An Observational Study in Participants With Indolent Systemic Mastocytosis (ISM)

April 17, 2026 updated by: Blueprint Medicines Corporation

An Observational Study in Patients With Indolent Systemic Mastocytosis

This is a Phase 4, non-interventional, observational study to collect detailed data on the clinical characteristics, clinical outcomes and medical management of ISM in real-world settings. The study will describe the demographic and clinical characteristics of ISM participants, including anaphylaxis and bone manifestations in ISM. Quality of life and disease control will be assessed through participant questionnaires. The study will also evaluate real world ISM treatment management, including use of avapritinib.

Study Overview

Status

Recruiting

Conditions

Study Type

Observational

Enrollment (Estimated)

150

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • United States
    • Massachusetts
      • Chestnut Hill, Massachusetts, United States, 02467
        • Recruiting
        • Brigham and Women's Allergy and Clinical Immunology, Mass General Brigham Healthcare Center (Chestnut Hill)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Participants with ISM who are currently being treated or plan to be treated with symptom-directed therapies and/or avapritinib for ISM.

Description

Inclusion Criteria:

  • Male or female adult participants (≥ 18 years of age) with a diagnosis of ISM according to the World Health Organization (WHO) diagnostic criteria
  • Participant is currently being treated or plans to be treated with symptom-directed therapies and/or avapritinib for ISM.

Exclusion Criteria:

  • Participants with advanced systemic mastocytosis (AdvSM) or another associated hematologic neoplasm
  • Participants with smoldering systemic mastocytosis
  • Ongoing participation in interventional studies in systemic mastocytosis (SM) at the time of enrollment
  • Participants currently receiving treatment with a KIT inhibitor other than avapritinib at the time of enrollment.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Participants With ISM
Patients who are currently being treated or plan to be treated for ISM

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Baseline Demographics
Time Frame: Baseline (Month 1)
Baseline (Month 1)
Change From Baseline in Patient-Reported Outcomes Scores
Time Frame: Baseline up to Month 61
Baseline up to Month 61
Change From Baseline in Serum KIT D816V Variant Allele Frequency (VAF)
Time Frame: Baseline up to Month 61
Baseline up to Month 61
Change From Baseline in Serum Tryptase
Time Frame: Baseline up to Month 61
Baseline up to Month 61
Change From Baseline in Indolent Systemic Mastocytosis (ISM) Symptom-Directed Therapies
Time Frame: Baseline up to Month 61
Baseline up to Month 61

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Blueprint Medicines Corporation

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 15, 2026

Primary Completion (Estimated)

December 1, 2032

Study Completion (Estimated)

December 1, 2032

Study Registration Dates

First Submitted

November 24, 2025

First Submitted That Met QC Criteria

November 24, 2025

First Posted (Actual)

December 4, 2025

Study Record Updates

Last Update Posted (Actual)

April 22, 2026

Last Update Submitted That Met QC Criteria

April 17, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • BLU-285-2406

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Indolent Systemic Mastocytosis

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Kosovo

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe