Researchers have found that greater gut microbial diversity in patients with metastatic kidney cancer is associated with better treatment outcomes in those receiving immunotherapy. These findings were published by Salgia et al in European Urology.
“We also reported the changes over time in the gut microbiome that occur during the course of therapy—the cumulative findings from our report open the door to therapies directed at the microbiome,” said Sumanta Pal, MD, one of the study's senior authors and Co-Director of the Kidney Cancer Program at City of Hope.
Sumanta Pal, MD
Gut Microbiome
The gut microbiome is composed of microbes like bacteria and viruses that reside in the gastrointestinal tract. In recent years, an increase in knowledge about the microbiome in relation to general health has led to deeper explorations of its role in disease states, as well as how its organisms may interact with treatments.
“Previous studies have suggested a relationship between the gut microbiome and response to immunotherapy in solid tumors, including metastatic kidney cancer,” said Nicholas Salgia, BSc, a clinical research assistant at City of Hope and the paper's lead author. “The results from our study build on earlier findings and reaffirm that the diversity and composition of patients' microbiomes are associated with clinical responses to anticancer therapies.”
Study Methods
The study, which collected data from 31 patients with metastatic kidney cancer, features the first reports of comparing microbiome sequencing at different time points in patients with cancer. Participants were asked to provide up to three stool samples: at baseline, 4 weeks into therapy, and 12 weeks into therapy.
Results
Using the clinical trial results, the team was able to identify changes in the microbiome over time in patients with kidney cancer receiving immunotherapy. The team found that a greater variety of organisms was associated with a benefit to patients, and also suggested that modulating the gut microbiome during the course of treatment may impact responses to therapy.
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“The patients with the highest benefit from cancer treatment were those with more microbial diversity, but also those with a higher abundance of a specific bacterium known as Akkermansia muciniphila,” said Sarah Highlander, PhD, a research professor in The Translational Genomics Research Institute’s Pathogen and Microbiome Division and one of the study's senior authors. “This organism has been associated with benefit in other immunotherapy studies.”
Dr. Highlander stated that one potential takeaway is that oncologists might encourage patients to pay attention to their gut microbiome by eating a high-fiber diet, including fruits and vegetables high in fructo-oligosaccharides, such as bananas, dried fruit, onions, leeks, garlic, asparagus, and artichokes, as well as grains with resistant starches such as barley or uncooked potato starch, for example.
Dr. Highlander added that next steps should include expanding the relatively small study to a much larger group of patients that are followed over a longer time period. At City of Hope, researchers have already embarked on a clinical trial to further explore the idea that modulating the microbiome during therapy could have an impact on clinical outcomes.
“We have random[ly assigned] patients with metastatic kidney cancer to receive a probiotic supplement in addition to a [U.S. Food and Drug Administration]-approved immunotherapy regimen or immunotherapy alone,” explained Mr. Salgia. “This work provided a strong framework for such a study.”
Disclosure: For full disclosures of the study authors, visit europeanurology.com.
