Furthermore, a phase I study evaluating capivasertib as monotherapy or in addition to fulvestrant in heavily pre-treated ER+ advanced breast cancer patients harboring the AKT1 E17K mutation showed favorable activity and tolerability of capivasertib as a single agent and in the combination regimen, suggesting the potential clinical utility of capivasertib in this patient population [12]. This evidence concerns the gene ESR1 and breast cancer.