NEFL and multiple sclerosis: In multiple sclerosis, the clinical importance of NfL assay at individual level is illustrated by the fact that response to treatment may be indicated by a reduction of NfL levels.52-56 Along this line, the use of NfL in multiple sclerosis is also suggested in clinical trial protocols.57 However, both standardization of NfL measurement techniques, including sample collection and assay methods, and well-defined diagnostic and prognostic cut-off levels for healthy individuals and patients are still needed.58