PARPi have demonstrated therapeutic efficacy in cancers characterized as HR deficient, including those with mutations in BRCA1, BRCA2, or other genes associated with "BRCAness," such as ATM, ATR, PALB2, and FANC8. 12,13 In clinical practice, PARPi are used to treat recurrent BRCA1 and BRCA2-mutated ovarian cancer,14,15,16,17 metastatic pancreatic cancer,18 and castration-resistant prostate cancer.19 The gene discussed is BRCA1; the disease is prostate cancer.