Having greater gut bacteria diversity may indicate a greater response to immunotherapy treatment in patients with malignant melanoma, according to new research conducted by scientists at the University of Texas MD Anderson Cancer Center.

To better understand why some patients respond positively to immunotherapy and some do not, the researchers studied over 200 mouth and over 100 gut microbiome samples from individuals with advanced melanoma.

Their analysis showed that those who responded to immunotherapy had more diversity in the types of bacteria found in their gut. Differences were also found in the type of bacteria in the gut of people whose cancer responded vs. those whose cancer did not, whereas no difference was seen in the type of mouth bacteria.  

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“Our research shows a really interesting link that may mean the immune system is aided by gut bacteria when responding to these drugs,” said Jennifer Wargo, the lead researcher. “Not all patients respond to immunotherapy drugs and it’s hard to know who will benefit from the treatment prior to it being given.”

These findings suggest that adapting an individual’s gut bacteria through antibiotics, probiotics, or fecal transplant before immunotherapy could increase the treatment’s efficacy.

“Gut microbes have been shown to influence the role of conventional chemotherapy, so it’s probably not surprising that they impact on response to new immunotherapies being used in the clinic,” said Dr. Pippa Corrie, chair of the National Cancer Research Institute’s Skin Cancer Clinical Studies Group. “Manipulating the gut flora may be a new strategy to enhance activity of immunotherapy drugs, as well as to manage problematic toxicity in the future.”

The research findings are being presented at the National Cancer Research Institute’s (NCRI) Cancer Conference.

For more information visit ncri.org.