Blueprint Medicines Highlights Leading Portfolio of Mast Cell-Targeted Therapies at 2025 AAAAI / WAO Joint Congress

Rhea-AI Summary

Blueprint Medicines (BPMC) presented comprehensive data on its mast cell therapy portfolio at the 2025 AAAAI/WAO Joint Congress, featuring 14 presentations. The company showcased three-year median follow-up data from the PIONEER trial for AYVAKIT® (avapritinib) in indolent systemic mastocytosis (ISM) treatment.

Key findings demonstrate that AYVAKIT 25mg daily was well-tolerated with no new safety signals after 3 years of exposure. The treatment showed sustained symptom improvements and quality-of-life benefits. Notable results include:

• 93% of patients showed improved or stable benefits in overall symptoms
• Positive impact on bone density improvements
• Successful treatment outcomes even in patients without detectable KIT D816V mutations

Additionally, the company reported positive Phase 1 data for BLU-808, their investigational oral wild-type KIT inhibitor. The healthy volunteer trial showed the drug was well-tolerated with no serious adverse events, achieving dose-dependent serum tryptase reductions exceeding 80%. Multiple proof-of-concept trials are being initiated with initial data expected later in 2025.

Positive

• AYVAKIT shows sustained long-term efficacy with 93% patient response rate
• BLU-808 achieves >80% serum tryptase reduction in Phase 1 trial
• AYVAKIT demonstrates positive impact on bone density
• Strong safety profile maintained after 3 years of treatment

Negative

• Common treatment-related adverse events include peripheral edema, periorbital edema, headache and nausea

Insights

Financial Analyst

Blueprint Medicines' presentation of extended clinical data for AYVAKIT and early-stage data for BLU-808 represents significant progress in their mast cell disease franchise. The three-year PIONEER trial data reinforces AYVAKIT's long-term safety profile and sustained efficacy, which should support continued adoption in the indolent systemic mastocytosis (ISM) market. The durability of response with up to five years of treatment data provides strong clinical validation that could expand the addressable patient population.

Particularly notable is how AYVAKIT demonstrated improvements in bone density, addressing a critical comorbidity affecting 67% of ISM patients compared to 34% in the control group. This differentiated benefit could strengthen AYVAKIT's position as the standard of care. The positive Phase 1 data for BLU-808 showing ≥80% serum tryptase reduction with favorable tolerability suggests Blueprint is building a robust pipeline beyond AYVAKIT. BLU-808's selective wild-type KIT inhibition offers expansion opportunities into additional mast cell disorders with larger patient populations.

With proof-of-concept trials for BLU-808 now underway and data expected later in 2025, Blueprint is executing a coherent pipeline strategy that could significantly expand their total addressable market in mast cell disorders beyond their current commercial footprint.

Biotechnology Expert

Blueprint's data presentations highlight their scientific leadership in targeting KIT-driven mast cell disorders. AYVAKIT's mechanism as a selective KIT D816V inhibitor has now demonstrated sustained disease modification with the three-year PIONEER data, validating their precision medicine approach to ISM. The bone health improvements are particularly significant as they suggest disease-modifying effects beyond symptom control, potentially addressing underlying pathophysiology.

The BLU-808 profile represents an important scientific advance in selective wild-type KIT inhibition. Achieving 80% tryptase reduction with no significant safety signals indicates a wide therapeutic window - important for chronic conditions requiring long-term treatment. The clean safety profile across multiple doses suggests Blueprint has successfully engineered selectivity to avoid off-target effects common with tyrosine kinase inhibitors. Most importantly, BLU-808's pharmacokinetic profile supporting once-daily dosing and sustained target coverage addresses key clinical needs for chronic therapy.

The company's 14 presentations demonstrate comprehensive clinical development, including novel biomarker research revealing how avapritinib impacts the plasma inflammatory proteome. The identification of correlations between multiple proteins and tryptase levels may provide new endpoints for future clinical studies and deeper understanding of disease pathology, potentially uncovering additional therapeutic targets within the mast cell activation pathway.

