CD274 and breast cancer: In 4T1 breast cancer model, RT plus PD-L1 blockade significantly reduced tumor burden by 38% when compared to RT alone (RT plus PD-L1 vs. RT: 184.3 ± 13.5 mm2 vs. 292.8 ± 14.3 mm2, respectively; p < 0.01) and significantly improved survival (p < 0.001) [11].