WLG]. Metabolic syndrome parameters were evaluated by fasting blood glucose, triglycerides, high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol, total cholesterol, blood pressure, and waist circumference [WC]. We also analysed serum leptin and ghrelin and cerebrospinal fluid NfL.

RESULTS

Our sample included 51 people with MS, 34 (66.7%) females, mean age of 38.20±12.12 years and median disease duration of 3 years (P25=2.0, P75=5.0). Multivariate linear regression analysis confirmed that WC correlates with EDSS (β=0.04, p=.001) and MSSS (β=0.07, p=.002) as well as Brief Visuospatial Memory Test-Revised (β=-0.29, p=.008), WLG (β=-0.20, p=.039). NfL is also negatively associated with HDL-C (β=-4.51, p=.038).

CONCLUSIONS

Waist circumference is associated with disability and deficits in cognitive tests. A decrease in HDL-C is associated with an increase in NfL. This suggests metabolic syndrome might be an important factor in MS disease course.

Effects of white matter lesion grading on the cognitive function of patients with chronic alcohol dependence

BACKGROUND

Alcohol dependence has become a major problem that poses a serious threat to public health. Long-term heavy alcohol consumption can lead to brain functional disorders. This study aimed to investigate the relationship of the severity of cerebral white matter lesions (WMLs), serum neurofilament light (NfL) and inflammatory factors, tumour necrosis factor alpha (TNF-α) and Interleukin-1β (IL-1β), with the cognitive function of patients with alcohol dependence.

METHODS

A total of 118 patients were enrolled in this prospective study, and divided into alcohol-dependent and non-alcohol-dependent groups. The severity of WMLs was assessed using the Fazekas scale based on magnetic resonance imaging analysis. The expression levels of NfL, TNF-α and IL-1β in the serum of the subjects were measured by enzyme-linked immunosorbent assay. The cognitive function and psychological status of the patients were assessed using the Minimum Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Hamilton Depression Rating Scale (HAMD) and Hamilton Anxiety Rating Scale (HAMA). The severity of WMLs and the expression levels of serum NfL, TNF-α and IL-1β in alcohol-dependent patients were analysed for their influence on cognitive function. This clinical trial was approved by China Clinical Trials Registry, and the trial number is ChiCTR2200066057 (http://www.chictr.org.cn/searchproj.aspx).

RESULTS

The score of Fazekas scale was higher, and the MMSE score and MoCA score were lower in the alcohol-dependent group than those in the non-alcohol-dependent group. Moreover, the Fazekas score of the alcohol-dependent group was negatively correlated with the MMSE and MoCA scores. The serum NfL, TNF-α and IL-1β levels were higher in the alcohol-dependent group than in the non-alcohol-dependent group, and the serum NfL, TNF-α and IL-1β levels in the alcohol-dependent group were negatively correlated with the MMSE and MoCA scores.

CONCLUSION

Alcohol-dependent patients have more severe cerebral WMLs and significant cognitive impairment, particularly in visuospatial and executive functions, attention, calculation, abstraction, delayed recall and orientation. Serum NfL, TNF-α and IL-1β may be used as biomarkers to assess alcohol related cognitive decline.

Effect of Estimated Blood Volume and Body Mass Index on GFAP and NfL Levels in the Serum and CSF of Patients With Multiple Sclerosis

BACKGROUND AND OBJECTIVES

To increase the validity of biomarker measures in multiple sclerosis (MS), factors affecting their concentration need to be identified. Here, we test whether the volume of distribution approximated by the patients' estimated blood volume (BV) and body mass index (BMI) affect the serum concentrations of glial fibrillary acidic protein (GFAP). As a control, we also determine the relationship between BV/BMI and GFAP concentrations in CSF. To confirm earlier findings, we test the same hypotheses for neurofilament light chain (NfL).

METHODS

NfL and GFAP concentrations were measured in serum and CSF (sNFL/sGFAP and cNFL/cGFAP) in 157 patients (n = 106 with MS phenotype and n = 51 with other neurologic/somatoform diseases). Using multivariate linear regressions, BV was tested in the MS cohort as a predictor for each of the biomarkers while controlling for age, sex, MS phenotype, Expanded Disability Status Scale score, gadolinium-enhancing lesions, and acute relapse. In addition, overweight/obese patients (BMI ≥25 kg/m2) were compared with patients with BMI <25 kg/m2 using the general linear model. The analyses were repeated including the neurologic/somatoform controls.

RESULTS

In the MS cohort, BV predicted sGFAP (ß = -0.301, p = 0.014). Overweight/obese patients with MS had lower sGFAP concentrations compared with patients with MS and BMI <25 kg/m2 (F = 4.732, p = 0.032). Repeating the analysis after adding patients with other neurologic/somatoform diseases did not change these findings (ß = -0.276, p = 0.009; F = 7.631, p = 0.006). Although sNfL was inversely correlated with BV (r = -0.275, p = 0.006) and body weight (r = -0.258, p = 0.010), those results did not remain significant after adjusting for covariates. BV and BMI were not associated with cGFAP or cNfL concentrations.

DISCUSSION

These findings support the notion that the volume of distribution of sGFAP approximated by BV and BMI is a relevant variable and should therefore be controlled for when measuring sGFAP in MS, while this might not be necessary when measuring cGFAP concentrations.

