So far, our data do neither support a genetic antagonism between ARID1A and EZH2 nor ARID1A-deficiency as predictive biomarker for EZH2-inhibitor treatment response in bladder cancer, underscoring the need for future bladder cancer-specific, high-throughput drug screens for successfull discovery of ARID1A-deficiency-based targeted drugs. This evidence concerns the gene EZH2 and urinary bladder cancer.