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NCT Number: NCT07264959

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

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.

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Key information

Conditions

Indolent Systemic Mastocytosis Immune System Diseases Mast Cell Activation Disorders Mastocytosis Mastocytosis, Systemic Neoplasms Neoplasms by Histologic Type Neoplasms, Connective Tissue Neoplasms, Connective and Soft Tissue

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Brigham and Women's Allergy and Clinical Immunology, Mass General Brigham Healthcare Center (Chestnut Hill)

Chestnut Hill, Massachusetts, 02467, United States

Location status: Recruiting

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Primary outcomes

  1. Baseline Demographics

    Time frame: Baseline (Month 1)

  2. Change From Baseline in Patient-Reported Outcomes Scores

    Time frame: Baseline up to Month 61

  3. Change From Baseline in Serum KIT D816V Variant Allele Frequency (VAF)

    Time frame: Baseline up to Month 61

  4. Change From Baseline in Serum Tryptase

    Time frame: Baseline up to Month 61

  5. Change From Baseline in Indolent Systemic Mastocytosis (ISM) Symptom-Directed Therapies

    Time frame: Baseline up to Month 61

Study contacts

Contact information is provided by the study sponsor or research team.

Blueprint Medicines

CONTACT

[email protected]

1-888-258-7768

Blueprint Medicines, EU Contact

CONTACT

[email protected]

+31 85 064 4001

Sponsors and collaborators

Lead sponsor

Blueprint Medicines Corporation

Industry

Registry information

Official study title

An Observational Study in Patients With Indolent Systemic Mastocytosis

Important dates

Study start
2026
Primary completion
2032
Study completion
2032
First posted
Dec 4, 2025
Registry last updated
Apr 22, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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