Blueprint Medicines Announces Publication in The Lancet Oncology Showing Durable Clinical Benefits of AYVAKIT™ (avapritinib) in NAVIGATOR Trial Patients with PDGFRA D842V Mutant GIST

CAMBRIDGE, Mass., June 29, 2020 /PRNewswire/ -- Blueprint Medicines Corporation (NASDAQ: BPMC), a precision therapy company focused on genomically defined cancers, rare diseases and cancer immunotherapy, today announced that The Lancet Oncology published data from the NAVIGATOR clinical trial showing an unprecedented overall survival (OS) rate and a well-tolerated safety profile for AYVAKIT™ (avapritinib) in patients with advanced PDGFRA D842V mutant gastrointestinal stromal tumor (GIST). The paper, titled "Avapritinib in advanced PDGFRA D842V-mutant gastrointestinal stromal tumour (NAVIGATOR): a multicentre, open-label, phase 1 trial," was published online in The Lancet Oncology on June 29, 2020.

"The data published in The Lancet Oncology show that patients with PDGFRA D842V mutant GIST treated with AYVAKIT had deep and durable clinical responses as well as a high overall survival rate. These results represent a transformative advancement for patients whose tumor type is resistant to other approved therapies," said Michael Heinrich, M.D., Professor of Medicine at Oregon Health & Science University and primary author of the paper. "As a scientist who has dedicated my career to understanding the molecular basis of GIST and as a clinician treating patients, it's tremendously rewarding to be able to offer – for the first time – a highly effective treatment option to my patients with PDGFRA D842V mutant GIST."

"Based on the compelling clinical data from the NAVIGATOR trial, AYVAKIT was granted a full approval by the FDA earlier this year and has become the new standard of care for patients with unresectable or metastatic GIST harboring a PDGFRA exon 18 mutation," said Andy Boral, M.D., Ph.D., Chief Medical Officer at Blueprint Medicines. "We are now focused on bringing AYVAKIT to additional patients with this genomically defined form of GIST in other geographies, including Europe."

Highlights from The Lancet Oncology Publication Data

The Lancet Oncology paper reported efficacy and safety results from the NAVIGATOR trial, including all patients enrolled in the dose escalation part of the trial and the subset of patients with PDGFRA D842V mutant GIST enrolled in the expansion part of the trial. The efficacy population comprised 56 patients with PDGFRA D842V mutant GIST. The safety population comprised 82 patients, including 26 patients with non-PDGFRA D842V mutant GIST enrolled in the dose escalation part of the trial. All results were as of a data cutoff date of November 16, 2018.

In patients with PDGFRA D842V mutant GIST, the overall response rate (ORR) was 88 percent (95% CI: 76-95%) with 9 percent of patients achieving a complete response. AYVAKIT demonstrated durable clinical benefit in this patient population with a 12-month duration of response rate of 70 percent (95% CI: 54-87%), a 12-month progression-free survival (PFS) rate of 81 percent (95% CI: 69-93%) and a 24-month OS rate of 81 percent (95% CI: 67-94%).

AYVAKIT was generally well-tolerated with most treatment-related adverse events (AEs) reported as Grade 1 or 2. The most common treatment-related AEs were nausea, fatigue, diarrhea, periorbital edema, anemia, decreased appetite, vomiting and memory impairment. Cognitive effects occurred in 40 percent of patients, with the majority of events reported as Grade 1.

About AYVAKIT (avapritinib)

AYVAKIT (avapritinib) is a kinase inhibitor approved by the U.S. Food and Drug Administration (FDA) for the treatment of adults with unresectable or metastatic GIST harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations. AYVAKIT is the first precision therapy approved to treat a genomically defined population of patients with GIST and the only highly active treatment for PDGFRA exon 18 mutant GIST. The FDA granted Breakthrough Therapy Designation to avapritinib for the treatment of unresectable or metastatic GIST harboring the PDGFRA D842V mutation. For more information, visit AYVAKIT.com.

Avapritinib is not approved for the treatment of any other indication in the U.S. by the FDA or for any indication in any other jurisdiction by any other health authority.

Blueprint Medicines is developing avapritinib globally for the treatment of advanced, smoldering and indolent systemic mastocytosis (SM). The FDA granted Breakthrough Therapy Designation to avapritinib for the treatment of advanced SM, including the subtypes of aggressive SM, SM with an associated hematologic neoplasm and mast cell leukemia.