The role of neurofilament light in genetic frontotemporal lobar degeneration

Genetic frontotemporal lobar degeneration caused by autosomal dominant gene mutations provides an opportunity for targeted drug development in a highly complex and clinically heterogeneous dementia. These neurodegenerative disorders can affect adults in their middle years, progress quickly relative to other dementias, are uniformly fatal and have no approved disease-modifying treatments. Frontotemporal dementia, caused by mutations in the GRN gene which encodes the protein progranulin, is an active area of interventional drug trials that are testing multiple strategies to restore progranulin protein deficiency. These and other trials are also examining neurofilament light as a potential biomarker of disease activity and disease progression and as a therapeutic endpoint based on the assumption that cerebrospinal fluid and blood neurofilament light levels are a surrogate for neuroaxonal damage. Reports from genetic frontotemporal dementia longitudinal studies indicate that elevated concentrations of blood neurofilament light reflect disease severity and are associated with faster brain atrophy. To better inform patient stratification and treatment response in current and upcoming clinical trials, a more nuanced interpretation of neurofilament light as a biomarker of neurodegeneration is now required, one that takes into account its relationship to other pathophysiological and topographic biomarkers of disease progression from early presymptomatic to later clinically symptomatic stages.

Neurofilament Light Chain Levels Are Predictive of Clinical Conversion in Radiologically Isolated Syndrome

BACKGROUND AND OBJECTIVES

To evaluate the predictive value of serum neurofilament light chain (sNfL) and CSF NfL (cNfL) in patients with radiologically isolated syndrome (RIS) for evidence of disease activity (EDA) and clinical conversion (CC).

METHODS

sNfL and cNfL were measured at RIS diagnosis by single-molecule array (Simoa). The risk of EDA and CC according to sNfL and cNfL was evaluated using the Kaplan-Meier analysis and multivariate Cox regression models including age, spinal cord (SC) or infratentorial lesions, oligoclonal bands, CSF chitinase 3-like protein 1, and CSF white blood cells.

RESULTS

Sixty-one patients with RIS were included. At diagnosis, sNfL and cNfL were correlated (Spearman r = 0.78, p < 0.001). During follow-up, 47 patients with RIS showed EDA and 36 patients showed CC (median time 12.6 months, 1-86). When compared with low levels, medium and high cNfL (>260 pg/mL) and sNfL (>5.0 pg/mL) levels were predictive of EDA (log rank, p < 0.01 and p = 0.02, respectively). Medium-high cNfL levels were predictive of CC (log rank, p < 0.01). In Cox regression models, cNfL and sNfL were independent factors of EDA, while SC lesions, cNfL, and sNfL were independent factors of CC.

DISCUSSION

cNfL >260 pg/mL and sNfL >5.0 pg/mL at diagnosis are independent predictive factors of EDA and CC in RIS. Although cNfL predicts disease activity better, sNfL is more accessible than cNfL and can be considered when a lumbar puncture is not performed.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in people with radiologic isolated syndrome (RIS), initial serum and CSF NfL levels are associated with subsequent evidence of disease activity or clinical conversion.

Neurofilament light chain in blood as a diagnostic and predictive biomarker for multiple sclerosis: A systematic review and meta-analysis

Background

Neurofilament light chain (NfL) in cerebrospinal fluid (CSF) is a biomarker of multiple sclerosis (MS). However, CSF sampling is invasive and has limited the clinical application. With the development of highly sensitive single-molecule assay, the accurate quantification of the very low NfL levels in blood become feasible. As evidence being accumulated, we performed a meta-analysis to evaluate the diagnostic and predictive value of blood NfL in MS patients.

Methods

We performed literature search on PubMed, EMBASE, Web of Science and Cochrane Library from inception to May 31, 2022. The blood NfL differences between MS vs. controls, MS vs. clinically isolated syndrome (CIS), progressive MS (PMS) vs. relapsing-remitting MS (RRMS), and MS in relapse vs. MS in remission were estimated by standard mean difference (SMD) and corresponding 95% confidence interval (CI). Pooled hazard ratio (HR) and 95%CI were calculated to predict time to reach Expanded Disability Status Scale (EDSS) score≥4.0 and to relapse.

Results

A total of 28 studies comprising 6545 MS patients and 2477 controls were eligible for meta-analysis of diagnosis value, and 5 studies with 4444 patients were synthesized in analysis of predictive value. Blood NfL levels were significantly higher in MS patients vs. age-matched controls (SMD = 0.64, 95%CI 0.44–0.85, P<0.001), vs. non-matched controls (SMD = 0.76, 95%CI 0.56–0.96, P<0.001) and vs. CIS patients (SMD = 0.30, 95%CI 0.18–0.42, P<0.001), in PMS vs. RRMS (SMD = 0.56, 95%CI 0.27–0.85, P<0.001), and in relapsed patients vs. remitted patients (SMD = 0.54, 95%CI 0.16–0.92, P = 0.005). Patients with high blood NfL levels had shorter time to reach EDSS score≥4.0 (HR = 2.36, 95%CI 1.32–4.21, P = 0.004) but similar time to relapse (HR = 1.32, 95%CI 0.90–1.93, P = 0.155) compared to those with low NfL levels.

Conclusion

As far as we know, this is the first meta-analysis evaluating the diagnosis and predictive value of blood NfL in MS. The present study indicates blood NfL may be a useful biomarker in diagnosing MS, distinguishing MS subtypes and predicting disease worsening in the future.

The prognostic significance of early blood neurofilament light chain concentration and magnetic resonance imaging variables in relapse-onset multiple sclerosis

BACKGROUND

Improved prognostication remains vital in multiple sclerosis to inform personalized treatment approaches. Blood neurofilament light (bNfL) is a promising prognostic biomarker, but to what extent it provides additional information, independent of established MRI metrics, is yet to be established.

