FD223 is a potent and selective phosphoinositide 3-kinase delta (PI3Kδ) inhibitor. FD223 displays high potency (IC50=1 nM) and good selectivity over other isoforms (IC50s of 51 nM, 29 nM and 37 nM, respectively for α, β and γ). FD223 exhibits efficient inhibition of the proliferation of acute myeloid leukemia (AML) cell lines by suppressing p-AKT Ser473 thus causing G1 phase arrest during the cell cycle. FD223 has potential for the research of leukemia such as AML.