PIK3CA mutations in patients with advanced cancers treated with PI3K/AKT/mTOR axis inhibitors.

Preclinical data suggest that PIK3CA mutations predict response to PI3K/AKT/mTOR inhibitors. Concomitant KRAS or BRAF mutations may mediate resistance. Therefore, tumors from patients referred to the phase I program for targeted therapy starting in October 2008 were analyzed for PIK3CA mutations using PCR-based DNA sequencing of exons 9 and 20.