Masitinib is an oral immunomodulatory drug being developed as a possible treatment for progressive forms of multiple sclerosis (MS) and other diseases, including diseases of the central nervous system like amyotrophic lateral sclerosis (ALS). Its developer, AB Sciences, is currently testing its safety and efficacy in a number of conditions, and the drug has been designated an Orphan Drug by the U.S. Food and Drug Administration (FDA) as a potential ALS treatment.
How Masitinib Works
Also referred as AB1010, masitinib belongs to a class of chemical compounds known as tyrosine kinase inhibitors (TKI). Tyrosine kinase is an enzyme responsible for the activation of proteins vital to several cell signaling processes related to the growth, division, and proliferation of cells in the body via its receptor, EGFR, which is attached to the surface of most cells, including immune cells. As a selective TKI, masitinib blocks the activity of tyrosine kinase and reduces inflammation. Mast cells (immune cells highly involved in allergic and anaphylactic reactions) are the main targets for this drug. According to AB Sciences, “through its activity on mast cells and microglia, and consequently the inhibition of the activation of the inflammatory process, masitinib can have an effect on the symptoms associated with some inflammatory and central nervous system diseases and the degeneration of these diseases.”
History of Masitinib
A pilot, 18-month Phase 2 study in 35 patients with primary or secondary forms of progressive MS was initiated in 2011. The results did not show a statistically significant difference between masitinib and placebo, but there were promising indications that justified its continued testing, the MS Society reported.
A Phase 2b/3 clinical trial is underway, involving an estimated 450 progressive MS patients, testing the efficacy and safety of masitinib (6 mg/kg/day) versus placebo. The trial was expected to run for 96 weeks and to finish in December 2015. Results are awaited.
AB Sciences announced in April 2016 that an interim analysis for a Phase 3 randomized and controlled trial evaluating masitinib in the treatment of amyotrophic lateral sclerosis had met its primary endpoint — a reduction in disease progression from baseline — after 48 weeks of treatment. Patients in this trial were being treated with masitinib in combination with riluzole, versus placebo in combination with riluzole.
The most common side effects masitinib reported in MS patients include nausea, loss of energy (asthenia), fatigue, fluid retention, and diarrhea.
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