Unlike normal cells, BRCA1/2-deficient cancer cells critically depend on PARP1 for backup DNA repair leading to selective killing of these cancer cells by targeting PARP1 and recent regulatory approval of several PARP1 inhibitors (PARPis) for BRCA1/2-linked OC (5, 6, 7, 8, 9). The gene discussed is PARP1; the disease is cancer.