An inhibitor of class I PI3K isoforms (IC50s = 14, 120, 500, and 36 nM for PI3Kα, PI3Kβ, PI3Kδ, and PI3Kγ, respectively); selective for these PI3K isoforms over PI3KC2α, PI3KC2β, Vps34, and mTOR (IC50s = 5,300, >10,000, >10,000, and 1,600 nM, respectively), as well as 26 additional protein kinases (IC50s = >10,000 nM); inhibits proliferation of HCT116, KPL-4, T47D, and SKOV3 cells containing the PI3KαH1047R activating mutation (IC50s = 200, 32, 56, and 120 nM, respectively); reduces tumor growth in a PC3 mouse xenograft model at 25 mg/kg per day