Cancer immunotherapy has emerged as a significant means of combating cancer, mainly including immune checkpoint therapy represented by CTLA-4 and PD-1 and adoptive T cell therapy represented by CAR-T therapy.332 Based on the established role of host microbiota in modulating immunotherapy responses, many studies have begun to attempt to manipulate the microbiome for therapeutic purposes; faecal microflora transplantation (FMT), probiotics, and antibiotics are examples of this approach. Here, PDCD1 is linked to cancer.