Masitinib Studies Suspended Over Ischemic Heart Disease Risk

Altogether, AB Science has been evaluating a tyrosine kinase inhibitor, masitinib, for a variety of conditions including amyotrophic lateral sclerosis (ALS), COVID-19, and mastocytosis. But according to ALS News Today, all masitinib clinical trials have been suspended following a potential link to ischemic heart disease. After researchers determined that using the drug could increase the risk of this disease, researchers are putting a hold on studies until this link can be further explored.


According to AB Science, masitinib is:

a first in class oral kinase inhibitor having a breakthrough mechanism of action by selectively targeting mast cells and macrophages/microglia. Based on this mechanism of action, masitinib addresses several indications in neurology, inflammatory, and oncology diseases.

Currently, the treatment was being explored in the following trials:

  • AB19001, a Phase 3 clinical trial. Within this trial, researchers were evaluating the efficacy of two masitinib doses in conjunction with riluzole compared to riluzole with a placebo.
  • A Phase 3 clinical trial evaluating masitinib for patients with treatment-averse severe indolent or smoldering systemic mastocytosis.
  • This Phase 2 clinical trial evaluating masitinib in conjunction with isoquercetin for hospitalized patients with moderate-to-severe COVID-19.

So far, within AB19001, 495 patients enrolled. In a prior Phase 2 trial, researchers determined that 4.5mg/kg masitinib slowed the progression of ALS and related symptoms. Further, it assisted patients in their ability to perform daily tasks. However, in a retrospective analysis, AB Science determined a potential link between masitinib use and ischemic heart disease. The American Heart Association describes ischemic heart disease, or coronary artery disease, as:

heart problems caused by narrowed heart arteries. When arteries are narrowed, less blood and oxygen reaches the heart muscle.

In a press release, AB Science affirms the company’s commitment to patient safety. Additionally, the company explains the desire to further masitinib development once regulatory approval is granted. Further, an investigation should highlight where the drug can improve to reduce the potential risk to patients.

Amyotrophic Lateral Sclerosis (ALS)

Also known as Lou Gehrig’s disease, amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease. While doctors do not know exactly what causes ALS, around 5-10% of patients have specific genetic mutations inherited by family members; this is known as familial ALS. Regardless, ALS results from nerve cell death in the spinal cord, brain stem, and brain. Motor neuron degeneration causes muscle weakening and wasting. As a result, patients lose voluntary movement. Eventually, ALS becomes fatal; many patients lose the ability to breathe following chest muscle wasting. Altogether, ALS affects those of all backgrounds. However, males are typically affected more than females, and ALS affects older individuals more than younger individuals. Symptoms include:

  • Frequent tripping and falling
  • Psychological stress
  • Changes in mood, personality, or behavior
  • Difficulty walking or performing normal daily tasks
  • Muscle stiffness, twitching, and/or cramping
  • Difficulty speaking and swallowing
  • Slow or slurred speech
  • Muscle weakness, particularly in the arms, hands, and legs
  • Poor posture
  • Inappropriate laughing, yawning, or crying


There are multiple forms of mastocytosis, a chronic immune disorder characterized by the over-accumulation of mast cells, a type of white blood cell. Typically, however, mastocytosis is caused by KIT gene mutations. These mutations overactive the mast cell receptors. As a result, these cells build up in the skin, spleen and liver, lymph nodes, bone marrow, and gastrointestinal tract. Certain triggers may prompt a mastocytosis attack. These include skin rubbing or friction, insect bites, stress, or even temperature changes.

Patients with cutaneous mastocytosis have mast cell accumulation in the skin. These patients experience symptoms such as:

  • Low blood pressure
  • Small, flat, brown skin lesions
    • Note: In pediatric patients (those under 3 years old), these lesions may blister.
  • Thickened or discolored skin
  • Pruritus (intense itching)
  • Diarrhea
  • Gastrointestinal bleeding
  • Anaphylactic shock

For patients with systemic mastocytosis, skin lesions often do not appear. This is the most common form of mastocytosis in adult patients. Often, systemic mastocytosis results in mast cell accumulation in the bones and organs. Ultimately, this could lead to impaired bone marrow, liver, and bone function or failure. Additionally, systemic mastocytosis could cause mast cell leukemia, a rare and aggressive blood cancer that is fatal.

Other symptoms of mastocytosis include:

  • Liver and spleen enlargement
  • Heartburn
  • Abdominal pain
  • Softened bones
  • Fainting
  • Flushing
  • Nausea and vomiting

Learn more about mastocytosis.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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