CD274 and neoplasm: In a mice model, Sivan et al. [33,34] supplied robust evidence about the impact of the GM on the efficacy of PD-L1 blockage: Bifidobacterium-treated mice improved tumor control in contrast with non-Bifidobacterium-treated mice, suggesting the possibility of enhancing the anti-tumor efficacy of anti-PD-L1 with probiotics.