Niraparib R-enantiomer is primarily used in the field of oncology, specifically for the treatment of certain types of cancer. It is an inhibitor of the enzyme poly (ADP-ribose) polymerase (PARP), which plays a crucial role in DNA repair. By inhibiting PARP, this compound prevents cancer cells from repairing their DNA, leading to cell death. This mechanism is particularly effective in cancers with deficiencies in homologous recombination repair, such as those with BRCA mutations. It is often administered as part of a therapeutic regimen for ovarian cancer, fallopian tube cancer, and primary peritoneal cancer, especially in patients who have undergone prior chemotherapy. The R-enantiomer form is studied for its potential to offer improved efficacy or reduced side effects compared to the racemic mixture. Ongoing research explores its application in other cancer types and combination therapies to enhance treatment outcomes.