11b (Avapritinib, BLU-285), developed by Blueprint Medicines for the treatment of gastrointestinal stromal tumors and systemic mastocytosis, is a potent, selective, orally active inhibitor of KIT and PDGFRα activation loop mutant kinases with IC50 values of 0.5 and 0.5 nM for KIT D816V and PDGFRα D842V mutant, respectively [202,203]. This evidence concerns the gene KIT and systemic mastocytosis.