Poly(ADP-ribose) polymerase (PARP) is a validated target for ovarian cancer and TNBC, especially for patients with homologous recombination deficiency (HRD), including loss-of-function mutations on BRCA1, BRCA2, and other genes important for DNA damage repair (DDR) and genomic loss of heterozygosity (gLOH). The gene discussed is BRCA1; the disease is ovarian cancer.