Niraparib is an oral, highly selective inhibitor of PARP1/2. This is the first randomized phase 3 trial of a PARP inhibitor as maintenance therapy post-platinum chemotherapy in patients (pts) with platinum-sensitive recurrent ovarian cancer.
Two independent cohorts were enrolled based on results of BRACAnalysis® testing: pts with a germline BRCA mutation (gBRCAmut), and pts who lacked these mutations (non-gBRCAmut). Within each cohort, pts were randomized (2:1) to receive niraparib 300 mg or placebo once daily. Three prospectively-defined populations were assessed: 1) the gBRCAmut cohort; 2) those in the non-gBRCAmut cohort whose tumors were retrospectively defined as deficient in homologous recombination (HRD) by the myChoice® HRD test; 3) the overall non-gBRCAmut cohort.
553 pts were enrolled in this international trial. 60% of pts had 2 lines of prior therapy, and 40% of pts had >2 prior lines. 76% of pts had stage IIIc or IV disease. Niraparib prolonged progression-free survival (PFS) as compared to placebo in all three pt populations (Table 1). Secondary endpoints of chemotherapy-free interval (CFI), time to first subsequent treatment (TFST), and PFS 2 also showed statistically significant improvement. Patient-reported outcomes (PRO) were similar for niraparib and placebo. Most common (≥10%) treatment-emergent grade 3/4 adverse events in niraparib-treated pts were thrombocytopenia (28%), anaemia (25%), and neutropenia (11%). There were no deaths during study treatment.