The Predictive Value And Underlying Mechanisms Of M1 Macrophage For Anti-PD-L1 Therapy Efficacy In Urothelial Cancer

Background and AimImmunotherapy represented by PD-1/PD-L1 inhibitors has completely revolutionized the treatment strategy of locally advanced or metastatic urothelial cancer.However,only a small subset of patients could benefit from immunotherapy.Therefore,robust biomarkers are urgently warranted to screen potential patient populations that can respond to immunotherapy.Based on the multi-omics data of 348 pretreatment samples from patients with locally advanced or metastatic urothelial cancer receiving anti-PD-L1 therapy from the IMvigor210 cohort,this study intends to explore new promising biomarkers to predict immunotherapy efficacy and discover underlying mechanisms associated with immunotherapy responses from immunome,genome,and metabolome aspects.Methods1.Utilizing tumor microenvironment deconvolution tools,single sample gene set enrichment analysis,and principal component analysis,we calculated and obtained tumor microenvironment,immune-related,and metabolism-related gene signature scores(n=7556).Using a new algorithm combining LASSO-COX regression model and bootstrapping method,we selected potential biomarkers for predicting immunotherapy efficacy from 7556 gene signature scores.2.Kaplan-Meier and receiver operating characteristic curve analyses were performed to compare the predictive capacity of M1-macrophage infiltration with published immunotherapy predictors.Meanwhile,predictive capacity was validated in other immunotherapy datasets.3.CIBERSORT was conducted to analyze the immune cell infiltration pattern of urothelial cancer tumor microenvironment.Utilizing unsupervised consensus clustering,urothelial cancer tumor microenvironment could be divided into two microenvironment subtypes TME cluster A and TME cluster B.We explored the association between tumor microenvironment subtypes and clinicopathological parameters.4.Differentially expressed genes of high and low M1 macrophage infiltration group in the IMvigor210 cohort and The Cancer Genome Atlas-bladder cancer(TCGA-BLCA)cohort were prepared to conduct Gene Ontology(GO)gene enrichment analysis,Kyoto Encyclopedia of Genes and Genomes(KEGG)gene enrichment analysis,and gene set enrichment analysis(GSEA)to explore the underlying mechanisms of M1 macrophage predicting immunotherapy efficacy.Besides,we evaluated the relationship between immune-related,and metabolism-related gene signature scores and macrophage infiltration.5.The Wilcoxon test was used to discover gene mutations associated with M1 macrophage infiltration,and to analyze the correlation between M1 macrophage and immune phenotypes,immune-related and metabolism-related gene signature scores.Results1.In the risk score model constructed by the LASSO-COX regression model,M1 macrophage infiltration level analyzed by CIBERSORT served as a vital gene signature score correlated with a better prognosis.Meanwhile,M1 macrophage was also the most frequently repeated gene signature in 10,000 random bootstrapping analyses,suggesting that M1 macrophage holds promise in predicting therapeutic response to PD-L1 blockade in urothelial cancer.2.The predictive power of M1 macrophage is non-inferior to that of tumor mutation burden and tumor neoantigen burden,but superior to PD-L1 expression and CD8+T cell.3.Two tumor microenvironment subtypes TME cluster A and TME cluster B were identified in the IMvigor210 cohort and TCGA-BLCA cohort.M1 macrophage infiltration level significantly elevated in the TME cluster A with immune activation.M1 macrophage infiltration level may also function as a robust indicator of tumor microenvironment subtypes.4.Immune activation pathway signature scores such as antigen presentation,CD8+T cell activation were significantly increased in the high M1 macrophage infiltration group.Besides,steroid metabolism and drug metabolism pathway scores were significantly increased in the low M1 macrophage infiltration group.5.FGFR mutated urothelial tumor with low M1 macrophage infiltration level prone to manifest as desert immune phenotype.Besides,downregulation of immune checkpoint pathways and upregulation of steroid metabolism pathways were observed in FGFR mutated urothelial tumor.ConclusionM1 macrophage is a robust biomarker for predicting immunotherapeutic response in urothelial cancer.