CCDC6 and urinary bladder cancer: However, in bladder cancer cells CCDC6 deficiency might result synthetic lethal with PARP-inhibition and the addiction of RRx-001, that exposes bladder cancer cells to oxidative damage, might amplify these effects, in accordance with the Dose Reduction Index that we calculated for each of the drugs, obtaining a value greater then 1 (DRI > 1).