Biomarker report from the phase II lamotrigine trial in secondary progressive MS - neurofilament as a surrogate of disease progression by Gnanapavan, S, Grant, D, Morant, S, Furby, J, Hayton, T, Teunissen, C, Leoni, V, Marta, M, Brenner, R, Palace, J, Miller, D, Kapoor, R, Giovannoni, G