CD274 and neoplasm: Anti-PD-L1 or isotype control was given at days 1 (along with the first 5 Gy fraction), 4, 7, and 10.39 Commencement of anti-PD-L1 with the first 5 Gy fraction was chosen to ensure therapeutic levels of anti-PD-L1 coincided with RT-induced PD-L1 upregulation in TRAMP-C1 tumours, and four doses were administered as this has no welfare implications in previous studies.39 Combined 3 × 5 Gy and anti-PD-L1 did not enhance tumour growth delay compared to 3 × 5 Gy alone in these conditions (Fig. 5d).