Patients with indolent systemic mastocytosis (ISM) who take avapritinib experience lasting improvements in itching, flushing and the appearance of skin spots, according to findings recently presented at the 2025 Fall Clinical Dermatology Conference.
“Symptom improvements continued to be durable for up to 3 years,” the researchers said.
Results were based on the PIONEER clinical trial, which previously demonstrated that participants taking avapritinib had improved skin symptoms compared to those receiving a placebo after 24 weeks.
The third portion of the trial, which is still ongoing, aims to follow individuals with ISM for up to five years to better understand the long-term impacts of the drug. The present analysis included 226 patients who received 25 mg avapritinib daily. Participants had an average age of 49.8 years, and 73% were female.
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All patients completed the ISM Symptom Assessment Form, in which individuals rank their symptom burden on a scale of 1 to 10. Additionally, the researchers took photographs of participants and used an AI tool to measure changes in skin appearance over one year.
After three years, self-reported appearance of skin spots decreased by an average of 3.1 points, itching decreased by 2.7 points and flushing decreased by 2.3 points compared to baseline levels.
Additionally, skin photography analysis revealed a significant improvement in skin lesion surface area by 24 weeks. This improvement was maintained at 48 weeks.
“These data highlight the ability of avapritinib to achieve long-term disease modification,” the authors concluded.
Avapritinib is an oral drug that was approved for adults with ISM in the United States in 2023, making it the first and only therapy approved for ISM.
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