PDCD1 and neoplasm: In CRC, colibactin‐producing Escherichia coli (CoPEC) can induce an immune microenvironment with protumor characteristics, leading to reduced antitumor T cell counts and subsequently triggering resistance to anti‐PD‐1 immunotherapy in tumor tissues; consequently, CoPEC is considered a potential microbial biomarker for predicting immunotherapy efficacy [205].