A Non-Interventional Study in Participants With Indolent Systemic Mastocytosis (ISM) in Germany

A Prospective Non-Interventional Study to Describe the Effectiveness of Avapritinib (BLU-285), a Selective KIT Mutation-Targeted Tyrosine Kinase Inhibitor, in Patients With Indolent Systemic Mastocytosis and Symptoms That Are Not Adequately Controlled With Symptomatic Treatments in Real-World Settings

This is a non-interventional study assessing the effectiveness of avapritinib (BLU-285) in the management of ISM in real-world settings in Germany. The study also seeks to address the existing data gap in the natural history and management of participants with ISM.

The study is designed to follow each participant up to a maximum of 24 months.

Study Overview

• Status: Recruiting
• Conditions: Indolent Systemic Mastocytosis
• Intervention / Treatment: Drug: Avapritinib

• Study Type: Observational
• Enrollment (Estimated): 80

Contacts and Locations

• Study Contact: Name: Blueprint Medicines, EU Contact; Phone Number: +31 85 064 4001; Email: medinfoeurope@blueprintmedicines.com

Study Locations

• Germany
  • Berlin, Germany, 10117
    • Recruiting
    • Charité Universitätmedizin Berlin, Klinik für Dermatologie, Venerologie und Allergologie
  • Bochum, Germany, 44791
    • Recruiting
    • Katholisches Klinikum Bochum
  • Deggendorf, Germany, 94469
    • Recruiting
    • MVZ Klinikum Deggendorf
  • Dresden, Germany, 01307
    • Recruiting
    • Universitätsklinikum Carl Gustav Carus Dresden Klinik und Poliklinik für Dermatologie
  • Göttingen, Germany, 37075
    • Recruiting
    • University Medical Center Goettingen - Georg August University of Goettingen
  • Tübingen, Germany, 72076
    • Recruiting
    • Universitats-Hautklinik Tubingen, Studienzentrum lmmundermatologie
  • Wiesbaden, Germany, 65205
    • Recruiting
    • HNO-Gemeinschaftspraxis Wiesbaden, GEKA Gesellschaft für Experimentelle und Klinische Atemwegsforschung mbH, Zentrum für Rhinologie und Allergologie
  • Wuppertal, Germany, 42283
    • Recruiting
    • Helios Universitätsklinikum Wuppertal

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Adult participants with ISM with moderate to severe symptoms inadequately controlled on symptomatic treatment, who are initiating treatment with commercial avapritinib according to the German approved label.

Description

Inclusion Criteria:

• Participants is starting avapritinib treatment at the HCP's discretion as part of their routine care (for ISM with moderate to severe symptoms inadequately controlled with symptomatic treatment) and in accordance with approved SmPC.

Exclusion Criteria:

• Participant with a potential increased risk for intracranial hemorrhage including those with a history of vascular aneurysm, intracranial hemorrhage, cerebrovascular accident within the prior year, or severe thrombocytopenia.
• Participant who has previously taken avapritinib as a commercial drug or as part of a clinical study.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Avapritinib; Participants will receive avapritinib as part of their treatment plan with their healthcare practitioner (HCP) and in accordance with the Summary of Product Characteristics (SmPC).	Drug: Avapritinib; Avapritinib will be administered as an oral tablet.; Other Names: BLU-285; Ayvakyt

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Change From Baseline in Mastocytosis Control-quality of Life (MC-QoL) Questionnaire Score at Month 6	Baseline, Month 6

Secondary Outcome Measures

Outcome Measure	Time Frame
Socio-demographic Variable: Participant Age	Baseline (Day -30 to Day -1)
Socio-demographic Variable: Participant Gender	Baseline (Day -30 to Day -1)
Socio-demographic Variable: Participant Ethnicity	Baseline (Day -30 to Day -1)
Socio-demographic Variable: Participant Race	Baseline (Day -30 to Day -1)
Baseline Serum Tryptase and KIT D816V Variant Allele Fraction (VAF)	Baseline (Day -30 to Day -1)
Number of Participants With Prior Medical History of Anaphylaxis	Baseline (Day -30 to Day -1)
Number of Participants with Comorbidity	Baseline up to Month 24
Number of Participants Initiating a New ISM-directed Medication, Discontinuing an ISM-directed Medication, and With Dose Increases or Decreases for ISM-directed Medications	Baseline up to Month 24
Number of Participants Prescribed a Life Support Kit	Baseline up to Month 24
Change From Baseline in Mastocytosis Activity Score (MAS) at Months 3, 6, 12, 18, and 24	Baseline, Months 3, 6, 12, 18, and 24
Change From Baseline in MC-QoL Questionnaire Score at Months 3, 6, 12, 18, and 24	Baseline, Months 3, 6, 12, 18, and 24
Change From Baseline in Mastocytosis Control Test (MCT) Score at Months 3, 6, 12, 18, and 24	Baseline, Months 3, 6, 12, 18, and 24
Time to Response as Assessed by MAS	Baseline up to Month 24
Change From Baseline in Serum Tryptase at Months 3, 6, 12, 18, and 24	Baseline, Months 3, 6, 12, 18, and 24
Number of Participants With Anaphylaxis Requiring Hospitalization, Emergency Room (ER) Visit, Epinephrine Autoinjector Use, or Other Medication	Baseline up to Month 24
Number of Participants Meeting the Definition of Polypharmacy (Use of Multiple Medications Simultaneously; Typically, 3 or More Symptom-directed Prescription Drugs)	Baseline up to Month 24
Number of Participants With ISM-related Hospital Visits and ER Visits	Baseline up to Month 24
Number of Participants With Changes in ISM Symptom-directed Therapies	Baseline up to Month 24
Number of Participants With Dose Modifications and Study/Treatment Discontinuations	Baseline up to Month 24

Collaborators and Investigators

• Sponsor: Blueprint Medicines Corporation

Study record dates

Study Major Dates

• Study Start (Actual): December 9, 2025
• Primary Completion (Estimated): December 1, 2028
• Study Completion (Estimated): December 1, 2028

Study Registration Dates

• First Submitted: November 20, 2025
• First Submitted That Met QC Criteria: November 20, 2025
• First Posted (Actual): December 1, 2025

Study Record Updates

• Last Update Posted (Actual): April 20, 2026
• Last Update Submitted That Met QC Criteria: April 17, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Mastocytosis; Tyrosine kinase inhibitor; Indolent systemic mastocytosis; ISM; Avapritinib; BLU-285; Selective KIT mutation-targeted tyrosine kinase inhibitor; Neoplastic mast cells
• Additional Relevant MeSH Terms: Mast Cell Activation Disorders; Neoplasms; Immune System Diseases; Neoplasms by Histologic Type; Neoplasms, Connective and Soft Tissue; Neoplasms, Connective Tissue; Mastocytosis; Mastocytosis, Systemic; avapritinib
• Other Study ID Numbers: BLU-285-2407