Promising early phase I/II trial data of gilteritinib demonstrated antileukaemic activity and acceptable side effects in relapsed/refractory AML patients from the USA, Germany, Italy and Japan (NCT02181660 and NCT02014558) [179, 180]; thus, it was approved in Japan and the USA for the treatment of relapsed or refractory AML with FLT3 mutation [181]. This evidence concerns the gene FLT3 and acute myeloid leukemia.