Background: The composition of the gut microbiota is associated with the response to
immunotherapy for different
cancers. However, the majority of previous studies have focused on a single
cancer and a single
immune checkpoint inhibitor. Here, we investigated the relationship between the gut microbiota and the clinical response to anti-
programmed cell death protein 1 (PD-1)
immunotherapy in patients with advanced
cancers. Method: In this comprehensive study,
16S rRNA sequencing was performed on the gut microbiota of pre-
immunotherapy and post-
immunotherapy, of 72 advanced
cancer patients in China. Results: At the phylum level, Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria were the main components of the microbiota in the 72 advanced
cancer patients. At the genus level, Bacteroides and Prevotella were the dominant microbiota among these 72 patients. The PD_whole_tree, Chao1, Observed_species and Shannon indices of R.0 and R.T were higher than those of NR.0 and NR.T. The results of LEfSe showed that Archaea, Lentisphaerae, Victivallaceae, Victivallales, Lentisphaeria, Methanobacteriaceae, Methanobacteria, Euryarchaeota, Methanobrevibacter, and Methanobacteriales were significantly enriched in the response group before
immunotherapy (R.0), and the Clostridiaceae was significantly enriched in the non-response group before
immunotherapy (NR.0) (p < 0.05). Lachnospiraceae and Thermus were significantly enriched in the response group after
immunotherapy (R.T), and Leuconostoc was significantly enriched in R.0 (p < 0.05). ROC analysis showed that the microbiota of R.T (AUC = 0.70) had obvious diagnostic value in differentiating Chinese
cancer patients based on their response to
immunotherapy. Conclusions: We demonstrated that the gut microbiota was associated with the clinical response to anti-PD-1
immunotherapy in
cancer patients. Taxonomic signatures enriched in responders were effective
biomarkers to predict the clinical response. Our findings provide a new strategy to improve the efficiency of responses to
immunotherapy among
cancer patients.