Immune-boosting gut microbes can help chemotherapy drugs

Certain microbes in the gut can help improve the effectiveness of chemotherapy drugs, according to a new study. 

The two types of bacteria identified activate immune cells, helping to boost the effectiveness of a commonly prescribed anticancer drug, says the report in Immunity. 

Co-lead author Mathias Chamaillard said that the finding “opens the way to improve treatment design,” for example by finding the best way to use antibiotics to enhance the activity of anticancer drugs.  

Recent studies have shown that some microbes living in our guts can promote the growth of tumours, while others can protect against cancer by interacting with the immune system. And the action of certain anticancer drugs, like cyclophosphamide, has been shown to be dependent on gut microbes. 

But which species of bacteria are important and how they contribute to these effects was unknown. 

For this latest study, conducted by a team based in France, the researchers used cells in a dish and results from mice to show that two different bacteria are involved in boosting the activity of cyclophosphamide. 

The species, Enterococcus hirae and Barnesiella intestinihominis, activate cancer-fighting T cell immune responses, boosting the effects of the chemotherapy drug cyclophosphamide.

And when the researchers looked at the blood of patients with advanced lung and ovarian cancer, they found that the presence of T cells with activity against these two bacterial species was linked with longer survival. 

Professor Tim Elliott, a Cancer Research UK expert on immunology, said that the study is “interesting” and could open up new avenues for boosting the power of the immune system against cancer. 

“Despite progress in immunotherapy, we actually know very little about how the immune system fights tumours.  

“We each have over a kilogram of ‘friendly bacteria’ living in our guts and this study highlights their importance for training our immune system to fight cancer better in combination with a common anticancer drug,” he added.  

The research team now wants to try and identify which specific bacterial molecules are responsible for enhancing the effects of the drug. 

Answering this question could provide a way to improve the survival of patients treated using cyclophosphamide by giving them drugs based on these molecules, says the research team