Niraparib, an orally available selective inhibitor of poly(adenosine 
diphosphate-ribose) polymerase (PARP), is the first PARP inhibitor approved for 
use in patients with ovarian cancer who do not harbor a germ-line or somatic 
mutation in the breast cancer gene (BRCA). Overall, niraparib is well tolerated 
and its toxicities, primarily hematologic, are manageable especially with 
recently released initial dose modification guidelines based on weight and 
baseline platelet count. The role of niraparib as maintenance following 
frontline platinum-based chemotherapy as well as in the treatment of recurrent 
high-grade serous ovarian cancer is an active area of investigation. Areas 
covered: This review focuses on niraparib, its pharmacology, clinical efficacy, 
and adverse effects as evidenced by prospective clinical trials, and licensed 
indications. Expert commentary: Niraparib introduced the use of PARP inhibitors 
regardless of biomarker status. Recent studies highlight the critical need for 
more accurate biomarkers to identify patients most likely to benefit from 
treatment with PARP inhibitors. In the next 5 years, we anticipate further 
expansion of and elucidation regarding the optimal indication for use of 
niraparib in the treatment of ovarian cancer.