Gut Microbiota Modulates the Efficiency of Programmed Cell Death Protein 1 Cancer Immunotherapies

Program cell death protein 1 (PD1) is considered as an inhibitory molecule that is expressed on the surface of activated T-cells and bound to PD-L1 and PD-L2 ligands. Several types of cancer cells express PD-L1 which can bind to PD1 on the surface of tumor-specific T-cells. PD1/PD-L1 ligation triggers a pathway to protect tumor cells from an effective response of tumor-specific T-cells. Different PD1/PD-L1 blocker antibodies are clinically used to promote the T-cell response against the cancer cells. Current studies suggest that the gut microbiome impacts the efficiency of PD1 blockade therapy in cancer patients. The association of several bacterial species with PD1 responder patients has been determined. The present study reviewed previous reports on the relation between the microbiome and immune checkpoint therapy (ICT). The results of studies were discussed considering adjuvant and molecular mimicry of microbial antigens by tumor-associated antigens and metabolic effects of microbial products on ICT.