D816V-targeted therapy provided robust symptom control in patients with indolent systemic mastocytosis, supporting its use as a long-term treatment.
New four-year clinical data from Blueprint Medicines, a Sanofi company, show that Ayvakit (avapritinib) enabled sustained symptom control in patients with the rare disease indolent systemic mastocytosis (ISM).
Real-world findings from the PIONEER clinical study found patients treated with the therapy in a community practice setting attained rapid, meaningful symptom improvement, within a median time of 36.5 days.
Patients showed continued improvement through four years in overall symptoms, including increased bone mineral density after three years.
Dr Mik Rinne, Head of Development at Blueprint Medicines, said: "Patients with indolent systemic mastocytosis and healthcare providers have expressed the need for a therapy that meaningfully improves quality of life through durable symptom benefit and a safety profile enabling long-term treatment, and Ayvakit is delivering this significant impact to a wide range of people living with the disease.
"Across clinical and real-world settings, Ayvakit has shown robust efficacy and a well-tolerated safety profile, helping patients realize the sustained benefit of KIT D816V-targeted therapy. In addition, emerging evidence continues to underscore the substantial burden of [systemic mastocytosis], highlighting the urgency to treat the underlying cause of the disease."
Across clinical and real-world settings, Ayvakit has shown robust efficacy and a well-tolerated safety profile, helping patients realize the sustained benefit of KIT D816V-targeted therapy"
These data from the long-term study were presented at the 2026 American Academy of Allergy, Asthma and Immunology (AAAAI) Annual Meeting.
Ayvakit was the first FDA-approved medicine for advanced systemic mastocytosis in June 2021 and ISM in May 2023.
Then it was authorised for EU patients with ISM in December 2023. At the time, Jens Panse, Deputy Director of the Department of Haematology/Oncology of the University Hospital RWTH Aachen in Germany, said: “Ayvakyt represents an important treatment breakthrough as the first medicine approved for patients living with ISM, and the only therapy designed to selectively target the primary genetic driver of the disease.”
Blueprint Medicines was acquired by Sanofi in July 2025 in a $9.5 billion deal that brought the company, in addition to Ayvakyt, CNS and inflammatory candidates and an established presence among allergists, dermatologists, and immunologists.
