Correlation of distribution characteristics and dynamic changes of gut microbiota with the efficacy of immunotherapy in EGFR-mutated non-small cell lung cancer.

BACKGROUND: The effects of gut microbiota and metabolites on the responses to immune checkpoint inhibitors (ICIs) in advanced epidermal growth factor receptor (EGFR) wild-type non-small cell lung cancer (NSCLC) have been studied. However, their effects on EGFR-mutated (EGFR +) NSCLC remain unknown. METHODS: We prospectively recorded the clinicopathological characteristics of patients with advanced EGFR + NSCLC and assessed potential associations between the use of antibiotics or probiotics and immunotherapy efficacy. Fecal samples were collected at baseline, early on-treatment, response and progression status and were subjected to metagenomic next-generation sequencing and ultra-high-performance liquid chromatography-mass spectrometry analyses to assess the effects of gut microbiota and metabolites on immunotherapy efficacy. RESULTS: The clinical data of 74 advanced EGFR + NSCLC patients were complete and 18 patients' fecal samples were dynamically collected. Patients that used antibiotics had shorter progression-free survival (PFS) (mPFS, 4.8 vs. 6.7 months; P = 0.037); probiotics had no impact on PFS. Two dynamic types of gut microbiota during immunotherapy were identified: one type showed the lowest relative abundance at the response time point, whereas the other type showed the highest abundance at the response time point. Metabolomics revealed significant differences in metabolites distribution between responders and non-responders. Deoxycholic acid, glycerol, and quinolinic acid were enriched in responders, whereas L-citrulline was enriched in non-responders. There was a significant correlation between gut microbiota and metabolites. CONCLUSIONS: The use of antibiotics weakens immunotherapy efficacy in patients with advanced EGFR + NSCLC. The distribution characteristics and dynamic changes of gut microbiota and metabolites may indicate the efficacy of immunotherapy in advanced EGFR + NSCLC.

Preservation of the fecal samples at ambient temperature for microbiota analysis with a cost-effective and reliable stabilizer EffcGut.

With the increasing researches on the role of gut microbiota in human health and disease, appropriate storage method of fecal samples at ambient temperature would conveniently guarantee the precise and reliable microbiota results. Nevertheless, less choice of stabilizer that is cost-efficient and feasible to be used in longer preservation period obstructed the large-scale metagenomics studies. Here, we evaluated the efficacy of a guanidine isothiocyanate-based reagent method EffcGut and compared it with the other already used storage method by means of 16S rRNA gene sequencing technology. We found that guanidine isothiocyanate-based reagent method at ambient temperature was not inferior to OMNIgene·GUT OM-200 and it could retain the similar bacterial community as that of -80 °C within 24 weeks. Furthermore, bacterial diversity and community structure difference were compared among different sample fraction (supernatant, suspension and precipitate) preserved in EffcGut and -80 °C. We found that supernatant under the preservation of EffcGut retained the similar community structure and composition as that of the low temperature preservation method.