Many small molecule PARP inhibitors (PARPi) targeting the catalytic activity of PARP-1 are now approved and clinically used in patients with breast, ovarian, prostate, and pancreatic cancers deficient in other DDR components, and the expanded utilities of small molecule PARP inhibitors in other cancer types are under consideration (Ramakrishnan Geethakumari et al., 2017; Zimmer et al., 2018; Hammel et al., 2020; Xie et al., 2020). The gene discussed is PARP1; the disease is cancer.