HALT: AB Science Announces Worldwide Voluntary Hold on Lead Compound Masitinib


After identifying a potential risk of ischemic heart disease in its primary clinical compound, masitinib, AB Science announced this morning that it is placing a worldwide voluntary hold on clinical studies involving the tyrosine kinase inhibitor.

Inclusions and treatment initiation will be paused in all ongoing clinical studies until an investigation into the potential safety issue is complete.

Ischemic heart disease, also known as coronary artery disease, is caused by a narrowing of the coronary arteries that supply blood to the heart muscle.   

Masitinib, which is currently being developed in neurology, oncology, inflammatory diseases, and viral illnesses such as COVID-19, targets mast cells and microglia, each of which plays an important role in immune function, by inhibiting the activation of the inflammatory process.

The Paris, France-based AB Science, which is focused on the development and commercialization of protein kinase inhibitors (PKIs), targets only diseases with high unmet medical need which are rare, often lethal with short-term survival odds, or refuse to yield to a previous line of treatment. 

Masitinib has broad potential in a wide range of such diseases, including Alzheimer’s, Amyotrophic Lateral Sclerosis (ALS), pancreatic cancer, and multiple sclerosis.   

In oncology, increased mast cell activity within the tumor microenvironment has been shown to promote disease progression through the release of pro-tumoral mediators and down-regulate the immune response to tumors.

The decision, which was made following consultation with French regulatory authorities (ANSM) and other regulators, was triggered by a review of controlled and unblinded studies of masitinib.

Today’s announced hold will have a direct impact on three late-stage trials: a phase III confirmatory trial in indolent systemic mastocytosis, a phase III confirmatory study in ALS, and a phase II study in patients with moderate and severe COVID-19. 

In December, AB Science reported promising data from its Phase IIb/III trial of masitinib in patients with confirmed mild to moderate Alzheimer’s disease. Meeting its primary endpoint, masitinib generated a significant treatment effect compared to the control arm on change from baseline in the Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog). Additionally, significantly fewer patients in the treatment arm progressed to severe dementia after 24 weeks on the drug. 

The safety results were deemed acceptable and in line with what was previously known about the drug. 18.9% of patients had at least one severe adverse event compared with 16.8% in the control group. The specific serious and adverse events were not disclosed.

Last week, AB Science announced that a phase III study showed that masitinib could be of value in the treatment of metastatic Castrate Refractory Prostate Cancer, particularly in the earlier stages of the disease.

In today’s statement, AB Science said that ensuring patient safety was the company’s priority and that it is working in full collaboration with the regulatory authorities in order to resume patient enrollment in the aforementioned studies.

BioSpace reached out to AB Science for further comment, but the company elected not to provide one at this time. 

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