Clinical significance of Akt2 in advanced pancreatic cancer treated with erlotinib

Akt2 is an isoform of Akt, and an association between Akt2 and resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has been suggested in pancreatic cancer (PC) in vitro. In this study, we investigated the association between Akt2 expression as evaluated using immunohistochemistry and the outcome of patients with advanced PC who had received treatment with erlotinib (an EGFR-TKI). Although the difference was not significant, patients with high levels of Akt2 expression tended to have a poorer response and a shorter progression-free survival period after treatment with erlotinib plus gemcitabine than those with low expression levels (P=0.16 and 0.19, respectively). In vitro, an Akt2-amplified PC cell line and Akt2-overexpressed cell lines exhibited resistance to anti-EGFR therapies, including erlotinib, but combined treatment with BYL719 (a PI3K inhibitor) cancelled this resistance. Our findings suggest that Akt2 might be associated with the resistance to anti-EGFR therapies, especially the use of erlotinib against PC, and that this resistance can be overcome by combined treatment with a PI3K inhibitor. Akt2 expression could become a predictive biomarker for erlotinib resistance in PC.