PIK3R5 and CD4+/CD56+ hematodermic neoplasm: PIK3R5 and PIK3CG, which encode a p101 regulatory and p110 catalytic subunit of PI3Kγ complex, are essential for the survival of a leukemia subset including blastic plasmacytoid dendritic cell neoplasm (BPDCN) and AMLs with high expression of PIK3R5 via a genome-wide CRISPR interference screening.