Alpelisib is the first PI3K inhibitor that has been approved for breast cancer, and the combination therapy of alpelisib and fulvestrant has been approved by the United States Food and Drug Administration (FDA) for male and postmenopausal female patients with PIK3CA (the gene encoding p110α, the PI3K catalytic subunit)‐mutated, HR‐positive/HER2‐negative advanced breast cancer who suffer from disease progression during or after endocrine therapy [5, 11, 14]. The gene discussed is PIK3CB; the disease is breast cancer.