In bladder cancer cells with HR defects caused by CCDC6 depletion (native or induced upon USP7 inhibitor addition) we observed that RRx-001, by exposing cancer cells to reactive oxygen species, enhanced the sensitivity to PARP-inhibitor drugs, as supported by the DRI value (DRI > 1) (Fig. 5a-e). The gene discussed is USP7; the disease is urinary bladder cancer.