Adults with indolent systemic mastocytosis (SM) now have a medicine to treat their disease after the groundbreaking approval of Ayvakit® (avapritinib) by the US Food and Drug Administration (FDA).

“Today’s approval of Ayvakit reflects more than a decade of collaboration and leadership in the field of SM, during which our team at Blueprint Medicines has worked closely with clinicians, patients and their families, and patient advocacy groups to advance innovative science and develop a transformational treatment for people living with the disease,” said Becker Hewes, MD, chief medical officer at Blueprint Medicines.

“Ayvakit is the first and only medicine approved by the FDA to treat ISM, marking a shift in the treatment paradigm from supportive care to disease modifying therapy. In addition, Ayvakit is the only treatment approved across the spectrum of indolent and advanced SM. With a broad indication for indolent SM and a strong label, we are now engaging healthcare providers to redefine what it means for their patients to be well-controlled as well as activating the patient community to seek out optimal care and treatment.”

The FDA’s approval is based on data from the phase 2, double-blind, placebo-controlled PIONEER trial, showing the efficacy and safety of avapritinib in adults with indolent SM.

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Participants receiving avapritinib (25 mg once daily) plus best supportive care experienced significant improvements versus placebo in the primary and all key secondary endpoints of the trial, including overall symptoms and measures of mast cell burden.

Moreover, avapritinib was well-tolerated, with most adverse reactions being mild to moderate in severity. The most common adverse reactions were eye edema, dizziness, peripheral edema, and flushing. Serious adverse reactions and discontinuations due to adverse reactions occurred in less than 1% of participants.

“After decades of caring for people with indolent SM, I have seen firsthand its profound impact on patients’ underlying mast cell burden, symptoms, physical and mental health, and ability to work and participate in daily activities,” said Cem Akin, MD, PhD, professor of medicine at the University of Michigan, and an investigator on the PIONEER trial.

“Despite the use of multiple supportive care treatments, a considerable number of patients with indolent SM continue to experience a substantial disease burden. Ayvakit advances the treatment of indolent SM by targeting KIT D816V, the primary underlying cause of the disease, and establishes a new standard of care for a broad population of patients with this disorder. Ayvakit delivered statistically significant and consistent clinical improvements in the PIONEER trial, and based on these practice-changing data, I feel a tremendous sense of hope for the future for all those affected by the disease.”

The FDA approved avapritinib for the treatment of advanced SM in June 2021.


FDA approves Ayvakit® (avapritinib) as the first and only treatment for indolent systemic mastocytosis. News release. Blueprint Medicines Corporation; May 22, 2023.