PIK3CA and neoplasm: Depending on the molecular profile of the tumor, ETs may also be administered in combination with inhibitors for therapeutic targets, such as cyclin-dependent kinase 4/6 (CDK4/6), mammalian target of rapamycin (mTOR), or phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) [3,4,5,6,7].