PARP1 and ovarian carcinoma: PARPi function by blocking PARP1 protein, inducing synthetic lethality in HGSOC containing mutations in genes involved in the homologous recombination pathway of DNA repair (HR).3, 4, 5, 6, 7, 8 Olaparib was the first PARPi to be introduced as a maintenance treatment for ovarian cancer patients.9