We treated an imatinib-sensitive GIST cell line (GIST822) harboring a KIT exon 13 mutation (K642E) and a second cell line, GIST48, harboring an imatinib-sensitive V560D mutation plus a secondary imatinib-insensitive activation loop mutation (D820A) with varying concentrations of quizartinib. This evidence concerns the gene KIT and gastrointestinal stromal tumor.