NEFL and primary progressive multiple sclerosis: The Ocrelizumab Biomarker Outcome Evaluation study in patients with RRMS suggested that ocrelizumab reduced serum neurofilament light chain (NfL), CSF NfL and CSF B cells, and in patients with PPMS, CSF NfL (p = 0.012) and CXCL13 (p = 0.020) were reduced (89, 90).