METHODS

We obtained all available bNfL data for 133 patients from a longitudinal observational cohort study. Patients were dichotomized into good or poor outcome groups based upon clinical and cognitive assessments performed 15 years after a clinically isolated syndrome. We performed longitudinal modeling of early NfL and MRI variables to examine differences between outcome groups.

RESULTS

The bNfL dataset was incomplete, with one to three (mean 1.5) samples available per participant. Within 3 months of onset, bNfL was similar between groups. The bNfL concentration subsequently decreased in those with a good outcome, and remained persistently elevated in those with a poor outcome. By year 5, NfL in the poor outcome group was approximately double that of those with a good outcome (14.58 [10.40-18.77] vs. 7.71 [6.39-9.04] pg/ml, respectively). Differences were reduced after adjustment for longitudinal changes in T2LV, but trends persisted for a greater rate of increase in NfL in those with a poor outcome, independent of T2LV.

CONCLUSIONS

This analysis requires replication in cohorts with more complete bNfL datasets, but suggests that persistently elevated blood NfL may be more common in patients with a poor long-term outcome. Persistent elevation of blood NfL may provide additional prognostic information not wholly accounted for by standard monitoring techniques.

Neurofilaments in neurologic disorders and beyond

Many neurologic diseases can initially present as a diagnostic challenge and even when a diagnosis is made, monitoring of disease activity, progression and response to therapy may be limited with existing clinical and paraclinical assessments. As such, the identification of disease specific biomarkers provides a promising avenue by which diseases can be effectively diagnosed, monitored and used as a prognostic indicator for long-term outcomes. Neurofilaments are an integral component of the neuronal cytoskeleton, where assessment of neurofilaments in the blood, cerebrospinal fluid (CSF) and diseased tissue has been shown to have value in providing diagnostic clarity, monitoring disease activity, tracking progression and treatment efficacy, as well as lending prognostic insight into long-term outcomes. As such, this review attempts to provide a glimpse into the structure and function of neurofilaments, their role in various neurologic and non-neurologic disorders, including uncommon conditions with recent knowledge of neurofilament-related pathology, as well as their applicability in future clinical practice.

Plasma neurofilament light chain levels suggest neuroaxonal stability following therapeutic remyelination in people with multiple sclerosis

BACKGROUND

Chronic demyelination is a major contributor to axonal vulnerability in multiple sclerosis (MS). Therefore, remyelination could provide a potent neuroprotective strategy. The ReBUILD trial was the first study showing evidence for successful remyelination following treatment with clemastine in people with MS (pwMS) with no evidence of disease activity or progression (NEDAP). Whether remyelination was associated with neuroprotection remains unexplored.

METHODS

Plasma neurofilament light chain (NfL) levels were measured from ReBUILD trial's participants. Mixed linear effect models were fit for individual patients, epoch and longitudinal measurements to compare NfL concentrations between samples collected during the active and placebo treatment period.

RESULTS

NfL concentrations were 9.6% lower in samples collected during the active treatment with clemastine (n=53, geometric mean=6.33 pg/mL) compared to samples collected during treatment with placebo (n=73, 7.00 pg/mL) (B=-0.035 [-0.068 to -0.001], p=0.041). Applying age- and body mass index-standardised NfL Z-scores and percentiles revealed similar results (0.04 vs 0.35, and 27.5 vs 33.3, p=0.023 and 0.042, respectively). Higher NfL concentrations were associated with more delayed P100 latencies (B=1.33 [0.26 to 2.41], p=0.015). In addition, improvement of P100 latencies between visits was associated with a trend for lower NfL values (B=0.003 [-0.0004 to 0.007], p=0.081). Based on a Cohen's d of 0.248, a future 1:1 parallel-arm placebo-controlled study using a remyelinating agent with comparable effect as clemastine would need 202 subjects per group to achieve 80% power.

CONCLUSIONS

In pwMS, treatment with the remyelinating agent clemastine was associated with a reduction of blood NfL, suggesting that neuroprotection is achievable and measurable with therapeutic remyelination.

TRIAL REGISTRATION NUMBER

NCT02040298.

Serum neurofilament light chain concentration predicts disease worsening in multiple sclerosis

Background:

Serum neurofilament light (sNfL) chain is a promising biomarker reflecting neuro-axonal injury in multiple sclerosis (MS). However, the ability of sNfL to predict outcomes in real-world MS cohorts requires further validation.

Objective:

The aim of the study is to investigate the associations of sNfL concentration, magnetic resonance imaging (MRI) and retinal optical coherence tomography (OCT) markers with disease worsening in a longitudinal European multicentre MS cohort.

Methods:

MS patients (n = 309) were prospectively enrolled at four centres and re-examined after 2 years (n = 226). NfL concentration was measured by single molecule array assay in serum. The patients’ phenotypes were thoroughly characterized with clinical examination, retinal OCT and MRI brain scans. The primary outcome was disease worsening at median 2-year follow-up.

Results:

Patients with high sNfL concentrations (⩾8 pg/mL) at baseline had increased risk of disease worsening at median 2-year follow-up (odds ratio (95% confidence interval) = 2.8 (1.5–5.3), p = 0.001). We found no significant associations of MRI or OCT measures at baseline with risk of disease worsening.

Conclusion:

Serum NfL concentration was the only factor associated with disease worsening, indicating that sNfL is a useful biomarker in MS that might be relevant in a clinical setting.

The relationship of CSF neurofilament levels with MRI lesion location and disease activity in Multiple Sclerosis

BACKGROUND

Neurofilament light chain (NfL) is an accepted biomarker of disease activity in MS, but its relationship with MRI activity, particularly in reference to lesion location and recurrent activity is not well understood.

