CD274 and adenocarcinoma: In parallel, we validated the function of gut microbiome-associated metabolites on PD-L1 production and immunotherapy treatment efficacy in PC cell lines and transgenic adenocarcinoma of the mouse prostate (TRAMP) models.<h4>Results</h4>We identified two metabolites, 16(R)-Hydroxyeicosatetraenoic acid (16(R)-HETE) and 6-Keto-Prostaglandin E1 (6-Keto-PGE1), that positively correlated with the plasma exosomal PD-L1 levels.