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

Neurofilament light chain as a biomarker for hereditary ATTR amyloidosis - correlation between neurofilament light chain and nerve conduction study

BACKGROUND

Neurofilament light chain (NfL) is a biomarker of neuronal injury in hereditary ATTR (ATTRv) amyloidosis. However, the correlation between NfL and nerve conduction study (NCS), the standard test for ATTRv neuropathy, has not been investigated.

OBJECTIVE

Elucidate the correlation between NfL and NCS parameters.

METHODS

227 serum NfL measurements were performed in 45 ATTRv patients, 5 asymptomatic carriers, and 12 controls. Among them, 177 simultaneous analyses of NCS and NfL were conducted in 45 ATTRv patients.

RESULTS

NfL levels of symptomatic patients were significantly higher than those of asymptomatic carriers and controls. Serum NfL levels were correlated with NCS parameters, especially compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes, indicators of axonal damage. CMAP and/or SNAP amplitudes were undetectable in 9 patients (no-amplitude group) due to advanced neuropathy. NfL levels in the no-amplitude group were significantly higher than those in patients with detectable CMAP/SNAP. NfL levels significantly decreased with patisiran, although no significant changes were observed in CMAP and SNAP.

CONCLUSIONS

NfL levels are found to be correlated with CMAP/SNAP amplitudes. Compared with NCS, NfL can be a more sensitive biomarker for detecting treatment response and active nerve damage even in patients with advanced neuropathy.

Serum neurofilament light chain levels correlate with small fiber related parameters in patients with hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN)

BACKGROUND

Recent evidence suggests that both serum neurofilament light chain (sNfL) levels and small fiber related diagnostic variables may be valuable disease biomarkers of hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN). Our study aimed to explore the relations between sNfL and small fiber related skin biopsy and quantitative sensory testing (QST) parameters in a cohort of ATTRv-PN patients and pre-symptomatic carriers.

METHODS

We retrospectively analyzed data from 13 ATTRv patients and 21 pre-symptomatic carriers who underwent sNfL dosage, skin biopsy, and QST, and analyzed correlations between sNFL, intraepidermal nerve fiber density (IENFD), and cold (CDT) and warm detection thresholds (WDT).

RESULTS

Both sNfL and small fiber related parameters significantly differed between carriers and patients (sNfL: p < 0.0001; IENFD: p = 0.0008; CDT, WDT: < 0.0001). sNFL levels were normal in all carriers, altered in 85% of patients, negatively correlated with distal IENFD (r = -0.47, p = 0.005), and significantly correlated with CDT (r = -0.68; p < 0.0001) and WDT (r = 0.57; p < 0.0001).

CONCLUSIONS

Our study showed that sNfL reliably discriminates symptomatic ATTRv-PN patients from pre-symptomatic carriers, and found significant relations between sNfL, skin biopsy, and QST small fiber related parameters, suggesting that sNfL might be a valuable biomarker of peripheral nerve involvement in ATTRv-PN and a supportive criterion for symptomatic disease transition.

Improving care for systemic light-chain amyloidosis patients: is a multidisciplinary approach best?

INTRODUCTION

Light chain (AL) amyloidosis is a rare and complex disease which can affect various systems of the body. In common with many rare and multisystemic diseases, the breadth of diagnostic, clinical, and supportive expertise required to care for such patients is best met by a multidisciplinary team.

AREAS COVERED

We outline different phases of the patients' journey, including diagnosis, staging, treatment, and response assessment, to highlight common clinical issues best resolved by a multidisciplinary approach.

EXPERT OPINION

To extend the benefit of multidisciplinary care to the majority of patients with AL amyloidosis, innovative healthcare models such as telehealth and multisite multidisciplinary team meetings need to be implemented. The need for a multidisciplinary approach where such a wide array of healthcare skills is required also highlights the shortcomings of our current diagnostic and monitoring assays. Better access to diagnostic and subtyping assays is necessary. The ability to characterize and measure the causative amyloidogenic light chain as well as imaging techniques to accurately diagnose and monitor response to therapy is also needed and is currently an area of research focus.

