Your condition is unique. Your care should be too.

Consider EXPLORER - a clinical trial of avapritinib for people with advanced systemic mastocytosis.

Learn More

About the EXPLORER clinical trial

The EXPLORER clinical trial will test an investigational drug called avapritinib in people with advanced systemic mastocytosis (SM). It is a phase 1 trial designed to test the safety and initial clinical activity of avapritinib.

Information about advanced 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. They help to fight infection and play a key role in triggering an allergic response.

There are many different types of advanced SM – including aggressive SM, SM with an associated hematologic neoplasm* and mast cell leukemia. Across all types of advanced SM, about 90-95% of people have a specific mutation (genetic alteration) in a gene called KIT. This gene provides the instructions for producing the KIT protein that is involved in signaling cell growth and division. The mutation, known as KIT D816V, is believed to play a central role in the activation and accumulation of mast cells in the body. Avapritinib is an investigational drug that was specifically designed to inhibit (block) D816V mutant KIT.

*SM with associated hematologic neoplasm is a form of advanced SM that occurs with another blood disorder, such as myelodysplastic syndrome.

Who is eligible
Find a trial site

Who is eligible to participate in the EXPLORER clinical trial?

You may be eligible to take part in the EXPLORER 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

Are at least 18 years old

*SM with associated hematologic neoplasm is a form of advanced SM that occurs with another blood disorder, such as myelodysplastic syndrome.

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

Who is eligible
Find a trial site

About the investigational drug

If you take part in the EXPLORER clinical trial, you will receive the investigational drug avapritinib. Avapritinib comes in a tablet form, and should be swallowed whole with water, once a day.

What does taking part involve?
Find a trial site

What does taking part in the EXPLORER 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 EXPLORER clinic visits
Find a trial site

EXPLORER 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

Vital signs(temperature, blood pressure, heart rate and weight)

ECG(painless heart scan)

Blood tests

Bone Marrow Biopsy


The length of these visits will also vary, but some may take up to 10 hours.

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 EXPLORER clinical trial.

How often will these visits take place?*

Cycle 1

6 times

Cycle 2

2 times

Cycle 3 onwards

Once per cycle

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

Find a trial site

Where is the EXPLORER clinical trial taking place?

United Kingdom

Guy's Hospital St. Thomas NHS Foundation Trust, London

Beatson West of Scotland Cancer Centre, Glasgow

United States

Stanford Cancer Center, Stanford, CA

University of Colorado Cancer Center, Denver, CO

Emory University, Atlanta, GA

Dana Farber Cancer Institute, Boston, MA

University of Michigan Health System, Ann Arbor, MI

Mount Sinai Hospital, New York, NY

University of Pennsylvania, Philadelphia, PA

MD Anderson Cancer Center, Houston, 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 EXPLORER trial?

If you think you meet the criteria specified above and are interested in taking part in the EXPLORER 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.

I have read and understand the Terms of Use and Privacy Policy for Blueprint Medicines. In addition, I hereby authorize Blueprint Medicines, together with any individuals or entities working for or on behalf of Blueprint Medicines, to contact me by mail or email for marketing purposes, including to conduct market research or to obtain similar information from me, and to provide information to me about Blueprint Medicines’ drug candidates, services, programs or other potential topics of interest. I understand that I may withdraw the above authorization and choose not to receive future information or updates from Blueprint Medicines at any time by either clicking the "unsubscribe" link at the bottom of this page, by clicking an “unsubscribe” link provided in any emails I receive from Blueprint Medicines or by contacting Blueprint Medicines at the following: Blueprint Medicines Corporation, 45 Sidney Street, Cambridge, MA 02139, telephone: +1 617-714-6707 , email: .