-- Updated data show AYVAKIT® (avapritinib) was safe and effective for long-term treatment of ISM, with sustained symptom and quality-of-life benefit and no new safety signals with multiple years of therapy --

-- AYVAKIT-treated patients achieved improvements in bone health based on an analysis of bone mineral density scans, underscoring the importance of treating patients early in the ISM disease course -- 

-- BLU-808 healthy volunteer trial results demonstrate wide therapeutic window for modulating mast cell activity, affirming potential as best- and first-in-class oral wild-type KIT inhibitor --

CAMBRIDGE, Mass., Feb. 28, 2025 /PRNewswire/ -- Blueprint Medicines Corporation (Nasdaq: BPMC) today announced data presentations reflecting its ongoing efforts to innovate the treatment of mast cell-driven diseases. The presentations include three-year median follow-up data from the registrational PIONEER trial demonstrating the strong long-term efficacy and safety of AYVAKIT® (avapritinib) in patients with indolent systemic mastocytosis (ISM), and real-world evidence further characterizing the substantial burden of the disease, highlighting the urgency to treat. In addition, the company will report positive data from the Phase 1 healthy volunteer trial evaluating BLU-808, an investigational, highly potent and selective oral inhibitor of wild-type KIT, consistent with top-line data previously announced in January 2025. A total of 14 data presentations, including two oral presentations, will be reported at the 2025 American Academy of Allergy, Asthma & Immunology (AAAAI) / World Allergy Organization (WAO) Joint Congress being held February 28-March 3 in San Diego.

"We are incredibly proud to showcase our mast cell therapy portfolio at AAAAI / WAO, with 14 presentations highlighting more than a decade of leadership and collaboration with the mast cell disease community, including renowned medical institutions pioneering innovative research and multi-disciplinary patient care," said Becker Hewes, M.D., Chief Medical Officer at Blueprint Medicines. "In ISM, new data have reinforced that AYVAKIT was very well-tolerated after multiple years of treatment, with a low discontinuation rate and safety results that have remained consistent with the safety profile from the placebo-controlled study as summarized in the FDA-approval label. This updated AYVAKIT data is particularly important for clinicians considering long-term treatment options for their ISM patients. Further, we are building on our foundational expertise in ISM with our oral wild-type KIT inhibitor BLU-808, with healthy volunteer data showing a differentiated clinical profile and wide therapeutic index that supports broad development across a range of mast cell diseases. Based on these data, we are initiating multiple proof-of-concept trials, with initial data expected later this year."

AYVAKIT: PIONEER Three-Year Efficacy and Safety Data in ISM

• AYVAKIT 25 mg once daily (QD) was well-tolerated and no new safety signals were identified with a median of 3 years of exposure, with some patients out to five years of treatment. The most common treatment-related adverse events (AEs; ≥5 percent) were low-grade peripheral edema, periorbital edema, headache and nausea.
• AYVAKIT 25 mg QD led to robust and durable improvements in overall symptoms, individual symptom domains (skin, gastrointestinal, neurocognitive) and quality of life through 144 weeks of treatment.
• In patients who had high disease burden and escalated to AYVAKIT 50 mg QD (median follow-up: 10.6 months since escalation), treatment was well-tolerated, with side effects consistent with those reported at AYVAKIT 25 mg QD and no patients discontinuing due to AEs. Nearly all patients (93 percent) had improved or stable benefits in overall symptoms.

Low Bone Density: Positive Clinical Impact of AYVAKIT and Real-World Prevalence in ISM

• In a single-site case series from the PIONEER trial, AYVAKIT showed clinically meaningful and durable improvements in bone density, including in the lumbar spine, femoral neck and total proximal femur.
• In real-world data generated from Mayo Clinic electronic health records, 67 percent of ISM patients had osteoporosis/osteopenia compared to 34 percent in a matched control cohort (p<0.0001).

AYVAKIT: Clinical Benefits in Patients with Undetected KIT D816V by ddPCR Assay

• In the PIONEER trial, 15 percent of patients with ISM did not have KIT D816V mutations detected by the commercially available Droplet Digital Polymerase Chain Reaction (ddPCR) assay. Within this group, most patients had KIT mutations identified by the more sensitive duplex sequencing method, and these patients achieved similar reductions in serum tryptase and improvements in symptoms as those with detectable KIT mutations by the ddPCR assay.