Blueprint Medicines has an exclusive collaboration and license agreement with CStone Pharmaceuticals for the development and commercialization of avapritinib and certain other drug candidates in Mainland China, Hong Kong, Macau and Taiwan. Blueprint Medicines retains development and commercial rights for avapritinib in the rest of the world.

About GIST

GIST is a sarcoma, or tumor of bone or connective tissue, of the GI tract. Tumors arise from cells in the wall of the GI tract and occur most often in the stomach or small intestine. Most patients are diagnosed between the ages of 50 to 80, and diagnosis is typically triggered by GI bleeding, incidental findings during surgery or imaging and, in rare cases, tumor rupture or GI obstruction.

About 5 to 6 percent of primary GIST cases are caused by a PDGFRA D842V mutation, the most common PDGFRA exon 18 mutation. Prior to the approval of AYVAKIT, there were no highly effective treatments for PDGFRA D842V mutant GIST. Published data have shown poor outcomes in patients with PDGFRA D842V mutant GIST treated with imatinib and other approved therapies, including a median OS of 15 months, a median PFS of 3 months and an ORR of 0 percent.¹

Important Safety Information

Intracranial hemorrhage (e.g., subdural hematoma, intracranial hemorrhage, and cerebral hemorrhage) occurred in 1% of 267 patients (0.7% Grade 3 or 4) with GIST and overall in 3% of 335 patients (1.2% Grade 3 or 4) who received AYVAKIT. Overall, 0.9% of patients receiving AYVAKIT required permanent discontinuation for an intracranial hemorrhage. Withhold AYVAKIT and then resume at a reduced dose upon resolution, or permanently discontinue AYVAKIT based on severity.

In 335 patients receiving AYVAKIT, CNS adverse reactions occurred overall in 58% of patients including cognitive impairment (41%; 3.6% Grade 3 or 4), dizziness (20%; 0.6% Grade 3 or 4), sleep disorders (15%; 0.3% Grade 3 or 4), mood disorders (13%; 1.5% Grade 3 or 4), speech disorders (6%; none Grade 3 or 4), and hallucinations (2.1%; none Grade 3 or 4). Overall, 3.9% of patients required permanent discontinuation of AYVAKIT for a CNS adverse reaction. Depending on severity, withhold AYVAKIT and then resume at the same dose or at a reduced dose upon improvement, or permanently discontinue AYVAKIT.

AYVAKIT can cause fetal harm when administered to a pregnant woman. Advise females of reproductive potential and pregnant women of the potential risk to a fetus. Advise females and males of reproductive potential to use an effective method of contraception during treatment with AYVAKIT and for 6 weeks after the final dose of AYVAKIT. Advise women not to breastfeed during treatment with AYVAKIT and for two weeks after the final dose. Advise females and males of reproductive potential that AYVAKIT may impair fertility.

In 204 patients with unresectable or metastatic GIST, the most common adverse reactions (≥ 20%) were edema, nausea, fatigue/asthenia, cognitive impairment, vomiting, decreased appetite, diarrhea, hair color changes, increased lacrimation, abdominal pain, constipation, rash and dizziness.

Avoid coadministration of AYVAKIT with strong and moderate CYP3A inhibitors. If coadministration with a moderate CYP3A inhibitor cannot be avoided, reduce dose of AYVAKIT. Avoid coadministration of AYVAKIT with strong and moderate CYP3A inducers.

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

About Blueprint Medicines

Blueprint Medicines is a precision therapy company striving to improve human health. With a focus on genomically defined cancers, rare diseases and cancer immunotherapy, we are developing transformational medicines rooted in our leading expertise in protein kinases, which are proven drivers of disease. Our uniquely targeted, scalable approach empowers the rapid design and development of new treatments and increases the likelihood of clinical success. We have one FDA-approved precision therapy and are currently advancing multiple investigational medicines in clinical development, along with a number of research programs. For more information, visit www.BlueprintMedicines.com and follow us on Twitter (@BlueprintMeds) and LinkedIn.

Reference

¹ Cassier PA, Fumagalli E, Rutkowski P., et al. Outcome of patients with platelet-derived growth factor receptor alpha-mutated gastrointestinal stromal tumors in the tyrosine kinase inhibitor era. Clin Cancer Res. 2012;18(16):4458-4464.

SOURCE Blueprint Medicines Corporation

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