ESR1 and breast cancer: Alpelisib, an oral α-specific PI3K inhibitor that selectively inhibits p110α, was recently approved, based on results of phase III SOLAR-1 trial (NCT02437318), for postmenopausal women, and men, with metastatic or advanced PIK3CA-altered, ER/PgR-positive, and HER2-negative breast cancer, indicating that the integration of genomic testing for PIK3CA mutation may be useful in the selection of therapy [154,155].