BLU-808: Positive Healthy Volunteer Data

• In the Phase 1 single-ascending dose (SAD) and multiple-ascending dose (MAD, 14-day dosing) trial, BLU-808 was well-tolerated at all doses tested. There were no serious AEs, no discontinuations or dose modifications due to AEs, and no significant changes in laboratory measures.
• BLU-808 achieved dose-dependent serum tryptase reductions exceeding 80 percent, reflecting evidence of mast cell target engagement.
• BLU-808 had a half-life supporting once-daily oral dosing and showed sustained target coverage across a range of doses.

Blueprint Medicines' AAAAI / WAO data presentations are listed below. Copies of the data presentations will be available in the "Science—Publications and Presentations" section of the company's website at www.BlueprintMedicines.com.

• Oral Presentation: Assessing Real-World Natural History of Indolent Systemic Mastocytosis: Retrospective Matched Cohort Study from Mayo Clinic Electronic Health Records (Abstract 955 – Monday, March 3)
• Oral Presentation: Responses to Avapritinib in Patients without Detectable KIT Mutations by ddPCR in Peripheral Blood Highlight Diagnostic Challenges and Opportunities in Indolent Systemic Mastocytosis (Abstract 965 – Monday, March 3)
• Poster Presentation: Patient Reported Burden of Indolent Systemic Mastocytosis in White vs. Non-White Patients (Abstract 220 – Friday, February 28)
• Poster Presentation: Identification of Clonal Mast Cell Disease in Patients with Anaphylaxis or Evidence of Systemic Mast Cell Activation: A Post Hoc Analysis from PROSPECTOR (Abstract 301 – Saturday, March 1)
• Poster Presentation: Avapritinib Impacts the Plasma Inflammatory Proteome in Patients with Indolent Systemic Mastocytosis (Abstract 517 – Saturday, March 1)
• Poster Presentation: Multiple Proteins Correlate with Tryptase Levels in Patients with Indolent Systemic Mastocytosis (ISM): Preliminary Results of Plasma Proteomic Analysis in PIONEER (Abstract 518 – Saturday, March 1)
• Poster Presentation: Comprehensive Analysis of Immunoglobulin E Levels in Healthy Donors and Patients with Indolent Systemic Mastocytosis Enrolled on the PIONEER Trial of Avapritinib (Abstract 521 – Saturday, March 1)
• Poster Presentation: Avapritinib and Bone Health in Indolent Systemic Mastocytosis: Learnings from the PIONEER Trial (Abstract 527– Saturday, March 1)
• Poster Presentation: PREDICT-SM: Development of Machine Learning Models to Support Screening for Undiagnosed Systemic Mastocytosis (Abstract 530 – Saturday, March 1)
• Poster Presentation (Trial in Progress): HARBOR: An Ongoing Phase 2/3 Study of Elenestinib in Patients with Indolent Systemic Mastocytosis (Abstract 533 – Saturday, March 1)
• Poster Presentation: Long-Term Quality of Life and Safety in Patients with Indolent Systemic Mastocytosis Treated with Avapritinib in the PIONEER Study (Abstract 534 – Saturday, March 1)
• Poster Presentation: BLU-808: A Potent and Selective Oral Small Molecule Wild-Type KIT Tyrosine Kinase Inhibitor for Allergic Conditions (Abstract 535 – Saturday, March 1)
• Poster Presentation: Utility of Large Language Models to Quantify Diagnostic Delays in Systemic Mastocytosis: A Multi-Center Real World Study (Abstract 544 – Saturday, March 1)
• Poster Presentation: Safety and Pharmacokinetics (PK) of BLU-808 Following Oral Dosing in Healthy Volunteers (Abstract 698 – Sunday, March 2)

About Systemic Mastocytosis

Systemic mastocytosis (SM) is a rare disease driven by the KIT D816V mutation in about 95 percent of cases. Uncontrolled proliferation and activation of mast cells result in chronic, severe and often unpredictable symptoms across multiple organ systems. The vast majority of those affected have indolent systemic mastocytosis (ISM). A broad range of symptoms, including anaphylaxis, maculopapular rash, pruritis, diarrhea, brain fog, fatigue and bone pain, frequently persist in patients with ISM despite treatment with multiple symptom-directed therapies. This burden of disease can lead to a profound, negative impact on quality of life. Patients often live in fear of severe, unexpected symptoms, have limited ability to work or perform daily activities, and isolate themselves to protect against unpredictable triggers. Until 2023, there were no approved therapies for the treatment of ISM.

