The study has been suspended but may start again in the future.

To evaluate the efficacy and safety of oral masitinib versus placebo in the treatment of patients with primary progressive or secondary progressive multiple sclerosis without relapse.

Masitinib is a selective tyrosine kinase inhibitor, targeting innate immune cells (mast cells and microglia) that are involved in the pathophysiology of progressive multiple sclerosis (MS). This is a multicenter, double-blind, randomized, placebo-controlled, comparative study of oral masitinib in the treatment of patients with progressive MS who were progressing but not clinically active.

Main inclusion criteria include:

• Patients with either primary progressive or secondary progressive multiple sclerosis with onset of symptoms at least five years before baseline and with no relapse diagnosed according to the 2017 revised McDonald's criteria at least two years before screening
• Patients with Expanded Disability Status Scale (EDSS) score between 3.0 to 6.0 (both inclusive) at screening and baseline
• Patients with an EDSS score progression ≥1 point with no improvement during 2 years
• Absence of T1 Gadolinium-enhancing brain lesions as measured by MRI at screening

Main exclusion criteria include:

• Patients suffering from a disease other than MS that would better explain the patient's neurological clinical signs and symptoms and/or MRI lesions observed at screening
• Inability to complete screening MRI (contraindications for MRI) and/or any known allergy or hypersensitivity or any contra-indication to gadolinium macrocyclic
• Patients treated with other disease modifying treatments in the time frames and conditions mentioned under previous treatment wash out period, assessed at baseline
• Patients with lymphocytes <1.0 × 10^9/L at screening and at baseline