Gut Microbiota in Cancer Immune Response and Immunotherapy

Trends Cancer. 2021 Jul;7(7):647-660. doi: 10.1016/j.trecan.2021.01.010. Epub 2021 Mar 2.


The gastrointestinal tract (GIT) is the largest immune organ and maintains systemic immune homeostasis in the presence of bacterial challenge. Immune elimination and immune escape are hallmarks of cancer, both of which can be partly bacteria dependent in shaping immunity by mediating host immunomodulation. In addition, host immunity regulates the microbiome by altering bacteria-associated signaling to influence tumor surveillance. Cancer immunotherapy, including immune checkpoint blockade (ICB), appears to have heterogeneous therapeutic effects in different individuals, partially attributed to the microbiota. Thus, the microbiome signature can predict clinical outcomes, prognosis, and immunotherapy responses. In this review, we summarize the intricate crosstalk among the gut microbiome, cancer immune response, and immunotherapy. Interactive modulation of the host microbiota provides new therapeutic strategies to promote anticancer therapy efficacy and/or reduce toxicity.

Keywords: cancer immune response; efficacy and toxicity; gut microbiota; immune checkpoint blockers; immunotherapy; precise bacterial manipulation.

Publication types

  • Review

MeSH terms

  • Adaptive Immunity
  • Animals
  • Anti-Bacterial Agents / adverse effects
  • Combined Modality Therapy / methods
  • Disease Models, Animal
  • Disease-Free Survival
  • Fecal Microbiota Transplantation
  • Gastrointestinal Microbiome / drug effects
  • Gastrointestinal Microbiome / immunology*
  • Host Microbial Interactions / drug effects
  • Host Microbial Interactions / immunology*
  • Humans
  • Immune Checkpoint Inhibitors / administration & dosage*
  • Immune Checkpoint Inhibitors / adverse effects
  • Immunotherapy / methods
  • Mice
  • Neoplasm Recurrence, Local / epidemiology*
  • Neoplasm Recurrence, Local / immunology
  • Neoplasm Recurrence, Local / prevention & control
  • Neoplasms / immunology
  • Neoplasms / microbiology
  • Neoplasms / mortality
  • Neoplasms / therapy*
  • Prebiotics / administration & dosage
  • Probiotics / administration & dosage
  • Prognosis
  • Progression-Free Survival


  • Anti-Bacterial Agents
  • Immune Checkpoint Inhibitors
  • Prebiotics