Gut microbiome features associate with immune checkpoint inhibitor response in individuals with non-melanoma skin cancers: an exploratory studyOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study examined whether gut microbiota structure and function relate to outcomes of immune checkpoint inhibitor (ICI) therapy in non-melanoma skin cancers. The researchers performed 16S rRNA V1-V2 gene amplicon sequencing on fecal samples collected longitudinally, then ran tumor-dependent differential analyses of bacterial composition alongside untargeted fecal metabolomics. The goal was to identify bacterial genera, species, and metabolic pathways associated with response versus non-response to ICI treatment.
Who was studied?
The analysis drew on 68 fecal samples collected longitudinally from individuals with basal cell carcinoma (n = 5), Merkel cell carcinoma (n = 5), or cutaneous squamous cell carcinoma (CSCC, n = 11). All participants were undergoing ICI therapy for a non-melanoma skin cancer. This is a small, exploratory cohort spanning three distinct tumor types rather than a single large patient population.
What were the most important findings?
Across all tumor types combined, the researchers identified 10 differential bacterial genera between ICI responders and non-responders. Within the CSCC subgroup specifically, 10 genera and 20 species distinguished responders from non-responders, and predicted functional pathway analyses found 8 pathways enriched in non-responders and 12 enriched in responders. Untargeted fecal metabolomics further identified nine KEGG pathways associated with ICI efficacy in CSCC, pointing to microbial metabolic activity as a correlate of treatment response.
What are the greatest implications of this study?
The findings suggest that gut microbiota composition and function are linked to ICI therapy outcomes in non-melanoma skin cancers, extending observations previously made mainly in melanoma to other skin cancer types. Because this is described as an exploratory study with a small sample size, the specific genera, species, and pathways identified should be viewed as hypothesis-generating rather than confirmed predictors. Larger studies are needed to validate these microbiome features before they could inform strategies to predict or improve ICI response in non-melanoma skin cancer.