A minority of patients have advanced SM, which encompasses a group of high-risk SM subtypes including aggressive SM (ASM), SM with an associated hematological neoplasm (SM-AHN) and mast cell leukemia (MCL). In addition to mast cell activation symptoms, advanced SM is associated with organ damage due to mast cell infiltration and poor survival.

About AYVAKIT (avapritinib)

AYVAKIT (avapritinib) is approved by the U.S. Food and Drug Administration (FDA) for the treatment of three indications: adults with ISM, adults with advanced SM, including ASM, SM-AHN and MCL, and adults with unresectable or metastatic gastrointestinal stromal tumor (GIST) harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations. Under the brand name AYVAKYT® (avapritinib), this medicine is approved by the European Commission for the treatment of adults with ISM with moderate to severe symptoms inadequately controlled on symptomatic treatment, adults with ASM, SM-AHN and MCL, after at least one systemic therapy, and adults with unresectable or metastatic GIST harboring the PDGFRA D842V mutation. The therapy is not recommended for the treatment of patients with low platelet counts (less than 50,000/µL).

Please click here to see the full U.S. Prescribing Information for AYVAKIT, and click here to see the European Summary of Product Characteristics for AYVAKYT.

Important Safety Information

Cognitive Effects — Cognitive adverse reactions can occur in patients receiving AYVAKIT and occurred in 7.8% of patients with ISM who received AYVAKIT + best supportive care (BSC) versus 7.0% of patients who received placebo + BSC; <1% were Grade 3. Depending on the severity, withhold AYVAKIT and then resume at the same dose, or permanently discontinue AYVAKIT.

Photosensitivity — AYVAKIT may cause photosensitivity reactions. In all patients treated with AYVAKIT in clinical trials (n=1049), photosensitivity reactions occurred in 2.5% of patients. Advise patients to limit direct ultraviolet exposure during treatment with AYVAKIT and for one week after discontinuation of treatment.

Embryo-Fetal Toxicity — AYVAKIT can cause fetal harm when administered to a pregnant woman. Advise pregnant women of the potential risk to a fetus. Advise females and males of reproductive potential to use an effective contraception during treatment with AYVAKIT and for 6 weeks after the final dose. Advise women not to breastfeed during treatment with AYVAKIT and for 2 weeks following the final dose.

Adverse Reactions — The most common adverse reactions (≥10%) in patients with ISM were eye edema, dizziness, peripheral edema, and flushing.

Drug Interactions — Avoid coadministration of AYVAKIT with strong or moderate CYP3A inhibitors or inducers. If contraception requires estrogen, limit ethinyl estradiol to ≤20 mcg unless a higher dose is necessary.

To report suspected adverse reactions, contact Blueprint Medicines Corporation at 1-888-258-7768 or the FDA at 1-800-FDA-1088 or visit www.fda.gov/medwatch.

AYVAKIT is available in 25-mg, 50-mg, 100-mg and 200-mg tablets.

Please click here to see the full Prescribing Information for AYVAKIT.

About Blueprint Medicines

Blueprint Medicines is a global, fully integrated biopharmaceutical company that invents life-changing medicines. We seek to alleviate human suffering by solving important medical problems in two core focus areas: allergy/inflammation and oncology/hematology. Our approach begins by targeting the root causes of disease, using deep scientific knowledge in our core focus areas and drug discovery expertise across multiple therapeutic modalities. We have a track record of success with two approved medicines, including AYVAKIT®/AYVAKYT® (avapritinib) which we are bringing to patients with systemic mastocytosis (SM) in the U.S. and Europe. Leveraging our established research, development, and commercial capability and infrastructure, we now aim to significantly scale our impact by advancing a broad pipeline of programs ranging from early science to advanced clinical trials in mast cell diseases including SM and chronic urticaria, breast cancer and other solid tumors. For more information, visit www.BlueprintMedicines.com and follow us on X (formerly Twitter; @BlueprintMeds) and LinkedIn.

