Over many recent years, multiple investigations had identified that reversions of BRCA1/2 at the genetic level are a cause of PARP inhibitor resistance during ovarian (Edwards et al., 2008; Kondrashova et al., 2017; Weigelt et al., 2017; Barber et al., 2013; Norquist et al., 2011; Domchek, 2017; Lin et al., 2019), prostate (Quigley et al., 2017; Goodall et al., 2017), breast (Weigelt et al., 2017; Barber et al., 2013; Afghahi et al., 2017), and pancreatic cancers (Pishvaian et al., 2017). The gene discussed is BRCA1; the disease is pancreatic neoplasm.