-- Significant scientific and clinical presence, including 10 presentations, underscores breadth and depth of SM leadership --

-- Blueprint Medicines to host investor conference call and webcast on Monday, February 27, 2023 --

CAMBRIDGE, Mass., Feb. 3, 2023 /PRNewswire/ -- Blueprint Medicines Corporation (NASDAQ: BPMC) today announced plans to present detailed results from the registrational PIONEER trial of AYVAKIT® (avapritinib) in indolent systemic mastocytosis (SM) at the 2023 American Academy of Allergy, Asthma and Immunology (AAAAI) Annual Meeting, February 24 to 27 in San Antonio. PIONEER data will be featured in two oral platform presentations on Sunday, February 26. One presentation will detail the statistically significant and clinically meaningful results AYVAKIT achieved across the primary and all key secondary endpoints in PIONEER, and a second late-breaking presentation will focus on the impact of AYVAKIT on skin signs and symptoms. An additional PIONEER poster presentation will feature data across a broad set of well-established quality-of-life measures.

Blueprint Medicines will share data across 10 presentations, further demonstrating the company's long-standing scientific leadership position and commitment to SM. Three presentations will focus on PIONEER results while the others will characterize the burden of disease and showcase new approaches to accelerate diagnostic rates, such as by collaborating with medical centers and community networks to generate novel testing algorithms.

"The breadth of data we are presenting at AAAAI reflects our ongoing partnership with the global systemic mastocytosis community, including clinicians and patient advocacy groups, to improve diagnosis, treatment and care, with the shared goal of transforming outcomes for patients living with this disease," said Becker Hewes, M.D., Chief Medical Officer at Blueprint Medicines. "PIONEER is the largest randomized controlled trial ever conducted in indolent SM, and we look forward to reporting study results on the significant clinical impact of AYVAKIT across measures of mast cell burden, symptoms and quality of life. AYVAKIT was designed to target the primary underlying driver of SM, and the totality of data from PIONEER highlights the treatment's potential to modify the disease and set a new standard of care, benefiting a broad range of patients with indolent SM."

Last month, Blueprint Medicines announced that the U.S. Food and Drug Administration (FDA) accepted the company's supplemental new drug application (sNDA) for AYVAKIT for the treatment of adults with indolent SM, and granted priority review with a May 22, 2023 action date under the Prescription Drug User Fee Act (PDUFA).

The accepted abstracts are listed below and are being published today in an online supplement to The Journal of Allergy and Clinical Immunology (JACI). To view the abstract supplement, go to https://www.jacionline.org/ or https://annualmeeting.aaaai.org.

Oral Presentations – AYVAKIT

Presentation Title: Efficacy and Safety of Avapritinib in Indolent Systemic Mastocytosis (ISM): Results from the Double Blinded Placebo-Controlled PIONEER Study
Session Title: Novel Mast Cell Targets to Treat Allergic Disease
Session Date & Time: Sunday, February 26, 2023 from 2:00 p.m. – 3:15 p.m. CT (3:00 p.m. – 4:15 p.m. ET)
Presentation Date & Time: Sunday, February 26, 2023 from 2:05 p.m. – 2:15 p.m. CT (3:05 p.m. – 3:15 p.m. ET)
Abstract Number: 627
Location: Convention Center, Meeting Room Level, Room 221C

Late-Breaking Presentation Title: Avapritinib Improved Skin Findings in Patients with Indolent Systemic Mastocytosis (ISM) in the Registrational, Double-Blind, Placebo Controlled PIONEER Study
Session Title: Late Breaking Oral Abstract Session: Clinical
Session Date & Time: Sunday, February 26, 2023 from 2:00 p.m. – 3:15 p.m. CT (3:00 p.m. – 4:15 p.m. ET)
Presentation Date & Time: Sunday, February 26, 2023 from 2:25 p.m. – 2:35 p.m. CT (3:25 p.m. – 3:35 p.m. ET)
Abstract Number: L69
Location: Convention Center, Ballroom Level, Room 304A

Poster Presentation – AYVAKIT

Presentation Title: Avapritinib Improved Symptoms and Quality of Life in Patients with Indolent Systemic Mastocytosis in the PIONEER Study
Session Date & Time: Friday, February 24, 2023 from 3:15 p.m. – 4:15 p.m. CT (4:15 p.m. – 5:15 p.m. ET)
Abstract Number: 151
Location: Convention Center, Lobby Level, Hall 2

Poster Presentations – Systemic Mastocytosis (SM)

Presentation Title: Patterns of Disease Progression in Patients with Non-Advanced Systemic Mastocytosis: A US Population-level Analysis Using Health Claims-Based Dataset
Session Date & Time: Friday, February 24, 2023 from 3:15 p.m. – 4:15 p.m. CT (4:15 p.m. – 5:15 p.m. ET)
Abstract Number: 149
Location: Convention Center, Lobby Level, Hall 2

Presentation Title: Symptomatology and Diagnostic Journey of Patients Diagnosed with Systemic Mastocytosis in The US Oncology Network
Session Date & Time: Friday, February 24, 2023 from 3:15 p.m. – 4:15 p.m. CT (4:15 p.m. – 5:15 p.m. ET)
Abstract Number: 157
Location: Convention Center, Lobby Level, Hall 2

Presentation Title: Real-World Chart Pull Data on the Clinical Presentation and Diagnosis of Indolent Systemic Mastocytosis
Session Date & Time: Friday, February 24, 2023 from 3:15 p.m. – 4:15 p.m. CT (4:15 p.m. – 5:15 p.m. ET)
Abstract Number: 160
Location: Convention Center, Lobby Level, Hall 2

