Recently, polyadenosine diphosphate–ribose polymerase inhibitors (PARPi) have revolutionized the therapeutic landscape of BRCA1/2-mutated tumors, especially of BRCA1/2 high-grade serous ovarian cancer (HGSC), taking advantage of HR deficiency through the synthetic lethality concept. The gene discussed is BRCA1; the disease is ovarian serous adenocarcinoma.