CC-223

CC-223 is a potent inhibitor of mTOR kinase, with an IC₅₀ value for mTOR kinase of 16 nM.

IC50: 16 nM (mTOR kinase), 0.84 μM (DNA-PK), 4.0 μM (PI3K-α)^[1]

CC-223 is a potent, selective, and orally bioavailable inhibitor of mTOR kinase, demonstrating inhibition of mTORC1 (pS6RP and p4EBP1) and mTORC2 [pAKT(S473)] in cellular systems. CC-223 is selective for mTOR kinase with >200-fold selectivity over the related PI3K-α (IC₅₀=4.0 μM). Of the PI3K related kinases tested, CC-223 shows no significant inhibition of ATR or SMG1 and inhibits DNA-PK with an IC₅₀ value of 0.84 μM. When screened in a single-point assay against a commercially available panel of 246 kinases, only three kinases other than mTOR are inhibited >80% at 10 μM by CC-223. Upon follow-up IC₅₀ value determination, only two are inhibited by CC-223 with IC₅₀ values below 1 μM; FLT4 (0.651 μM) and cFMS (0.028 μM). The exquisite kinase selectivity of CC-223 is confirmed upon evaluation in cellular systems using ActivX KiNavtiv profiling. Other than mTOR kinase, no kinase target is identified when HCT 116 or A549 cells are treated for 1 hour with 1 μM CC-223 and assayed for kinase activity. CC-223 shows a concentration-dependent reduction in each marker, with IC₅₀ values of 31±2 nM for pS6RP, 405±47 nM for p4EBP1, and 11±10 nM for pAKT(S473) in western blot analysis. Inhibition of these pathway biomarkers is investigated in additional cell types from a variety of tissue origins. CC-223 inhibits both mTORC1 (S6RP and 4EBP1) and mTORC2 [AKT(S473)] markers across the panel with IC₅₀ ranges of 27 to 184 nM for pS6RP, 120 to 1,050 nM for p4EBP1 and 11 to 150 nM for pAKT(S473) ^[1].

The antitumor activity of CC-223 in the PC-3 xenograft model is determined using a number of dosing paradigms. CC-223 significantly inhibits PC-3 tumor growth in a dose- and schedule-dependent manner. Dosing at 10 or 25 mg/kg, once daily, results in 46% (P<0.001) and 87% (P<0.001) reduction in tumor volume, respectively. Similar dose dependency is observed with twice-daily dosing at 5 or 10 mg/kg, corresponding to 65% (P<0.001) and 80% (P<0.001) tumor volume reductions. All dose levels are tolerated in the once-daily and twice-daily dosing studies, with only the 25 mg/kg/d group showing any significant body weight loss. These mice lost approximately 10% of their initial body weight after 3 weeks of dosing^[1].