METHODS

In 139 MS patients who underwent lumbar punctures with follow up in 25, we evaluated the relationship between CSF NFL and cranial MRI based on lesion location and lesion number. Spearman rank correlation was used to assess the association between CSF NFL and MRI lesion location and lesion counts at baseline and follow up at 1 year. Multiple linear regression analysis was performed to assess which lesion location was most strongly associated with CSF NFL values.

RESULTS

The associations between baseline CSF NFL and lesion location and follow-up lesions were modest, whilst those between baseline MRI and follow-up CSF NFL were greater: periventricular (r=0.31, p=0.141), juxtacortical (r=0.47, p=0.022), infratentorial (r=0.71, p≤0.001), and cord lesions (r=0.60, p=0.002). All associations, however improved following adjustment for disease duration and type of MS. Modelling revealed 53% of (log) CSF NfL could be explained by variance in baseline MRI lesion location.

CONCLUSIONS

Baseline CSF NFL did not correlate with current or future MRI activity and lesion location. However, baseline MRI activity explained around 53% variation in the follow up CSF NfL, suggesting that the relationship between MRI and CSF NfL is mainly precedent rather than an association, one occurring before another.

Biological Markers in Early Multiple Sclerosis: the Paved Way for Radiologically Isolated Syndrome

Radiologically Isolated Syndrome (RIS) is characterized by MRI-typical brain lesions fulfilling the 2009 Okuda criteria, detected in patients without clinical conditions suggestive of MS. Half of all RIS patients convert to MS within 10 years. The individual course of the disease, however, is highly variable with 12% of RIS converting directly to progressive MS. Demographic and imaging markers have been associated with the risk of clinical MS in RIS: male sex, younger age, infra-tentorial, and spinal cord lesions on the index scan and gadolinium-enhancing lesions on index or follow-up scans. Although not considered as a distinct MS phenotype, RIS certainly shares common pathological features with early active and progressive MS. In this review, we specifically focus on biological markers that may help refine the risk stratification of clinical MS and disability for early treatment. Intrathecal B-cell activation with cerebrospinal fluid (CSF) oligoclonal bands, elevated kappa free light chains, and cytokine production is specific to MS, whereas neurofilament light chain (NfL) levels reflect disease activity associated with neuroaxonal injury. Specific microRNA profiles have been identified in RIS converters in both CSF and blood. CSF levels of chitinases and glial acidic fibrillary protein (GFAP) reflecting astrogliosis might help predict the evolution of RIS to progressive MS. Innovative genomic, proteomic, and metabolomic approaches have provided several new candidate biomarkers to be explored in RIS. Leveraging data from randomized controlled trials and large prospective RIS cohorts with extended follow-up to identify, as early as possible, biomarkers for predicting greater disease severity would be invaluable for counseling patients, managing treatment, and monitoring.

Serum-Based Biomarkers in Neurodegeneration and Multiple Sclerosis

Multiple Sclerosis (MS) is a debilitating disease with typical onset between 20 and 40 years of age, so the disability associated with this disease, unfortunately, occurs in the prime of life. At a very early stage of MS, the relapsing-remitting mobility impairment occurs in parallel with a progressive decline in cognition, which is subclinical. This stage of the disease is considered the beginning of progressive MS. Understanding where a patient is along such a subclinical phase could be critical for therapeutic efficacy and enrollment in clinical trials to test drugs targeted at neurodegeneration. Since the disease course is uneven among patients, biomarkers are needed to provide insights into pathogenesis, diagnosis, and prognosis of events that affect neurons during this subclinical phase that shapes neurodegeneration and disability. Thus, subclinical cognitive decline must be better understood. One approach to this problem is to follow known biomarkers of neurodegeneration over time. These biomarkers include Neurofilament, Tau and phosphotau protein, amyloid-peptide-β, Brl2 and Brl2-23, N-Acetylaspartate, and 14-3-3 family proteins. A composite set of these serum-based biomarkers of neurodegeneration might provide a distinct signature in early vs. late subclinical cognitive decline, thus offering additional diagnostic criteria for progressive neurodegeneration and response to treatment. Studies on serum-based biomarkers are described together with selective studies on CSF-based biomarkers and MRI-based biomarkers.

Axonal injury in asymptomatic individuals preceding onset of multiple sclerosis

Axonal loss is the main cause of irreversible disability in multiple sclerosis (MS). Serum neurofilament light (sNfL) is a biomarker of axonal disintegration. In this nested case-control study, blood samples from 519 presymptomatic persons (age range 4-39 years) who later received an MS diagnosis showed higher sNfL concentrations than 519 matched controls (p < 0.0001), noticeable at least 10 years before clinical MS onset. Mean values for pre-MS and control groups were 9.6 pg/mL versus 7.4 pg/mL 0-5 years before onset, and 6.4 pg/mL versus 5.8 pg/mL 5-10 years before onset. These results support that axonal injury occurs early in MS pathogenesis.

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.

Emerging Biomarkers of Multiple Sclerosis in the Blood and the CSF: A Focus on Neurofilaments and Therapeutic Considerations

INTRODUCTION

Multiple Sclerosis (MS) is the most common immune-mediated chronic neurodegenerative disease of the central nervous system (CNS) affecting young people. This is due to the permanent disability, cognitive impairment, and the enormous detrimental impact MS can exert on a patient's health-related quality of life. It is of great importance to recognise it in time and commence adequate treatment at an early stage. The currently used disease-modifying therapies (DMT) aim to reduce disease activity and thus halt disability development, which in current clinical practice are monitored by clinical and imaging parameters but not by biomarkers found in blood and/or the cerebrospinal fluid (CSF). Both clinical and radiological measures routinely used to monitor disease activity lack information on the fundamental pathophysiological features and mechanisms of MS. Furthermore, they lag behind the disease process itself. By the time a clinical relapse becomes evident or a new lesion appears on the MRI scan, potentially irreversible damage has already occurred in the CNS. In recent years, several biomarkers that previously have been linked to other neurological and immunological diseases have received increased attention in MS. Additionally, other novel, potential biomarkers with prognostic and diagnostic properties have been detected in the CSF and blood of MS patients.

