Avapritinib 4-Year Data Show Durable Quality of Life Gains in ISM

Clinicians who weigh symptom control and biomarker response more heavily than quality of life risk overlooking the emotional and social toll of indolent systemic mastocytosis (ISM). Even when symptoms and biomarkers look controlled, patients may experience daily fear, activity avoidance, and social withdrawal.

In an interview with HCPLive, Thanai Pongdee, MD, of Mayo Clinic, discussed the equal importance of these 3 domains—symptom control, biomarker response, and quality of life—when it comes to avapritinib.

“We have to keep in mind quality of life because that's really what's affecting patients…the most on a day-to-day basis," Pongdee said.

The 4-year PIONEER analysis, presented at the European Academy of Allergy & Clinical Immunology (EAACI) 2026 Annual Meeting in Istanbul by Pongdee and colleagues, showed that avapritinib continues to improve emotional well-being and social functioning in patients from baseline through 1 and 4 years, as reflected in ISM-Symptom Assessment Form and Macrocytosis Quality of Life Questionnaire scores.

“Longer-term data is more encouraging and more reassuring,” Pongdee said. “Certainly, keeping track of those features over time would be good to see.”

Pongdee said the safety profile remained consistent through 4 years, with low rates of treatment-related discontinuation and no new safety signals identified.² Continued follow-up on symptom control, quality of life, and safety will help clinicians counsel patients with ISM who are considering long-term avapritinib therapy, he said.

Counseling Patients Starting Avapritinib for ISM

According to Pongdee, patients starting avapritinib typically have 2 main questions: how the drug works, and how it will make them feel. He added that many are also managing polypharmacy for ISM, so as symptoms improve, patients often hope to reduce their other medications.

The data reflected that pattern, as 52% of participants had reduced or discontinued ≥ 1 class of best supportive care therapy by 3 years.¹,² Pongdee observed the most reductions with cromolyn sodium, anti-immunoglobulin E therapy, and H1 and H2 antihistamines.

“If the disease burden is less, then I would expect my symptoms to get better, and then hopefully that means I don't have to take as many medicines, and then all that equals greater quality of life,” Pongdee said.

Read more about the new PIONEER 4-year data here, along with the first part of our interview with Pongdee.

Reported disclosures for Pongdee include GlaxoSmithKline and Blueprint Medicines Corporation.

References

1. Broesby-Olsen S, Siebenhaar F, Oude Elberink H, et al. Mastocytosis Treated With Avapritinib: Updated 4-Year Results From The PIONEER Trial. Presented at European Academy of Allergy & Clinical Immunology (EAACI) 2026 Annual Meeting from June 12-15, 2026 in Istanbul, Türkiye.

2. Pongdee T. Avapritinib 4-Year PIONEER Data: Sustained QoL Gains in ISM. HCPLive. Published on July 13, 2026. https://www.hcplive.com/view/avapritinib-4-year-pioneer-data-ism-quality-of-life