Longitudinal analysis of serum neurofilament light chain levels as marker for neuronal damage in hereditary transthyretin amyloidosis

OBJECTIVE

To evaluate serum neurofilament light chain (sNfL) as biomarker of disease onset, progression and treatment effect in hereditary transthyretin (ATTRv) amyloidosis patients and TTR variant (TTRv) carriers.

METHODS

sNfL levels were assessed longitudinally in persistently asymptomatic TTRv carriers (N = 12), persistently asymptomatic ATTRv amyloidosis patients (defined as asymptomatic patients but with amyloid detectable in subcutaneous abdominal fat tissue) (N = 8), in TTRv carriers who developed polyneuropathy (N = 7) and in ATTRv amyloidosis patients with polyneuropathy on treatment (TTR-stabiliser (N = 20) or TTR-silencer (N = 18)). Polyneuropathy was confirmed by nerve conduction studies or quantitative sensory testing. sNfL was analysed using a single-molecule array assay.

RESULTS

sNfL increased over 2 years in persistently asymptomatic ATTRv amyloidosis patients, but did not change in persistently asymptomatic TTRv carriers. In all TTRv carriers who developed polyneuropathy, sNfL increased from 8.4 to 49.8 pg/mL before the onset of symptoms and before polyneuropathy could be confirmed neurophysiologically. In symptomatic ATTRv amyloidosis patients on a TTR-stabiliser, sNfL remained stable over 2 years. In patients on a TTR-silencer, sNfL decreased after 1 year of treatment.

CONCLUSION

sNfL is a biomarker of early neuronal damage in ATTRv amyloidosis already before the onset of polyneuropathy. Current data support the use of sNfL in screening asymptomatic TTRv carriers and in monitoring of disease progression and treatment effect.

Validating the usefulness of Sudoscan in ATTRv: a single centre experience

BACKGROUND

Variant transthyretin amyloidosis (ATTRv) can cause sensorimotor and autonomic neuropathy. Objective quantification of sudomotor function may be essential for early diagnosis and early initiation of treatment. The aim of this study is to evaluate the diagnostic value of the Sudoscan® in ATTRv.

METHODS

Electrochemical skin conductance (ESC) was measured in V30M ATTRv patients, asymtomatic V30M carriers and healthy controls. Comparisons between the three groups were made using the Kruskal-Wallis test, and ROC curves were used to estimate the discriminatory power of ESC values between groups.

RESULTS

ESC was measured in 52 ATTRv patients, 107 asymptomatic carriers and 40 healthy controls. ESC was significantly lower in ATTRv patients compared to asymptomatic carriers and healthy controls in both feet and hands; median values are as follows: 40 µS, 78 µS and 81 µS, respectively (p < 0.001), and 53 µS, 69 µS and 74 µS, respectively (p < 0.001). ESC in feet < 70.5 µS had a sensitivity of 89.7% and specificity of 84.6% to discriminate asymptomatic carriers from patients with ATTRv.

CONCLUSION

The determination of ESC by Sudoscan® is a rapid, noninvasive and easily reproducible technique capable of discriminating patients with ATTRv from asymptomatic carriers and healthy controls with adequate sensitivity and specificity.

Serum neurofilament light chain in hereditary transthyretin amyloidosis: validation in real-life practice

BACKGROUND

Neurofilament light chain (NfL) has emerged as a sensitive biomarker in hereditary transthyretin amyloid polyneuropathy (ATTRv-PN). We hypothesise that NfL can identify conversion of gene carriers to symptomatic disease, and guide treatment approaches.

METHODS

Serum NfL concentration was measured longitudinally (2015-2022) in 59 presymptomatic and symptomatic ATTR variant carriers. Correlations between NfL and demographics, biochemistry and staging scores were performed as well as longitudinal changes pre- and post-treatment, and in asymptomatic and symptomatic cohorts. Receiver-operating analyses were performed to determine cut-off values.

