Blueprint Medicines showcases Ayvakit® data highlighting survival benefits and disease-modifying potential in systemic mastocytosis at ASH 2024

Blueprint Medicines Corporation (Nasdaq: BPMC) today announced data presentations that continue to demonstrate the long-term clinical benefits of AYVAKIT® (avapritinib) in advanced systemic mastocytosis (advanced SM), and reflect the company’s ongoing partnership with the SM community to redefine the future of patient care – from improving diagnostic rates to raising the bar on treatment outcomes. The datasets, which include one oral presentation and three poster presentations, will be reported at the 66th American Society of Hematology (ASH) Annual Meeting and Exposition, taking place December 7-10 in San Diego.

“Systemic mastocytosis is associated with mast cell infiltration across multiple organ systems, chronic inflammation caused by immune dysregulation, unpredictable symptoms that may worsen over time, and serious comorbidities such as osteoporosis, highlighting the urgency to treat patients early in the course of their disease,” said Becker Hewes, M.D., Chief Medical Officer at Blueprint Medicines. “AYVAKIT has fundamentally changed the treatment paradigm by targeting the disease at its source, showing prolonged survival outcomes for patients with advanced SM, as well as durable symptom control and quality-of-life improvements for patients with ISM. Based on the substantial datasets we have amassed over more than a decade, and our continued collaboration with the SM community, we have designed the HARBOR trial of elenestinib – a next-generation KIT D816V inhibitor – to rigorously assess a broad range of endpoints reflecting disease-modifying impact.”

Data reported at ASH highlight the survival benefits of front-line AYVAKIT use in patients with advanced SM, and support Blueprint Medicines’ plans to evaluate novel clinical measures indicative of disease modification – such as bone density and biomarkers of chronic inflammation – in the registrational HARBOR trial. Key results include:

• In pooled analyses from the PATHFINDER and EXPLORER trials, treatment-naïve patients with advanced SM showed significant survival benefits with AYVAKIT, when indirectly compared to real-world outcomes for midostaurin.
• In the PATHFINDER trial, AYVAKIT led to sustained improvements in bone density for advanced SM patients who had low bone mass at baseline.
• In the PIONEER trial, patients with indolent SM (ISM) had significant baseline levels of immune dysregulation relative to healthy donors, reflecting the chronic inflammatory burden of the disease.

Non-Invasive, Blood-Based Assay Identified KIT Mutations Not Previously Detectable by Existing Tests

ASH data show that ultra-sensitive KIT testing in the peripheral blood – a novel tool in clinical development that is more sensitive than current commercially available methods – identified previously undetected KIT mutations in a number of PIONEER trial patients. Emerging clinical research with ultra-sensitive KIT assays suggest SM may be more prevalent than previously thought.

An additional data presentation highlights the application of machine learning techniques to analyze baseline, blood-based parameters of Blueprint Medicines’ clinical trial participants. Following these analyses, a predictive model was developed to distinguish between advanced SM and ISM, and its accuracy was validated by an independent dataset from Dana-Farber Cancer Institute.

Collectively, these data build on Blueprint Medicines’ collaborative efforts with clinical experts to improve and accelerate how SM is diagnosed and treated.

Data presentations will be made available in the “Science―Publications and Presentations” section of Blueprint Medicines’ website.

• Oral Presentation: Analysis of Avapritinib Clinical Trial Data Generates a Highly Accurate Predictive Model for Advanced Systemic Mastocytosis Versus Indolent Systemic Mastocytosis Based on Peripheral Blood Testing (Abstract 107 – Saturday, December 7)
• Poster Presentation: Overall Survival and Duration of Treatment in Patients with Advanced Systemic Mastocytosis Receiving Avapritinib Versus Midostaurin or Best Available Therapy in a Real-World Setting (Abstract 1801 – Saturday, December 7)
• Poster Presentation: Ultra-Sensitive KIT Testing Uncovers Previously Undetected KIT Mutations in Patients with Indolent Systemic Mastocytosis: Results from the PIONEER Trial (Abstract 3164 – Sunday, December 8)
• Poster Presentation: Disease-Modifying Effects of Avapritinib in Patients with Advanced Systemic Mastocytosis: Improvements in Bone Density (Abstract 4544 – Monday, December 9)
• Publication-Only Abstract: Blood-Based Proteomics for Deeper Insights into Indolent Systemic Mastocytosis: the PIONEER Trial Experience (Abstract 6569)