The Gut Microbiome Is Associated with Clinical Response to Anti-PD-1/PD-L1 Immunotherapy in Gastrointestinal CancerOriginal 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?
Researchers examined whether gut microbiome composition tracks with clinical response to anti-PD-1/PD-L1 immunotherapy in gastrointestinal cancer. This association had previously been shown in melanoma, non-small cell lung cancer, and renal cell carcinoma but not GI cancers.
How was it studied?
The team recruited 74 patients with advanced-stage GI cancer receiving anti-PD-1/PD-L1 treatment, collecting fecal samples before and during immunotherapy alongside clinical evaluations. Samples underwent 16S rRNA taxonomy surveying and shotgun metagenomic sequencing.
What did they find?
Responders showed an elevated Prevotella/Bacteroides ratio, and a responder subgroup had significantly higher Prevotella, Ruminococcaceae, and Lachnospiraceae. Short-chain fatty acid producing bacteria, including Eubacterium, Lactobacillus, and Streptococcus, were positively associated with response across GI cancer types, alongside differential microbial pathways in nucleoside, lipid, and sugar metabolism.
Why it matters
The identified bacterial taxa predicted patient stratification in both this GI cancer cohort and in melanoma patients from two prior published studies. This suggests the gut microbiome could serve as a marker for immune-checkpoint blockade response across cancer types.