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Study of BLU-263 and Azacitidine for Patients with Advanced Systemic Mastocytosis and Other KIT Altered Blood Cancers

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying treatments for certain blood-related diseases, specifically those involving changes in a gene called KIT. The diseases being studied include Advanced Systemic Mastocytosis and other related blood cancers. The trial is testing a medication called Elenestinib (BLU-263), which is being evaluated both on its own and in combination with another drug called Azacitidine. Azacitidine is a medication that is typically used to treat certain types of blood disorders and cancers.

The purpose of the study is to determine the best dose of BLU-263 when used alone and when combined with Azacitidine, as well as to assess the safety and effectiveness of these treatments. The study is divided into two parts: one part involves taking BLU-263 by itself, and the other part involves taking BLU-263 together with Azacitidine. Participants will receive the medication either as a tablet taken by mouth or as an injection under the skin or into a vein, depending on the treatment plan.

Throughout the study, participants will be monitored to see how their bodies respond to the treatment, including any side effects they may experience. The study aims to gather information on how well the treatments work in managing the diseases and improving the health of the participants. The trial is expected to continue until 2030, allowing researchers to collect comprehensive data on the long-term effects and benefits of the treatments.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, the patient will be assigned to one of two groups: monotherapy or combination therapy.

    The assignment is based on the specific diagnosis and medical history.

  2. Step 2

    Monotherapy group

    Patients in the monotherapy group will receive BLU-263 as a single treatment.

    The medication is administered orally in the form of a film-coated tablet.

    The dosage and frequency will be determined during the dose escalation phase, which aims to find the recommended dose (RD).

    The initial phase lasts for 28 days, during which the safety and effectiveness of the treatment are closely monitored.

  3. Step 3

    Combination therapy group

    Patients in the combination therapy group will receive BLU-263 along with azacitidine.

    BLU-263 is taken orally as a film-coated tablet, while azacitidine is administered either intravenously (IV) or subcutaneously (SC).

    The combination therapy also begins with a dose escalation phase to determine the RD, starting from Day 15 of the first or second cycle.

    The safety and tolerability of the combination are assessed over a 28-day period.

  4. Step 4

    Dose expansion phase

    After determining the RD, patients continue to receive the treatment at this dose in the dose expansion phase.

    This phase further evaluates the safety and effectiveness of the treatment over a longer period.

  5. Step 5

    Monitoring and assessments

    Throughout the trial, regular monitoring of health status, including vital signs, laboratory tests, and any side effects, is conducted.

    Patients may undergo bone marrow biopsies to assess the response to treatment.

  6. Step 6

    End of trial

    The trial is expected to conclude by November 2030.

    Upon completion, the overall response to the treatment and any long-term effects will be evaluated.

Who can join the trial?

11 criteria

  • The participant must have an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2. This is a scale that measures how well a person can perform daily activities.
  • The participant must have a new Bone Marrow (BM) biopsy or use a previous sample taken within 56 days before the first day of the study. They must also agree to have follow-up BM biopsies.
  • If the participant received cancer treatment in the last 12 weeks, they must have stopped because the treatment was not working, the disease got worse, or they could not tolerate it.
  • Participants who have been treated with one prior selective KIT inhibitor (a type of medication) can join the study if they have a specific mutation called KIT D816V and have written approval from the study Sponsor. However, if they stopped the previous treatment due to a severe side effect related to it, they cannot participate.
  • For Arm 1 (Monotherapy), participants must have one of the following diagnoses confirmed by a central laboratory:
    • Aggressive Systemic Mastocytosis (ASM).
    • Systemic Mastocytosis with an Associated Hematologic Neoplasm (SM-AHN) that is not suitable for a specific type of therapy called Hypomethylating agent (HMA) monotherapy. If they have a low-grade condition like chronic lymphocytic leukemia that doesn't need treatment, they are eligible.
    • Mast Cell Leukemia (MCL), including cases with another blood-related condition that doesn't need a specific finding called a C-finding.
    • Other blood-related conditions with abnormal KIT or PDGFR genes may be considered for enrollment after discussion with the Sponsor.
    • For Arm 2 (Combination Therapy), participants must have a diagnosis of SM-AHN confirmed by a central laboratory. Other blood-related conditions that may benefit from the combination treatment of BLU-263 and HMA can be considered after discussion with the Sponsor.
    • Participants of all genders are eligible.
    • The study includes vulnerable populations, which means it considers people who might need extra protection or care.

Who cannot join the trial?

9 criteria

  • Patients who have a different condition than Advanced Systemic Mastocytosis cannot participate. This is a specific condition involving an abnormal increase of certain cells in the body.
  • Patients who are not within the specified age range for the study cannot participate. The study is open to certain age groups only.
  • Patients who are not able to follow the study procedures or take the study medication as required cannot participate.
  • Patients who have other medical conditions that might interfere with the study or make it unsafe for them to participate cannot join the study.
  • Patients who are pregnant or breastfeeding cannot participate in the study.
  • Patients who are currently participating in another clinical trial cannot join this study.
  • Patients who have had a recent major surgery or are recovering from a major illness may not be eligible to participate.
  • Patients who have a history of allergic reactions to the study medication or similar drugs cannot participate.
  • Patients who have certain abnormal laboratory test results that indicate a health issue may not be eligible to participate.
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Investigated drugs

  • BLU-263

    is a medication being studied for its potential to treat certain blood cancers that have changes in the KIT gene. In this trial, it is being tested both on its own and in combination with another medication. The study aims to find the right dose and to see how safe and effective it is for patients with these specific types of cancer.

  • Azacitidine

    is a medication used in combination with BLU-263 in this trial. It is commonly used to treat certain blood disorders and cancers by helping to slow down the growth of abnormal blood cells. The trial is exploring how well it works together with BLU-263 and whether the combination is safe for patients.

What is already known about the treatment

BLU-263 – This medication is administered orally and is currently being studied in clinical trials for its effectiveness in treating advanced systemic mastocytosis, a rare blood disorder. BLU-263 is in the investigational stage, with ongoing research to determine its safety, tolerability, and optimal dosing. It works by targeting and inhibiting specific proteins involved in the growth and survival of abnormal cells. BLU-263 is classified as a tyrosine kinase inhibitor, a type of drug that blocks signals needed for tumors to grow.

Investigated diseases

Advanced Systemic Mastocytosis – This is a rare disorder characterized by the accumulation of mast cells in various tissues, including the skin, bone marrow, liver, and spleen. These mast cells release chemicals that can cause symptoms such as skin rashes, abdominal pain, and anaphylaxis. Over time, the disease can lead to organ dysfunction due to the infiltration of mast cells. The progression of the disease varies, with some individuals experiencing a slow progression while others may have a more aggressive form. Symptoms can fluctuate, with periods of stability followed by episodes of increased severity. The condition is considered advanced when it significantly affects the function of one or more organs.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase ITrial ID2023-510144-20-00Protocol codeBLU-263-2101Estimated enrolment60 patientsSponsorBlueprint Medicines Corp.

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).