Treatment options for patients with FLT3-mutated AML who relapse after transplant are limited to chemotherapy, second allo-HSCT, and FLT3 inhibitors alone or combined with DLI, all of which are rarely effective in the long term, even though, a small fraction of those patients can achieve long-standing responses with sorafenib (22, 96–99). This evidence concerns the gene FLT3 and acute myeloid leukemia.