Presentation Title: PROSPECTOR: A Global, Prospective Study to Determine the Prevalence of the KIT D816V Mutation in Peripheral Blood (PB) from Patients with Evidence of Systemic Mast Cell Activation (MCA)
Session Date & Time: Friday, February 24, 2023 from 3:15 p.m. – 4:15 p.m. CT (4:15 p.m. – 5:15 p.m. ET)
Abstract Number: 161
Location: Convention Center, Lobby Level, Hall 2

Presentation Title: Development of a Clinical Scoring System to Identify Conditions of Mast Cell Proliferation in a Community Setting
Session Date & Time: Friday, February 24, 2023 from 3:15 p.m. – 4:15 p.m. CT (4:15 p.m. – 5:15 p.m. ET)
Abstract Number: 162
Location: Convention Center, Lobby Level, Hall 2

Presentation Title: Calculation of Disability-adjusted Life Years (DALY) in Patients with Indolent Systemic Mastocytosis (ISM)
Session Date & Time: Friday, February 24, 2023 from 3:15 p.m. – 4:15 p.m. CT (4:15 p.m. – 5:15 p.m. ET)
Abstract Number: 164
Location: Convention Center, Lobby Level, Hall 2

Presentation Title: Development of Scalable, Electronic Health Record (EHR)-based Screening for Undiagnosed Systemic Mastocytosis: PREDICT-SM
Session Date & Time: Sunday, February 26, 2023 from 9:45 a.m. – 10:45 a.m. CT (10:45 p.m. – 11:45 p.m. ET)
Abstract Number: 566
Location: Convention Center, Lobby Level, Hall 2

Investor Conference Call Information

Blueprint Medicines will host a live conference call and webcast at 8:00 a.m. ET on Monday, February 27, 2023 to discuss the registrational PIONEER trial data of AYVAKIT in indolent SM. The conference call may be accessed by dialing 844-200-6205 (domestic) or 929-526-1599 (international), and referring to conference ID 163491. A webcast of the call will also be available under "Events and Presentations" in the Investors & Media section of the Blueprint Medicines website at http://ir.blueprintmedicines.com/. The archived webcast will be available on the Blueprint Medicines website approximately two hours after the conference call and will be available for 30 days following the call.

About AYVAKIT (avapritinib)

AYVAKIT (avapritinib) is a kinase inhibitor approved by the FDA for the treatment of adults with Advanced SM, including aggressive SM (ASM), SM with an associated hematological neoplasm (SM-AHN) and mast cell leukemia (MCL), and adults with unresectable or metastatic gastrointestinal stromal tumor (GIST) harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations. For more information, visit AYVAKIT.com. This medicine is approved in Europe (AYVAKYT®) for the treatment of adults with ASM, SM-AHN or MCL, after at least one systemic therapy, and adults with unresectable or metastatic GIST harboring the PDGFRA D842V mutation. 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. AYVAKIT/AYVAKYT is not approved for the treatment of any other indication in the U.S. or Europe.

To learn about ongoing or planned clinical trials, contact Blueprint Medicines at medinfo@blueprintmedicines.com or 1-888-BLU-PRNT (1-888-258-7768). Additional information is available at blueprintclinicaltrials.com or clinicaltrials.gov.

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 are delivering our approved medicines to patients in the United States and Europe, and we are globally advancing multiple programs for systemic mastocytosis, lung cancer, breast cancer and other genomically defined cancers, and cancer immunotherapy. For more information, visit www.BlueprintMedicines.com 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 the FDA's acceptance of an sNDA for AYVAKIT for the treatment of indolent SM; plans and timing for presenting detailed data from the PIONEER trial of AYVAKIT in patients with non-advanced SM, and, expectations regarding the potential benefits of AYVAKIT in treating patients with non-advanced SM; statements regarding plans, strategies, timelines and expectations for interactions with the FDA and other regulatory authorities; 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' 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, risks and uncertainties related to the impact of the COVID-19 pandemic to Blueprint Medicines' business, operations, strategy, goals and anticipated milestones, including Blueprint Medicines' ongoing and planned research and discovery activities, ability to conduct ongoing and planned clinical trials, clinical supply of current or future drug candidates, commercial supply of current or future approved products, and launching, marketing and selling current or future approved products; Blueprint Medicines' ability and plans in continuing to establish 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 and GAVRETO 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, GAVRETO or any drug candidates it is developing; Blueprint Medicines' ability to develop and commercialize companion diagnostic tests for AYVAKIT/AYVAKYT, GAVRETO or any of its current and future drug candidates; Blueprint Medicines' ability to successfully expand its operations, research platform and portfolio of therapeutic candidates, and the timing and costs thereof; Blueprint Medicines' ability to realize the anticipated benefits of its executive leadership transition plan; 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 its most recent Quarterly Report on Form 10-Q and 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, GAVRETO and associated logos are trademarks of Blueprint Medicines Corporation.

View original content to download multimedia:https://www.prnewswire.com/news-releases/blueprint-medicines-to-present-positive-data-from-pioneer-trial-of-ayvakit-avapritinib-in-indolent-systemic-mastocytosis-at-2023-aaaai-annual-meeting-301738110.html

SOURCE Blueprint Medicines Corporation

Media Relations Contact: Andrew Law, +1 (617) 844-8205, media@blueprintmedicines.com; Investor Relations Contact: Jenna Cohen, +1 (857) 209-3147, ir@blueprintmedicines.com