Serum neurofilament light chain and glial fibrillary acidic protein for predicting response to apheresis in steroid‐refractory multiple sclerosis relapses.

Background and purpose: The predictive value of serum neurofilament light chain (sNfL) and serum glial fibrillary acidic protein (sGFAP) for apheresis outcome in steroid‐refractory multiple sclerosis (MS) relapse has not yet been evaluated. Methods: We used pre‐ and postapheresis serum samples from 38 participants of the IAPEMS trial (clinicaltrials.gov: NCT02671682), which investigated the use of immunoadsorption versus plasma exchange for the treatment of steroid‐refractory MS attacks. Response to apheresis was classified based on improvement on (i) the Expanded Disability Status Scale (EDSS), (ii) the affected functional system scores (FSS) of the EDSS, or (iii) the visual acuity for patients with optic neuritis, 4 weeks postapheresis. sNFL and sGFAP were measured by single molecule arrays. Results: Preprocedural sGFAP levels could discriminate between responders and nonresponders, determined by FSS improvement (p = 0.017). In multivariate logistic regression analysis, younger age (odds ratio [OR] = 0.781, 95% confidence interval [CI] = 0.635–0.962, p = 0.020) and lower sGFAP levels (OR = 0.948, 95% CI = 0.903–0.995, p = 0.031) could predict response to apheresis in the overall cohort. We could observe a trend towards a favourable apheresis outcome with higher sNfL levels (OR = 1.413, 95% CI = 0.965–2.069, p = 0.076). Analysis of the sNfL‐to‐sGFAP ratio showed an OR of 1.924 (95% CI = 1.073–3.451, p = 0.028) for predicting apheresis response. The ratio showed a better predictive value than the individual parameters. Neither biomarker was affected by the number of steroid cycles preapheresis. Conclusions: Lower sGFAP levels, a higher sNfL‐to‐sGFAP ratio, and younger age are associated with a favourable apheresis outcome. [ABSTRACT FROM AUTHOR]