PP242

PP242 is a first selective inhibitor that targets ATP domain of mTOR. PP242 displays selectivity for mTOR over other PI 3K family kinases (IC50 values are 0.102, 0.408, 1.27, 1.96 and 2.2 μM for p110γ, DNA-PK, p110δ, p110α and p110β respectively). PP242 induced ERK activation in MM cell lines as well as primary cells. PP242 could also inhibit phosphorylation of AKT on serine 473, a TORC2 substrate, while rapamycin was ineffective. PP242 was more effective than rapamycin in achieving cytoreduction and apoptosis in MM cells. In addition, PP242 was an effective agent against primary MM cells in vitro and growth of 8226 cells in mice. PP242 inhibits both S6K and 4EBP1 phosphorylation; activity causes a decrease in cap-dependent protein translation.