To determine if serum neurofilament light chain (sNFL) concentration is associated with MD1003 (high dose of pharmaceutical grade biotin, 300 mg/day) treatment in progressive MS.

MS-SPI study showed that MD1003 achieved sustained reversal of MS-related disability in a subset of patients with progressive MS (Tourbah et al., 2016).

Various neuronal diseases with concomitant neuronal damage have been shown to be associated with elevated NFL concentrations in CSF. In MS, a recent study suggests serum NFL level as a sensitive and clinically meaningful biomarker to monitor tissue damage and biotherapies effects (Disanto et al., 2017).

Monocentric phase 4, 2 years prospective single arm study of MD1003 in progressive MS patients followed with clinical, MRI data and biological sampling (Inclusion: January 2016-October 2017).

Primary end point: sNFL concentration (SIMOA^TM technology) at baseline, 6 months, 1 and 2 years.

Secondary end point: Clinical/MRI efficacy and adverse events.

Data will be compared to similar cohorts from ASCEND, EXPAND, INFORMS and ORATORIO trials.

To date, 203 patients have been included. We present an intermediate analysis in a sub-group of 65 patients with 1-year follow-up.

We observed that sNFL levels increase from base line (mean 11.8 +/- 5.6 pg/ml) to 6 months of MD1003 (mean 16.1 +/- 14.1 pg/ml; p = 0.0043, Wilcoxon matched-paired), reaching a plateau at 1 year (mean 16.9 +/- 12.9 pg/ml). Analyses of 40 patients’ sNFL level at 2 years will be presented.

23% of the patients experienced a clinical improvement. Active disease, defined as a clinically-defined relapse and/or a Gd-enhancing T1 lesion, was observed in 11 % of the patients. However, sNFL level was not associated with neither clinical nor MRI aggravation.

This intermediate analysis suggests that MD1003 has an impact on sNFL and clinical evolution. However, sNFL levels are not predictive of disease worsening.