On June 12, 2025 Blueprint Medicines Corporation (Nasdaq: BPMC) reported data presentations reflecting over a decade of collaboration with clinical experts and patient advocates to transform the treatment of systemic mastocytosis (SM) (Press release, Blueprint Medicines, JUN 12, 2025, View Source [SID1234653853]). Key results continue to position AYVAKIT/AYVAKYT (avapritinib) as the durable standard of care across indolent and advanced SM, and highlight the real-world burden of the disease, reinforcing the importance of treating with a therapy that addresses the root cause of SM. These data will be reported at the 2025 European Hematology Association (EHA) (Free EHA Whitepaper) (EHA2025) Hybrid Congress, being held June 12 to 15 in Milan, Italy, and the European Academy of Allergy and Clinical Immunology (EAACI) Congress 2025, being held June 13 to 16 in Glasgow, United Kingdom.

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"Our presentations feature large patient populations from the PIONEER, PATHFINDER and EXPLORER trials, with follow-up reaching up to five years in ISM and up to 6.5 years in advanced SM, reflecting both the favorable long-term benefits of AYVAKIT and the unprecedented datasets we have amassed over time," said Becker Hewes, M.D., Chief Medical Officer at Blueprint Medicines. "AYVAKIT has shown transformative clinical outcomes for patients across the spectrum of SM, including sustained disease control in ISM and prolonged survival in advanced SM. These compelling results have translated into real-world practice, with clinicians expanding their view of who is an appropriate candidate for disease-modifying therapy after positive AYVAKIT experiences, and treatment durations trending toward multiple years."

PIONEER Three-Year Data: Durable Clinical Benefits and Consistent Safety Profile with Long-Term AYVAKIT Use in ISM

As previously presented,1 AYVAKIT demonstrated robust improvements through 144 weeks in overall symptom and symptom domain measures (skin, gastrointestinal, neurocognitive) representative of real-world patient impacts. AYVAKIT showed a well-tolerated safety profile and a low discontinuation rate due to treatment-related adverse events (TRAEs; 3 percent) with a median of three years of exposure, and some patients out to five years on therapy. Common TRAEs included low-grade edemas, headache and nausea.
In newly reported data, AYVAKIT showed sustained clinical benefits across quality-of-life measures that reflect general health status and are broadly recognized by allergists/immunologists, validating previously presented results from the disease-specific, Mastocytosis Quality of Life (MC-QoL) questionnaire.
This data presentation follows the May 2025 online publication of PIONEER two-year efficacy and safety data in The Journal of Allergy and Clinical Immunology: In Practice.

PATHFINDER/EXPLORER Multi-Year Data: Long-Term Survival Benefits of AYVAKIT in Advanced SM

AYVAKIT showed prolonged overall survival (OS) in PATHFINDER and EXPLORER, when indirectly compared to real-world data for midostaurin from the German Registry on Disorders of Eosinophils and Mast Cells (GREM).
AYVAKIT led to meaningful survival benefits in patients across all prognostic categories (low, intermediate and high risk), per the Revised Mutation-Adjusted Risk Score (MARS-R) – a new OS risk assessment tool for advanced SM.
Conducted in collaboration with University Hospital Mannheim, the analyses validate the MARS-R tool’s ability to assess OS risks in advanced SM patients treated with AYVAKIT or midostaurin, using clinical and genetic parameters. The MARS-R was developed to inform physician care decisions based on individual patient needs.
PRISM Data: Substantial Disease Burden Across Broad Population of Patients with ISM

PRISM is one of the largest studies characterizing the impact of SM from both patient and clinical perspectives.
Across the spectrum of disease severity, patients with ISM experienced physical, social and emotional challenges that caused meaningful disruption to their daily lives.
Patients reported a broad constellation of disease-related impacts, including limitations to physical activities, work/college and relationships; problems with pain/discomfort and anxiety/depression; and adjustments in their daily lives to avoid certain foods, extended sun exposure and smells.
Data Presentations

EHA2025 Congress

Oral Presentation: The Revised Mutation-Adjusted Risk Score (MARS-R) for Predicting Overall Survival in Patients with Advanced Systemic Mastocytosis Treated with Midostaurin or Avapritinib (Abstract S216)
Poster Presentation: Blood-Based Proteomics for Deeper Insights Into Indolent Systemic Mastocytosis: The PIONEER Trial Experience (Abstract PS1838)
Poster Presentation: High Accuracy of Peripheral Blood Testing Using Machine Learning–Derived Predictive Models to Distinguish Advanced from Indolent Systemic Mastocytosis: Analysis of Avapritinib and Elenestinib Trial Data (Abstract PF1310)
Publication-Only Abstract: Phase 2/3 HARBOR Study of Elenestinib in ISM: A Trial-in-Progress Update of Novel Endpoints and Biomarkers Aimed at Evaluating Disease Modification (Abstract PB3108)
EAACI Congress 2025

Flash Talk Presentation: Favorable Benefit-Risk Profile of Avapritinib in Indolent Systemic Mastocytosis Is Maintained After 3 Years of Therapy: Longer-Term Analysis of the PIONEER Study (Abstract 000621)
Flash Talk Presentation: The Socio-Emotional Impact of Indolent Systemic Mastocytosis: Insights from the PRISM Survey (Abstract 000488)
Poster Presentation: The Phase 2/3 Study of Elenestinib, a Highly Potent and Selective Tyrosine Kinase Inhibitor, in Patients with Indolent Systemic Mastocytosis (Abstract 001121)
Data presentations are being made available in the "Science―Publications and Presentations" section of the company’s website at www.blueprintmedicines.com.