Cancer treatment results improved by healthy gut microbiome

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A new study confirmed a positive correlation between the gut microbiome health of melanoma patients and their response to cancer immunotherapy.

The study, published in Nature Medicine, was conducted by researchers at King’s College London, CIBIO Department of the University of Trento and European Institute of Oncology in Italy, and University of Groningen in the Netherlands. While previous studies indicated a connection between the gut microbiome and clinical responses to immune checkpoint inhibitor (ICI) treatment, none identified the specific contributing factors of a patient’s gut microbiome that led to better ICI treatment outcomes.

This study sought to reveal what microbiome-based signatures are linked to better immune responses. To do so, a team of researchers collected stool samples from 165 subjects from five observational cohorts with advanced cutaneous melanoma prior to their ICI initiation and performed shotgun metagenomic sequencing.

Results showed a correlation between healthy gut microbiomes and successful responses to ICI treatment as well as progression-free survivals (PFS). For the most part, bacterial species were not consistent across cohorts. The researchers identified three bacteria: Bifidobacterium pseudocatenulatum, Roseburia spp., and Akkermansia muciniphila, that seemed to be connected to better immune responses, however researchers were not able to confirm the bacteria as biomarkers across all studies.

"Our study shows that studying the microbiome is important to improve and personalize immunotherapy treatments for melanoma,” said the study’s co-author, Nicola Segata, PhD, of the University of Trento in a statement. “However, it also suggests that because of the person-to-person variability of the gut microbiome, even larger studies must be carried out to understand the specific gut microbial features that are more likely to lead to a positive response to immunotherapy."

While this study was unable to identify specific biomarkers in the gut microbiome associated with immune responses, it confirmed a link between gut health and ICI treatment outcomes. With a larger sample size, more in-depth future studies may be able to identify specific species in the gut microbiome that contribute to better immune responses and exploit them for new cancer treatments.