In preclinical models of CRC, colonization with engineered E. coli Nissle (EcN), which converts ammonia—a metabolic waste product in the tumor microenvironment—into l-arginine, has been shown to enhance T cell infiltration and synergize with anti-PD-L1 treatment (Canale et al., 2021). Here, CD274 is linked to colorectal carcinoma.