PI-103 is a multi-targeted PI3K inhibitor for p110α/β/δ/γ with IC50 of 2 nM/3 nM/3 nM/15 nM in cell-free assays, less potent to mTOR/DNA-PK with IC50 of 30 nM/23 nM.
PI-103 potently inhibits both the rapamycin-sensitive (mTORC1) and rapamycin-insensitive (mTORC2) complexes of the protein kinase mTOR.  PI-103 inhibits constitutive and growth factor-induced PI3K/Akt, as well as mTORC1 activation.  In blast cells, PI-103 inhibits leukemic proliferation, the clonogenicity of leukemic progenitors and induces mitochondrial apoptosis, especially in the compartment containing leukemic stem cells. PI-103 inhibits p110α >200-fold more potently than p110β. PI-103 also potently blocks production of PI(3,4)P2 and PIP3 in adipocytes and PIP3 in myotubes.  PI-103 inhibits phosphorylation of Akt with an IC95 100-fold lower than that for LY294002. Strikingly, PI-103 completely protects animals from insulin-stimulated decline in blood glucose. PI-103 has additive proapoptotic effects with etoposide in blast cells and in immature leukemic cells.