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Blueprint Medicines is a fully integrated global biopharmaceutical company that invents life-changing medicines across two strategic focus areas of allergy/inflammation and oncology/hematology. Our approach combines deep scientific expertise, modality-agnostic drug discovery capabilities, and a proven track record of R&D success. Currently, we are commercializing our approved medicine AYVAKIT/AYVAKYT® (avapritinib) in the U.S. and Europe, as well as in other regions of the world through partnerships.

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Blueprint Medicines' AYVAKYT® (avapritinib) Receives Positive CHMP Opinion as the First and Only Therapy for Indolent Systemic Mastocytosis

November 10, 2023 at 8:00 AM EST

-- For the first time, the estimated 40,000 patients with indolent SM in the EU1,2* would have a medicine that treats the primary disease driver3,4 --

-- Opinion based on the positive PIONEER trial, in which once-daily AYVAKYT achieved significant improvements across a broad range of symptoms with a comparable safety profile to placebo3,4 --

CAMBRIDGE, Mass., Nov. 10, 2023 /PRNewswire/ -- Blueprint Medicines Corporation (Nasdaq: BPMC) today announced the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) has issued a positive opinion recommending the approval of AYVAKYT® (avapritinib) for the treatment of adult patients with indolent systemic mastocytosis (ISM) with moderate to severe symptoms inadequately controlled on symptomatic treatment. Pending European Commission (EC) approval, AYVAKYT will become the first and only therapy for people living with ISM in Europe.

Systemic mastocytosis (SM) is a rare hematologic disorder that can lead to a range of debilitating symptoms across multiple organ systems and a significant impact on patients' quality of life.3,5,6 Most patients rely on polypharmacy of best supportive care medications for the management of symptoms, which often are inadequately controlled.5,6 AYVAKYT was designed to potently and selectively inhibit KIT D816V, the primary underlying driver of the disease4,7 and has the potential to help the estimated 40,000 people with ISM in the European Union move beyond multiple, symptom-directed therapies.1,2* Currently, AYVAKYT is approved by the EMA for the treatment of advanced SM and PDGFRA D842V-mutant gastrointestinal stromal tumors.4

"Indolent systemic mastocytosis is often characterized by severe symptoms, significant morbidities and high healthcare resource utilization, with a profound impact on patients and their families," said Becker Hewes, M.D., Chief Medical Officer at Blueprint Medicines. "With significant improvements in overall symptoms shown by AYVAKYT in the PIONEER trial, and a positive CHMP opinion for a broad population of patients with ISM, we are advancing a shift in the treatment paradigm from supportive care to disease modifying therapy. Today's opinion reflects important progress in our goal to elevate the standard of care for patients with SM around the world." 

The CHMP based its positive opinion on data from the registrational double-blind, placebo-controlled PIONEER trial – the largest study ever conducted for this disease – in which patients received AYVAKYT 25 mg or placebo once daily plus best supportive care.3 As previously reported in NEJM Evidence, AYVAKYT demonstrated clinically meaningful improvements versus placebo in the primary and all key secondary endpoints, including overall symptoms and measures of mast cell burden.3

"In Europe, patients with ISM currently have no approved therapies to target the underlying driver of disease, and the need to advance treatment beyond supportive care has never been more critical," said PD Dr. Frank Siebenhaar, Head of University Outpatient Clinic at Charité Institute of Allergology in Berlin. "As a physician who specializes in treating and researching ISM, I have seen firsthand the significant impact ISM has on the daily lives of patients and their families. The PIONEER trial results demonstrate the potential to improve quality of life and transform the standard of care for the ISM community."

In PIONEER, AYVAKYT was well-tolerated with a favorable safety profile, and most adverse events were mild in severity, with the most common being flushing, edema, increased blood alkaline phosphatase and insomnia.3

The CHMP opinion will now be reviewed by the EC and a final decision to expand AYVAKYT's indication to include ISM is expected in Q1 2024.

About AYVAKYT® (avapritinib) 

AYVAKYT® (avapritinib) is a kinase inhibitor approved by the European Commission for the treatment of adult patients with aggressive systemic mastocytosis (ASM), systemic mastocytosis with an associated hematological neoplasm (SM-AHN) or mast cell leukemia (MCL), after at least one systemic therapy and for the treatment of adult patients with unresectable or metastatic gastrointestinal stromal tumors (GIST) harboring the PDGFRA D842V mutation.4 Under the brand name AYVAKIT®, the medicine is approved in the U.S. for the treatment of three indications: adults with indolent systemic mastocytosis (ISM), adults with Advanced SM, including ASM, SM-AHN and MCL, and adults with unresectable or metastatic GIST harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations.8

It is also approved under the brand name AYVAKIT in Mainland China for the treatment of adults with unresectable or metastatic GIST harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations, and in Hong Kong and Taiwan for the treatment of adults with unresectable or metastatic GIST harboring a PDGFRA D842V mutation.9,10,11  

To learn about ongoing or planned clinical trials, contact Blueprint Medicines at and +31 85 064 4001. Additional information is available at and

Please click here to see the Summary of Product Characteristics for AYVAKYT.  

