Genomic Sequencing for Bladder Urothelial Carcinoma and Its Clinical Implications for Immunotherapy.

Purpose This study aimed to explore the genomic and transcriptomic landscape of bladder cancer (BC) and its implication for treatment with an immune checkpoint inhibitor (ICI). Materials and Methods We analyzed whole-exome and -transcriptome sequences of tumor samples from 64 BC patients who underwent surgical resection with either transurethral resection or radical cystectomy. For exploratory purposes, programmed death-ligand 1 (PD-L1) expression was evaluated in a subset of patients (n=57) including those treated with ICI (n=8). Results We identified frequent molecular dysregulations in chromatin regulatory genes (KDM6A, ARID1A, MLL2, and STAG2) and recurrent copy number alterations. Thirty-five samples (54.7%) were PD-L1-positive (PD-L1 combined positive score ≥ 1) with a significantly higher exonic tumor mutational burden (TMB) compared to PD-L1-negative BC samples (p=0.010). We observed that various immune-responsive pathways, including the PD-L1 signaling pathway, were enriched significantly in PD-L1-positive BCs. Interestingly, genes in the CTLA4 pathway were enriched significantly in PD-L1-positive BC as well. Among eight patients who received ICI, progressive disease was confirmed in one patient, whose tumor had low exonic TMB, negative PD-L1 status, and a relatively colder microenvironment. Conclusion Gaining new insights into the molecular landscape of BC will improve treatment strategies. Our analysis suggests a rationale for studying dual checkpoint inhibition against BC.