RESULTS

NfL levels correlated with examination scores (CMTNS, NIS and MRC; all p < .01) and increased with disease severity (PND and FAP; all p < .05). NfL was higher in symptomatic and sensorimotor converters, than asymptomatic or sensory converters irrespective of time (all p < .001). Symptomatic or sensorimotor converters were discriminated from asymptomatic patients by NfL concentrations >64.5 pg/ml (sensitivity= 91.9%, specificity = 88.5%), whereas asymptomatic patients could only be discriminated from sensory or sensorimotor converters or symptomatic individuals by a NfL concentration >88.9 pg/ml (sensitivity = 62.9%, specificity = 96.2%) However, an NfL increment of 17% over 6 months could discriminate asymptomatic from sensory or sensorimotor converters (sensitivity = 88.9%, specificity = 80.0%). NfL reduced with treatment by 36%/year and correlated with TTR suppression (r = 0.64, p = .008).

CONCLUSIONS

This data validates the use of serum NfL to identify conversion to symptomatic disease in ATTRv-PN. NfL levels can guide assessment of disease progression and response to therapies.

Neurological affection and serum neurofilament light chain in wild type transthyretin amyloidosis

In contrast to inherited transthyretin amyloidosis (A-ATTRv), neuropathy is not a classic leading symptom of wild type transthyretin amyloidosis (A-ATTRwt). However, neurological symptoms are increasingly relevant in A-ATTRwt as well. To better understand the role of neurological symptoms in A-ATTRwt, A-ATTRwt patients were prospectively characterized at Amyloidosis Center Charité Berlin (ACCB) between 2018 and 2023 using detailed neurological examination, quality of life questionnaires, and analysis of age- and BMI-adapted serum neurofilament light chain (NFL) levels. 16 out of 73 (21.9%) patients presented with a severe neuropathy which we defined by a Neuropathy Impairment Score (NIS) of 20 or more. In this group, quality of life was reduced, peripheral neuropathy was more severe, and spinal stenosis and joint replacements were frequent. Age- and BMI matched serum NFL levels were markedly elevated in patients with a NIS ≥ 20. We therefore conclude that highly abnormal values in neuropathy scores such as the NIS occur in A-ATTRwt, and have an important impact on quality of life. Both peripheral neuropathy and spinal canal stenosis are likely contributors. Serum NFL may serve as a biomarker for neurological affection in patients with A-ATTRwt. It will be important to consider neurological aspects of A-ATTRwt for diagnosis, clinical follow-up, and future treatment development.

Neurofilament Light Chains in Systemic Amyloidosis: A Systematic Review

Peripheral and autonomic neuropathy are common disease manifestations in systemic amyloidosis. The neurofilament light chain (NfL), a neuron-specific biomarker, is released into the blood and cerebrospinal fluid after neuronal damage. There is a need for an early and sensitive blood biomarker for polyneuropathy, and this systematic review provides an overview on the value of NfL in the early detection of neuropathy, central nervous system involvement, the monitoring of neuropathy progression, and treatment effects in systemic amyloidosis. A literature search in PubMed, Embase, and Web of Science was performed on 14 February 2024 for studies investigating NfL levels in patients with systemic amyloidosis and transthyretin gene-variant (TTRv) carriers. Only studies containing original data were included. Included were thirteen full-text articles and five abstracts describing 1604 participants: 298 controls and 1306 TTRv carriers or patients with or without polyneuropathy. Patients with polyneuropathy demonstrated higher NfL levels compared to healthy controls and asymptomatic carriers. Disease onset was marked by rising NfL levels. Following the initiation of transthyretin gene-silencer treatment, NfL levels decreased and remained stable over an extended period. NfL is not an outcome biomarker, but an early and sensitive disease-process biomarker for neuropathy in systemic amyloidosis. Therefore, NfL has the potential to be used for the early detection of neuropathy, monitoring treatment effects, and monitoring disease progression in patients with systemic amyloidosis.

