PIK3CA and breast cancer: Several PI3K/Akt inhibitors are currently in routine clinical use for the treatment of cancers other than gastric cancer with alpelisib (also known as BYL719), a p110α-specific, small molecule PI3K inhibitor (Figure 1A), currently used in combination with hormone therapy in metastatic HER2-negative, PIK3CA-mutated breast cancer [26,27].