Gilteritinib (Xospata®) is an orally available small molecule receptor tyrosine 
kinase inhibitor developed by Astellas Pharma in collaboration with Kotobuki 
Pharmaceutical for the treatment of acute myeloid leukaemia (AML) harbouring 
FMS-like tyrosine kinase 3 (FLT3) mutations. Gilteritinib inhibits FLT3 (STK1 or 
FLK2), AXL (UFO or JTK11) and anaplastic lymphoma kinase (ALK or CD246). 
Gilteritinib inhibits FLT3 signalling in cells expressing FLT3 internal tandem 
duplication (ITD), tyrosine kinase domain mutation FLT3-D835Y and the double 
mutant FLT3-ITD-D835Y, thereby inducing apoptosis. Gilteritinib also binds to 
and inhibits the wild-type and mutated forms of ALK, resulting in reduced tumour 
cell proliferation in cancer cell types that overexpress the mutation. 
Gilteritinib is approved in Japan for the treatment of relapsed or refractory 
AML with FLT3 mutation. Recently, it was also approved in the USA for the 
treatment of adult patients who have relapsed or refractory AML with a FLT3 
mutation, as detected by an FDA-approved test. Clinical development of 
gilteritinib is underway in several countries worldwide. Development for 
non-small cell lung cancer and solid tumours has been discontinued.