AREAS COVERED

In this review, we summarise the most up-to-date knowledge and research conducted on the already known and most promising new biomarker candidates found in the CSF and blood of MS patients.

DISCUSSION

the current diagnostic criteria of MS relies on three pillars: MRI imaging, clinical events, and the presence of oligoclonal bands in the CSF (which was reinstated into the diagnostic criteria by the most recent revision). Even though the most recent McDonald criteria made the diagnosis of MS faster than the prior iteration, it is still not an infallible diagnostic toolset, especially at the very early stage of the clinically isolated syndrome. Together with the gold standard MRI and clinical measures, ancillary blood and CSF biomarkers may not just improve diagnostic accuracy and speed but very well may become agents to monitor therapeutic efficacy and make even more personalised treatment in MS a reality in the near future. The major disadvantage of these biomarkers in the past has been the need to obtain CSF to measure them. However, the recent advances in extremely sensitive immunoassays made their measurement possible from peripheral blood even when present only in minuscule concentrations. This should mark the beginning of a new biomarker research and utilisation era in MS.

Blood GFAP as an emerging biomarker in brain and spinal cord disorders

Blood-derived biomarkers for brain and spinal cord diseases are urgently needed. The introduction of highly sensitive immunoassays led to a rapid increase in the number of potential blood-derived biomarkers for diagnosis and monitoring of neurological disorders. In 2018, the FDA authorized a blood test for clinical use in the evaluation of mild traumatic brain injury (TBI). The test measures levels of the astrocytic intermediate filament glial fibrillary acidic protein (GFAP) and neuroaxonal marker ubiquitin carboxy-terminal hydrolase L1. In TBI, blood GFAP levels are correlated with clinical severity and extent of intracranial pathology. Evidence also indicates that blood GFAP levels hold the potential to reflect, and might enable prediction of, worsening of disability in individuals with progressive multiple sclerosis. A growing body of evidence suggests that blood GFAP levels can be used to detect even subtle injury to the CNS. Most importantly, the successful completion of the ongoing validation of point-of-care platforms for blood GFAP might ameliorate the decision algorithms for acute neurological diseases, such as TBI and stroke, with important economic implications. In this Review, we provide a systematic overview of the evidence regarding the utility of blood GFAP as a biomarker in neurological diseases. We propose a model for GFAP concentration dynamics in different conditions and discuss the limitations that hamper the widespread use of GFAP in the clinical setting. In our opinion, the clinical use of blood GFAP measurements has the potential to contribute to accelerated diagnosis and improved prognostication, and represents an important step forward in the era of precision medicine.

NFL during acute spinal cord lesions in MS: a hurdle for the detection of inflammatory activity

INTRODUCTION

Levels of neuro-filament light chain (NFL) correlate with clinical and radiological activity in multiple sclerosis (MS) and have been used as a surrogate biomarker of axonal destruction related to inflammatory activity. The main objective of this work is to explore the specific contribution of acute inflammation within the spinal cord to the elevation of NFL levels.

PATIENTS AND METHODS

MS patients with a baseline study of NFL at diagnosis of the disease and a brain and spinal cord MRI scan were selected. Patients were classified according to the presence, number and location of gadolinium enhancing lesion (GEL) and the relationship between NFL levels and both brain and spinal cord GEL were explored.

RESULTS

Seventy-seven patients were selected. NFL levels were significantly higher in patients with only one GEL restricted to the brain than those without GEL (1702 pg/ml vs 722.7 pg/mL, p = 0.03) and correlated with number. However, no differences were seen among patients with GEL limited to the spinal cord and those without GEL (735.2 pg/ml vs 722.7 pg/mL).

CONCLUSION

Our study reaffirms the value of NFL levels in monitoring asymptomatic inflammatory activity in the brain measured by GEL. However, NFL concentration is not as useful when only inflammatory activity occurs in the spinal cord.

Iron Rims in Patients With Multiple Sclerosis as Neurodegenerative Marker? A 7-Tesla Magnetic Resonance Study

Introduction: Multiple sclerosis (MS) is a demyelinating and neurodegenerative disease of the central nervous system, characterized by inflammatory-driven demyelination. Symptoms in MS manifest as both physical and neuropsychological deficits. With time, inflammation is accompanied by neurodegeneration, indicated by brain volume loss on an MRI. Here, we combined clinical, imaging, and serum biomarkers in patients with iron rim lesions (IRLs), which lead to severe tissue destruction and thus contribute to the accumulation of clinical disability.

Objectives: Subcortical atrophy and ventricular enlargement using an automatic segmentation pipeline for 7 Tesla (T) MRI, serum neurofilament light chain (sNfL) levels, and neuropsychological performance in patients with MS with IRLs and non-IRLs were assessed.

