Gut Bacteria Linked to Immunotherapy Success

Researchers discover which type of gut bacteria may influence the effectiveness of chemotherapy.

With the recent focus on emerging immunotherapy treatments, it is well known that the body and its processes are important to preventing or treating cancer. Gut bacteria has been shown have both positive and negative effects on health.

A recent study found that gut bacteria can even affect the health of patients with chronic kidney disease.

In a study published by Immunity, researchers further demonstrated the relationship between chemotherapy, the immune system, and gut bacteria. Scientists discovered that 2 types of gut bacteria are able to boost the effect of the immunosuppressive chemotherapy drug cyclophosphamide.

These gut bacteria, Enterococcus hirae and Barnesiella intestinihominis, are able to activate T cells in the body, which are able to fight infections and diseases, including cancer. The gut bacteria were also shown to increase progression-free survival in patients treated with chemo-immunotherapy drugs, according to the study.

Scientists believe that these findings suggest that antibiotics, oncomicrobiotics, or bioactive metabolites could be used to increase the efficacy of these treatments. In the study, the bacteria were examined in separate mouse models undergoing chemotherapy.

Researchers found that oral administration of E. hirae increased T cell response in the spleen. Increased T cell activity along with cisplatin chemotherapy was able to stop tumor growth, according to the study.

They discovered similar results from treatment with B. intestinihominis, and saw that the bacteria caused T cells to enter cancer cells.

Scientists then tested T cell responses in 38 patients with advanced lung and ovarian cancer through a blood sample, and found that patients with memory T cell responses to both bacteria were able to predict progression-free survival. Future studies will be conducted to determine the specific metabolites or immune-modulating molecules can increase the effect of chemotherapy, according to the study.

“Answering this question may provide a way to improve the survival of cyclophosphamide-treated cancer patients by supplementing them with bacterial-derived drugs instead of live microorganisms,” said co-senior author of the study Mathias Chamaillard, PhD.