Forging a new path in systemic mastocytosis

Introducing PATHFINDER - a clinical trial of avapritinib for people with advanced systemic mastocytosis.

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About systemic mastocytosis

PATHFINDER is a phase 2 clinical trial that will test the safety and effectiveness of an investigational drug called avapritinib (formerly known as BLU-285) in people with advanced systemic mastocytosis (SM).

Advanced SM is a rare condition caused by the accululation of mast cells in the body's organs, including the bone marrow. Mast cells are an important type of immune cell that normally play a role in the body to help fight infection and trigger the allergic response. In advanced systemic mastocytosis, mast cells are inappropriately released causing symptoms in multiple organs around the body.

There are three different subtypes of advanced SM (advSM) - aggressive SM (ASM), SM with an associated hematological neoplasm (SM-AHN), and mast cell leukemia (MCL). Across all subtypes, up to 95% of people have a specific mutation (genetic alteration) in a gene called KIT. The mutation, known as KIT D816V, plays a central role in the activation and accumulation of mast cells in people with systemic mastocytosis. Avapritinib is an investigational drug that was specifically designed to selectively target the KIT D816V mutation.

Who is eligible
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Who is eligible to participate in the PATHFINDER clinical trial?

You may be able to take part in the PATHFINDER clinical trial if you:

Have one of several types of advanced systemic mastocytosis, including aggressive systemic mastocytosis, systemic mastocytosis with associated hematologic neoplasm,* or mast cell leukemia

Have a measurable clinical finding, also known as C-Finding, that is determined to be related to SM (not applicable to patients with mast cell leukemia)*

Have elevated levels of serum tryptase, a marker of mast cell activity

Are at least 18 years old

*SM-related C findings are defined by international criteria for the diagnosis of SM and the measurement of clinical response to treatment. Using these criteria, the PATHFINDER clinical trial will measure the effect of avapritinib on one or more C findings. Talk to your doctor or contact us to learn more about C findings.

You are not eligible to take part in the PATHFINDER clinical trial if you:

Have acute myeloid leukemia

Have indolent or smoldering SM*

*Contact us for more information regarding a separate clinical trial planned by Blueprint Medicines.

Other eligibility criteria apply and these will be assessed at your screening.

About the investigational drug
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About the investigational drug

If you take part in the PATHFINDER clinical trial, you will receive the investigational drug avapritinib. Avapritinib is designed to selectively target KIT D816V, the underlying driver of systemic mastocytosis. Avapritinib comes in a tablet and should be swallowed whole with water once a day.

What does taking part involve?
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What does taking part in the PATHFINDER clinical trial involve?

*There is no maximum duration for this trial. You will continue with your cycles of treatment until:

  • Your disease worsens
  • You can’t tolerate any side effects you may have
  • You decide to leave the trial
  • The trial doctor decides you should leave the trial
  • The trial sponsor decides to discontinue the trial

About PATHFINDER clinic visits
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PATHFINDER trial clinic visits

During the trial, a variety of health assessments will be conducted to see how you are responding to the investigational drug. In most cases, these assessments will be done at a clinical site.

Health assessments will vary between visits, but may include:

MRI or CT scan and X-ray

Bone marrow biopsy

ECG(painless heart scan)

Blood tests

Quality of life Questionnaires

More information about health assessments and visit length will be found in the informed consent form, which you will need to read and sign if you want to take part in the PATHFINDER clinical trial.

How often will these visits take place?*

Cycle 1

2 times

Cycle 2

Every month

Cycle 3 onwards

Every 2-3 months

*Please note that these numbers are approximate. One treatment cycle is 28 days.

Find a trial site

Where is the PATHFINDER clinical trial taking place?

United States

Stanford University, Stanford, CA

Dana Farber Cancer Institute, Boston, MA

Herbert Irving Comprehensive Cancer Center, New York, NY

Mays Cancer Center, San Antonio, TX

Huntsman Cancer Institute, Salt Lake City, UT

More information about this clinical trial, including participating trial sites, is available on Last updated: 30 Jan 2019.

How can I learn more about the PATHFINDER trial?

If you think you meet the criteria specified above and are interested in taking part in the PATHFINDER trial, or you would simply like more information, please call: +1 617-714-6707 or email: A member of our team will talk you through the next steps and will connect you to a suitable trial doctor.

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