AB Science SA announced that it has been authorized by the French Medicine Agency, ANSM, to initiate a Phase III study (AB20009) evaluating masitinib in patients with Primary Progressive Multiple Sclerosis (PPMS) or non-active Secondary Progressive Multiple Sclerosis (nSPMS). Study AB20009 is titled ‘A 96-Week, Prospective, Multicenter, Randomised, Double-Blind, Placebo-Controlled, Phase 3 Study to Compare Efficacy and Safety of Masitinib Dose Titration to 4.5 mg/kg/day versus Placebo in the Treatment of Patients with Primary Progressive or Secondary Progressive Multiple Sclerosis Without Relapse'. The study will enroll 800 patients from numerous study centers with Expanded Disability Status Scale (EDSS) score between 3.0 to 6.0 and absence of T1 Gadolinium-enhancing brain lesions as measured by magnetic resonance imaging (MRI).

The primary objective of the study will be to evaluate the effect of masitinib on time to confirmed disability progression, with progression defined as 1-point worsening when EDSS baseline score =5.5, or 0.5 if baseline score >5.5 from randomization to week 96. This confirmatory study follows successful completion of a first Phase 2B/3 study (AB07002) in primary progressive (PPMS) and non-active secondary progressive (nSPMS) multiple sclerosis. Results from that study were presented during the 8th Joint Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) – European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) Meeting (MSVirtual2020).

The study met its primary analysis endpoint, demonstrating a statistically significant reduction in cumulative change on EDSS with masitinib 4.5 mg/kg/day (p=0.0256). This treatment-effect was consistent for PPMS and nSPMS. In addition, masitinib significantly reduced the risk of first disability progression by 42% and the risk of confirmed (3 months) disability progression by 37%. Masitinib also significantly reduced the risk of reaching an EDSS score of 7.0, corresponding to disability severe enough that the patient is restricted to a wheelchair (p=0.0093).

Multiple sclerosis is an autoimmune disease of the central nervous system that affects more than 100,000 people in France and for which no definitive treatment exists to date. It is characterized by a progressive degradation of the nerve cells of the central nervous system by the patient's immune system and comes in two main forms. The relapsing-remitting form characterized by relapses of the disease. During these relapses, patients experience the onset of new symptoms or the worsening of symptoms already present.

These flare-ups are usually followed by recovery periods of varying length, after which some symptoms may persist. The relapsing-remitting forms of multiple sclerosis are mostly associated with dysfunctions of adaptive immunity (B cells and T cells). The progressive form, characterized by a constant and regular worsening of the symptoms of the disease, without a distinct relapse or period of recovery.

The rate of onset of severe, disabling, and irreversible disability is much higher in the progressive forms of the disease than in the relapsing remitting forms. In progressive multiple sclerosis, innate immune cells such as macrophages, microglia or mast cells have been shown to probably play a major role.