Prognostic value of neurofilament light in blood in patients with polyneuropathy: A systematic review

Neurofilament light protein (NfL) is a part of the neuronal skeleton, primarily expressed in axons, and is released when nerves are damaged. NfL has been found to be a potential diagnostic biomarker in different types of polyneuropathies. However, whether NfL levels can be used as a predictor for the risk of disease progression is currently less understood. We searched MEDLINE (PubMed), Embase, Cochrane Library, and Web of Science Searches and included longitudinal studies with a baseline and follow-up examination of adult patients with polyneuropathy and NfL measured in blood. Twenty studies investigating NfL as a predictor of disease progression were identified, examining eight polyneuropathy subtypes. The results from studies in Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) patients were divergent, with two out of five studies finding a significant association between NfL levels and clinical outcomes. Meta-analysis of the three Guillian-Barré Syndrome (GBS) studies found higher odds for the inability to run after 1 year in patients with high levels of NfL (odds ratio 2.18, 95% confidence interval 1.04-4.56). Results from studies examining other subacute or chronic polyneuropathies like Charcot-Marie-Tooth (CMT) varied in study design and results. Our findings suggest NfL can be used as a predictor of disease progression, particularly in polyneuropathies such as CIDP and GBS. However, NfL may not serve as a reliable and cost-effective biomarker for slowly progressive polyneuropathies like CMT. Future standardized studies considering NfL as a prognostic blood biomarker in patients with different types of polyneuropathies are warranted.

Biomarkers of axonal damage to favor early diagnosis in variant transthyretin amyloidosis (A-ATTRv)

Early identification of ATTRv amyloidosis disease onset is still often delayed due to the lack of validated biomarkers of this disease. Light chain neurofilament (NfL) have shown promising results in early diagnosis in this disease, but data is still needed, including with alternative measuring methods. Our aim was to study the levels of NfL measured by ELISA. Furthermore, interstitial matrix metalloproteinase type 1 (MMP-1) serum levels were measured as a potential new biomarker in ATTRv. Serum NfL and MMP-1 were measured using ELISA assays in 90 participants (29 ATTR-V30M patients, 31 asymptomatic V30M-TTR variant carriers and 30 healthy controls). Median NfL levels among ATTRv amyloidosis patients were significantly higher (116 pg/mL vs 0 pg/mL in both comparison groups). The AUC comparing ATTRv amyloidosis patients and asymptomatic carriers was 0.90 and the NfL concentration of 93.55 pg/mL yielded a sensitivity of 79% and a specificity of 87%. NfL levels had a significant positive correlation with NIS values among patients. We found a negative significant correlation between eGFR and NfL levels. Finally, MMP1 levels were not different between groups. Evidence of NfL use for early diagnosis of ATTR-PN amyloidosis is growing. ELISA seems a reliable and available technique for it quantification. Decreased GFR could influence NfL plasma levels.

Serum neurofilament light chain: a promising early diagnostic biomarker for hereditary transthyretin amyloidosis?

BACKGROUND AND PURPOSE

Hereditary transthyretin amyloidosis (ATTRv) is a life-threatening disease caused by mutations in the gene encoding transthyretin (TTR). The recent therapeutic advances have underlined the importance of easily accessible, objective biomarkers of both disease onset and progression. Preliminary evidence suggests a potential role in this respect for neurofilament light chain (NfL). In this study, the aim was to determine serum NfL (sNfL) levels in a late-onset ATTRv population and evaluate whether it might represent a reliable biomarker of disease onset (i.e., 'conversion' from the asymptomatic status to symptomatic disease in TTR mutation carriers).

METHODS

In all, 111 individuals harbouring a pathogenic TTR variant (61 symptomatic ATTRv patients and 50 presymptomatic carriers) were consecutively enrolled. Fifty healthy volunteers were included as the control group. Ella™ apparatus was used to assess sNfL levels.

RESULTS

Serum NfL levels were increased in ATTRv patients compared to both presymptomatic carriers and healthy controls, whilst not differing between carriers and healthy controls. An sNfL cut-off of 37.10 pg/mL could discriminate between asymptomatic and symptomatic individuals with high diagnostic accuracy (area under the curve 0.958; p < 0.001), sensitivity (81.4%) and specificity (100%).

CONCLUSIONS

Serum NfL seems to be a promising biomarker of peripheral nerve involvement in ATTRv amyloidosis and might become a reliable, objective measure to detect the transition from the presymptomatic stage to the onset of symptomatic disease. Further longitudinal studies are needed to confirm such a role and determine whether it could equally represent a biomarker of disease progression and response to therapy.