FLT3 and graft versus host disease: Adults age 18 - 75, ECOG 0-2 with FLT3-ITD+ AML undergoing first allo-HSCT with 7/8 or 8/8 donors who are in morphologic CR after day +30. Donor chimerism ≥ 70% (peripheral blood) and adequate blood counts (ANC ≥1000, PLT ≥ 50,000) are required. Active GVHD requiring prednisone ≥ 0.5mg/kg/day is exclusionary.