SPI2

Treatment tested

• Biotin

Placebo or sham

• PLACEBO

Other measures (4)

Inclusion Criteria: * Patient aged 18-65 years old * Signed and dated written informed consent form in accordance with local regulations: having freely given their written informed consent to participate in the study * Diagnosis of primary or secondary progressive MS fulfilling revised McDonald criteria (2010) and Lublin criteria (2014) * Documented evidence of clinical disability progression within the 2 years prior to inclusion, i.e. a) progression of EDSS during the past two years of at least 1 point sustained for at least 6 months if inclusion EDSS is from 3.5 to 5.5 or at least 0.5 point increase sustained for at least 6 months if inclusion EDSS is from 6 to 6.5 or b) increase of TW25 by at least 20% in the last two years sustained for at least 6 months or c) other well-documented objective worsening validated by the Adjudication Committee * EDSS at inclusion from 3.5 to 6.5 * TW25 \< 40 seconds at inclusion visit * Kurtzke pyramidal functional subscore ≥2 defined as "minimal disability: patient complains of motor-fatigability or reduced performance in strenuous motor tasks (motor performance grade 1) and/or BMRC grade 4 in one or two muscle groups" Exclusion Criteria: * Clinical evidence of a relapse in 24 months prior to inclusion * Treatment with any product containing biotin as single ingredient within six months prior to inclusion (multivitamin supplementation authorized if biotin \< 1mg per day) * Concomitant treatment with fampridine at inclusion or in the 30 days prior to inclusion * New immunosuppressive/immunomodulatory drug initiated less than 90 days prior to inclusion * Treatment with botulinum toxin (except for cosmetic purpose) initiated within 6 months prior to inclusion * In-patient rehabilitation program within the 3 months prior to inclusion * Pregnancy, breastfeeding or women with childbearing potential without acceptable form of contraception * Men unwilling to use an acceptable form of contraception * Any general chronic handicapping/incapacitating disease other than MS * Any serious disease necessitating biological follow-up with biological tests using biotinylated antibodies or substrates * Past history of rhabdomyolysis/metabolic myopathy * Known fatty acids beta oxidation defect * Known hypersensitivity or intolerance to biotin, analogues or excipients, patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption * Patients with hypersensitivity or any contra-indication to Gadolinium * Patients with uncontrolled hepatic disorder, renal or cardiovascular disease, or cancer * Laboratory tests out of normal ranges considered by the investigator as clinically significant with regards to the study continuation * Patients with history or presence of alcohol abuse or drug addiction * Untreated or uncontrolled psychiatric disorders, especially suicidal risk assessed by Columbia-Suicide Severity Rating Scale (C-SSRS) * Participation in another research study involving an investigational product (IP) in the 90 days prior to inclusion, or planned use during the study duration * Patients likely to be non-compliant to the study procedures or for whom a long-term follow-up seems to be difficult to achieve * Relapse that occurs between inclusion and randomization visit

The purpose of this study is to demonstrate the superiority of MD1003 over placebo in the disability of patients suffering from progressive multiple sclerosis and especially those with gait impairment.