Molecular pathways: PI3K pathway targets in triple-negative breast cancers.

The triple-negative breast cancer (TNBC) subtype, defined clinically by the lack of estrogen, progesterone, and Her2 receptor expression, accounts for 10% to 15% of annual breast cancer diagnoses. Currently, limited therapeutic options have shown clinical benefit beyond cytotoxic chemotherapy. Defining this clinical cohort and identifying subtype-specific molecular targets remain critical for new therapeutic development. The current era of high-throughput molecular analysis has revealed new insights into these targets and confirmed the phosphoinositide 3-kinase (PI3K) as a key player in pathogenesis. The improved knowledge of the molecular basis of TNBC in parallel with efforts to develop new PI3K pathway-specific inhibitors may finally produce the therapeutic breakthrough that is desperately needed.