TKT and urinary bladder cancer: Furthermore, approximately 80% of newly diagnosed bladder cancer patients have non-muscle-invasive bladder cancer (NMIBC) or carcinoma in situ (CIS) [26], so bladder instillation may be clinically effective for RGDAd-UPII-TK and GCV delivery, and the bystander killing effect of phosphorylated GCV can expand the apoptosis of the remaining uninfected bladder cancer cells [18].