Background: Capivasertib is a potent, selective pan-AKT inhibitor. In CAPItello-291, the addition of capivasertib to fulvestrant resulted in a statistically significant (P < 0.001) improvement in progression-free survival over fulvestrant monotherapy in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer and disease progression on or after aromatase inhibitor-based therapy. Characterization of the capivasertib-fulvestrant adverse event (AE) profile as managed in CAPItello-291 can inform future management guidance and optimize clinical benefit. Patients and methods: Seven hundred and eight patients were randomized 1 : 1 to capivasertib (400 mg twice daily; 4 days on, 3 days off) or placebo, plus fulvestrant, on a 4-week cycle. Dose reductions/interruptions for capivasertib/placebo were permitted (up to two dose reductions). S...