Study Status: Completed
Recruit Status: Completed
Study Type: Interventional
Official Title: An Open Label Study of the Pharmacokinetics of DMF and the Effects of DMF on Exploratory Biomarkers in Subjects With Secondary Progressive Multiple Sclerosis
Brief Summary: The purpose of this study is to explore whether DMF (Dimethyl Fumarate) or MMF (monomethyl fumarate) its main bioactive metabolite, is capable of entering the central nervous system in SPMS patients that are being treated with Tecfidera®. PK samples (pharmacokinetics - or the amount of study drug in blood) will be tested to compare with PK samples, the amount of study drug, in spinal fluid (CSF).