PIK3CA and breast cancer: A variety of targeted drugs against PI3K are currently in clinical trials for breast cancer (Mayer & Arteaga, 2016); they range in specificity from dual PI3K/mTOR inhibitors, pan-PI3K inhibitors, to isoform specific inhibitors of PI3K (e.g. Alpelisib or BYL719, a p110-alpha/PIK3CA specific inhibitor).