Niraparib is a poly (ADP-ribose) polymerase (PARP) inhibitor. It binds to the catalytic domain of PARP enzymes (PARP-1 and PARP-2), preventing them from repairing DNA single-strand breaks. This leads to the accumulation of DNA damage and the formation of double-strand breaks, ultimately resulting in cell death, particularly in cancer cells with pre-existing defects in DNA repair mechanisms, such as those with BRCA mutations.

Niraparib is indicated for the maintenance treatment of adult patients with deleterious or suspected deleterious germline BRCA-mutated recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in a complete or partial response to platinum-based chemotherapy. It is also used for recurrent or advanced prostate cancer. By exploiting the DNA repair vulnerabilities of certain cancers, niraparib provides a targeted and effective maintenance therapy option.