Immunosuppressive therapy reduces axonal damage in progressive multiple sclerosis.

BACKGROUND In progressive multiple sclerosis (PMS), disease-modifying therapies have not been shown to reduce disability progression. OBJECTIVE The impact from immunosuppressive therapy in PMS was explored by analyzing cerebrospinal fluid (CSF) biomarkers of axonal damage (neurofilament light protein, NFL), astrogliosis (glial fibrillary acidic protein, GFAP), and B-cell regulation (CXCL13). METHODS CSF was obtained from 35 patients with PMS before and after 12-24 months of mitoxantrone (n=30) or rituximab (n=5) treatment, and from 14 age-matched healthy control subjects. The levels of NFL, GFAP, and CXCL13 were determined by immunoassays. RESULTS The mean NFL level decreased by 51% (1781 ng/l, SD 2018 vs. 874 ng/l, SD 694, p=0.007), the mean CXCL13 reduction was 55% (9.71 pg/ml, SD 16.08, vs. 4.37 pg/ml, SD 1.94, p=0.008), while GFAP levels remained unaffected. Subgroup analysis showed that the NFL reduction was confined to previously untreated patients (n=20) and patients with Gd-enhancing lesions on magnetic resonance imaging (n=12) prior to study baseline. CONCLUSIONS Our data imply that 12-24 months of immunosuppressive therapy reduces axonal damage in PMS, particularly in patients with ongoing disease activity. Determination of NFL levels in CSF is a potential surrogate marker for treatment efficacy and as endpoint in phase II trials of MS.