Gut microbes linked to immunotherapy response in melanoma patients

Patients with malignant melanoma – whose disease has spread – are more likely to respond to immunotherapy treatment if they had greater diversity in their gut bacteria, according to new research presented at the National Cancer Research Institute’s (NCRI) Cancer Conference in Liverpool.

Scientists at the University of Texas MD Anderson Cancer Centre studied over 200 mouth and over 100 gut microbiome samples from people who had advanced melanoma.

Bacteria in the gut

They discovered that people whose cancer responded to immunotherapy treatment had more diversity in the types of bacteria found in their gut. They also found significant differences in the type of bacteria found in the gut of people whose cancer responded versus those who didn’t.

There was no difference in the type of mouth bacteria between patients.

Pre clinical studies

Early studies in mice have shown that changing the type of bacteria that live in the gut can improve the response to immunotherapy, but this is one of the first studies to look at the link in patients.

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Immunotherapy, which harness the body’s immune system to target cancer cells, is an exciting avenue of cancer treatment. However, not all patients respond to these treatments, and researchers are trying to understand why.

Pre immunotherapy treatment

This research suggests that adapting people’s gut bacteria, such as giving antibiotics, probiotics, or a faecal transplant before immunotherapy, could increase the benefits already achieved with new immunotherapy drugs now being used to treat several different types of cancer. However, this needs to be tested clinical trials.

“The gut microbiome can be changed through a number of different strategies, so there is real potential here to modify the gut microbiome to boost an immunotherapy response.”

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Dr Pippa Corrie, Chair of the NCRI’s Skin Cancer Clinical Studies Group, said: “There is growing evidence that gut bacteria play a vital role in warding off disease, absorbing nutrients from the food we eat, and maintaining normal function of our immune systems.

This research was funded by the Melanoma Research Alliance and by the Melanoma Moon Shot Program at MD Anderson Cancer Center.