PIK3CA and breast cancer: Thus, in May 2019, the U.S. Food and Drug Administration (FDA) approved a α-selective PIK3CA inhibitor, alpelisib (BYL719; Novartis Pharma AG), in combination with fulvestrant for the treatment of postmenopausal patients diagnosed with HR+/HER2−PIK3CA-mutated, advanced breast cancer or MBC, following the progression on or after an endocrine-based regimen (37, 38).