Avapritinib granted FDA approval for the treatment of indolent systemic mastocytosis

On May 22, 2023, the U.S. Food and Drug Administration (FDA) approved avapritinib for the treatment of patients diagnosed with indolent systemic mastocytosis.¹ This approval was supported by results from the randomized phase II PIONEER trial (NCT03731260), which showed avapritinib plus best supportive care significantly improved outcomes for patients versus best supportive care alone.¹

• Results from the PIONEER trial highlighted a statistically significant difference in mean total symptom score (TSS) after 24 weeks in patients treated with avapritinib compared with placebo (p = 0.003).
  • Patients treated with avapritinib experienced a mean TSS reduction of 15.6 points at Week 24 and 20.2 points at Week 48.
  • In contrast, patients treated with placebo experienced a mean TSS reduction of 9.2 points at Week 24.
• A total of 53.9% of patients treated with avapritinib showed a reduction of serum tryptase of ≥50%.
  • In comparison, 0% of patients treated with placebo experienced a serum tryptase reduction of ≥50% (p < 0.0001).
• Avapritinib treatment was well tolerated, with most toxicities being mild or moderate.
• The most common adverse events experienced by ≥10% of patients were:
  • Eye edema
  • Dizziness
  • Peripheral edema
  • Flushing
• Less than 1% of patients experienced serious adverse events or those that led to discontinuation of treatment.