Gut microbiome influences efficacy of PD-1-based immunotherapy against epithelial tumors

Area of Science:

• Immunology
• Oncology
• Microbiome Research

Background:

• Immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 axis offer clinical benefits for some cancer patients.
• Primary resistance to ICIs is a significant challenge in cancer therapy.
• The gut microbiome's role in ICI efficacy is increasingly recognized.

Purpose of the Study:

• To investigate the impact of gut microbiome composition on primary resistance to PD-1 blockade therapy.
• To explore the potential of modulating the gut microbiome to enhance ICI efficacy.

Main Methods:

• Analysis of gut microbiome composition in cancer patients undergoing ICI therapy.
• Studies using fecal microbiota transplantation (FMT) in germ-free or antibiotic-treated mice.
• Oral supplementation with specific bacterial species (Akkermansia muciniphila).
• Assessment of antitumor effects and immune cell infiltration in mouse models.

Main Results:

• Abnormal gut microbiome composition was linked to primary resistance to ICIs.
• Antibiotic treatment diminished the clinical benefit of ICIs.
• FMT from ICI-responding patients restored antitumor effects in mice, while FMT from non-responders did not.
• Akkermansia muciniphila abundance correlated with clinical response.
• Oral A. muciniphila supplementation restored ICI efficacy in mice colonized with non-responder microbiota.

Conclusions:

• Gut microbiome dysbiosis contributes to primary resistance to PD-1 blockade.
• Akkermansia muciniphila plays a crucial role in mediating the efficacy of PD-1 blockade.
• Modulating the gut microbiome, specifically with A. muciniphila, represents a potential strategy to overcome ICI resistance.