The ER degrader fulvestrant combined with a p110α and p110β isoform inhibitor induced apoptosis and suppressed PTEN-deficient xenograft tumor growth by inhibiting PI3K downstream substrates, indicating that it is an effective strategy to overcome endocrine resistance in the luminal B subtype of breast cancer due to reduced PTEN levels (Hosford et al., 2017). This evidence concerns the gene PIK3CA and breast cancer.