Recently, positive results from the phase III CAPItello-291 trial evaluating capivasertib in combination with fulvestrant versus fulvestrant alone in patients with ER+ advanced breast cancer after progression on endocrine therapy, with or without an CDK4/6 inhibitor, showed that the addition of capivasertib to endocrine therapy significantly improved PFS in the overall patient population, independent of the AKT mutational status (7.2 vs. 3.6 months, p < 0.001) (7.3 vs. 3.1 months, p < 0.001) [42]. Here, ESR1 is linked to breast cancer.