Serum neurofilament light chain as a biomarker in multiple sclerosis: A cross-sectional observation in real-world...

Despite growing evidence on serum neurofilament light (sNfL) as a biomarker in Multiple Sclerosis (MS), its implementation and performance in clinical practice remain underexplored. This study aimed to evaluate the application of NfL testing comparing two immunoassays-the current gold-standard Simoa by Quanterix and the most recent Elecsys by Roche-in real-world conditions, moving beyond controlled research environments.

This cross-sectional study recruited 97 patients with Relapsing-Remitting MS (RRMS), collecting baseline and retrospective demographic, clinical and MRI data as part of routine care. Serum NfL levels were measured using Simoa and Elecsys immunoassays and were log10-transformed. Associations between sNfL levels and outcomes were evaluated using generalized linear and binary logistic regression models, with covariate adjustments reflective of clinical conditions.

Elecsys sNfL highly correlated with Simoa levels (R²≈0.891) with a strong negative bias of 88.19 %. Despite this, both assays showed that sNfL significantly associated with disease-modifying treatment, time since last relapse, Expanded Disability Status Scale, Symbol Digit Modalities Test, Timed 25-Foot Walk, brain atrophy, GD-enhancing T2 brain lesions, new or enlarging T2 brain lesions and infratentorial T2 brain lesions. Subgroup analyses showed Elecsys and Simoa sNfL models had similar performance metrics compared to clinical-only models, though Elecsys sNfL demonstrated mixed findings with some markers of disease activity (e.g. GD+ lesions) and progression (e.g. T1-hypointense, infratentorial and cervical spinal cord lesion burden).

Our results support the use of sNfL as a robust and informative biomarker within the real-world complexities of clinical care, with either the Elecsys or Simoa immunoassays offering reliable options.