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 for patients across the spectrum of SM.3,5,6 Approximately 1 in 10,000 people live with SM and the vast majority of those affected have indolent systemic mastocytosis (ISM).1,2* 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.8,12,13,14 This burden of disease can lead to a profound, negative impact on quality of life.3,5,6 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.3,5,6 

About Blueprint Medicines 

Blueprint Medicines is a global precision therapy company that invents life-changing therapies for people with cancer and blood disorders. Applying an approach that is both precise and agile, we create medicines that selectively target genetic drivers, with the goal of staying one step ahead across stages of disease. Since 2011, we have leveraged our research platform, including expertise in molecular targeting and world-class drug design capabilities, to rapidly and reproducibly translate science into a broad pipeline of precision therapies. Today, we have brought our approved medicines to patients in the United States and Europe, and we are globally advancing multiple programs for mast cell disorders, including systemic mastocytosis and chronic urticaria, breast cancer and other cancers vulnerable to CDK2 inhibition, as well as EGFR-mutant lung cancer. For more information, visit and follow us on 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 Blueprint Medicines' views with respect to the implications of the approval of AYVAKYT for people living with ISM in Europe; plans, strategies, timelines 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' financial performance, strategy, goals and anticipated milestones, 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: preliminary activity and safety data may not be representative of more mature data; the risk of delay of any current or planned clinical trials or the development of Blueprint Medicines' current or future drug candidates; risks related to 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; preclinical and clinical results for Blueprint Medicines' drug candidates 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 may be delayed or slower than anticipated; actions of regulatory agencies may affect the initiation, timing and progress of clinical trials; the success of Blueprint Medicines' current and future collaborations, financing arrangements, partnerships or licensing arrangements may impact Blueprint Medicines' ability to capitalize on the market potential of its approved drugs and drug candidates; and risks related to Blueprint Medicines' ability to obtain, maintain and enforce patent and other intellectual property protection for its products and current or future drug candidates it is developing. 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.


 *Based on Cohen 2014 study of 548 adults with SM diagnosed from 1997 to 2010 in linked Danish national health registries, with a 14-year limited-duration prevalence estimated at 9.59 per 100,000 as of 1 January 2011


Cohen SS et al. Epidemiology of systemic mastocytosis in Denmark. Br J Haematol. 2014;166(4):521-8.


OrphaNet. Indolent systemic mastocytosis. Available at: Accessed October 2023.


Gotlib J, et al. Avapritinib versus Placebo in Indolent Systemic Mastocytosis. NEJM Evid 2023;2(6) May 23, 2023.


AYVAKYT SMPC. Available at: product-information/ayvakyt-epar-product-information_en.pdf Accessed October 2023.


Mesa R.A et al. Perceptions of patient disease burden and management approaches in systemic mastocytosis: Results of the TouchStone Healthcare Provider Survey. Cancer. 2022;128(20):3700-3708.


Mesa RA et al. Patient-reported outcomes among patients with systemic mastocytosis in routine clinical practice: Results of the TouchStone SM Patient Survey. Cancer. 2022 Oct;128(20):3691-3699.


Akin C et al. Tyrosine kinase inhibitors for the treatment of indolent systemic mastocytosis: Are we there yet?,J Allergy Clin Immunol 2022;149:1912–8


Blueprint Medicines. AYVAKIT (avapritinib) Prescribing Information. Available at: Accessed October 2023.


CStone Announces China NMPA New Drug Approval of Precision Therapy AYVAKIT® (avapritinib) for the Treatment of Adults with Unresectable or Metastatic PDGFRA Exon 18 Mutant Gastrointestinal Stromal Tumor. CStone Pharmaceuticals. Available at: Accessed October 2023.


CStone announced new drug approval of precision therapy AYVAKIT® (avapritinib) in Hong Kong, China for the treatment of PDGFRA D842V mutant gastrointestinal stromal tumors (GIST)." CStone Pharmaceuticals. Available at: Accessed October 2023.


CStone Announces Acceptance of New Drug Application in Hong Kong for Avapritinib for the Treatment of Adults with Unresectable or Metastatic PDGFRA D842V Mutant Gastrointestinal Stromal Tumor." Available at: Accessed October 2023.


Gilreath JA, Tchertanov L and Deininger MW, 'Novel approaches to treating advanced systemic mastocytosis', Clin Pharmacol 2019;11:77-92


Lim K-H, et al. 'Systemic mastocytosis in 342 consecutive adults: survival studies and prognostic factors', Blood 2009;113(23):5727-5136. 12


Sperr WR, et al. 'International prognostic scoring system for mastocytosis (IPSM): a retrospective cohort study'. Lancet 2019;6(12):e638-e649.


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