Abstract The phosphatidylinositol-3-kinase (PI3K) pathway is frequently dysregulated in human breast cancer. Approximately 30%of all patients with breast cancer will carry mutations of the PIK3CA gene, which encodes the PI3K catalytic subunit isoform p110a. Mutations in PIK3CA have been associated with resistance to endocrine therapy, HER2-directed therapy, and cytotoxic therapy. Early trials of pan-PI3K inhibitors… Read more »