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ObjectiveTo 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.MethodsIn 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.ResultsFor 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.ConclusionsSerum 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.

Background: Chronic inflammatory demyelinating polyradiculoneuropathy trials have demonstrated the efficacy of IV immunoglobulin vs placebo. However, these trails have not addressed the long-term impact on health-related quality of life (HRQoL). Methods: One hundred seventeen patients in a randomized, double-blind, response-conditional crossover trial received immune globulin IV, 10% caprylate/chromatography purified (IGIV-C [Gamunex®]), or placebo every 3 weeks for up to 24 weeks in the first period (FP). Participants whose inflammatory neuropathy cause and treatment disability score did not improve by ≥1 point received alternate treatment in a 24-week crossover period (CP). In either period, participants who improved and completed treatment were eligible to be randomly reassigned to a blinded 24-week extension phase (EP). HRQoL analyses were conducted using the Short Form-36® (SF-36) and the Rotterdam Handicap Scale (RHS). Results: In the FP, greater improvements in both SF-36 physical and mental component scores were observed with IGIV-C vs placebo, with a significant improvement in the physical component score (difference 4.4 points; 95% confidence interval [CI] 0.7–8.0). Improvements in all SF-36 domains favored IGIV-C vs placebo, with physical functioning, role–physical, social functioning, and mental health reaching significance. Participants receiving IGIV-C experienced a larger improvement in RHS vs those receiving placebo (difference 3.4 points; 95% CI 1.4–5.5; p = 0.001). In the CP, similar general trends were observed. In the EP, mean SF-36 improvements were generally improved or maintained in participants who continued IGIV-C therapy; however, worsening was observed in participants re-randomized to placebo. Conclusions: Long-term therapy with immune globulin IV, 10% caprylate/chromatography purified, improves and maintains health-related quality of life in chronic inflammatory demyelinating polyradiculoneuropathy.