Bladder cancer is a common malignant disease, with non-muscle-invasive bladder 
cancer (NMIBC) representing the majority of tumors. This cancer subtype is 
typically treated by transurethral resection. In spite of treatment, up to 70% 
of patients show local recurrences. Intravesical BCG (Bacillus Calmette-Guerin) 
immunotherapy has been widely used to treat NMIBC, but it fails to suppress 
recurrence of bladder tumors in up to 40% of patients. Therefore, the 
development of prognostic markers is needed to predict the progression of 
bladder cancer and the efficacy of intravesical BCG treatment. This study 
demonstrates the effectiveness of an E2F4 signature for prognostic prediction of 
bladder cancer. E2F4 scores for each sample in a bladder cancer expression 
dataset were calculated by summarizing the relative expression levels of E2F4 
target genes identified by ChIP-seq, and then the scores were used to stratify 
patients into good- and poor-outcome groups. The molecular signature was 
investigated in a single bladder cancer dataset and then its effectiveness was 
confirmed in two meta-bladder datasets consisting of specimens from multiple 
independent studies. These results were consistent in different datasets and 
demonstrate that the E2F4 score is predictive of clinical outcomes in bladder 
cancer, with patients whose tumors exhibit an E2F4 score >0 having significantly 
shorter survival times than those with an E2F4 score <0, in both 
non-muscle-invasive, and muscle-invasive bladder cancer. Furthermore, although 
intravesical BCG immunotherapy can significantly improve the clinical outcome of 
NMIBC patients with positive E2F4 scores (E2F4>0 group), it does not show 
significant treatment effect for those with negative scores (E2F4<0 group).
IMPLICATIONS: The E2F4 signature can be applied to predict the 
progression/recurrence and the responsiveness of patients to intravesical BCG 
immunotherapy in bladder cancer.