Methods: In total 29 patients with MS [15 women, 24 relapsing-remitting multiple sclerosis (RRMS), and five secondary-progressive multiple sclerosis (SPMS)] aged 38 (22–69) years with an Expanded Disability Status Score of 2 (0–8) and a disease duration of 11 (5–40) years underwent neurological and neuropsychological examinations. Volumes of lesions, subcortical structures, and lateral ventricles on 7-T MRI (SWI, FLAIR, and MP2RAGE, 3D Segmentation Software) and sNfL concentrations using the Simoa SR-X Analyzer in IRL and non-IRL patients were assessed.

Results: (1) Iron rim lesions patients had a higher FLAIR lesion count (p = 0.047). Patients with higher MP2Rage lesion volume exhibited more IRLs (p <0.014) and showed poorer performance in the information processing speed tested within 1 year using the Symbol Digit Modalities Test (SDMT) (p <0.047). (2) Within 3 years, patients showed atrophy of the thalamus (p = 0.021) and putamen (p = 0.043) and enlargement of the lateral ventricles (p = 0.012). At baseline and after 3 years, thalamic volumes were lower in IRLs than in non-IRL patients (p = 0.045). (3) At baseline, IRL patients had higher sNfL concentrations (p = 0.028). Higher sNfL concentrations were associated with poorer SDMT (p = 0.004), regardless of IRL presence. (4) IRL and non-IRL patients showed no significant difference in the neuropsychological performance within 1 year.

Conclusions: Compared with non-IRL patients, IRL patients had higher FLAIR lesion counts, smaller thalamic volumes, and higher sNfL concentrations. Our pilot study combines IRL and sNfL, two biomarkers considered indicative for neurodegenerative processes. Our preliminary data underscore the reported destructive nature of IRLs.

Plasma Neurofilament Light and p-tau181 and Risk of Psychosis in Parkinson's Disease

BACKGROUND

Neuropsychiatric symptoms are common and important to people with Parkinson's disease (PD), but their etiology is poorly understood. Plasma neurofilament light (NfL) and p-tau181 are biomarkers of neuro-axonal degeneration and tau pathology respectively, which have yet to be explored in association with the affective and psychotic symptoms in PD.

OBJECTIVE

To investigate the relationship between plasma NfL and p-tau181 with the affective and psychotic symptoms in PD.

METHODS

We assessed the baseline concentration of plasma NfL and p-tau181 in a cohort of 108 patients with PD and 38 healthy controls. A subgroup of patients (n = 63) were assessed annually with clinical measures for up to 7 years. Psychotic symptoms were assessed using the Non-Motor Symptom Scale and affective symptoms were measured in the Hospital Anxiety and Depression Scale.

RESULTS

Baseline plasma NfL was a significant predictor of psychotic symptoms longitudinally across the study adjusted for age, Hoehn and Yahr stage, duration of follow up, duration of disease, baseline levodopa and dopamine agonist medication, and baseline cognition: (OR 8.15 [95% CI 1.40-47.4], p = 0.020). There was no association between NfL concentration and the cumulative prevalence of affective symptoms. Plasma p-tau181 concentration was not associated with psychotic or affective symptoms.

CONCLUSION

These findings suggest psychotic symptoms are associated with greater neurodegeneration in PD. Further studies are needed to explore NfL as a potential biomarker for psychosis in PD.

Factors contributing to CSF NfL reduction over time in those starting treatment for multiple sclerosis: An observational study

BACKGROUND

In multiple sclerosis (MS) neurofilament light chain (NfL) is a marker of neuronal damage secondary to inflammation and neurodegeneration. NfL levels drop after commencement of disease-modifying treatment, especially the highly active ones. However, the factors that influence this drop are unknown.

OBJECTIVE

To examine the patient and treatment-related factors that influence CSF NfL before and after starting treatment.

METHODS

Eligible patients across two centres with two CSF NfL measurements, clinical and MRI data were included as part of an observational cohort study.

RESULTS

Data were available in 61 patients, of which 40 were untreated at the first CSF sampling (T1) and treated at the second (T2; mean T1-T2: 19 months). CSF NfL reduction correlated with age (beta = 1.24 95%CI(1.07,1.43); R² = 0.17; p = 0.005), Expanded Disability Status Scale (EDSS) (beta = 1.12 95%CI(1.00,1.25); R² = 0.21; p = 0.05) and the type of MS (beta = 0.63 95%CI(0.43, 0.92); R² = 0.12; p = 0.018; reference=relapsing MS). The treatment effect on a baseline NfL of 702 pg/mL was 451 pg/ml 95%CI(374,509) in a 30-year-old versus 228 pg/ml 95%CI(63,350) in a 60-year-old. There was no association in CSF NfL reduction with BMI, disease duration or sex. In cladribine- and alemtuzumab-treated patients, the CSF NfL T2/T1 ratio did not correlate with lymphocyte depletion rate at 23 weeks.

CONCLUSIONS

In this observational study, we found that factors reflecting early disease stage, including a younger age, lower disability and relapsing MS were associated with treatment response in CSF NfL. Other factors were not found to be related, including lymphopaenia in highly-active treatments.

Drug and Neurofilament Levels in Serum and Breastmilk of Women With Multiple Sclerosis Exposed to Natalizumab During Pregnancy and Lactation

Objective

To determine the transfer of the monoclonal antibody natalizumab into breastmilk and to evaluate drug and serum neurofilament light chain ((s)NfL) levels in natalizumab exposed pregnancies and lactation periods.

Methods

Eleven women with relapsing remitting multiple sclerosis treated with natalizumab during pregnancy and lactation were included in this study. Breastmilk samples were collected up to 302 days after delivery and analyzed for natalizumab concentration and NfL. Additionally, maternal drug levels and sNfL were determined preconceptually, in each trimester, at delivery and postpartum. Clinical and radiological disease activity was systemically assessed across pregnancy and postpartum period.

