AT7867

AT7867 is a potent ATP-competitive inhibitor of Akt1/Akt2/Akt3 and p70S6K/PKA with IC₅₀s of 32 nM/17 nM/47 nM and 85 nM/20 nM, respectively. IC50 & Target:IC50: 32 nM/17 nM/47 nM (Akt1/Akt2/Akt3), 85 nM/20 nM (p70S6K/PKA)^[1] In Vitro: The inhibition of AKT2 by AT7867 is shown to be ATP-competitive with a K_i of 18nM. AT7867 also displays potent activity against the structurally related AGC kinases p70S6K and PKA, but shows a clear window of selectivity against kinases from other kinase sub-families. In vitro growth inhibition studies show that AT7867 blocks proliferation in a number of human cancer cell lines. AT7867 appears to be most potent at inhibiting proliferation in MES-SA uterine, MDA-MB-468 and MCF-7 breast, and HCT116 and HT29 colon lines (IC₅₀ values range from 0.9-3 μM), and least effective in the two prostate lines tested (IC₅₀ values range from 10-12 μM) ^[1]. In Vivo: In vivo: Following oral administration at 20 mg/kg, the elimination of AT7867 from plasma appears to be similar to that observed after i.v. administration. Plasma levels of AT7867 remain above 0.5 μM for at least 6 hours following an oral dose of 20 mg/kg. Assuming linear pharmacokinetics following i.v. administration, the bioavailability by the oral route is calculated to be 44%. In vivo pharmacodynamic (PD) biomarker studies are therefore performed with this model. Following pharmacokinetic and tolerability studies, doses of AT7867 (90 mg/kg p.o. or 20 mg/kg i.p.) are administered to athymic mice bearing MES-SA tumors and the phosphorylation status of GSK3β and S6RP in tumors is monitored over time. Clear inhibition of phosphorylation of the two markers of pathway activity is seen at 2 and 6 hours following treatment with AT7867. By 24 hours, total levels of both GSK3β and S6RP are greatly reduced^[1].