PDGFRA and mastocytosis: FDA-approved avapritinib (approval: Jan 9, 2020, brand name Ayvakit) is used in adults with unresectable or metastatic GIST who harbor a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation and for advanced and indolent systemic mastocytosis (in phase 2 development) [192,193].