This bacterium can directly bind the butyric acid it produces to Toll-like receptor 5 (TLR5) on CD8+ T cells, activating the TLR5-dependent NF-κB pathway to enhance the function of cytotoxic CD8+ T cells, thereby exerting anti-tumor effects and enhancing the efficacy of anti-PD-1 therapy (116). The gene discussed is PDCD1; the disease is neoplasm.