Results

The mean average natalizumab concentration in breast milk was low at 0.06 µg/ml [standard deviation (SD) 0.05] in the eight patients who provided serial breastmilk samples with an estimated mean absolute infant dose of 0.007 mg/kg/d (SD 0.005). The relative infant dose (RID), a metric comparing the infant with maternal drug exposure was low as well with a mean of 0.04% (SD=0.03). Most patients had a maximum concentration in breast milk at one to eight days after infusion. Pregnancy was associated with a non-significant decline of the median natalizumab serum concentration. All patients exposed to natalizumab prior (n=10) and during pregnancy (n=11) kept free of disease activity during gestation. While pregnancy was associated with low sNfL levels in patients treated with natalizumab prior and during pregnancy, the postpartum period was linked to a transient sNfL increase in some patients without any evidence of clinical or radiological disease activity. NfL was detectable in the majority of breastmilk samples with a median concentration of 1.7 pg/ml (range 0.004-18.1).

Conclusion

We determined transfer of natalizumab into breastmilk with an RID far below the threshold of concern of 10%. Studies including childhood development assessment are needed in order to gain safety data about natalizumab-exposed breastfeeding. SNfL assessment might be a useful adjunct to monitor silent disease activity and therapeutic response during pregnancy and postpartum period. However, further investigations regarding transient postpartum sNfL increases are required to determine its association to parturition per se or to a silent disease activity in people with multiple sclerosis.

Exploring CSF neurofilament light as a biomarker for MS in clinical practice; a retrospective registry-based study

Background:

Neurofilament light (NFL) has been increasingly recognized for prognostic and therapeutic decisions.

Objective:

To validate the utility of cerebrospinal fluid NFL (cNFL) as a biomarker in clinical practice of relapsing-remitting multiple sclerosis (RRMS).

Methods:

RRMS patients (n = 757) who had cNFL analyzed as part of the diagnostic work-up in a single academic multiple sclerosis (MS) center, 2001–2018, were retrospectively identified. cNFL concentrations were determined with two different immunoassays and the ratio of means between them was used for normalization.

Results:

RRMS with relapse had 4.4 times higher median cNFL concentration (1134 [interquartile range (IQR) 499–2744] ng/L) than those without relapse (264 [125–537] ng/L, p < 0.001) and patients with gadolinium-enhancing lesions had 3.3 times higher median NFL (1414 [606.8–3210] ng/L) than those without (426 [IQR 221–851] ng/L, p < 0.001). The sensitivity and specificity of cNFL to detect disease activity was 75% and 98.5%, respectively. High cNFL at MS onset predicted progression to Expanded Disability Status Scale (EDSS) ⩾ 3 (p < 0.001, hazard ratios (HR) = 1.89, 95% CI = 1.44–2.65) and conversion to secondary progressive MS (SPMS, p = 0.001, HR = 2.5, 95% CI = 1.4–4.2).

Conclusions:

cNFL is a robust and reliable biomarker of disease activity, treatment response, and prediction of disability and conversion from RRMS to SPMS. Our data suggest that cNFL should be included in the assessment of patients at MS-onset.

Plasma neurofilament light chain concentrations as a biomarker of clinical and radiologic outcomes in relapsing multiple sclerosis: Post hoc analysis of Phase 3 ozanimod trials

Background and purpose

We investigated plasma neurofilament light chain concentration (pNfL) as a biomarker for neuroaxonal damage and disease activity using data from Phase 3 trials of ozanimod in relapsing multiple sclerosis (RMS).

Methods

pNfL was measured before and after ozanimod 0.46 mg or 0.92 mg daily or interferon β‐1a 30 µg weekly in the randomized, double‐blind SUNBEAM and RADIANCE trials. In these post hoc analyses, we investigated relationships between pNfL (at baseline and median percentage change from baseline to Month 12 [SUNBEAM] or 24 [RADIANCE]) and clinical and magnetic resonance imaging outcomes.

Results

Median (Q1, Q3) baseline pNfL, available in 1244 of 1346 SUNBEAM participants, was 14.70 (10.16, 23.26) pg/ml and in 1109 of 1313 RADIANCE participants was 13.35 (9.42, 20.41) pg/ml. Baseline gadolinium‐enhancing (GdE) and T2 lesion counts increased and brain volume decreased with increasing baseline pNfL. Baseline pNfL was higher in those with versus without on‐treatment relapse. Median percentage reduction in pNfL at 12 months in SUNBEAM (n = 1238) and 24 months in RADIANCE (n = 1088) was greater for ozanimod (20%–27%) than interferon β‐1a (13%–16%; p < 0.01). Greater pNfL reduction was associated with fewer GdE lesions, fewer new/enlarging T2 lesions per scan, less loss of brain volume, lower annualized relapse rate (ARR), and no evidence of disease activity. The following models predicted ARR: 0.5111 + 0.0116 × ΔNfL at 12 months (SUNBEAM) and 0.4079 + 0.0088 × ΔNfL at 24 months (RADIANCE).

Conclusions

pNfL was associated with clinical and radiologic measures of disease and treatment effects in RMS, supporting its use as a biomarker.

Disease biomarkers in multiple sclerosis: current serum neurofilament light chain perspectives

The continuous neuroinflammatory and neurodegenerative pathology in multiple sclerosis (MS) results in irreversible accumulation of physical and cognitive disability. Reliable early detection of MS disease processes can aid in the diagnosis, monitoring and treatment management of MS patients. Recent assay technological advancements now allow reliable quantification of serum-based neurofilament light chain (sNfL) levels, which provide temporal information regarding the degree of neuroaxonal damage. The relationship and predictive value of sNfL with clinical and cognitive outcomes, other paraclinical measures and treatment response is reviewed. sNfL measurement is an emerging, noninvasive and disease-responsive MS biomarker that is currently utilized in research and clinical trial settings. Understanding sNfL confounders and further assay standardization will allow clinical implementation of this biomarker.

