ESR1 and breast cancer: In contrast to findings in other AR + diseases, including AR + TNBC, here we demonstrate that AR inhibition with enzalutamide, apalutamide, darolutamide and seviteronel, degradation of AR with the AR PROTAC degrader, ARD-61, or knockout of AR using CRISPR-Cas9, does not radiosensitise AR+/ER+ breast cancer cells in vitro.