65 yo male with FLT3 positive myeloid sarcoma status post 3 cycles of FLAG-IDA underwent PB MUD AlloSCT using conditioning regimen: Flu/Mel + 3rd party fucosylated UCB Tregs at dose: 1×106 cells/kg on day −1 and donor cells on day 0; where the ratio of Treg:Tcon was 1:132. Here, FLT3 is linked to myeloid sarcoma.