The drug is advancing in clinical trials as a possible therapeutic for numerous disorders, from cancer and inflammatory diseases to those of the central nervous system (CNS), such as ALS.
How Masitinib works
It is an oral therapy that targets cells of the immune system called the mast cells and macrophages. It works by blocking the activation of proteins called tyrosine kinases, which are thought to play a role in inflammation and chronic inflammatory states.
Masitinib in clinical trials
The drug was recently evaluated in a Phase 2/3 clinical trial (NCT02588677) that compared the safety and efficacy of masitinib combined with the approved ALS drug called Rilutek (riluzole), against placebo plus Rilutek.
The study included 394 ALS patients who were randomized to treatment with either 4.5 mg/kg/day of masitinib and Rilutek, a 3 mg/kg/day of masitinib and Rilutek, or placebo and Rilutek, for up to 48 weeks.
The study’s primary objective was changes in patients’ scores in the revised ALS Functional Rating Scale (ALSFRS-R), which measures such abilities as walking, speech, hand control, and respiration. A secondary objective was to determine patients’ progression-free survival, which trial researchers defined as a deterioration of less than nine points in the ALSFRS-R score.
In March 2017, AB Science announced that the Phase 2/3 clinical trial met its main goal of improving the functioning of ALS patients. The results showed that administered at 4.5 mg/kg/day in combination with Rilutek improved patients’ quality of life and survival.
In May 2017, AB Science also provided results showing that patients treated with 3 mg/kg/day of masitinib and Rilutek also had improvements in ALSFRS, progression-free (through delayed disease progression), and quality of life scores compared to those given a placebo and Rilutek. Masitinib was found to be safe, and no major adverse effects were reported.
Results from this study were presented at the 2017 European Network for the Cure of ALS conference in Ljubljana, Slovenia.
A new Phase 3 trial (NCT03127267) also assessing masitinib in combination with Rilutek, against a placebo combination, in about 400 ALS patients is scheduled to begin in September.
The European Medicines Agency (EMA) accepted a conditional marketing authorization application for masitinib to treat ALS in October 2016. Under such authorization, early access to the therapy is provided for patients but the company is required to conduct further testing and submit more data. A final EMA decision on masitinib as an ALS treatment is expected by the close of 2017.
The EMA’s conditional marketing authorization was based on the results from the Phase 2/3 trial and on data from preclinical studies that demonstrated the neuroprotective effects of masitinib in ALS through the targeting of microglial cells. These results were published in the Journal of Neuroinflammation.
The U.S. Food and Drug Administration (FDA) designated masitinib an orphan drug in 2015, a designation that provides incentives to companies to advance the development of potential treatments for rare diseases.
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