Many factors within the host environment may play a role in modulating an immune response. Outside of the tumor microenvironment, factors such as smoking, diet, UV exposure, infectious agents, and the gut microbiome can favorably or unfavorably affect the antitumor immune response.1-3
Microbiome: a collection of bacteria in a particular environment (ie, the gut and oral cavity) that can be assessed via WGS and prokaryotic ribosomal sequencing.4-7 Abrogation and/or alteration of the microbiota may play a role in the incidence and progression of cancer.8 Certain bacterial species can help prime immune cells and increase their surveillance.6-9
Faecalibacterium has been associated with increased systemic T-cell circulation, whereas Akkermansia muciniphila is linked to secretion of IL-12, a cytokine crucial for T-cell function.7-9
The microbiome is being studied as a potential biomarker of response to immunotherapy.
REFERENCES – Host Environment
- Chen DS, Mellman I. Elements of cancer immunity and the cancer-immune set point. Nature. 2017;541(7637):321-330.
- Alexandrov LB, Nik-Zainal S, Wedge DC, et al. Signatures of mutational processes in human cancer. Nature. 2013;500(7463):415-421.
- Sharma P, Allison JP. The future of immune checkpoint therapy. Science. 2015;348(6230):56-61.
- National Cancer Institute. Microbiome. NCI Dictionary of Cancer Terms. www.cancer.gov/publications/dictionaries/cancer-terms/def/microbiome. Accessed May 10, 2018.
- Turnbaugh PJ, Ley RE, Hamady M, Fraser-Liggett CM, Knight R, Gordon JI. The human microbiome project. Nature. 2007;449(7164):804-810.
- Routy B, Le Chatelier E, Derosa L, et al. Gut microbiome influences efficacy of PD-1–based immunotherapy against epithelial tumors. Science. 2018;359(6371):91-97.
- Gopalakrishnan V, Spencer CN, Nezi L, et al. Gut microbiome modulates response to anti–PD-1 immunotherapy in melanoma patients. Science. 2018;359(6371):97-103.
- Zitvogel L, Galluzzi L, Viaud S, et al. Cancer and the gut microbiota: an unexpected link. Sci Transl Med. 2015. doi:10.1126/scitranslmed.3010473.
- Kaiser J. Gut microbes shape response to cancer immunotherapy. Science. 2017;358(6363):573.