FDA approves Blueprint Medicines’ Ayvakit for indolent systemic mastocytosis

The US Food and Drug Administration (FDA) has approved Blueprint Medicines’ Ayvakit (avapritinib) as the first and only medicine designed to treat indolent systemic mastocytosis (ISM).

Systemic mastocytosis (SM) is a rare haematologic disorder that can lead to a range of debilitating symptoms across multiple organ systems.

ISM accounts for the vast majority of SM cases and, despite the availability of multiple supportive care treatments, a number of ISM patients continue to experience a substantial disease burden.

Ayvakit, which has been approved in the US to treat advanced SM since June 2021, works by targeting the primary underlying cause of the disease – a mutation known as KIT D816V.

Blueprint’s chief medical officer, Becker Hewes, said the approval marked "a shift in the treatment paradigm from supportive care to disease modifying therapy” for ISM patients.

"With a broad indication for ISM 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,” Hewes said.

The approval of the drug for adult ISM patients is supported by positive results from the PIONEER trial, in which patients received a once-daily 25mg dose of Ayvakit or placebo.

Ayvakit was associated with significant improvements versus placebo in the primary and all key secondary endpoints, according to Blueprint, including overall symptoms and measures of mast cell burden.

The company added that Ayvakit was well-tolerated with a favourable safety profile compared to placebo, and most adverse reactions were mild to moderate in severity.

Cem Akin, an investigator on the PIONEER trial and professor of medicine at the University of Michigan, US, said: “Ayvakit advances the treatment of ISM 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."