KIT and leukemia: However, the most prevalent KIT mutation in CBF AML, substituting valine for aspartic acid at codon 816 (KIT D816V), was demonstrated to be basically insensitive towards quizartinib in in vitro and ex vivo leukemia cell lines, primary myeloblasts, and in an isogenic Ba/F3 cell model – while substitution of a tyrosine residue (D816Y) retained some sensitivity to quizartinib.