ESR1 and breast cancer: A study by Hudson et al. showed that when administrated intermittently PI3Kα/δ inhibitor AZD8835 showed better anti-tumor efficacy in breast cancer xenograft models as a monotherapy and in combination with an ER inhibitor (Fulvestrant) and CDK4/6 inhibitor (Palbociclib) that suppressed AKT activation and induced cell death [46].