To find out if BG00012 (also known as Tecfidera or dimethyl fumarate) is effective in slowing the progression of disability in people with SPMS. The safety of BG00012, how well people tolerate it, and the effect it may have on the results of tests and evaluations used to assess SPMS. It will also look at the effect of BG00012 on biomarkers (naturally occuring substances in the body - e.g., proteins, ribonucleic acid {RNA} in the blood.
Who may be Eligible
People with SPMS who are between 18 and 58 years of age ,and who have confirmed evidence of disease progression independent of clinical relapses over the 1 year prior to entry into the study.