Positive Results for Phase 2/3 Masitinib Clinical Trial Announced

Last week, AB Science announced that the Masitinib phase 2/3 clinical trial reached its primary endpoint of ALSFRS-R in people living with ALS. Currently, the company has applied for conditional marketing approval to the European Medicines Agency (EMA) in Europe and is sharing results with officials at the Federal Drug Administration (FDA) to decide next steps in the U.S. The ALS Association is encouraged by the limited results released by AB Science and looks forward to hearing more later this year. Here is a brief overview of the phase 2/3 Masitinib study.


Masitinib is a “tyrosine kinase inhibitor” drug, which targets immune cells called macrophages, microglia and mast cells. Its job is to inhibit specific kinases (a type of enzyme) from working, thereby preventing an immune response. While ALS is not primarily an inflammatory disease, inflammation within the central nervous system (CNS) is believed to accelerate the disease once it has begun. Thus, treatments to reduce this inflammation may help slow disease progression. Based on its inhibitory function, it is also being developed to target inflammation in other conditions in oncology, inflammatory diseases and diseases of the CNS.

Study Goals

The phase 2/3 blinded, placebo-controlled trial of Masitinib evaluated endpoints for safety and efficacy.  Throughout the study, all participants were taking the drug or placebo with an add-on riluzole.

The Study

Close to 400 people with ALS were enrolled in the trial under three treatment arms with a 1:1:1 randomization: Masitinib 4.5mg/kg/day + riluzole; Masitinib 3.5mg/kg/day + riluzole; placebo + riluzole. The study duration was 48 weeks.

The primary endpoint was changes in the ALS Functional Rating Scale – Revised (ALSFRS-R) at week 48. ALSFRS-R is the most widely used test to measure function in ALS clinical trials based on 12-questions, each rated on a 5-point scale. It is designed to assess disease progression over time, which correlates with quality of life and survival.


According to the presentation provided online by AB Science that reported on released trial results, primary analysis showed that Masitinib at 4.5mg/kg/day improved ALSFRS-R at 48 weeks and was statistically significant. Both Quality of Life as measured by ALSAQ-40 and secondary analysis of Progression Free Survival (PFS) was also reported as statistically significant. Forced Vital Capacity was not reported. There was not benefit of overall survival at either dose.

Full efficacy and safety data will be submitted for presentation at the European Network for the Cure of ALS (ENCALS) annual meeting in May 18-20, 2017 in Ljublijana, Slovenia.

Next steps

Currently, Masitinib is not approved for marketing by the European Medicines Agency (EMA) in Europe or the Federal Drug Administration (FDA) in the U.S. A confirmatory phase 3 study is expected to begin in the third quarter of 2017, run through 2018, with final results expected by fourth quarter 2019.

AB Science applied for conditional marketing authorization to the EMA in September 2016 and is waiting to hear a decision by the last quarter of 2017. Note that with conditional marketing authorization “a drug can be marketed for a full market authorization” without waiting for results of a confirmatory study.

AB Science is communicating its final data to the FDA to discuss next steps in the U.S.

The ALS Association is encouraged by these positive phase 2/3 results and is committed to working with the FDA to bring treatments to people living with ALS in the U.S. as quickly and efficiently as possible. We look forward to learning the full results of this study during upcoming scientific meetings in 2017 and in a published peer reviewed journal. The Association will keep the ALS community updated on future reports out of AB Science.

“We are looking forward to hearing more about this encouraging trial data.” – Dr. Lucie Bruijn, Chief Scientist of The ALS Association


Read AB Science Masitinib phase 2/3 trial full press release here.

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