# Correlation between gut microbiota and their metabolites and the efficacy of chemotherapy combined with immunotherapy for extensive-stage small cell lung cancer

## TL;DR

This study explores how gut bacteria and their metabolites relate to treatment outcomes in small cell lung cancer patients receiving chemotherapy and immunotherapy.

## Contribution

The study identifies specific gut bacteria and metabolites associated with longer progression-free survival in small cell lung cancer patients.

## Key findings

- Streptococcus, Actinomyces, and Roseburia differ between long and short progression-free survival groups.
- Metabolites like stearidonic acid and leukotriene B4 show potential as biomarkers for treatment response.
- Gut microbiota and metabolites may help improve cancer treatment efficacy through translational applications.

## Abstract

Gut microbiota has been reported to be associated with the host’s immune system and immunotherapy response, as well as immune-related adverse events (irAEs). Additionally, gut microbial metabolites have various immunomodulatory effects. Our study focused on the differences in gut microbiota and their metabolites between long progression-free survival (PFS) and short PFS in patients with small cell lung cancer before and after chemotherapy combined with immunotherapy.

The enrolled patients collected in our department were divided into long PFS and short PFS groups according to whether the PFS was ≥6 months, and the stool samples before and after treatment were analyzed using metagenomics and metabolomics.

The results showed that Streptococcus (P = 0.00648), Actinomyces (P = 0.0124), and Roseburia (P = 0.0127) differed between the long and short PFS groups. In the analysis of differential metabolites, we found that indirubin-3’-monoxime (AUC 0.611), stearidonic acid (AUC 0.867), leukotriene B4 (AUC 0.844), trans-cinnamic acid (AUC 0.792), and L-tyrosine (AUC 0.751) could be used as potential biomarkers.

Gut microbiota and their metabolites hold broad prospects for translational applications in cancer clinical management, such as the development of microbial biomarkers and the modulation of microbiota to enhance the efficacy of chemotherapy and immunotherapy.