Implications of extreme serum neurofilament light chain levels for the management of patients with relapsing multiple sclerosis

BACKGROUND

Serum neurofilament light chain (sNfL) is a promising biomarker to complement the decision-making process in multiple sclerosis (MS) patients. However, although sNfL levels are able to detect disease activity and to predict future disability, the growing evidence has not yet been translated into practicable recommendations for an implementation into clinical routine.

METHODS

The observation of a patient with extensive inflammatory activity in magnetic resonance imaging (MRI) along with an extremely high sNfL level in the absence of any clinical symptoms prompted us to investigate common characteristics of our MS patients with the highest sNfL levels in a retrospective cohort study. The 97.5th percentile was chosen as a cut-off value because the mean sNfL level of the resulting extreme neurofilament light chain (NfL) cohort corresponded well to the sNfL level of the presented case. Patient characterization included clinical and MRI assessment with a focus on disease activity markers. sNfL levels were determined by single molecule array.

RESULTS

The 97.5th percentile of our MS cohort (958 sNfL measurements in 455 patients) corresponded to a threshold value of 46.1 pg/ml. The mean sNfL level of the extreme sNfL cohort (n = 24) was 95.6 pg/ml (standard deviation 68.4). Interestingly, only 15 patients suffered from a relapse at the time point of sample collection, whereas nine patients showed no signs of clinical disease activity. sNfL levels of patients with and without relapse did not differ [median 81.3 pg/ml (interquartile range [IQR] 48.0-128) versus 80.2 pg/ml (IQR 46.4-97.6), p = 0.815]. The proportion of patients with contrast-enhancing lesions was high and also did not differ between patients with and without relapse (92.9% versus 87.5%, p = 0.538); 78.9% of the patients not receiving a high-efficacious therapy had ongoing disease activity during a 2-year follow-up.

CONCLUSION

Extremely high sNfL levels are indicative of subclinical disease activity and might complement treatment decisions in ambiguous cases.

Natalizumab Pharmacokinetics and -Dynamics and Serum Neurofilament in Patients With Multiple Sclerosis

Background: Natalizumab (NAT) is a high-efficacy treatment for relapsing remitting multiple sclerosis (RRMS). However, it is associated with an increased risk of progressive multifocal leukoencephalopathy that sometimes requires treatment cessation with a risk of returning disease activity. The aim of this study was to characterize the pharmacokinetics and -dynamics as well as neurodestruction marker serum neurofilament light chain (sNfL) in patients with RRMS and secondary progressive MS (SPMS) stopping NAT in correlation to clinical data. Methods: In this study, 50 RRMS and 9 SPMS patients after NAT cessation were included. Five RRMS patients on NAT treatment holiday were evaluated. Clinical and radiological disease activity were systemically assessed by frequent exams after NAT stop. Free NAT concentration, cell bound NAT, α4-integrin expression and α4-integrin-receptor saturation as well as immune cell frequencies were measured for up to 4 months after NAT withdrawal. Additionally, sNfL levels were observed up to 12 months in RRMS and up to 4 months in SPMS patients. Results: NAT cessation was associated with a return of disease activity in 38% of the RRMS and 33% of the SPMS patients within 12 and 7 months, respectively. Concentration of free and cell bound NAT as well as α4-integrin-receptor saturation decreased in the RRMS and SPMS patients whereas α4-integrin expression increased over time. NAT induced increase of lymphocytes and its subsets normalized and a non-significant drop of NK and Th17 T-cells counts could be detected. All RRMS patients showed physiological sNfL levels <8pg/ml 1 month after last NAT infusion. During follow-up period sNfL levels peaked up to 16-fold and were linked to return of disease activity in 19 of the 37 RRMS patients. Treatment holiday was also associated with a return of disease activity in 4 of 5 patients and with an increase of sNfL at an individual level. Conclusions: We demonstrate the reversibility of NAT pharmacodynamic and -kinetic markers. sNfL levels are associated with the recurrence of disease activity and can also serve as an early marker to predict present before onset of clinical or radiological disease activity on the individual level.

The Evolution of Neurofilament Light Chain in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune, inflammatory neurodegenerative disease of the central nervous system characterized by demyelination and axonal damage. Diagnosis and prognosis are mainly assessed through clinical examination and neuroimaging. However, more sensitive biomarkers are needed to measure disease activity and guide treatment decisions in MS. Prompt and individualized management can reduce inflammatory activity and delay disease progression. Neurofilament Light chain (NfL), a neuron-specific cytoskeletal protein that is released into the extracellular fluid following axonal injury, has been identified as a biomarker of disease activity in MS. Measurement of NfL levels can capture the extent of neuroaxonal damage, especially in early stages of the disease. A growing body of evidence has shown that NfL in cerebrospinal fluid (CSF) and serum can be used as reliable indicators of prognosis and treatment response. More recently, NfL has been shown to facilitate individualized treatment decisions for individuals with MS. In this review, we discuss the characteristics that make NfL a highly informative biomarker and depict the available technologies used for its measurement. We further discuss the growing role of serum and CSF NfL in MS research and clinical settings. Finally, we address some of the current topics of debate regarding the use of NfL in clinical practice and examine the possible directions that this biomarker may take in the future.