Identification of as a Gastric Fungus Associated with PD-L1 Expression and Overall Survival of Patients with Gastric Cancer.

Background: Microbiotas affected the prognosis of cancer patients by regulating programmed death ligand-1 (PD-L1) expression. However, the relationship between gastric fungi and PD-L1 expression is still unclear in gastric cancer (GC). We aimed at exploring the association of gastric fungi with PD-L1 expression and overall survival in GC.

Methods: A total of 61 GC patients were divided into the two groups based on the PD-L1 combined positive scores (CPS). Fungal profiling was performed by internal transcribed spacer rDNA sequencing, and the survival analyses were performed by Kaplan-Meier curves.

Results: We observed a taxonomic difference of fungi between the PD-L1-High ( ≥ 10) and PD-L1-Low group ( < 10) by principal coordinates analysis (PCoA) ( = 0.014 for Bray-Curtis and = 0.042 for Jaccard). had a higher abundance in the PD-L1-High group compared to the PD-L1-Low group ( = 0.045). elevated significantly in the PD-L1-High group. GC patients with PD-L1 low expression and low abundance of had a longer overall survival (OS) than others ( = 0.047). was associated with PD-L1 expression (  = 3.509, 95% Confidence Interval: 1.056-11.656, = 0.040). was associated with the tumor size ( = 0.031) and PD-L1 status ( = 0.024). GC patients with a high abundance of had shorter OS than others ( = 0.028). was an independent factor (  = 3.080, 95% Confidence Interval: 1.140-8.323, = 0.027) for OS after adjusting for tumor stage. was figured out to be associated with- fatty acid and lipid biosynthesis and degradation via LIPASYN pathway. was identified as a PD-L1 expression-associated gastric fungus and associated with OS of GC patients, which calls for more studies to further explore its potential in PD-L1/PD-1 targeted immunotherapy.