Systemic mastocytosis (SM) is a rare disorder in which excess abnormal mast cells build up in the body. Mast cells are a type of white blood cell that helps the immune system function normally and helps protect from disease. Mast cells are found in connective tissues throughout the body. In SM, a surplus of abnormal mast cells collects in the skin, bone marrow, digestive tract, or other body organs. When triggered, these excess abnormal mast cells release histamines and other chemicals that can cause symptoms similar to those that occur in an allergic reaction, as well as inflammation that may be severe enough to result in organ damage. 

ISM is a rare disease that affects the production and accumulation of abnormal mast cells, a type of white blood cell. Normally, your body makes mast cells as part of your immune response, but a buildup of abnormal mast cells in different parts of the body can lead to symptoms similar to severe allergic reactions.

SM is a rare blood disorder characterized by a build up of abnormal mast cells in the bone marrow and other organs. As an indolent, non-advanced form of SM, ISM usually has less build up of abnormal mast cells compared to advanced forms of SM.

However, people with ISM may have serious symptoms that could affect various organs, including potentially life-threatening anaphylaxis.

For most people, ISM is caused by a change (or mutation) in a gene known as the KIT D816V gene mutation. This gene mutation plays a role in the development of mast cells.

No, you do not need to have the KIT D816V gene mutation to be prescribed AYVAKIT.

ISM is diagnosed by a doctor who may measure signs of excess mast cells by:

• Performing a tryptase test. A doctor will draw blood from your arm to measure the amount of tryptase (an enzyme that is released by mast cells) in your blood.
• Taking biopsies. Biopsies are tissue samples taken for closer examination. Organ and/or bone marrow biopsies are used to measure the number of mast cells within tissue and to detect abnormalities.
• Testing for KIT D816V gene mutation. There are different types of KIT tests available that vary in sensitivity. High-sensitivity tests may be required to detect the mutation.

Each patient with ISM may experience different symptoms in different ways. Various symptoms are associated with ISM, including:

• Brain fog
• Dizziness
• Headache
• Fatigue
• Flushing
• Bone pain
• Itching
• Spots on the skin
• Abdominal pain
• Diarrhea
• Nausea

Across all types, systemic mastocytosis is estimated to occur in about 1 out of every 10,000 people—with ISM representing 75-90% of those cases.

Once you’ve been prescribed AYVAKIT, your doctor sends your prescription to an eligible pharmacy or to YourBlueprint^®. The pharmacy will verify your insurance coverage and work directly with your healthcare provider to obtain prior authorization if needed. Then, when coverage is approved, your pharmacy will contact you to communicate your out-of-pocket costs and arrange for delivery or pickup of your medication.

Over 99% of all commercial insurance plans and 99% of Medicare plans offer coverage for AYVAKIT.*

*Data on coverage and co-pay assistance is as of December 2023. Cost-sharing data is for those patients with commercial insurance.

Yes. YourBlueprint^® offers financial assistance options to help qualifying patients get on and stay on treatment.