RB1 and cancer: Currently, many conditionally replicating OAVs have been proved safe for clinical trials52,53 and recently the Food and Drug Administration has granted both fast track and breakthrough therapy designations to cretostimogene grenadenorepvec (CG0070), a conditionally replicating OAV targeting Rb-defective cancer cells for use as a prospective treatment in patients with high-risk BCG-unresponsive non-muscle invasive bladder cancer.54