The FDA approved niraparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, on March 27, 2017, for maintenance treatment of patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in response to platinum-based chemotherapy. Approval was based on data from the NOVA trial comparing niraparib with placebo in two independent cohorts, based on germline mutation status (gm vs. non-gm). Progression-free survival (PFS) in each cohort was the primary endpoint. In the gm cohort, estimated median PFS on niraparib was 21 months versus 5.5 months on placebo [HR, 0.26; 95% confidence interval (CI), 0.17-0.41; < 0.0001]. In the non-gm cohort, estimated median PFS for niraparib and placebo was 9.3 and 3.9 months, respectively (HR, 0.45; 95% CI, 0.34-0.61; < 0.0001). Common adverse reactions (>20% and higher incidence in the niraparib arm) with niraparib included thrombocytopenia, anemia, neutropenia, nausea, constipation, vomiting, mucositis, fatigue, decreased appetite, headache, insomnia, nasopharyngitis, dyspnea, rash, and hypertension. There were five cases of myelodysplastic syndrome and acute myeloid leukemia (1.4%) in patients treated with niraparib compared with two cases (1.1%) on placebo. Niraparib is the first PARP inhibitor approved as maintenance therapy for patients with ovarian, fallopian tube, or primary peritoneal cancer, with improvement in PFS, regardless of gm status. .