Key Points

  • Researchers have identified a connection between unfavorable gut bacteria and laboratory markers of inflammation in patients with non–small cell lung cancer, which in turn correlate with a poor response to immune checkpoint inhibitor therapy.
  • Three phase 1 studies demonstrate the feasibility of oral fecal microbiota transfer as a supportive measure to potentially reduce toxicity and boost the efficacy of immunotherapy.
  • Although the data are encouraging, fecal microbiota transfer is not yet ready for mainstream adoption based on the clinical evidence generated to date.


The role of the gut microbiome in cancer is gradually coming into focus. According to mounting research, shifts in the makeup of the normal gut microbiota can alter cancer progression through assorted mechanisms, most notably through promotion or suppression of inflammation. The gut microbiota also appears to affect the response to immunotherapy.

“There’s more and more evidence suggesting that there are molecular interactions between the microbiota and the host immunity,” remarked independent ASCO Daily News expert Jason Luke, MD, who directs the Immunotherapy and Drug Development Center at the UPMC Hillman Cancer Center and University of Pittsburgh. “A number of different mechanisms have been proposed, including modulation of myeloid cells associated with the gut lumen, as well as activation of the cGAS-STING and type I interferon pathway, where good microbiota put some patients in a physiologic state where they are highly likely to respond to immunotherapy versus bad microbiota, which suppress that.”

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