An orally bioavailable inhibitor of the receptor tyrosine kinases (RTKs) FMS-related tyrosine kinase 3 (FLT3, STK1, or FLK2), AXL (UFO or JTK11) and anaplastic lymphoma kinase (ALK or CD246), with potential antineoplastic activity. Gilteritinib binds to and inhibits both the wild-type and mutated forms of FLT3, AXL and ALK. This may result in an inhibition of FLT3, AXL, and ALK-mediated signal transduction pathways and reduction of tumor cell proliferation in cancer cell types that overexpress these RTKs. FLT3, AXL and ALK, overexpressed or mutated in a variety of cancer cell types, play a key role in tumor cell growth and survival.