Dr Tashi on the Effect of Avapritinib on Long-Term Bone Health in Indolent Systemic Mastocytosis

"Overall, the data showed that treatment with avapritinib in these patients demonstrated a trend toward increased bone mineral density. [This indicates] the positive [effect of avapritinib] on bone health, regardless of whether patients were receiving concurrent osteoporosis therapy."

Tsewang Tashi, MD, a hematologist/oncologist at the University of Utah Huntsman Cancer Institute in Salt Lake City, shared long-term bone health data from a retrospective analysis of the phase 2 PIONEER trial (NCT03731260). The study investigated the impact of avapritinib (Ayvakit) in patients with indolent systemic mastocytosis (SM), a condition frequently complicated by bone-related comorbidities such as osteoporosis and osteopenia.

In the current analysis, 79 patients underwent DXA scans at baseline and at least once during the post-baseline follow-up period, Tashi noted. Findings shared at the 2025 ASH Annual Meeting showed that treatment with avapritinib led to consistent increases in mean bone mineral density (BMD) across several key anatomical sites. In the lumbar spine, mean BMD increased by 1.66% after one year of treatment and reached a 4.05% increase by year 3. The left total hip showed an increase of 2.19% at one year and 3.31% at three years, while the left femoral neck demonstrated gains of 1.62% and 2.08% at the same intervals, respectively.

Tashi noted that a significant portion of the cohort who presented with baseline bone density issues were already receiving established anti-osteoporosis therapies. He cautioned that while these concurrent treatments act as confounding factors, they are essential to consider when interpreting the long-term results.

Overall, the data indicate a strong trend toward improved bone density over the three-year period. Tashi emphasized that the positive effect of avapritinib on bone health was observed regardless of whether patients were also receiving traditional osteoporosis medications. This suggests that the therapy may play a beneficial role in stabilizing or improving bone structure in patients with indolent SM, he concluded.