Biomarkers of response to Akt inhibitor MK-2206 in breast cancer.

1054 Background: Akt significantly contributes to cancer pathogenesis. PTEN, a negative regulator of PI3K/Akt signaling, is mutated or decreased, and PIK3CA is frequently mutated in multiple cancer lineages. We hypothesized that MK-2206, an allosteric Akt inhibitor, would inhibit Akt signaling thus blocking cancer cell growth, and PTEN and/or PIK3CA mutations may confer MK-2206 sensitivity in breast cancer. Methods: After determining sensitivity to MK-2206 in16 cell lines, the effect on Akt signaling was tested by reverse-phase protein array analysis and western blotting. The effect to cell cycle progression and cell death were analyzed by flow cytometry. Using RNA knockdown technique, the effect of PTEN, PIK3CA and Akt on MK2206 sensitivity was tested. Anti-tumor effect in vivo with or without paclitaxel was tested using PTEN-mutant ZR75-1 breast cancer xenografts. Results: MK-2206 inhibited Akt signaling and cell cycle progression, and increased apoptosis in a dose-dependent manner in breast cancer cell...