The PATHFINDER Study is no longer enrolling new patients.

An expanded access program (NCT04714086) is open in the
United States for patients
with advanced SM. For
additional information, visit

Forging a new path in systemic mastocytosis

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


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 accumulation 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 to participate in the PATHFINDER clinical trial?

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

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

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Have a confirmed diagnosis of an advanced form of systemic mastocytosis, which can include aggressive systemic mastocytosis with associated hematologicalneoplasm, or mast cell leukemia
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Have elevated levels of serum tryptase, a marker of mast cell activity
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Are at least 18 years old

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

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Have acute myeloid leukemia
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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

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 in the PATHFINDER clinical trial involve?

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Screening period

During screening, certain tests will be done to assess if your disease meets the criteria for the study. The screening period varies and could take up to 8 weeks in some cases (from start of screening to your first dose of avapritinib).

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Dosing period

28-day cycles*

As a single-arm trial, there is no placebo (sugar-pill) group and all eligible participants are guaranteed to receive the investigational drug.

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Follow up period

All participants must have a follow-up visit 14 days after their last dose of investigational drug. Follow-up calls and site visits may be required periodically thereafter.

*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

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:

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MRI or CT scan and X-Ray

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Bone marrow biopsy

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(painless heart scan)

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Blood tests

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Quality of life Questionnaires



How often will these visits take place?*

Cycle 1

2 times

Cycle 2

Every month

Cycle 3 onwards

Every 2-3 months

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.

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

    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: +1 888-BLU-PRNT (+1 888-258-7768) (US/Canada only) or email: A member of our team will connect you to a suitable trial site.

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