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Host Environment Factors

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

UV exposure
Infectious agents


Alteration of the microbiome, a collection of bacteria in a specific environment, may correlate with immune-cell activity. Bacteria species present in a microbiome can be measured using WGS and ribosomal sequencing.

Click below to learn more about the microbiome as a potential predictive Immuno-Oncology (I-O) biomarker.
  • A microbiome is a collection of bacteria in a particular environment (ie, the gut and oral cavity)4
  • Abrogation and/or alteration of the microbiota may play a role in the incidence and progression of cancer5-9
    • Faecalibacterium has been associated with increased systemic T-cell circulation
    • Akkermansia muciniphila is linked to secretion of IL-12, a cytokine crucial for T-cell function5-9
The microbiome is being studied as a potential biomarker of response to immunotherapy.

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References–Host environment factors

1. Chen DS, Mellman I. Elements of cancer immunity and the cancer-immune set point. Nature. 2017;541(7637):321-330. 2. Alexandrov LB, Nik-Zainal S, Wedge DC, et al. Signatures of mutational processes in human cancer. Nature. 2013;500(7463):415-421. 3. Sharma P, Allison JP. The future of immune checkpoint therapy. Science. 2015;348(6230):56-61. 4. National Cancer Institute. Microbiome. NCI Dictionary of Cancer Terms. Accessed May 10, 2018. 5. Zitvogel L, Galluzzi L, Viaud S, et al. Cancer and the gut microbiota: an unexpected link. Sci Transl Med. 2015. doi10.1126/scitranslmed. 3010473. 6. 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. 7. 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. 8. Kaiser J. Gut microbes shape response to cancer immunotherapy. Science. 2017;358(6363):573. 9. Li Q, Gao Z, Wang H, et al. Intestinal immunomodulatory cells (T lymphocytes): a bridge between gut microbiota and diabetes. Mediators Inflamm. 2018. doi:10.1155/2018/9830939. 10. Ranjan R, Rani A, Metwally A, McGee HS, Perkins DL. Analysis of the microbiome: advantages of whole genome shotgun versus 16S amplicon sequencing. Biochem Biophys Res Commun. 2016;469(4):967–977. 11. Turnbaugh PJ, Ley RE, Hamady M, Fraser-Liggett C, Knight R, Gordon JI. The human microbiome project. Nature. 2007;449(7164):804-810.