Sodium butyrate, as one of the gut microbiota metabolites, upregulates PD-L1 expression in glioma cells by regulating the PI3K/AKT pathway, helping to transform GBM cells from a “cold tumor” to a “hot tumor”, and improving the efficacy of PD-1 inhibitors for GBM treatment. The gene discussed is PDCD1; the disease is neoplasm.