Blood and CSF biomarkers for multiple sclerosis: emerging clinical applications

Neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), chitinase-3-like protein 1 (CHI3L1), and other protein assays are being developed as diagnostic or prognostic biomarkers in multiple sclerosis. An increase in NfL concentrations reflects axonal damage resulting from the acute new inflammatory disease activity that occurs during a relapse. NfL concentrations can also reflect the occurrence of new MRI lesions. GFAP concentrations are increased in people with progressive forms of multiple sclerosis, and GFAP is an emerging biomarker of progression independent of relapses. CHI3L1 is an emerging biomarker associated with progression independent of relapse activity and several MRI lesion types, including paramagnetic rim lesions. Some biomarkers, particularly NfL, can help monitoring treatment response, and combinations of multivariate biomarkers provide additional accuracy in specific clinical scenarios. In multiple sclerosis, fluid-based biomarkers are quickly emerging as instruments for clinical monitoring of disease course and patients' response to treatment.