Gut microbiome changes seen in later-stage melanoma

Key takeaways:

• Gut microbiome analysis found differences in those with early- and late-stage melanoma compared with controls.
• Findings suggest gut microbiome changes can help identify future intervention targets.

Fecal microbiome samples showed significant differences in patients with melanoma compared with control subjects, as well as in those with early- and late-stage disease, according to a study.

“The gut microbiome represents the largest collection of microbial communities within the human body and has become increasingly recognized for its potential effect on clinical cancer outcomes,” Russell G. Witt, MD, MAS, of the department of surgical oncology at The University of Texas MD Anderson Cancer Center, and colleagues wrote.

“In melanoma, an association between the presence of specific microbes in the gut and response to immunotherapy has been demonstrated in both preclinical models and patient cohorts with metastatic melanoma, but limited data exist on the microbiome composition in patients with localized or early-stage melanoma or if differences exist compared with individuals without melanoma,” the researchers continued.

Witt and colleagues conducted a single-site, case-controlled study that included fecal samples from 228 subjects, of which 49 were control subjects without melanoma, 38 had early-stage melanoma and 141 had late-stage melanoma.

The samples were profiled by 16S ribosomal RNA gene sequencing.

A higher relative abundance of Fusobacterium was found in the samples of patients with melanoma as compared with the controls (0.19% vs. 0.003%; P < .001); however, when adjusted for covariates, the association was lessened (P = .09).

Higher alpha diversity was observed in samples from those with early-stage melanoma as compared with those with late-stage disease, as well as a higher abundance of Roseburia.

“Interestingly, we identified the genus Fusobacterium to be differentially enriched among patients with melanoma compared with controls on initial univariate analysis,” the authors wrote. “Fusobacterium has been previously implicated in colorectal cancer, upper aerodigestive squamous cell carcinoma, and breast cancer tumorigenesis and progression by activating the Wnt pathway and inhibiting antitumoral immune responses.”

These findings suggest a link between melanomagenesis and disease progression.

“Further investigation is needed to confirm these findings and determine whether modifying the gut microbiome could influence melanoma development and progression,” the authors added.