ERBB2 and breast carcinoma: PI3K inhibitors are also being studied in HER2+ breast cancer: EPIK-B2 (NCT04208178) is a phase 3 study assessing the role of the PI3K-alpha inhibitor alpelisib in combination with trastuzumab and pertuzumab as maintenance for patients with HER2+, PIK3CA mutant advanced breast cancer.