Biomarker discovery using NUcleic Acid-Linked Immuno-Sandwich Assay in multiple sclerosis patients experiencing progression independent of relapse activity

Background/Objectives: This cohort study aimed to identify blood-based biomarkers associated with progression independent of relapse activity (PIRA) in persons with multiple sclerosis (pwMS) using the multiplex NUcleic Acid-Linked Immuno-Sandwich Assay (NULISA). Methods: NULISA ‘CNS Disease Panel’ and ‘Inflammation Panel’ were applied on plasma samples from pwMS following B cell-depleting therapy (BCDT; n = 185) or fingolimod ( n = 200), median follow-up 4.0 (BCDT) and 9.1 (fingolimod) years. Plasma NULISA results (322 unique proteins; 0.9 and 1 year after treatment start, respectively) were investigated for their potential to prognosticate PIRA. Results: ‘CNS Disease Panel’ derived glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) were identified as predictive of PIRA by multivariable Cox regression models (GFAP: BCDT: hazard ratio (HR) = 1.79, 95% confidence interval (CI) = 1.26–2.55, p = 0.0011; fingolimod: HR = 1.73, 95% CI = 1.14–2.64, p = 0.0104; NfL: BCDT: HR = 1.99, 95% CI = 1.31–3.02, p = 0.0013). GFAP derived from the ‘Inflammation Panel’ exhibited patterns like those observed with ‘CNS Disease Panel’ derived GFAP. Beyond GFAP and NfL, 12 biomarker candidates predictive of PIRA were identified. No target passed multiple test corrections, but GFAP consistently showed the highest hazard. Conclusion: Among over 300 proteins investigated by NULISA, GFAP was the main biomarker significantly associated with future PIRA risk in our cohort.