PI-103 is a potent and selective inhibitor of class I PI3K, mTOR and DNA-PK with IC50 values of 2, 3, 3, 15, 30 and 23 nM for p110α, p110β, p110δ, p110γ, mTOR and DNA-PK, respectively .
PI-103 showed potent antiproliferation activities in various cancer cell lines such as prostate, ovary and glioblastoma. It exerted GI50 values of 0.14, 0.06, 0.13, 0.10, 0.12 and 0.08 μM in U87MG, IGROV-1, DETROIT-562, PC3, SKOV-3 and HUVEC cells, respectively. In U87MG cells, 2 hour-treatment of PI-103 caused inhibition effects on various phosphorylated protein biomarkers of PI3K pathway with IC50 values of 15, 36, 111, 106 and 105 nM for p-AKTSer473, p-AKTThr308, p-GSK3βSer9, p-p70S6KThr421/Ser424 and p-S6RPSer235/Ser236, respectively .
 Raynaud F I, Eccles S A, Patel S, et al. Biological properties of potent inhibitors of class I phosphatidylinositide 3-kinases: from PI-103 through PI-540, PI-620 to the oral agent GDC-0941. Molecular cancer therapeutics, 2009, 8(7): 1725-1738.