Gut Microbiota Potentiates the Effect of Immune Checkpoint Therapy against Cancers

Immune checkpoints have been aggressively investigated for anti-cancer immunotherapy. The power of microbiota on the outcome of this immunotherapy has attracted much attention. For example, intestinal microorganisms play a key role in the effectiveness of programmed cell death 1 (PD1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA4) blockade. Additionally, short-chain fatty acids produced in the gut may modulate anti-CTLA4 and anti-PD1 stimulated immune responses and their anti-tumor efficacy. Enhancing the anti-tumor effects of CTLA4 blockade depends on specific Bacteroides sp. of the gut microbiota, suggesting novel approaches to improve such immunotherapies. However, the molecular mechanism of the immune-potentiation remains largely unknown. Changes in the microbiota are influenced by dietary and environmental factors. Here, we have suggested the molecular mechanism of action regarding the interplay between gut microbiota and the anti-cancer immune system with APRO family proteins, which might contribute to innovative cancer therapy in the future.