 Several FLT3 inhibitors have been evaluated or are currently being tested in the setting of relapsing AML. In most trials to date, patients were only eligible if the FLT3-ITD mutation was present. Disappointing results were reported with the first generation of FLT3 inhibitors, including lestaurtinib CEP-701, midostaurin PKC-412 and sorafenib. Second generation FLT3 inhibitors such as quizartinib AC220 are currently under investigation with promising results. However, the hematologic toxicity of AC220 will likely present a major limitation in evaluating AC220 combined with standard or high-dose chemotherapy. 