Poly ADP-ribose polymerase (PARP) inhibitors (PARPi) are a well-established maintenance therapy in stage III and IV ovarian cancer, with evidence of efficacy, especially in patients with germline and/or somatic pathogenic variants (PVs) in the BRCA1/2 genes and in patients with homologous recombination deficiency. The gene discussed is BRCA1; the disease is ovarian cancer.