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, statements regarding expectations for the potential benefits of AYVAKIT in treating patients with ISM; Blueprint Medicines' ability to transform treatment across the spectrum of SM; the development and potential benefits of BLU-808; statements regarding plans and expectations for Blueprint Medicines' current or future approved drugs and drug candidates; the potential benefits of any of Blueprint Medicines' current or future approved drugs or drug candidates in treating patients; and Blueprint Medicines' strategy, goals, business plans and focus. The words "aim," "may," "will," "could," "would," "should," "expect," "plan," "anticipate," "intend," "believe," "estimate," "predict," "project," "potential," "continue," "target" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements in this press release are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this press release, including, without limitation, risks and uncertainties related to Blueprint Medicines' ability and plans in continuing to build out and expand a commercial infrastructure, and successfully launching, marketing and selling current or future approved products; Blueprint Medicines' ability to successfully expand the approved indications for AYVAKIT/AYVAKYT or obtain marketing approval for AYVAKIT/AYVAKYT in additional geographies in the future; the delay of any current or planned clinical trials or the development of Blueprint Medicines' current or future drug candidates; Blueprint Medicines' advancement of multiple early-stage efforts; Blueprint Medicines' ability to successfully demonstrate the safety and efficacy of its drug candidates and gain approval of its drug candidates on a timely basis, if at all; the preclinical and clinical results for Blueprint Medicines' drug candidates, which may not support further development of such drug candidates either as monotherapies or in combination with other agents or may impact the anticipated timing of data or regulatory submissions; the timing of the initiation of clinical trials and trial cohorts at clinical trial sites and patient enrollment rates; actions of regulatory agencies, which may affect the initiation, timing and progress of clinical trials; Blueprint Medicines' ability to obtain, maintain and enforce patent and other intellectual property protection for AYVAKIT/AYVAKYT or any drug candidates it is developing; Blueprint Medicines' ability to successfully expand its operations, research platform and portfolio of therapeutic candidates, and the timing and costs thereof; and the success of Blueprint Medicines' current and future collaborations, financing arrangements, partnerships or licensing arrangements. These and other risks and uncertainties are described in greater detail in the section entitled "Risk Factors" in Blueprint Medicines' filings with the Securities and Exchange Commission (SEC), including Blueprint Medicines' most recent Annual Report on Form 10-K, as supplemented by any other filings that Blueprint Medicines has made or may make with the SEC in the future. Any forward-looking statements contained in this press release represent Blueprint Medicines' views only as of the date hereof and should not be relied upon as representing its views as of any subsequent date. Except as required by law, Blueprint Medicines explicitly disclaims any obligation to update any forward-looking statements.

Trademarks

Blueprint Medicines, AYVAKIT, AYVAKYT and associated logos are trademarks of Blueprint Medicines Corporation.

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SOURCE Blueprint Medicines Corporation

FAQ

What were the key findings from AYVAKIT's 3-year PIONEER trial data for ISM treatment?

AYVAKIT showed sustained efficacy and safety at 25mg daily, with no new safety signals after 3 years. 93% of patients had improved or stable symptoms, with benefits in skin, gastrointestinal, and neurocognitive domains.

How did AYVAKIT affect bone density in ISM patients during the PIONEER trial?

AYVAKIT demonstrated clinically meaningful and durable improvements in bone density, including improvements in lumbar spine, femoral neck, and total proximal femur.

What were the results of BLU-808's Phase 1 healthy volunteer trial?

BLU-808 was well-tolerated with no serious adverse events, achieved >80% serum tryptase reductions, and showed a half-life supporting once-daily dosing.

How effective was AYVAKIT in ISM patients without detectable KIT D816V mutations?

These patients (15% of trial participants) achieved similar reductions in serum tryptase and symptom improvements as those with detectable KIT mutations.