Breast and ovarian cancers with defects in the homologous recombination (HR) repair pathway, especially BRCA1 and BRCA2 mutant tumors, are sensitive to poly ADP‐ribose polymerase (PARP) inhibitors such as olaparib (Farmer et al, 2005; Bryant et al, 2005; Ashworth & Lord, 2018). The gene discussed is PARP1; the disease is ovarian carcinoma.