CD274 and neoplasm: We therefore asked whether fulvestrant could enhance or prolong the anti-tumor response to RT in combination with immune checkpoint inhibitors using the experimental design shown in Fig. 6A. In contrast to the minimal effects of ICIs when added to RT alone in this system, resembling clinical findings [18], fulvestrant added to RT+ α-PDL1 significantly delayed tumor regrowth (Fig. 6C–E, G), and prolonged survival (Fig. 6F).