GFAP and myeloid sarcoma: We have identified and confirmed serum glial fibrillary acidic protein (sGFAP) as a promising biomarker of disease progression in MS4, –6 and serum neurofilament light chain (sNfL) is also, albeit to a lesser degree associated with MS disease progression.7,8 However, more blood biomarkers are needed for individualized patient management and disease monitoring.