Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

RecruitingRare disease

Study of Elenestinib for Patients with Indolent Systemic Mastocytosis

Fast replyInvestigationalNo placebo
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

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

This clinical trial is focused on studying a condition called Indolent Systemic Mastocytosis, which is a type of disease where certain cells in the body, known as mast cells, grow uncontrollably and cause various symptoms. The trial will test a new treatment called ELENESTINIB, also known by its code name BLU-263. This medication is taken as a film-coated tablet and is being studied to see if it can help manage the symptoms of this condition.

The purpose of the study is to determine the right dose of ELENESTINIB for treating Indolent Systemic Mastocytosis. Participants in the study will be randomly assigned to receive either the medication or a placebo, which looks like the medication but does not contain the active ingredient. The study will be conducted in a double-blind manner, meaning neither the participants nor the researchers will know who is receiving the actual medication or the placebo. This helps ensure the results are unbiased. The study will last for several weeks, during which participants will take the medication or placebo and have regular check-ups to monitor their health and any changes in their symptoms.

Throughout the study, the safety and tolerability of ELENESTINIB will be closely monitored by checking for any side effects or changes in health indicators like vital signs and laboratory test results. The effectiveness of the treatment will be assessed by measuring changes in symptoms and other health markers. The study aims to provide valuable information on whether ELENESTINIB can be a safe and effective treatment option for people with Indolent Systemic Mastocytosis.

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 informed about the trial's purpose and procedures. The patient must meet specific criteria, such as age and health conditions, to participate.

    The patient will provide informed consent, acknowledging understanding of the study and agreeing to participate.

  2. Step 2

    Screening period

    During the screening period, the patient's health status and eligibility will be assessed. This includes confirming the diagnosis of indolent systemic mastocytosis (ISM) or smoldering systemic mastocytosis (SSM) through medical tests.

    The patient must have stable symptom management for at least 14 days before starting the trial.

  3. Step 3

    Randomization and treatment assignment

    The patient will be randomly assigned to receive either the study medication, elenestinib, or a placebo. This process is double-blind, meaning neither the patient nor the researchers know which treatment is being administered.

    The medication is provided in the form of film-coated tablets for oral use.

  4. Step 4

    Treatment phase

    The patient will take the assigned medication daily. The dosage and specific instructions will be provided by the study team.

    The treatment phase is divided into parts, with assessments at various intervals to monitor the patient's response and any side effects.

  5. Step 5

    Monitoring and assessments

    Regular monitoring will occur throughout the study to evaluate the safety and effectiveness of the treatment. This includes checking vital signs, conducting laboratory tests, and completing symptom assessments.

    The primary goal is to observe changes in symptoms and any adverse effects.

  6. Step 6

    End of treatment and follow-up

    At the end of the treatment period, the patient will undergo final assessments to determine the overall impact of the medication.

    Follow-up visits may be scheduled to ensure the patient's well-being and to gather additional data on long-term effects.

Who can join the trial?

12 criteria

  • Patient must be at least 16 years old at the time of signing the consent form. In some countries like France, Sweden, Germany, and Spain, patients must be at least 18 years old.
  • Patient must have a specific genetic marker called KIT D816V in their blood or bone marrow, or have a type of cell called CD25+ Mast cells in their bone marrow.
  • Patient must have symptoms that match those of mast cell activation, affecting at least two body systems. These symptoms can include skin flushing, fast heartbeat, fainting, low blood pressure, diarrhea, nausea, vomiting, and stomach cramps. They must also have a blood test result called sBT above 8 ng/mL, or have severe and repeated allergic reactions known as anaphylaxis.
  • Patient must have a confirmed diagnosis of SSM (Smoldering Systemic Mastocytosis) through a bone marrow biopsy reviewed by a central pathology team, following specific diagnostic criteria.
  • Patient must have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 to 2, which is a scale used to assess how well a patient can perform daily activities.
  • Patient must have moderate-to-severe symptoms based on a symptom score from a specific assessment form over a 14-day period.
  • Patient must have a confirmed diagnosis of ISM (Indolent Systemic Mastocytosis) through a bone marrow biopsy reviewed by a central pathology team, following specific diagnostic criteria.
  • Patient must have tried and not achieved adequate symptom control with at least two different types of treatments, such as antihistamines, acid reducers, or other medications.
  • Patient must have their current symptom management stabilized for at least 14 days before starting the screening process.
  • If the patient is taking corticosteroids, the dose must be 20 mg or less per day of prednisone or an equivalent medication, and the dose must be stable for at least 14 days.
  • Patient must have a condition called mMCAS (mast cell activation syndrome) confirmed by a bone marrow biopsy reviewed by a central pathology team.
  • Patient must have a blood test result called tryptase that is less than 20 ng/mL.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

RecruitingNot yet recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

BLU-263 is a medication being studied for its potential to treat indolent systemic mastocytosis. This condition involves an abnormal accumulation of mast cells in the body, which can lead to various symptoms. The trial aims to evaluate the effectiveness and safety of BLU-263 in managing these symptoms and improving the quality of life for patients with this condition.

What is already known about the treatment

Elenestinib – Elenestinib is administered orally in the form of tablets. It is currently being studied in clinical trials, specifically in a Phase 2/3 study, to evaluate its effectiveness and safety. The main therapeutic indication for elenestinib is the treatment of indolent systemic mastocytosis, a condition characterized by the accumulation of mast cells in various tissues. At the molecular level, elenestinib works by inhibiting specific enzymes that are involved in the growth and survival of these mast cells. It is classified pharmacologically as a tyrosine kinase inhibitor.

Investigated diseases

  • Indolent Systemic Mastocytosis

    This is a condition where there is an abnormal accumulation of mast cells in various tissues of the body. These mast cells release substances that can cause symptoms like skin rashes, itching, and abdominal discomfort. The disease progresses slowly and is often characterized by mild symptoms. Over time, patients may experience more frequent or severe episodes of symptoms. The condition is considered a rare disease and can vary greatly in how it affects individuals.

  • Smoldering Systemic Mastocytosis

    This is a subtype of systemic mastocytosis that is more advanced than indolent systemic mastocytosis but not as severe as aggressive forms. It involves a higher burden of mast cells in the body, which can lead to more pronounced symptoms. Patients may experience symptoms such as fatigue, bone pain, and gastrointestinal issues. The progression of the disease can lead to an increase in symptom severity and frequency. It is also classified as a rare disease and requires careful monitoring.

Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2024-516728-32-00Protocol codeBLU-263-1201Estimated enrolment591 patientsSponsorBlueprint Medicines Corp.

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

ClinicalTrials.eu

Every clinical trial in Europe, in plain language.

Explore the full ecosystem of clinical research in Europe.

Search trials

Legal notice · Published by CTIN POLAND sp. z o.o., ul. rtm. Witolda Pileckiego 67/109, 02-781 Warsaw, Poland · KRS 0001111334 · REGON 528919042 · NIP 9512598637

© 2026 Clinical Trials EU – European Clinical Trials Information Network

GDPR compliance, ISO 9001 and ISO 27001 certified (LL-C Certification)

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).