#1335

Gut Microbiota Affects the Efficacy of Neoadjuvant Chemotherapy Combined with Immunotherapy in Muscle-Invasive Bladder Cancer

P. Lei¹, T. Qi², T. Li², G. Gao², F. Zhu², K. Wu^2,1

¹Yulin Hospital of the First Affiliated Hospital of Xi’an Jiaotong University, Department of Urology, Yulin, China
²First Affiliated Hospital of Xi'an Jiaotong University, Department of Urology, Xi'an, China

Introduction:

For patients with muscle-invasive bladder cancer (MIBC), the main treatment methods are radical cystectomy, however, approximately 50% of patients experience metastasis following surgical intervention. Currently, neoadjuvant chemotherapy with cisplatin is the standard recommendation as per clinical guidelines, while immunotherapy based on immune checkpoint inhibitors (ICIs) has emerged as a promising alternative. Recent studies suggest that primary resistance to ICIs may be associated with dysbiosis of the gut microbiota. This study aims to investigate the differences in gut microbiota among MIBC patients exhibiting varied responses to neoadjuvant chemotherapy combined with immunotherapy (chemo-immunotherapy), especially to elucidate the effects of gut microbiota on treatment efficacy and identify specific bacterial taxa as potential biomarkers for clinical decision-making.

Material and methods:

Patients with pathologically confirmed MIBC (T2-4aN0M0) from the First Affiliated Hospital of Xi'an Jiaotong University were included. Based on postoperative pathological response, patients were stratified into non-response (NR, ≥pT2) and response (R,

Results:

A total of 38 patients undergoing neoadjuvant chemo-immunotherapy were enrolled in this study, comprising 22 patients (57.89%) in the R group and 16 patients (42.11%) in the NR group. Metagenomic sequencing revealed a statistically significant difference in alpha diversity assessed by the Shannon index (p=0.0086). Principal Coordinates Analysis (PCoA) based on Bray-Curtis distance demonstrated significant differences in beta diversity (p=0.001). Furthermore, the microbial composition analysis identified 255 species with statistically significant differences at the species level between the groups. Notably, Bifidobacterium longum was significantly elevated in the R group (p < 0.001). Linear discriminant analysis coupled with effect size (LEfSe) confirmed Bifidobacterium longum as a potential biomarker to distinguish the efficacy of neoadjuvant chemo-immunotherapy.