We validated the potential use of low XRCC1 expression as a biomarker for PARPi use by demonstrating that XRCC1 loss enhances PCa cell killing by olaparib, rucaparib, and talazoparib compared to the XRCC1 proficient cell lines (Fig. 3). The gene discussed is XRCC1; the disease is posterior cortical atrophy.