Plasma neurofilament light chain levels in patients with MS switching from injectable therapies to fingolimod.

BACKGROUND

Neurofilament light chain (NFL) is a cerebrospinal fluid (CSF) marker of neuroaxonal damage in multiple sclerosis (MS).

OBJECTIVE

To determine the correlation of NFL in CSF and serum/plasma, and in plasma after switching from injectable MS therapies to fingolimod.

METHODS

A first cohort consisted of MS patients ( n = 39) and neurological disease controls ( n = 27) where CSF and plasma/serum had been collected for diagnostic purposes. A second cohort ( n = 243) consisted of patients from a post-marketing study of fingolimod. NFL was determined with Single Molecule Array (Simoa™) technology (detection threshold 1.95 pg/mL).

RESULTS

Mean NFL pg/mL (standard deviation ( SD)) was 341 (267) and 1475 (2358) in CSF and 8.2 (3.58) and 17.0 (16.94) in serum from controls and MS, respectively. CSF/serum and plasma/serum levels were highly correlated ( n  = 66, rho  = 0.672, p  < 0.0001 and n  = 16, rho  = 0.684, p  = 0.009, respectively). In patients starting fingolimod ( n = 243), mean NFL pg/mL ( SD) in plasma was reduced between baseline (20.4 (10.7)) and at 12 months (13.5 (7.3), p < 3 × 10), and levels remained stable at 24 months (13.2 (6.2)).

CONCLUSION

NFL in serum and CSF are highly correlated and plasma NFL levels decrease after switching to highly effective MS therapy. Blood NFL measurement can be considered as a biomarker for MS therapy response.