The phase 3 CAPItello-291 study (NCT04305496) demonstrated that the combination of fulvestrant and capivasertib led to significantly prolonged progression-free survival (PFS) compared to treatment with fulvestrant alone (median PFS: 7.2 vs. 3.6, Hazard ratio: 0.6, 95% CI: 0.51–0.71, P < 0.001) in patients with HR-positive, HER2-negative advanced breast cancer who had experienced disease progression during or after previous aromatase inhibitor therapy with or without a CDK4/6 inhibitor (Turner et al., 2023). This evidence concerns the gene CYP19A1 and breast cancer.