Validation of serum neurofilaments as prognostic and potential pharmacodynamic biomarkers for ALS

Abstract

<jats:sec><jats:title>Objective</jats:title><jats:p>To identify preferred neurofilament assays and clinically validate serum neurofilament light (NfL) and phosphorylated neurofilament heavy (pNfH) as prognostic and potential pharmacodynamic biomarkers relevant to amyotrophic lateral sclerosis (ALS) therapy development.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>In this prospective, multicenter, longitudinal observational study of patients with ALS (n = 229), primary lateral sclerosis (n = 20), and progressive muscular atrophy (n = 11), biological specimens were collected, processed, and stored according to strict standard operating procedures (SOPs). Neurofilament assays were performed in a blinded manner by independent contract research organizations.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>For serum NfL and pNfH measured using the Simoa assay, there were no missing data (i.e., technical replicates below the lower limit of detection were not encountered). For the Iron Horse and Euroimmun pNfH assays, such missingness was encountered in ∼4% and ∼10% of serum samples, respectively. Mean coefficients of variation for NfL in serum and CSF were both ∼3%. Mean coefficients of variation for pNfH in serum and CSF were ∼4%–5% and ∼2%–3%, respectively, in all assays. Baseline serum NfL concentration, but not pNfH, predicted the future Revised ALS Functional Rating Scale (ALSFRS-R) slope and survival. Incorporation of baseline serum NfL into mixed effects models of ALSFRS-R slopes yields an estimated sample size saving of ∼8%. Depending on the method used to estimate effect size, use of serum NfL (and perhaps pNfH) as pharmacodynamic biomarkers, instead of the ALSFRS-R slope, yields significantly larger sample size savings.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Serum NfL may be considered a clinically validated prognostic biomarker for ALS. Serum NfL (and perhaps pNfH), quantified using the Simoa assay, has potential utility as a pharmacodynamic biomarker of treatment effect.</jats:p></jats:sec>

CSF Neurofilament Light Chain Elevation Predicts ALS Severity and Progression

“…In recent years, there has been strong evidence from independent groups, large cohorts of patients, and multicenter studies that neurofilament light chains are potentially valuable ALS biomarkers ( 3 , 5 – 13 , 21 , 23 ). Verde et al showed that serum NFL is increased in ALS compared to other conditions and can serve as a diagnostic and prognostic biomarker using ultrasensitive single-molecule array technology ( 6 ).…”

“…In a relatively large cohort of 190 ALS patients and 130 with other neurological diseases, Rossi et al confirmed that CSF NFL and p-NFH were valuable diagnostic and prognostic biomarkers in ALS ( 10 ). A prospective, multicenter, longitudinal study validated NfL values as prognostic biomarker for ALS, comparing serum and CSF NfL values ( 13 ). Tortelli et al found that CSF NFL levels were increased in ALS compared to other neurodegenerative disorders and peripheral neuropathies and were correlated with disease severity and progression ( 23 ).…”

“…There is growing evidence that the levels of NFs, especially phosphorylated neurofilament heavy chains (p-NFH) and neurofilament light chains (NFL), reflect axonal injury and are potentially of value in ALS and other neurological disorders with axon damage. Cerebrospinal fluid (CSF) and blood levels of NFs are increased in ALS ( 3 – 13 ) and other neurological disorders, including Alzheimer's disease ( 14 , 15 ), multiple sclerosis ( 16 , 17 ), multiple system atrophy predominated by parkinsonism ( 18 ), Charcot–Marie–Tooth disease ( 19 ), and cerebrovascular disease ( 20 ). NFs are non-specific markers of axon damage.…”

Neurofilaments in motor neuron disorders: towards promising diagnostic and prognostic biomarkers

“…In univariate regression models, NF levels retain a high hazard risk for death [57,70,81]. More importantly, in multivariate models encompassing all other known prognostic factors such as ALSFRS-r, site of onset, age at onset, weight loss, and respiratory measures, only serum NfL concentration and some clinical variable different from one study to another (FVC [90] age, baseline ALSFRS-R, ΔFRS [86]), resulted as independent predictors of survival [90,91]. Considering ALSFRS-R slope as the outcome, and taking into account baseline serum NfL and pNfH together with potential clinical predictors of prognosis (age, sex, C9ORF72 status, site of disease onset, baseline ALSFRS-R and ΔFRS), only progression rate resulted a meaningful clinical predictor.…”

“…Considering ALSFRS-R slope as the outcome, and taking into account baseline serum NfL and pNfH together with potential clinical predictors of prognosis (age, sex, C9ORF72 status, site of disease onset, baseline ALSFRS-R and ΔFRS), only progression rate resulted a meaningful clinical predictor. Nevertheless adding to the model baseline serum NfL, but not pNfH adds prognostic value not explainable otherwise (for every 1-point increase in log serum NfL level, the progression rate [92] is worsened by an additional 0.42 points/month [86]). Other studies supported the use of baseline serum or CSF NfL levels as an independent prognostic factor, with equal, if not superior value, of progression rate at diagnosis (delta-FS) [71], one of the most widely accepted clinical prognostic index computed at diagnosis [83].…”